Diet of beluga whales, Delphinapterus leucas, in Alaska from stomach contents, March-November.

Introduction

At least five stocks of beluga whales, Delphinapterus leucas, occur in the waters of Alaska (Fig. 1). These stocks were tentatively identified by their summer distributions (Frost and Lowry, 1990; Richard et al., 2001), and were later confirmed genetically (O'Corry-Crowe et al., 1997, 2002, 2010). The distribution of beluga whales in Alaska is discontinuous from Yakutat Bay (1,2) to Cook Inlet to Bristol Bay. The entire area from Bristol Bay northward and eastward to Canada is used by belugas; the Bering and Chukchi seas are used year-round and the Beaufort Sea is used in summer (Frost and Lowry, 1990).

Beluga whales in Alaska appear to follow one of two life history strategies; migratory and nonmigratory. Migratory stocks use shallow nearshore and deepwater offshore habitats (Hazard, 1988; Frost and Lowry, 1990), and include the eastern Chukchi Sea stock (population size ~4,000 (Allen and Angliss, 2011)) and the Beaufort Sea or Mackenzie stock (population size ~39,000 (Harwood et al., 1996; Allen and Angliss, 2011)).

Nonmigratory stocks use shallow, estuarine habitats year-round and include the Bristol Bay and Cook Inlet stocks. The Bristol Bay population is increasing (Lowry et al., 2008) and is estimated to be ~3,000 (Allen and Angliss, 2011). Local sightings and satellite telemetry confirm that belugas occur in Bristol Bay in all months of the year (Harrison and Hall, 1978; Frost and Lowry, 1990; Lensink (3); Quakenbush and Citta (4); Quakenbush (5)).

The population in Cook Inlet is estimated to be 312 whales and appears to be decreasing at 1.6% per year (Hobbs et al., 2015). The population declined dramatically between 1994 and 1998 (Hobbs et al., 2000) and the stock was determined to be depleted under the Marine Mammal Protection Act in 2000 (NOAA, 2000); the original cause of the decline is believed to be overharvest. Between 1999 and 2006 the harvest was restricted to five belugas, and after 2006 no harvest has been allowed.

In October 2008, the Cook Inlet beluga whale population was listed as endangered under the Endangered Species Act (NOAA, 2008). Aerial surveys (1994-2011) and satellite telemetry (1999-2002) have shown that Cook Inlet beluga whales remain in the Cook Inlet area all year (Rugh et al., 2000, Hobbs et al., 2005). Except for Cook Inlet belugas, the other four beluga stocks in Alaska continue to be harvested for subsistence by coastal indigenous people and harvests are sustainable (Allen and Angliss, 2011). The Beaufort Sea stock is also harvested in Canada during summer; most of the Alaska harvest of this stock occurs during the spring migration.

The eastern Bering Sea beluga stock is found in the Yukon-Kuskokwim Delta area and in Norton Sound in summer. Aerial surveys conducted there provide a population estimate of ~18,000 (Allen and Angliss, 2011). The winter range of the eastern Bering Sea stock is unknown; therefore it is not known whether this stock is migratory.

Throughout their range, belugas feed on a variety of fish and invertebrates, often on prey that form concentrations such as schooling fish and shrimp (Seaman et al., 1982). Beluga whale diet has been described in Canada (Doan and Douglas, 1953; Sergeant, 1973; Vladykov (6)), Russia (Kleinenberg et al., 1964; Tomlin, 1967), and Svalbard and northwestern Europe (Lono and Oynes, 1961). In Alaska, information on beluga whale diet is limited to one published paper by Seaman et al. (1982) describing stomach contents from 119 beluga whales from six locations in the Bering and Chukchi seas but none from Cook Inlet. Additional Bristol Bay diet information was recorded in unpublished Alaska Department of Fish and Game (ADFG) reports (Brooks (7-8); Lensink (3); Klinkhart (9); Vania (10)) and by Frost et al. (1984).

Information collected since Seaman et al. (1982) from Kotzebue Sound is provided in an unpublished report by Lowry et al. (11) Based on traditional ecological knowledge, Huntington et al. (1999) described the diet of belugas in the nearshore areas of the eastern Bering Sea, Kotzebue Sound, and the eastern Chukchi Sea to include a variety of prey items, but primarily fish. Cook Inlet beluga prey have been indirectly described by relating whale movements to seasonal fish runs in a publication on traditional ecological knowledge from the beluga hunters of Cook Inlet (Huntington, 2000) and in published and unpublished reports (Fall et al., 1984; Hobbs et al. (12)).

This paper provides: 1) an updated description of the diet of beluga whales in Alaska using identifiable prey items found in their stomachs between 1954 and 2012, and 2) a comprehensive description of diet from stomach contents of Cook Inlet beluga whales.

Methods

Data included in this study came from the stomachs of beluga whales: 1) harvested for subsistence, 2) found dead, and 3) collected for published (Frost et al., 1984) and unpublished ADFG diet studies (Brooks (7,8); Lensink (3); Vania (10); Lowry et al. (11); and ADFG (13)). We assigned each beluga to a stock based on collection timing and location (Fig. 1). Collections were made between March and November.

Stomachs and stomach contents were handled in several ways: 1) stomachs were collected whole and frozen, 2) stomach contents were removed and frozen, or 3) stomach contents were removed and placed in 10% formalin. In the laboratory, contents were weighed to the nearest 0.1 g and then rinsed with fresh water on a 1.0 mm sieve stacked on a 0.5 mm sieve. For frozen whole stomachs, all parts of the stomach were opened and rinsed over sieves so that all otoliths, fish bones, and cephalopod beaks that tend to adhere to the stomach lining were collected. In some cases, incomplete stomachs or a subsample of contents were collected, and in other cases prey items were identified visually in the field without collecting the stomach; these were noted by individual beluga in the database. Prey items were sorted into major taxonomic groups and identified to the lowest taxonomic level.

Fish were tabulated by counting whole fish when present and by adding the maximum count of left or right otoliths plus half of the count of otoliths that could not be identified as left or right. Lengths of otoliths that did not appear degraded were measured to the nearest 0.1 mm. Otolith lengths were converted to fish lengths using conversion equations (e.g., Frost and Lowry, 1981; Seaman et al., 1982; Harvey et al., 2000) when possible. Converted lengths are considered minimum lengths because erosion of the otoliths caused by digestion is expected to decrease otolith length and because some equations are known to have poor correlations (Harvey et al., 2000).

Cephalopods were identified by their beaks (Clarke, 1986). We used the maximum count of upper or lower beaks to determine the number consumed. The lower beak hood lengths were measured to the nearest 0.1 mm and used to estimate cephalopod total body weight using an equation for a closely related species, Octopus vulgaris (Clarke, 1986).

For 17 stomachs from Cook Inlet beluga whales between 1992 and 2001, only a subsample of the stomach contents was collected, and only fresh or slightly digested material was identified. Few otoliths were recorded in these samples, but, diagnostic bones of fish were identified by Pacific Identifications Inc. (14), Victoria, British Columbia, Canada. No invertebrate prey items were recorded or identified.

We present fish prey in beluga stomachs as the percent number (% N) of fish by taxon by beluga whale stock. We determined the total number of fish identified in all fish taxa for all stomachs of that stock of beluga whale and then calculated the percentage of the total represented by each taxon. For example, if we estimated 100 individual fish from fish taxon A (e.g., saffron cod, Eleginus gracilis) and 300 fish from all fish taxa in all stomachs sampled from that beluga stock, then the % N of taxon A (saffron cod) for that stock was 100/300 or 33%. For invertebrates, % N was not calculated because we often could not determine the number of individuals from the parts available.

The percent frequency of occurrence (% FO) is provided for all major prey types and was calculated for each stock as the number of stomachs containing that prey type divided by the total number of stomachs that contained any prey. For example, if 100 stomachs contained prey of any kind and 75 of those stomachs contained parts of echiurid worms, the % FO of echiurids would be 75%. Due to differential digestion rates, volume measurements were not considered representative of the true volume of prey consumed and were not analyzed.

Results

Our dataset includes 365 beluga whale stomachs, 233 of which had never been reported before, and 132 from unpublished ADFG reports. Stomachs from the ADFG studies included 22 collected in 1982 at Elephant Point (Eschscholtz Bay) in Kotzebue Sound (Lowry et al. (11)) and 109 collected in Bristol Bay during 1954 and 1955 (Brooks (7,8)), 1965 and 1966 (Vania (10)), and in 1982 and 1983 (Frost et al., 1984), and one collected in Cook Inlet (Baxter and Baxter (15)). Of the 365 stomachs, 82 were empty (22%) or contained only nonfood items and 283 (78%) contained prey remains (Table 1).

Stomachs were collected from Cook Inlet to Barrow from 217 beluga whales harvested for subsistence, 102 collected for research, 41 found dead, and for 5 animals for which the type of death was not recorded. Most of the whales found dead were in Cook Inlet (n = 30; 73%).

Prior to 1982, beluga whales regularly occurred and were harvested in Kotzebue Sound. After 1982, occurrence became irregular and infrequent, and it is not known to what stock these belugas belonged. For this study, we considered stomachs collected from belugas in Kotzebue Sound to be Kotzebue Sound belugas, even though some of them may have been from other stocks.

For all locations in Alaska, a minimum total of 37 fish species and 40 invertebrate species were identified in beluga whale stomachs (Table 2, 3). Other species may have been present that we were not able to identify. Nonfood items included sand, pebbles, wood and other vegetation, kelp, feathers, and a piece of bone.

Beaufort Sea Stock

We analyzed stomach contents from 62 beluga whales from the Beaufort Sea stock collected between 1983 and 2003 at Point Hope and Diomede (Table 1). All were collected during April, May, and June. Sex was reported for all but one (19 males and 42 females) and length was reported for all but two. The mean length for males was 355 cm (range 203-462) and for females 332 cm (range 240-396) (Table 4). Twenty-one stomachs (34%) contained a minimum total of 418 fish of at least eight different species from five families (Table 2). The predominant species was Arctic cod, Boreogadus saida, which comprised 82% N and 21% FO (Table 2) and one stomach contained otoliths from 190 Arctic cod. Forty-one stomachs (66%) contained only invertebrates.

Otoliths from six fish species were measured to estimate the sizes of fish eaten. The largest fish were Arctic staghorn sculpin, Gymnocantheus tricuspis, with an estimated mean length of 17.9 cm (range 16.1-18.9), followed by shorthorn sculpin, Myoxocephalus scorpius, at 16.2 cm (range 12.1-18.5; Table 5). Arctic cod were next in estimated length (mean 14.2 cm, range 8.2-21.2) followed by walleye pollock, Theragra chalcogramma, and saffron cod, which were similar in estimated length at 10.7 cm (range 8.2-12.3) and 10.3 cm (range 7.6-16.3), respectively. Pacific sand lance, Ammodytes hexapterus, were the smallest with a mean length of 9.9 cm (range 8.1-11.3; Table 5).

Most stomachs (n = 57; 92%) contained invertebrates that represented 16 species from multiple taxonomic groups: predominately shrimp (60% FO), cephalopods (52% FO), echiurids (19% FO), and amphipods (11% FO; Table 3). Shrimp included at least five species from at least three families. All cephalopods were octopus (n = 358), 266 (74%) of which were identified as smoothskin octopus, Benthoctopus leioderma (Table 3). Three that were not identified to species were of the same genus and 89 were only recorded as octopus. The number of octopus per stomach ranged from 0 to 144 individuals, with two stomachs having >100 lower or upper octopus beaks each. Based upon 35 measurable beaks of 107 beaks present in a beluga stomach harvested near Point Hope in 1997, the average estimated weight per octopus was 1,015 g (SD = 442, range 140-1,965). The average estimated weight per octopus, calculated from 50 of 144 octopus beaks in a beluga whale harvested near Little Diomede in 2003, was 881 g (SD = 415, range 155-1,965).

Eastern Chukchi Sea Stock

Stomachs from 67 beluga whales from the eastern Chukchi Sea stock were collected between 1983 and 2010 (Table 1). Most (58 or 87%) were collected near Point Lay during June and July, and most (37 or 55%) were empty. The other nine stomachs were from belugas harvested near Barrow in June, July, and August, none of which were empty. Although it is not entirely clear whether belugas near Barrow in summer belong to the Beaufort Sea or eastern Chukchi Sea stock, movements from satellite telemetry data suggest they are more likely to be eastern Chukchi Sea belugas (Fig. 1; Richard et ah, 2001; Suydam et ah, 2001).

Sex was known for all 67 belugas; 36 were males and 31 were females (Tabic 4). Mean body length for males (n = 26) was 390 cm (range 280-478) and for females (n = 25) was 349 cm (range 253-410). At least five species of fish from four families (Table 2), and 15 species of invertebrates from nine taxonomic groups were identified (Table 3). Of the 30 stomachs that contained food items nine (30%) contained fish for which the most prevalent species was saffron cod (7% FO).

Otoliths from three fish species were measured to estimate the sizes of fish eaten. The largest fish were saffron cod with an estimated mean length of 13.6 cm (range 6.5-20.7), followed by Pacific sand lance at 10.1 cm (range 9.7-10.5; Table 5). The otoliths from two Canadian eelpout, Lycodes polaris, were also measureable, but because no size or weight conversions have been developed for this species, fish size could not be estimated (Table 5).

Of the 30 stomachs that contained food items, 21 (70%) contained only invertebrates (Table 3). Shrimp occurred most often (73% FO), followed by echiurid worms (27% FO), polychaetes (17% FO), and cephalopods (10% FO).

Between 1989 and 2010, 13 of 28 stomachs (46%) were reported to contain sand or "mud balls" but no food. Whether the mud was ingested incidentally or intentionally is unknown; however, stomachs with food usually had only minor amounts of nonfood items like sand and wood. In 2012, we examined stomach contents from two of the belugas harvested at Point Lay on 30 June 2009 where the contents appeared to be mostly fine grain sand; however, we found evidence of both fish and invertebrate prey. The first stomach was that of a white female and contained 3.9 kg of sand and parts of 63 tunicates (3 Pelonaia corrugate, 10 Chelysoma spp., and 50 unidentified to species), parts of at least 53 shrimp (all from the family Crangonidae, including 26 Sclerocrangon boreas), and 11 polychaetes (8 Nereis spp. and 3 from the family Polynoidea). The second stomach, that of a white-gray male, contained 2.1 kg of sand, and parts of 17 tunicates (7 Pelonaia corrugate, and 10 unidentified), at least 15 crangonid shrimp (including 5 Sclerocrangon boreas), and 4 otoliths; two each from saffron cod and Pacific sand lance. It is possible that stomachs visually inspected in the past and thought to contain only mud balls also contained invertebrates and otoliths mixed with the mud.

Kotzebue Sound

We analyzed stomach contents from 29 beluga whales harvested in Kotzebue Sound; 22 were harvested in June 1982 (two (9%) were empty), six were harvested in July 2007 (five (83%) were empty), and one was harvested in October 2008 (with food) (Table 1). Of 27 belugas where sex was known, 14 were males and 13 were females. Body lengths of three males averaged 304 cm (257, 310, and 345 cm) and five females averaged 346 cm (range 297363) (Table 4). In 1982, stomach contents were identified and counted only from subsamples. For the more recent stomachs, all were analyzed completely but only two had contents. The only stomach with prey in 2007 contained a single gastropod operculum. The one stomach collected in 2008 contained both fish and invertebrates.

Of the 22 stomachs from Kotzebue with food, 21 contained fish (Table 2). At least six species of fish were identified representing six families. Saffron cod (95% FO) and rainbow smelt, Osmerus mordax, (55% FO) were most prevalent, followed by sculpins (9% FO). Pacific sand lance; Pacific herring, Clupea pal las ii; and slender eelblenny, Lumpenus fabricii, were each represented at 5% FO (Table 2). Saffron cod were also numerically dominant; 1,279 of 1,354 (94% N) total fish eaten were saffron cod (Table 2).

Otoliths from 23 saffron cod were measured to estimate the average fish length at 23.8 cm (range 7.4-41.9; Table 5). One otolith from a Pacific sand lance provided a length estimate of 15.0 cm and two otoliths from rainbow smelt estimated fish lengths at 12.2 cm (range 11.1-13.2). One otolith from a slender eelblenny was measured but no conversion was available.

All but one stomach with food contained invertebrates (n = 21; 95%); including at least nine species. Shrimp was the dominant group (86% FO) followed by amphipods (41% FO); gastropods and isopods were represented equally at 36% FO (Table 3).

Eastern Bering Sea Stock

Stomach contents from 39 belugas from the eastern Bering Sea stock were collected between 1993 and 2012 during May (n = 17), June (n = 7), July (n = 1), September (n = 2), October (n = 9), and month unknown (n = 3). Seven of the 39 (18%) stomachs, six of which were collected in mid-June 1995, were empty (Table 1). Of 28 belugas where sex was known, the sex ratio was even at 14 each. Body length of 13 males averaged 389 cm (range 279-A75), and nine females averaged 351 cm (range 238-414) (Table 4).

Stomachs from 11 beluga whales harvested near Elim in 1996 were only visually inspected and are not included in Tables 2 or 3: those stomachs contained saffron cod, and one also contained rainbow smelt. One of the 11 stomachs (9%) contained invertebrates, which were only identified as shrimp.

Of the 21 stomachs with food that were fully analyzed all contained cod: saffron cod (95% FO), Arctic cod (43% FO), and walleye pollock (10% FO; Table 2). In addition to cod, the overall fish diet by % FO included rainbow smelt (62%), several species of flounder and sculpin (both at 48%), slender eelblenny (38%), Pacific sand lance; capelin, Mallotus villosus; and Pacific herring (all at 24%); Arctic lamprey, Lethenteron camtschaticum (19%); snailfish (14%); and two species of salmon (coho, Oncorhynchus kisutch, and chum, O. keta, each at 5%). Nine stomachs contained evidence of >100 individual saffron cod (range 121-474). Overall, a minimum of 25 species of fish from 12 families were identified (Table 2).

The average estimated lengths of fish, from largest to smallest, was Pacific herring (24.1 cm, range 19.1-28.5); belligerent sculpin, Megalocottus platycephalus (23.0 cm, range 20.5-26.9); shorthorn sculpin (20.2 cm, range 17.3-22.1); saffron cod (19.3 cm, range 8.4-36.0); Arctic cod (14.5 cm, range 11.9-17.6); rainbow smelt (13.9 cm, range 5.7-25.9); and capelin (12.4 cm, range 11.6-14.0). Walleye pollock and Pacific sand lance each had one otolith with an estimated fish length of 8.9 cm. Otoliths were measured for several other species for which conversions were not available to estimate length (Table 5).

Of the 21 stomachs that contained food items, 19 (90%) contained invertebrates. At least 22 species of invertebrates were represented, of which shrimp was predominant at 86% FO followed by polychaetes and isopods at 38% FO each, then bivalves at 33% FO, echiurids and amphipods at 29% FO each, mysids at 24% FO, crab and tunicates at 14% FO; gastropods, cephalopods, and bryozoans were each represented at 10% FO (Tabic 3).

Three of the belugas, whose stomach contents are included above, were caught in the same net near Elim, in Norton Sound, on 30 Sept. 2000. One was an adult male (357 cm) and two were smaller females (238 and 245 cm). All three stomachs contained Arctic cod and saffron cod, but the male had also eaten two adult salmon (one coho and one chum); the female stomachs had no salmon but contained other smaller fish (e.g., slender eelblenny, smelt, sculpin) and the larger female's stomach also contained shrimp and cephalopods.

Six stomachs were collected on 27 Oct. 2012 in Flooper Bay, one white male and five females (one white, three white-gray, and one dependent calf). These belugas were part of a larger group of about 80 belugas that hunters noted were after fish, possibly cod (Simon (16)). Five of these stomachs contained a wide variety of fish and in vertebrates (Table 6). The sixth stomach, from the calf, was empty.

Bristol Bay Stock

Stomach contents from 115 beluga whales from the Bristol Bay stock were collected between 1954 and 2011 in May (n = 25), June (n = 31), July (n = 32), August (n = 26), and October (n = 1). Of the 115 stomachs, 14 (12%) were empty (Table 1). Of the 101 stomachs that contained prey 100 (99%) contained fish. One beluga stomach from August 2010 was only visually inspected and is not included in Table 2; this stomach was reported to be full of adult coho salmon.

The dominant fish family was Salmonidae (81% FO and 83% N), with all five salmon species identified (Table 2). Sockeye, Oncorhynchus nerka, was the most prevalent species (55% FO and 58% N) followed by pink, O. gorbuscha, (18% FO), chum (15% FO), coho (10% FO), and Chinook, O. tshawytscha, (3% FO). Osmeridae, the smelt family, was the only other prevalent family (43% FO), with rainbow smelt the majority by species. Although Table 2 shows rainbow smelt only representing 5% FO of the 43% FO of all smelt, most smelt were not reported by species in the early data. It is likely that the majority of these unidentified smelt were rainbow smelt as they are the predominant species in Bristol Bay. Evidence of more than 300 smelt per stomach was found in seven stomachs (range 368-710 individuals). Other stomachs with large numbers of fish included 14 stomachs with >500 salmon smolts (range 531-2,798) and four stomachs with seven or more adult sockeye salmon (range 7-9).

At least 14 different species from eight fish families were represented in Bristol Bay beluga stomachs during this time (Table 2). The lengths of two sockeye salmon were measured at 54.9 and 73.8 cm. The lengths of two rainbow smelt were measured at 17.6 and 21.5 cm, whereas the lengths of six rainbow smelt estimated from otoliths averaged 13.7 cm (range 4.1- 17.0) (Table 5).

Of the 101 stomachs that contained prey, 24 stomachs (24%) contained invertebrates from at least four species from four taxonomic groups. Shrimp was the most dominant invertebrate (21% FO), followed by isopods (4% FO) and bivalves (3% FO). A few shrimp were identified as crangonids, however, most were recorded only as shrimp (Table 3).

Cook Inlet Stock

A total of 53 stomachs were analyzed from Cook Inlet (Table 1); however, stomachs collected between 1992 and 2001 (n = 24) were analyzed separately from stomachs collected between 2002 and 2012 (n = 28). Contents were only visually inspected and not quantified during the earlier time period, whereas entire stomachs were analyzed and all identifiable prey items enumerated during the later time period. The contents of one stomach from one female beluga killed near the mouth of the Katnu River in 1961 was reported by Baxter and Baxter (17) to include Dolly Varden, Salvelinus malma; Pacific staghorn sculpin, Leptocottus armatus; "gray sand shrimp" (likely a crangonid shrimp species), and other unidentifiable fish remains. Only data from complete stomachs collected from 2002 to 2012 appear in Tables 2 and 3.

Stomachs from the earlier time period (1992-2001) were collected between April and October; 7 of the 24 (29%) were empty. Eulachon, Thaleichthys pacificus, and Chinook salmon were the only prey identified to species during this time period. No invertebrates were reported in those stomachs with prey, however, cursory visual inspections could have missed invertebrate remains. We believe that invertebrates were part of the diet during this time period, but they were not identified or reported. Empty stomachs occurred in summer and fall. Of the 24 belugas sampled, 16 belugas were harvested, 5 were found dead, and for 3 the cause of death was unrecorded.

Twenty-eight stomachs analyzed during 2002-2012 were collected between March and November. Ten of 28 stomachs (36%) were empty; one collected in June, two in August, two in September, four in October, and one in November. Of the 18 stomachs with food 17 (94%) contained fish remains and 9 (50%) contained invertebrates (Tables 2, 3). Three beluga whales were harvested, 24 were found dead, and for one the type of death was unrecorded. A minimum of 12 fish species and 8 invertebrate species were identified (Tables 2, 3).

The 12 fish species represented seven families (Table 2). Salmon (67% FO), cod (39% FO), smelt (11% FO), and flounder (11% FO) were most prevalent (Table 2). Salmon that could be identified to species included coho (28% FO, 21% N), chum (17% FO, 8% N), and Chinook (11% FO, 2% N). Cod species included saffron cod (22% FO, 26% N), walleye pollock (17% FO, 10% N), and Pacific cod, Gadus macrochephalus (6% FO, 1% N). Eulachon (11% FO 12% N) was the only smelt identified, and yellowfin sole, Limanda aspera (11% FO, 2% N) and starry flounder, Platichthys stellatus (6% FO, 1% N) were the only flounders. One longnose sucker, Catostomus catostomus, was the only freshwater fish found.

Salmon were the largest fish eaten by Cook Inlet beluga whales. Coho salmon averaged 62.1 cm (range 58.3-64.1) in length, and chum salmon averaged 60.0 cm (range 56.0-65.0) (Table 5). Other fish in which lengths could be estimated included saffron cod (18.9 cm, range 11.8-22.6), and eulachon (17.4 cm, range 15.7-18.5) (Table 5). For three beluga whale stomachs that were relatively full when collected one contained 12 whole coho salmon (27.8 kg), the second had five whole chum salmon (15.6 kg), and the third had three whole coho salmon and two partially digested salmon of unidentified species (15.0 kg).

Shrimp, polychaetes, and amphipods made up the bulk of the invertebrate prey. Of the 18 stomachs that contained prey, 9 (50%) contained eight species of invertebrates, predominantly shrimp (39% FO), followed by polychaetes and amphipods, each represented at 11% FO (Table 3).

Discussion

Data Limitations

Diet studies using stomach contents have well known biases (Tollit et al., 2010; Bowen and Iverson, 2012). Stomach contents represent some portion of an individual's most recent feeding activity. Small and soft parts digest more quickly and completely (Sheffield et al., 2001), which in our dataset could result in an under-representation of prey such as polychaetes and salmon smolts. Hard parts (e.g., otoliths and cephalopod beaks) can remain in the stomach longer and can accumulate through several feedings (Jobling and Breiby, 1986), which can result in an over-representation of prey such as saffron cod (large otoliths) and octopus (beaks tend to adhere to stomach lining and are resistant to digestion: Pitcher, 1980; Bigg and Fawcett, 1985). Stomachs collected from belugas found dead may be less likely to contain prey than harvested belugas; if the animals were sick or injured they may not have been feeding normally prior to death. Because most of the nonharvested belugas came from Cook Inlet, this concern mostly applies to that stock.

In addition to biases due to differential feeding and digestion, seasonality of prey (relative to the time of sampling), individual prey preferences, and perhaps other factors we have not identified may also affect results of diet studies. For example, adult salmon runs occur at specific times of year, and some species are available over a longer period of time than others. Many of the stomachs we examined were from belugas harvested by subsistence hunters. Thus, the timing of sample collection was often linked to the timing of subsistence activities.

Depending upon when stomachs are collected, what is present (or not present) in them will vary. If no stomachs were collected during a particular time of year, prey species specific to that time of year would be missing from our analysis. Samples from the subsistence harvest were collected in spring, summer, and fall when people hunt, and samples from belugas found dead were collected in summer and fall when people are most likely to observe and respond to them. Furthermore, there appears to be considerable variation in diet among individuals. For example, the three belugas that were caught in the same net on the same night near Elim in the eastern Bering Sea each contained different food items.

In spite of such biases, stomach contents collected from the harvest and from belugas found dead provide valuable information regarding prey consumed (often identified to species), and the number and frequency of their occurrence. With adequate samples sizes, stomach content data provide valuable information about the diet of each stock. Other methods of diet analysis (e.g., stable isotopes and fatty acids) result in qualitative information regarding trophic level and general categories of prey. Quantitative information from these indirect approaches require complete prey libraries (often difficult to obtain) in order to interpret diet to the species level (Budge et al., 2006; Newsome et ah, 2010).

Non-feeding Periods

Beluga whales in some areas of Alaska are known to eat large amounts of fish in spring and summer, although it is not known if other activities take precedence over feeding during this time or how much feeding occurs in winter. Most stomachs (66%) collected from Point hay (eastern Chukchi Sea stock) were empty. These belugas were harvested in June and July when migrating, molting, calving, or other behavior may have been more important than feeding. Histological studies of liver and pancreas tissue from belugas harvested at Point hay indicated that they were likely fasting prior to harvest (Woshner, 2000). Belugas may fast during the annual skin molt.

Another reason belugas may have empty stomachs, in addition to illness or injury, may be due to the avoidance of marine mammal-eating killer whales, Orcinus orca. Belugas harvested in Kotzebue Sound in July 2007 were believed to be avoiding killer whales because they would not leave shallow water even while being approached by boats to be hunted; five of six stomachs examined were empty, and one contained only one operculum from a gastropod. Belugas sometimes regurgitate food when being chased (Quakenbush (5)), which could result in empty stomachs at the time of sampling.

In Bristol Bay, Lensink (3) found that in early June, beluga stomachs were mostly empty. Six stomachs collected during 6-15 Jun. 1959 and 1960 were empty except for a few shrimp fragments, indicating there may be a period of reduced feeding after salmon smolts migrate to sea and before adult salmon are available. Lensink (3) also reported that eight beluga stomachs collected during 11-25 Sept. 1959 and 1960 contained only small quantities of shrimp, small flatfish, and a lamprey, possibly indicating another reduced feeding period after adult salmon runs end in the fall. Very few stomachs were collected in fall and winter for any beluga stock in Alaska.

Comparison with Other Studies

Prior to this study, Seaman et al. (1982) provided the most complete information on beluga whale diet in Alaska. At the time it was published, diet data for Cook Inlet belugas were not available. Our study identified 34 fish prey to species, one sculpin to genus, Hemilephidotus, and two that could only be identified to family; Gasterosteidae (sticklebacks), and Agonidae (poachers). Fish eaten by belugas in our study that were not found by Seaman et al. (1982) included Arctic lamprey, pond smelt, Hypomesus olidus; eulachon, capelin, five species of Pacific salmon, Pacific cod, walleye pollock, poachers, variegated snailfish, eelblenny, and Pacific sand lance. We did not identify any whitefish, Coregonus sp., in our study, which were found by Seaman et al. (1982) and by Huntington (2000). While Seaman et al. (1982) reported the general categories of flatfish and sculpin as prey; we identified seven flatfish and six sculpin to species (Table 2). Two of the species identified in our study alone were found exclusively in Cook Inlet: eulachon and Pacific cod.

Although capelin are sometimes observed in large concentrations near Point Lay and Barrow and are likely important to belugas wherever they are available (Suydam (17)) we only found them in five stomachs from the Eastern Chukchi Sea stock, and they were not found by Seaman et al. (1982). Capelin may be an example of a prey species that has a strong regional and seasonal component that our opportunistic collection regime does not often detect.

We identified invertebrates that were not found by Seaman et al. (1982), including several additional taxa of amphipods, shrimps, crabs, and bivalves. Our findings relative to cephalopods were similar in that more octopus than squid was eaten (Table 3). Some of the invertebrates found in beluga stomachs could be due to secondary ingestion, because sculpin and saffron cod eat shrimp, amphipods, crabs, and polychaetes. Seaman et al. (1982) considered octopus, shrimp, and sometimes isopods to be directly consumed by belugas.

By looking at stomachs with no fish remains (n = 65), we found that polychaetes, gastropods, cephalopods, isopods, amphipods, shrimp, echiurids, and tunicates were present and were likely ingested directly as prey by beluga whales. Echiurid setae are commonly found in beluga stomachs, appear to be resistant to digestion, and may have delayed passage through the stomach. Evidence of echiurids was found in stomachs from all stocks, except Bristol Bay, in this study.

Our findings that the predominant fish species of the Beaufort Sea stock was Arctic cod was also found by Loseto et al. (2009) using fatty acid analysis. Overall however, we found invertebrates in more stomachs than fish; 66% of all stomachs contained invertebrates only. Loseto et al. (2009) did not find invertebrates to be important prey relative to the importance of Arctic cod.

Regional Differences

Stocks were sampled during different seasons making seasonal comparisons difficult. A comparison of the overall diet of the different stocks, however, showed that the northernmost migratory stock (Beaufort Sea) predominantly fed on shrimp (60% FO), octopus (42% FO), and Arctic cod (21% FO). The eastern Chukchi Sea stock fed mostly on shrimp (73% FO), echiurids (27% FO), polychaetes (17% FO), and saffron cod (7% FO). The eastern Bering Sea stock and Kotzebue belugas fed mostly on saffron cod (both 95% FO) and shrimp (both 86% FO). Six other invertebrate taxa were notable for the eastern Bering stock; polychaetes and isopods each at 38% FO, bivalves at 33%, echiuriids and amphipods each at 29% FO, and crabs and tunicates each at 14% FO. In addition to shrimp, four other invertebrate taxa were prominent for Kotzebue belugas; amphipods (41% FO), gastropods and isopods each at 36% FO, and mysids at 14% FO. The two nonmigratory stocks (Bristol Bay and Cook Inlet) were the stocks in which most salmon were found, but they also ate smelt, cod, and shrimp; although invertebrates appeared to be much less important compared to the other stocks (Table 3).

Prior to 2002, Cook Inlet beluga stomachs were not completely analyzed, and therefore less information is available for this time period, especially regarding invertebrate prey. Although Chinook salmon was identified in one of the earlier stomach samples and subsistence hunters reported 19 adult Chinook salmon in one harvested beluga (Huntington, 2000), we only identified Chinook salmon in two stomachs sampled after 2002 (n = 18). The main Chinook salmon runs in Cook Inlet occur April-July (Barrett et a) 1(8, 19). McKinley and Fleischman (20), 21)). Six of the 18 stomachs we analyzed after 2002 were collected during this time period, and therefore could have contained Chinook salmon.

Otoliths of all species of salmon are small and degrade easily, making identification of salmon to species more difficult. Similarly, in Bristol Bay where all five salmon species are available, Chinook salmon were the least represented in the beluga diet, but again this may be due to the difference in the timing of collections relative to timing of specific salmon runs.

Other Differences

In addition to the seasonality of prey availability, prey size may also influence diet. Beluga whales swallow their prey whole (Brooks (8); this study), thus smaller (i.e., young) belugas are limited by the size of their esophagus to smaller prey (Fay, 1971). Brooks (8) found that unweaned calves ate small bottomfish and shrimp. Yearlings mainly ate smaller fish and few adult salmon. Therefore, many Chinook, and some chum and coho salmon, may be too large for smaller belugas to eat, thereby limiting the suitability of some adult salmon as prey even when they are available.

Our sample sizes of beluga sex and length, and fish length did not allow us to analyze diet by beluga sex or age class, although subadult belugas have been found to eat more invertebrates, while adult females ate smaller fish and adult males ate larger fish (Seaman et al., 1982).

On the other hand, all sizes of belugas likely eat salmon smolts during smolt migration to the sea. Although not represented in any samples, salmon smolts are known to be important to Bristol Bay belugas in the spring (Brooks (7,8)) and may be important to Cook Inlet belugas as well.

Prior to 2002 in Cook Inlet, more beluga stomachs were collected from harvested animals, while after 2002, more stomachs were collected from stranded animals due to the restricted harvest. No invertebrates were recorded in the earlier sample of Cook Inlet beluga stomachs. This is most likely due to an artifact of the field methods used to determine diet. Stomach contents appeared to have been examined in a more cursory fashion that may have resulted in invertebrate prey items being missed. Although not detecting invertebrates in the earlier stomach samples does not necessarily change the number of fish species eaten, it does indicate the difference in the methods used to analyze diet could have influenced the fish results as well. Seasonal distribution of stomachs was similar for both time periods.

Beluga distribution within Cook Inlet has been shifting to the upper Inlet from a broader distribution that more regularly included the lower (Kachemak Bay) and the mid-inlet (Rugh et Al 2000). Belugas used to feed on herring in Kachemak Bay prior to the late 1920's when herring declined there (Rounsefell, 1930). In April, hunters from Nanwalek would harvest belugas when they fed on herring in Halibut Cove within Kachemak Bay (Rounsefell, 1930; Stanek, 1994). The distributional shift to the upper Inlet could be due to fewer belugas available to fill the historic habitat, the upper Inlet becoming better habitat, or the lower Inlet becoming poorer habitat. Fewer fish, however, does not explain why belugas use the Kenai River less than in the past, because salmon runs there are believed to be at least as large as those in the Susitna River in the upper Inlet (McKinley and Fleischman (20-21)). Other activities, such as a commercial beluga harvest in the 1960's (Mahoney and Shelden, 2000) and increased boat traffic, may be factors in the decline in use of the Kenai River area.

The two nonmigratory stocks, Cook Inlet and Bristol Bay, have several things in common that may allow them to be resident year-round. Both regions are large, tidally influenced estuarine systems with multispecies salmon runs and shallow-water habitat for escape from killer whales. Both regions also have an abundance of smelt, although eulachon in Cook Inlet may be more seasonally restricted than rainbow smelt in Bristol Bay.

The tides in both areas keep the sea ice broken all winter, which allows belugas access to the bays, but the floating ice restricts killer whale access in winter. Beluga whales do not have a dorsal fin (an advantage for surfacing in sea ice), and they can swim and feed in very shallow, muddy water (<1 m). These adaptations and their distribution may serve as defenses against killer whales (Frost and Lowry, 1990). Killer whales appear to avoid ice likely because their large dorsal fin limits their ability to surface and breathe in broken ice covered water (Matthews et al., 2011; Higdon et al., 2012). The migratory stocks of belugas may rely on sea ice as escape habitat while the resident stocks may rely on shallow water. In addition to food, habitat selection may also involve molting and calving areas, protection from killer whales, and human activity.

Although the eastern Bering Sea stock also has access to large multispecies salmon runs in summer in the Yukon-Kuskokwim Delta and Norton Sound areas, these areas freeze more completely in winter due to weaker tides that are unable to keep the ice broken. It is not clear why more salmon were not found in stomachs of belugas from the eastern Bering Sea, but it may be due to timing of harvests and the importance of commercial fishing in the area. Some hunters may be fishing instead of pursuing belugas at a time when salmon may be an important prey item. It is clear that the migratory stocks of belugas take advantage of the seasonal abundance of forage fish nearshore in summer.

Beluga whales were harvested regularly and in significant numbers in Kotzebue Sound prior to 1982 (e.g., Eschscholtz Bay belugas from Seaman et al. (22) came from this harvest). After 1983, 10 or fewer belugas have been harvested in the sound in most years (Frost and Suydam, 2010). However, two unusual events have occurred resulting in high harvests, one in 1996 and another in 2007. The belugas harvested in 1996 were genetically similar (using mtDNA) to those harvested in the late 1970's and early 1980's; however, those harvested in 2007 were not (O'Corry-Crowe (23)).

Few belugas have been seen or harvested near Kotzebue in recent years; however, in July 2007 a large group (~150) of mostly adult male belugas went deep into Kotzebue Sound, and many were harvested. The genetic (mtDNA haplotypic) composition of this group was distinct from all previously sampled beluga whale groups from Kotzebue Sound. As a group, the whales harvested in 2007 had very strong genetic similarities (mtDNA and nDNA) to the Beaufort Sea stock. Genetic analysis is ongoing to determine whether the 2007 belugas were from the Beaufort Sea stock, were a mix of two or more stocks of whales, or were from a previously unidentified stock (O'Corry-Crowe (23)).

Interspecies Overlap in Diet

Interspecies overlap in fish prey is most likely to occur among belugas and seals, although other possibilities include Steller sea lions, Eumetopias jubatus, and harbor porpoises, Phocoena phocoena, in some areas. The Beaufort Sea, eastern Chukchi Sea, and eastern Bering Sea beluga stocks likely overlalp with ringed, Pusa hispida, and spotted, Phoca largha, seals, for all fish species (Gol'tsev, 1971; Bukhtiyarov et al., 1984; Quakenbush et al. (24, 25)) and with bearded seals, Erignathus barbatus, for Pacific sand lance, Arctic cod, saffron cod, sculpins, eelblenny, and flatfish (Kosygin, 1971; Lowry et al., 1980; Antonelis et al., 1994; Quakenbush et al. (26)). In Bristol Bay, the most abundant seals are spotted and harbor, Phoca vitulina, seals and in Cook Inlet, only harbor seals are present. Overlap with fish species important to humans is also possible for the eastern Bering Sea, Bristol Bay, and Cook Inlet stocks where commercial and subsistence fisheries for herring and salmon exist.

Interspecies overlap for invertebrate prey is most likely to occur among belugas and both Pacific walrus, Odobenus rosmarus, and bearded seals for many benthic invertebrates. Only the Cook Inlet stock is exempt from such overlap as walruses and bearded seals are not found there. Invertebrate taxonomic groups of importance to belugas that are also eaten by walrus and bearded seals include polychaetes, gastropods, bivalves, octopi, mysiids, isopods, amphipods, shrimp, crabs, echiuriids, and ascidians (Lowry et al., 1980; Fay, 1982; Quakenbush et al. (26)).

Diversity and Amount of Prey

The greatest diversity of fish prey was found in the eastern Bering Sea stock where 25 species of fish were eaten, followed by Bristol Bay with 14 species and Cook Inlet with 12 species (Table 7). The greatest diversity of invertebrates was also found in the eastern Bering Sea stock where 22 species were found followed by the Beaufort Sea stock with 16 species and the eastern Chukchi stock with 15 species.

Although we did not often determine the total amount of a prey item eaten by individual beluga whales, there were a few instances of whole fish (e.g., 12 whole coho salmon weighing 27.8 kg), numbers of otoliths (e.g., otoliths indicating a total of 951 fish eaten including 128 rainbow smelt, 390 saffron cod, and 399 Arctic cod, Table 6), and numbers of octopus beaks (e.g., > 144 for an estimated total weight of 127 kg) that suggest prey numbers and volumes consumed can be large. Such numbers indicate that, at least seasonally, beluga whales eat substantial amounts of food.

In summary, beluga whale diets in Alaska waters varies somewhat by stock, with the northernmost stocks feeding mostly on shrimp, octopus, and Arctic cod. To the south, saffron cod replaces Arctic cod and octopus is no longer prevalent. In the two most southern stocks, Arctic and saffron cod are largely replaced by salmon and smelt (rainbow smelt in Bristol Bay and eulachon in Cook Inlet). Shrimp are common prey for all beluga stocks in Alaska. Beluga whales swallow their prey whole, thus size of prey may be related to beluga size (i.e., age) although there also may be individual preferences. Younger belugas may be more limited in prey available to them. Our results may be influenced by biases due to stomach content analyses, nonrandom hunting affecting our sample of stomachs, seasonal changes in prey availability, lack of samples during winter, and other factors. Very little is known about what and how much beluga whales eat during winter and whether accumulating fat stores in summer and fall is important for survival.

Acknowledgments

We thank the many beluga hunters who provided stomachs for this study including Rex Tuzroyluk, Charles Saccheus, and Albert Simon. We also thank ADFG personnel Geoff Carroll for collecting stomachs, and Gay Sheffield, Letty Flughes, Juan Leon Guerrero, Louise Foster, Heidi Isemhagen, and others for processing them. Additional thanks go to members of the stranding response crews who collected Cook Inlet stomachs. Fish otoliths and cephalopod beaks not identified within our own lab were identified by William Walker. Noncephalopod invertebrates not identified by us were identified by Chris Stark and Ken Coyle at the University of Alaska, Fairbanks (UAF), Institute of Marine Science. Funding was provided by the Alaska Beluga Whale Committee and the Alaska Regional Office, National Marine Fisheries Service. Research was conducted under NMFS research permits 782-1694 and 10091.

Lori T. Quakenbush is with the Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701 (e-mail: lori.quakenbush@ alaska.gov). Robert S. Suydam is with the Department of Wildlife Management, North Slope Borough, P. O. Box 69, Barrow, AK 99723. Anna L. Bryan is with the Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701. Lloyd F. Lowry and Kathryn J. Frost are at 73-43S8 Pa'iaha Street, Kailua Kona, HI 96740-9311. And Barbara A. Mahoney is with the Alaska Regional Office, National Marine Fisheries Service, NOAA, 222 W. 7th Ave., #43, Anchorage, AK 99513-7577.

doi: dx.doi.org/10.7755/MFR.77.1.7

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(7) Brooks, J. W. 1954. Beluga. In 1954 Annual Rep., Alaska Dep. Fish Game, Juneau, p. 51-57.

(8) Brooks, J. W. 1955. Beluga. In 1955 Annual Rep., Alaska Dep. Fish Game, Juneau, p. 98-106.

(9) Klinkhart, E. G. 1966. The beluga whale in Alaska. Alaska Dep. Fish Game Rep., 11 p.

(10) Vania, J. 1967. Beluga. In 1966 Annual Rep., Alaska Dep. Fish Game, Juneau, p. 21-24

(11) Lowry, L. F., K. J. Frost, and G. A. Seaman. 1986. Investigations of belukha whales in coastal waters of western and northern Alaska. Part III. Food habits. Final Rep. U.S. Dep. Commer. NOAA, Anchorage, from Alaska Dep. Fish Game, 24 p.

(12) Hobbs, R. C., K. E. W. Shelden, D. J. Vos, K. T. Goetz, and D. J. Rugh. 2006. Status review and extinction assessment of Cook Inlet belugas (Delphinapterus leucas). U.S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Alaska Fish. Sci. Cent. Proc. Rep. 2006-16, 74 p.

(13) Alaska Dep. Fish Game. Unpubl. data on file at 1300 College Road, Fairbanks, AK 99701.

(14) Mention of trade names or commercial firms does not imply endorsement by the National Marine Fisheries Service, NOAA.

(15) Baxter, R., and S. Baxter. 1961. Cook Inlet data report series 61-1, stream surveys west side Cook Inlet -1961. Alaska Dep. Fish Game, Homer, 43 p. + 10.

(16) Simon, A., Native Village of Paimiut, P.O. Box 91, Hooper Bay, AK 99604. Personal observ.

(17) Suydam, R., North Slope Borough, P.O. Box 69, Barrow, AK 99723. Personal observ.

(18) Barrett, B. M., F. M. Thompson, and S. N. Wick. 1984. Adult anadromous fish investigations: May-October 1983. Sustina Hydro Aquatic Studies. Rep. No. 1. Alaska Dep. Fish Game, Anchorage.

(19) Barrett, B. M., F. M. Thompson, and S. N. Wicks. 1985. Adult salmon investigations: May-October 1984. Susitna Aquatic Studies Program. Rep. No. 6. Alaska Dep. Fish Game, APA Doc. No. 2748, Anchorage.

(20) McKinley, T. R., and S. Fleischman. 2010a. Stock assessment of late-run Chinook salmon in the Kenai River, 1999-2006. Alaska Dep. Fish Game, Fishery Data Series No. 10-96, Anchorage.

(21) McKinley, T. R., and S. Fleischman. 2010b. Stock assessment of early-run Chinook salmon in the Kenai River, 1999-2006. Alaska Dep. Fish Game, Fishery Data Series No. 10-19, Anchorage.

(22) Seaman, G. A., K. J. Frost, and L. F. Lowry. 1985. Investigations of belukha whales in coastal waters of western and northern Alaska. Part 1. Distribution, abundance and movements. U.S. Dep. Commer., NOAA, OCSEAP Final Rep. 56:153-220 (avail, from NOAA-OMA-OAD, Alaska Office, 701 C. Street, P.O. Box 56, Anchorage, AK. 99513).

(23) O'Corry-Crowe, G., FI Atl. Univ., Harbor Br., 5600 U.S. 1 North, Fort Pierce, FL 34946. Personal commun, July 2012.

(24) Quakenbush, L., J. Citta, and J. Crawford. 2009. Biology of the spotted seal (Phoca larga) in Alaska from 1962 to 2008. Prelim. Rep. Natl. Mar. Fish. Serv., Natl. Mar. Mammal Lab., Seattle, 66 p.

(25) Quakenbush, L., J. Citta, and J. Crawford. 2011a. Biology of the ringed seal (Phoca hispida) in Alaska, 1960-2010. Final Rep. Natl. Mar. Fish. Serv., Natl. Mar. Mammal Lab., Seattle, 72 p.

(26) Quakenbush, L., J. Citta, and J. Crawford. 2011b. Biology of the bearded seal (Erignathus barbatus) in Alaska, 1960-2009. Final Rep. Natl. Mar. Fish. Serv., Natl. Mar. Mammal Lab., Seattle, 71 p.

Table 1.--Number of stomachs analyzed from Alaska's beluga
whales belonging to five stocks and from a Kotzebue Sound
population collected between 1954 and 2012.

                            Number of Stomachs

Stock ID               Total   Empty (%)    Month

Beaufort Sea            62       0(0)        4-6
Eastern Chukchi Sea     67      37 (55)      6-8
Kotzebue Sound          29      7 (24)      6,7,10
Eastern Bering Sea      39      7 (18)     5-7,9,10
Bristol Bay             115     14 (12)     5-8,10
Cook Inlet              53      17 (32)      3-11

Total                   365     82 (22)      3-11

Stock ID               Range of years    No. of years

Beaufort Sea              1983-2003           5
Eastern Chukchi Sea       1983-2010           13
Kotzebue Sound            1982-2008           3
Eastern Bering Sea        1993-2012           12
Bristol Bay               1954-2011           11
Cook Inlet             1961, 1992-2010        17

Total                     1954-2012           30

Table 2.--Percent number and percent frequency of occurrence
of fish identified from stomach contents of beluga whales
collected in Alaska by location, 1954-2012. Per-cent number
is the number of fish from a taxa divided by the total
number of all fish eaten (x 100). Percent frequency of
occurrence is the number of stomachs that con-tained a fish
taxon divided by the total number of stomachs that contained
prey (x100).

                                                          1983-2003
                                                          Beaufort

                                                   Percent    Percent
                                                   number    frequency
                                                   n = 21     n = 62
          Stomachs that contained fish (%)                      34
        Taxon Stomachs that contained only                       8
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron camtschaticum
All Clupeidae
    Pacific herring, Clupea pallasii
All Catostomidae
    Longnose sucker, Catostomus catostomus
All Osmeridae                                        <1          2
    Pond smelt, Hypomesus olidus
    Rainbow smelt, Osmerus mordax
    Eulachon, Thaleichthys pad ficus
    Capelin, Mallotus villosus
All Salmonidae
    Dolly Varden, Salvelinus malma
    Pink salmon, Oncorhynchus gorbuscha
    Coho salmon, Oncorhynchus kisutch
    Chinook salmon, Oncorhynchus tshawytscha
    Chum salmon, Oncorhynchus keta
    Sockeye salmon, Oncorhynchus nerka
All Gadidae                                          86         23
    Arctic cod, Boreogadus saida                     82         21
    Saffron cod, Eleginus gracilis                    1          5
    Walleye pollock, Theragra chalcogramma            3          3
    Pacific cod, Gadus macrochephalus
All Gasterosteidae, stickleback spp.                 <1          2
All Cottidae                                          9          5
    Arctic staghorn sculpin, Gymnocanthus             1          3
      tricuspis
    Sculpin species, Hemilepidotus spp.
    Pacific staghorn sculpin, Leptocottus
      armatus
    Belligerent sculpin, Megalocottus
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius         7          3
    Sculpin species, Myoxocephalus spp.
    Ribbed sculpin, Triglops pingelii
    Sculpin species, Triglops spp.
All Agonidae, poachers
All Liparidae
    Variegated snailfish, Liparis gibbus
All Zoarcidae
    Canadian eelpout, Lycodes polaris
All Stichaeidae
    Stout eelblenny, Anisarchus medius
    Slender eelblenny, Lumpenus fabricii
    Slender eelblenny or snake prickleback,
      Lumpenus spp.
All Ammodytidae                                       3          8
    Pacific sand lance, Ammodytes hexapterus          3          8
All Pleuronectidae
    Pacific halibut, Hippoglossus stenolepis
    Flathead sole, Hippoglossoides elassodon
    Starry flounder, Platichthys stellatus
    Northern rock sole, Lepidopsetta polyxystra
    Unidentified rock sole, Lepidopsetta spp.
    Longhead dab, Limanda proboscidea
    Yellowfin sole flounder, Limanda aspera
    Arctic flounder, Pleuronectes glacialis
All Unidentified fish                                 1          5
    Minimum no. of fish species eaten                 8
      (total = 37)
    Minimum no. of fish eaten                        418

                                                          1983-2010
                                                          E. Chukchi

                                                   Percent    Percent
                                                   number    frequency
                                                    n = 9     n = 30
          Stomachs that contained fish (%)                      30
        Taxon Stomachs that contained only                       7
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron camtschaticum
All Clupeidae
    Pacific herring, Clupea pallasii
All Catostomidae
    Longnose sucker, Catostomus catostomus
All Osmeridae                                         7          3
    Pond smelt, Hypomesus olidus
    Rainbow smelt, Osmerus mordax                     7          3
    Eulachon, Thaleichthys pad ficus
    Capelin, Mallotus villosus
All Salmonidae
    Dolly Varden, Salvelinus malma
    Pink salmon, Oncorhynchus gorbuscha
    Coho salmon, Oncorhynchus kisutch
    Chinook salmon, Oncorhynchus tshawytscha
    Chum salmon, Oncorhynchus keta
    Sockeye salmon, Oncorhynchus nerka
All Gadidae                                          40         13
    Arctic cod, Boreogadus saida                      7          3
    Saffron cod, Eleginus gracilis                   20          7
    Walleye pollock, Theragra chalcogramma
    Pacific cod, Gadus macrochephalus
All Gasterosteidae, stickleback spp.
All Cottidae
    Arctic staghorn sculpin, Gymnocanthus
      tricuspis
    Sculpin species, Hemilepidotus spp.
    Pacific staghorn sculpin, Leptocottus
      armatus
    Belligerent sculpin, Megalocottus
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius
    Sculpin species, Myoxocephalus spp.
    Ribbed sculpin, Triglops pingelii
    Sculpin species, Triglops spp.
All Agonidae, poachers
All Liparidae
    Variegated snailfish, Liparis gibbus
All Zoarcidae                                        13          3
    Canadian eelpout, Lycodes polaris                13          3
All Stichaeidae
    Stout eelblenny, Anisarchus medius
    Slender eelblenny, Lumpenus fabricii
    Slender eelblenny or snake prickleback,
      Lumpenus spp.
All Ammodytidae                                      13          3
    Pacific sand lance, Ammodytes hexapterus         13          3
All Pleuronectidae
    Pacific halibut, Hippoglossus stenolepis
    Flathead sole, Hippoglossoides elassodon
    Starry flounder, Platichthys stellatus
    Northern rock sole, Lepidopsetta polyxystra
    Unidentified rock sole, Lepidopsetta spp.
    Longhead dab, Limanda proboscidea
    Yellowfin sole flounder, Limanda aspera
    Arctic flounder, Pleuronectes glacialis
All Unidentified fish                                27         13
    Minimum no. of fish species eaten                 5
      (total = 37)
    Minimum no. of fish eaten                        15

                                                          1982-2008
                                                          Kotzebue

                                                   Percent    Percent
                                                   number    frequency
                                                   n = 21     n = 22
          Stomachs that contained fish (%)                      95
        Taxon Stomachs that contained only                       5
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron camtschaticum
All Clupeidae                                        <1          5
    Pacific herring, Clupea pallasii                 <1          5
All Catostomidae
    Longnose sucker, Catostomus catostomus
All Osmeridae                                         3         55
    Pond smelt, Hypomesus olidus
    Rainbow smelt, Osmerus mordax                     3         55
    Eulachon, Thaleichthys pad ficus
    Capelin, Mallotus villosus
All Salmonidae
    Dolly Varden, Salvelinus malma
    Pink salmon, Oncorhynchus gorbuscha
    Coho salmon, Oncorhynchus kisutch
    Chinook salmon, Oncorhynchus tshawytscha
    Chum salmon, Oncorhynchus keta
    Sockeye salmon, Oncorhynchus nerka
All Gadidae                                          95         95
    Arctic cod, Boreogadus saida                      -          -
    Saffron cod, Eleginus gracilis                   94         95
    Walleye pollock, Theragra chalcogramma
    Pacific cod, Gadus macrochephalus
All Gasterosteidae, stickleback spp.
All Cottidae                                          1          9
    Arctic staghorn sculpin, Gymnocanthus
      tricuspis
    Sculpin species, Hemilepidotus spp.
    Pacific staghorn sculpin, Leptocottus
      armatus
    Belligerent sculpin, Megalocottus
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius
    Sculpin species, Myoxocephalus spp.
    Ribbed sculpin, Triglops pingelii
    Sculpin species, Triglops spp.
All Agonidae, poachers
All Liparidae
    Variegated snailfish, Liparis gibbus
All Zoarcidae
    Canadian eelpout, Lycodes polaris
All Stichaeidae                                      <1          5
    Stout eelblenny, Anisarchus medius
    Slender eelblenny, Lumpenus fabricii             <1          5
    Slender eelblenny or snake prickleback,
      Lumpenus spp.
All Ammodytidae                                      <1          5
    Pacific sand lance, Ammodytes hexapterus         <1          5
All Pleuronectidae
    Pacific halibut, Hippoglossus stenolepis
    Flathead sole, Hippoglossoides elassodon
    Starry flounder, Platichthys stellatus
    Northern rock sole, Lepidopsetta polyxystra
    Unidentified rock sole, Lepidopsetta spp.
    Longhead dab, Limanda proboscidea
    Yellowfin sole flounder, Limanda aspera
    Arctic flounder, Pleuronectes glacialis
All Unidentified fish
    Minimum no. of fish species eaten                 6
      (total = 37)
    Minimum no. of fish eaten                       1,354

                                                          1993-2012
                                                          E. Bering

                                                   Percent    Percent
                                                   1 number  frequency
                                                   n = 21     n = 21
          Stomachs that contained fish (%)                      100
        Taxon Stomachs that contained only                      10
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.                    <1         19
    Arctic lamprey, Lethenteron camtschaticum        <1         19
All Clupeidae                                         1         24
    Pacific herring, Clupea pallasii                  1         24
All Catostomidae
    Longnose sucker, Catostomus catostomus
All Osmeridae                                        14         67
    Pond smelt, Hypomesus olidus
    Rainbow smelt, Osmerus mordax                    13         62
    Eulachon, Thaleichthys pad ficus
    Capelin, Mallotus villosus                       <1         24
All Salmonidae                                       <1         10
    Dolly Varden, Salvelinus malma
    Pink salmon, Oncorhynchus gorbuscha
    Coho salmon, Oncorhynchus kisutch                <1          5
    Chinook salmon, Oncorhynchus tshawytscha
    Chum salmon, Oncorhynchus keta                   <1          5
    Sockeye salmon, Oncorhynchus nerka
All Gadidae                                          78         100
    Arctic cod, Boreogadus saida                     29         43
    Saffron cod, Eleginus gracilis                   48         95
    Walleye pollock, Theragra chalcogramma           <1         10
    Pacific cod, Gadus macrochephalus
All Gasterosteidae, stickleback spp.
All Cottidae                                          4         48
    Arctic staghorn sculpin, Gymnocanthus            <1          5
      tricuspis
    Sculpin species, Hemilepidotus spp.              <1          5
    Pacific staghorn sculpin, Leptocottus
      armatus
    Belligerent sculpin, Megalocottus                <1         19
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius        <1         14
    Sculpin species, Myoxocephalus spp.              <1         14
    Ribbed sculpin, Triglops pingelii                <1          5
    Sculpin species, Triglops spp.                    3          5
All Agonidae, poachers                               <1          5
All Liparidae                                        <1         14
    Variegated snailfish, Liparis gibbus             <1         14
All Zoarcidae                                        <1          5
    Canadian eelpout, Lycodes polaris                <1          5
All Stichaeidae                                      <1         38
    Stout eelblenny, Anisarchus medius               <1          5
    Slender eelblenny, Lumpenus fabricii             <1         38
    Slender eelblenny or snake prickleback,
      Lumpenus spp.
All Ammodytidae                                      <1         24
    Pacific sand lance, Ammodytes hexapterus         <1         24
All Pleuronectidae                                    2         48
    Pacific halibut, Hippoglossus stenolepis         <1          5
    Flathead sole, Hippoglossoides elassodon         <1          5
    Starry flounder, Platichthys stellatus
    Northern rock sole, Lepidopsetta polyxystra      <1         14
    Unidentified rock sole, Lepidopsetta spp.
    Longhead dab, Limanda proboscidea                <1         29
    Yellowfin sole flounder, Limanda aspera
    Arctic flounder, Pleuronectes glacialis          <1         14
All Unidentified fish                                <1         14
    Minimum no. of fish species eaten                25
      (total = 37)
    Minimum no. of fish eaten                       5,781     26,721

                                                          1954-2005
                                                          Bristol Bay

                                                   Percent    Percent
                                                   number    frequency
                                                   n = 99     n = 100
          Stomachs that contained fish (%)                      99
        Taxon Stomachs that contained only                      76
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.                    <1          3
    Arctic lamprey, Lethenteron camtschaticum
All Clupeidae
    Pacific herring, Clupea pallasii
All Catostomidae
    Longnose sucker, Catostomus catostomus
All Osmeridae                                        16         43
    Pond smelt, Hypomesus olidus                     <1          1
    Rainbow smelt, Osmerus mordax                     2          5
    Eulachon, Thaleichthys pad ficus
    Capelin, Mallotus villosus
All Salmonidae                                       83         81
    Dolly Varden, Salvelinus malma                   <1          1
    Pink salmon, Oncorhynchus gorbuscha              <1         18
    Coho salmon, Oncorhynchus kisutch                <1         10
    Chinook salmon, Oncorhynchus tshawytscha         <1          3
    Chum salmon, Oncorhynchus keta                   <1         15
    Sockeye salmon, Oncorhynchus nerka               58         55
All Gadidae                                          <1          3
    Arctic cod, Boreogadus saida
    Saffron cod, Eleginus gracilis                   <1          2
    Walleye pollock, Theragra chalcogramma
    Pacific cod, Gadus macrochephalus
All Gasterosteidae, stickleback spp.                 <1          3
All Cottidae                                         <1          6
    Arctic staghorn sculpin, Gymnocanthus
      tricuspis
    Sculpin species, Hemilepidotus spp.
    Pacific staghorn sculpin, Leptocottus
      armatus
    Belligerent sculpin, Megalocottus
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius
    Sculpin species, Myoxocephalus spp.
    Ribbed sculpin, Triglops pingelii
    Sculpin species, Triglops spp.
All Agonidae, poachers
All Liparidae
    Variegated snailfish, Liparis gibbus
All Zoarcidae
    Canadian eelpout, Lycodes polaris
All Stichaeidae                                       1          7
    Stout eelblenny, Anisarchus medius
    Slender eelblenny, Lumpenus fabricii
    Slender eelblenny or snake prickleback,
      Lumpenus spp.
All Ammodytidae
    Pacific sand lance, Ammodytes hexapterus
All Pleuronectidae                                   <1         10
    Pacific halibut, Hippoglossus stenolepis
    Flathead sole, Hippoglossoides elassodon
    Starry flounder, Platichthys stellatus
    Northern rock sole, Lepidopsetta polyxystra
    Unidentified rock sole, Lepidopsetta spp.        <1          1
    Longhead dab, Limanda proboscidea
    Yellowfin sole flounder, Limanda aspera
    Arctic flounder, Pleuronectes glacialis
All Unidentified fish                                <1          3
    Minimum no. of fish species eaten                14
      (total = 37)
    Minimum no. of fish eaten

                                                          2002-2010
                                                          Cook Inlet

                                                   Percent    Percent
                                                   number    frequency
                                                   n = 17     n = 18
          Stomachs that contained fish (%)                      94
        Taxon Stomachs that contained only                      50
Taxon     fish (%)

Fishes
All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron camtschaticum
All Clupeidae
    Pacific herring, Clupea pallasii
All Catostomidae                                      1          6
    Longnose sucker, Catostomus catostomus            1          6
All Osmeridae                                        12         11
    Pond smelt, Hypomesus olidus
    Rainbow smelt, Osmerus mordax
    Eulachon, Thaleichthys pad ficus                 12         11
    Capelin, Mallotus villosus
All Salmonidae                                       38         67
    Dolly Varden, Salvelinus malma
    Pink salmon, Oncorhynchus gorbuscha
    Coho salmon, Oncorhynchus kisutch                21         28
    Chinook salmon, Oncorhynchus tshawytscha          2         11
    Chum salmon, Oncorhynchus keta                    8         17
    Sockeye salmon, Oncorhynchus nerka
All Gadidae                                          42         39
    Arctic cod, Boreogadus saida
    Saffron cod, Eleginus gracilis                   26         22
    Walleye pollock, Theragra chalcogramma           10         17
    Pacific cod, Gadus macrochephalus                 1          6
All Gasterosteidae, stickleback spp.
All Cottidae                                          1          6
    Arctic staghorn sculpin, Gymnocanthus
      tricuspis
    Sculpin species, Hemilepidotus spp.
    Pacific staghorn sculpin, Leptocottus             1          6
      armatus
    Belligerent sculpin, Megalocottus
      platycephalus
    Shorthorn sculpin, Myoxocephalus scorpius
    Sculpin species, Myoxocephalus spp.
    Ribbed sculpin, Triglops pingelii
    Sculpin species, Triglops spp.
All Agonidae, poachers
All Liparidae
    Variegated snailfish, Liparis gibbus
All Zoarcidae
    Canadian eelpout, Lycodes polaris
All Stichaeidae                                       1          6
    Stout eelblenny, Anisarchus medius
    Slender eelblenny, Lumpenus fabricii
    Slender eelblenny or snake prickleback,           1          6
      Lumpenus spp.
All Ammodytidae
    Pacific sand lance, Ammodytes hexapterus
All Pleuronectidae                                    3         11
    Pacific halibut, Hippoglossus stenolepis
    Flathead sole, Hippoglossoides elassodon
    Starry flounder, Platichthys stellatus            1          6
    Northern rock sole, Lepidopsetta polyxystra
    Unidentified rock sole, Lepidopsetta spp.
    Longhead dab, Limanda proboscidea
    Yellowfin sole flounder, Limanda aspera           2         11
    Arctic flounder, Pleuronectes glacialis
All Unidentified fish                                 2         11
    Minimum no. of fish species eaten                12
      (total = 37)
    Minimum no. of fish eaten                        106

Table 3.--Percent frequency of occurrence of invertebrates
identified from stomach contents of beluga whales collected
in Alaska by location, 1954-2012. Percent frequen-cy of
occurrence is the number of stomachs that contained an
invertebrate taxon divided by the total number of stomachs
containing prey (x100).

                                                 Percent frequency
                                                   of occurrence

                                               1983-2003   1983-2010
                                               Beaufort    E. Chukchi
                                                n = 62       n = 30
        Stomachs containing                       92           93
          invertebrates (%)
        Stomachs containing only                  66           70
Taxon   invertebrates (%)
Invertebrates
All Porifera
All Polychaeta                                     5           17
    Polynoidae                                                 7
    Nereididae, Nereis spp.                                    7
    Pectinariidae
All Bivalvia
    Astartidae, Astarte spp.
    Myidae
    Clinocardiinae, Serripes groenlandicus
    Tellinidae, Tellina spp.
All Cephalopoda                                   52           10
    Squid, Gonatus spp.                                        3
      Minimum number of squid                                  3
Octopus                                           42           7
    Benthoctopus leioderma, smoothskin             8           3
      octopus
    Benthoctopus spp.                              2
      Minimum number of octopi                    358          4
All Gastropoda                                                 7
    Polinices spp.
All Cirripedia, barnacles                          2
All Mysidae
    Mysis oculata
    Neomysis rayii
    Neomysis spp.
All Isopoda                                                    3
    Saduria entomon
    Saduria spp.                                               3
All Amphipoda                                     11           7
    Ampeliscidae, Ampelisca spp.                   2
      Byblis spp.                                  3
    Lysianassidae, Orchomene spp.
    Uristidae, Anonyx spp.                         2
    Senticaudata
    Anisogammaridae, Anisogammarus                 2
      pugettensis
    Calliopiidae                                               3
    Gammaridae                                     3
      Gammarus spp.                                2           3
    Melitidae, Melita spp.
All shrimp                                        60           73
    Caridea                                                    3
    Hippolytidae                                   2
    Eualus spp.                                    2
    Crangonidae                                    8           30
      Argis dentata                                3
      Argis lar                                    3           3
      Argis spp.                                  13           30
      Crangon alaskensis or septemspinosa
      Crangon franciscorum
      Crangon spp.                                11
      Sclerocrangon boreas                         2           23
    Pandalidae, Pandalus spp.                      3
All crabs                                          2           3
    Majidae
    Oregoniidae, Chionoecetes bairdi
    Chionoecetes opilio                                        3
    Hyas lyratus                                   2
All Sipuncula                                                  3
All Echiuridae                                    19           27
All Bryozoa
Clypeasteroida, sand dollar                        2
All Ascidiacea, tunicates                                      7
    Chelysoma spp.                                             3
    Pelonaia corrugata                                         7
All unidentified invertebrates                     3           10
Minimum no. of species eaten (total = 40)         16           15

                                                 Percent frequency
                                                   of occurrence

                                               1982-2008   1993-2012
                                               Kotzebue    E. Bering
                                                n = 22       n = 21
        Stomachs containing                       95           90
          invertebrates (%)
        Stomachs containing only                   5           0
Taxon   invertebrates (%)
Invertebrates
All Porifera                                       5           5
All Polychaeta                                                 38
    Polynoidae                                                 24
    Nereididae, Nereis spp.                                    10
    Pectinariidae                                              5
All Bivalvia                                       5           33
    Astartidae, Astarte spp.                                   5
    Myidae                                                     5
    Clinocardiinae, Serripes groenlandicus                     5
    Tellinidae, Tellina spp.                                   5
All Cephalopoda                                    5           10
    Squid, Gonatus spp.
      Minimum number of squid
Octopus                                            5
    Benthoctopus leioderma, smoothskin
      octopus
    Benthoctopus spp.
      Minimum number of octopi                     1
All Gastropoda                                    36           10
    Polinices spp.                                27
All Cirripedia, barnacles
All Mysidae                                       14           24
    Mysis oculata                                              24
    Neomysis rayii                                             19
    Neomysis spp.                                 14
All Isopoda                                       36           38
    Saduria entomon                               18           33
    Saduria spp.                                  18
All Amphipoda                                     41           29
    Ampeliscidae, Ampelisca spp.
      Byblis spp.
    Lysianassidae, Orchomene spp.
    Uristidae, Anonyx spp.
    Senticaudata
    Anisogammaridae, Anisogammarus
      pugettensis
    Calliopiidae
    Gammaridae                                    14           5
      Gammarus spp.                               27           19
    Melitidae, Melita spp.                                     5
All shrimp                                        86           86
    Caridea                                                    29
    Hippolytidae
    Eualus spp.
    Crangonidae                                                19
      Argis dentata
      Argis lar                                                5
      Argis spp.
      Crangon alaskensis or septemspinosa         32           29
      Crangon franciscorum
      Crangon spp.                                59           10
      Sclerocrangon boreas                                     5
    Pandalidae, Pandalus spp.
All crabs                                                      14
    Majidae                                                    5
    Oregoniidae, Chionoecetes bairdi
    Chionoecetes opilio
    Hyas lyratus
All Sipuncula
All Echiuridae                                     5           29
All Bryozoa                                                    10
Clypeasteroida, sand dollar
All Ascidiacea, tunicates                                      14
    Chelysoma spp.
    Pelonaia corrugata                                         5
All unidentified invertebrates
Minimum no. of species eaten (total = 40)          9           22

                                                 Percent frequency
                                                   of occurrence

                                                1954-2005    2002-2010
                                               Bristol Bay   Cook Inlet
                                                 n = 100       n = 18
        Stomachs containing                        24            50
          invertebrates (%)
        Stomachs containing only                    1            6
Taxon   invertebrates (%)
Invertebrates
All Porifera                                                     6
All Polychaeta                                                   11
    Polynoidae
    Nereididae, Nereis spp.
    Pectinariidae
All Bivalvia                                        3
    Astartidae, Astarte spp.
    Myidae
    Clinocardiinae, Serripes groenlandicus
    Tellinidae, Tellina spp.
All Cephalopoda
    Squid, Gonatus spp.
      Minimum number of squid
Octopus
    Benthoctopus leioderma, smoothskin
      octopus
    Benthoctopus spp.
      Minimum number of octopi
All Gastropoda
    Polinices spp.
All Cirripedia, barnacles
All Mysidae                                                      6
    Mysis oculata
    Neomysis rayii                                               6
    Neomysis spp.
All Isopoda                                         4
    Saduria entomon                                 3
    Saduria spp.                                    1
All Amphipoda                                                    11
    Ampeliscidae, Ampelisca spp.
      Byblis spp.
    Lysianassidae, Orchomene spp.                                6
    Uristidae, Anonyx spp.
    Senticaudata
    Anisogammaridae, Anisogammarus
      pugettensis
    Calliopiidae
    Gammaridae
      Gammarus spp.
    Melitidae, Melita spp.
All shrimp                                         21            39
    Caridea                                                      17
    Hippolytidae
    Eualus spp.
    Crangonidae
      Argis dentata
      Argis lar
      Argis spp.
      Crangon alaskensis or septemspinosa                        6
      Crangon franciscorum                                       6
      Crangon spp.                                  2            6
      Sclerocrangon boreas
    Pandalidae, Pandalus spp.
All crabs                                           1            6
    Majidae                                         1
    Oregoniidae, Chionoecetes bairdi                             6
    Chionoecetes opilio
    Hyas lyratus
All Sipuncula
All Echiuridae                                                   6
All Bryozoa
Clypeasteroida, sand dollar
All Ascidiacea, tunicates
    Chelysoma spp.
    Pelonaia corrugata
All unidentified invertebrates                                   6
Minimum no. of species eaten (total = 40)           4            8

Table 4.--Sex and body length for some Alaska beluga whales
belonging to five stocks and from a Kotzebue Sound
population analyzed for stomach contents collected between
1954 and 2012.

Stock Location                          Sex
                                Male   Female   Unknown

Beaufort                         19      42        1
    Pt. Hope, Diomede
Eastern Chukchi                  36      31        0
    Barrow, Pt. Lay
Kotzebue                         14      13        2
    Escholtz Bay, Kotzebue
Eastern Bering                   14      14       11
    Elim, Koyuk, Unalakleet,
    Hooper Bay
Bristol Bay                      31      55       27

Cook Inlet                       20      21       10

                                Male body length   Female body length
Stock Location                    (cm) n; mean        (cm) n; mean
                                   (SD) range          (SD) range

Beaufort                         19; 355 (68.7)      41; 332 (32.0)
    Pt. Hope, Diomede               203-462             240-396
Eastern Chukchi                  26; 390 (49.5)      25; 349 (30.9)
    Barrow, Pt. Lay                 280-478             253-410
Kotzebue                         3; 304 (44.7)       5; 346 (27.5)
    Escholtz Bay, Kotzebue          257-345             297-363
Eastern Bering                   13; 389 (66.2)      9; 351 (66.9)
    Elim, Koyuk, Unalakleet,        279-475             238-414
    Hooper Bay
Bristol Bay                      29; 333 (78.6)      47; 317(49.2)
                                    187-470             193-387
Cook Inlet                       8; 391 (72.7)       15; 337(67.1)
                                    256-463             160-391

Table 5.--Mean, standard deviation (SD), and range of
otolith lengths (mm), fish length (cm), and weight (g) of
fish collected from beluga whale stomachs. Fish length and
weight were converted from equations or measured directly
from whole fish.
                                                Mean otolith
                                                  length in
Fish                       Beluga stock    n    mm (SD) range

Clupeidae
    Pacific herring        E. Bering      18      4.9 (0.5)
                                                   4.0-5.8
Osmeridae
    Pond smelt             Bristol Bay     2      2.7 (0.4)
                                                   2.4-3.0
    Rainbow smelt          Kotzebue        2      4.4 (0.6)
                                                   4.0-4.8
                           E. Bering      233     5.0 (1.0)
                                                   2.0-9.5
                           Bristol Bay     6      5.0 (1.8)
                                                   1.4-6.2
                           Bristol Bay     2

                           Bristol Bay     1
    Eulachon               Cook Inlet      4      4.3 (0.3)
                                                   3.9-4.5
    Capelin                E. Bering       5      2.5 (0.3)
                                                   2.3-3.0
Salmonidae
    Coho salmon            Cook Inlet     10      4.9 (0.2)
                                                   4.5-5.2
                           Cook Inlet      3

                                           4      5.4 (0.2)
                                                   52-5.5
                           Cook Inlet      5

    Sockeye salmon         Bristol Bay     2      5.4 (1.6)
                                                   4.3-6.5
Gadidae
    Arctic cod             Beaufort       84      5.9 (1.3)
                                                   3.0-8.9
                           E. Bering      467     5.9 (0.5)
                                                   4.7-7.3
    Saffron cod            Beaufort        4      5.9 (2.2)
                                                   4.4-9.1
                           E. Chukchi      2      7.4 (5.1)
                                                  3.3-11.0
                           Kotzebue       23     12.1 (5.2)
                                                  4.3-20.1
                           E. Bering      558     10.3(2.2)
                                                  4.9-17.6
                           Bristol Bay     1      4.2 (NA)
                           Cook Inlet      3     11.5 (3.3)
                                                  7.7-13.4
    Walleye pollock        Beaufort        3      5.0 (1.0)
                                                   3.9-5.7
                           E. Bering       1      4.2 (NA)

Cottidae
    Arctic staghorn        Beaufort        4      5.6 (0.3)
      sculpin                                      5.1-5.8
    Belligerent sculpin    E. Bering       7      6.8 (0.7)
                                                   6.2-7.8
    Shorthorn sculpin      Beaufort       17      5.1 (0.5)
                                                   4.1-5.7
                           E. Bering       4      6.1 (0.6)
                                                   5.4-6.6
Stichaeidae
    Stout eelblenny        E. Bering       1      1.4 (NA)
    Slender eelblenny      Kotzebue        1      2.2 (NA)
                           E. Bering       9      2.5 (0.3)
                                                   2.1-2.9
Liparidae
    Variegated             E. Bering       2      2.7 (0.1)
      snailfish                                    2.6-2.8
Zoarcidae
    Canadian eelpout       E. Chukchi      2      5.9 (0.5)
                                                   5.5-62
Ammodytidae
    Pacific sand lance     Beaufort        3      1.9 (0.4)
                                                   1.5-2.3
                           E. Chukchi      2      2.0 (0.1)
                                                   1.9-2.1
                           Kotzebue        1      3.2 (NA)
                           E. Bering       1      1.7 (NA)
Pleuronectidae
    Longhead dab           E. Bering       3      3.1 (0.6)
                                                   2.5-3.6
    Arctic flounder        E. Bering       3      4.3 (0.2)
                                                   4.1-4.4

                                            Mean fish       Mean fish
                                            length in       weight in
Fish                       Beluga stock   cm (SD) range   g (SD) range

Clupeidae
    Pacific herring        E. Bering       24.1 (2.8)     228.6 (85.5)
                                            19.1-28.5      99.4-388.3
Osmeridae
    Pond smelt             Bristol Bay

    Rainbow smelt          Kotzebue        12.2 (1.5)      14.1 (5.6)
                                            11.1-13.2       10.1-18.0
                           E. Bering       13.9 (2.8)      24.6(19.1)
                                            5.7-25.9        1.1-162.6
                           Bristol Bay     13.7 (5.0)      27.0(15.7)
                                            4.1-17.0         0.4-41
                           Bristol Bay     19.6 (2.8)      67.3 (30.1)
                                            17.6-21.5       46.0-88.6
                           Bristol Bay                      53.1 (NA)
    Eulachon               Cook Inlet       17.4(1.2)      51.2(10.5)
                                            15.7-18.5       36.4-60.6
    Capelin                E. Bering       12.4 (0.9)       15.6(4.0)
                                            11.6-14.0       12.3-22.4
Salmonidae
    Coho salmon            Cook Inlet

                           Cook Inlet      62.1 (2.6)      3,124 (357)
                                            58.3-64.1      2,747-3,476

                           Cook Inlet      60.0 (3.8)      2,989 (600)
                                            56.0-65.0      2,275-3,661
    Sockeye salmon         Bristol Bay     64.4 (13.4)    3,478 (2,493)
                                            54.9-73.8      1,715-5,240
Gadidae
    Arctic cod             Beaufort        14.2 (2.9)      24.6 (16.0)
                                            8.2-21.2        2.8-78.3
                           E. Bering       14.5 (1.0)      21.5 (5.3)
                                            11.9-17.6       10.5-41.4
    Saffron cod            Beaufort         10.3(4.0)       9.7(12.4)
                                            7.6-16.3        2.6-28.2
                           E. Chukchi      13.6 (10.0)     30.5 (40.7)
                                            6.5-20.7        1.7-59.3
                           Kotzebue        23.8(11.3)     151.6 (142.7)
                                            7.4-41.9        2.4-522.7
                           E. Bering        19.3(4.8)      56.9(41.7)
                                            8.4--36.0       3.7-329.2
                           Bristol Bay      7.2 (NA)        2.3 (NA)
                           Cook Inlet      18.9 (6.2)      77.6 (55.8)
                                            11.8-22.6      13.1-111.3
    Walleye pollock        Beaufort         10.7(2.2)       8.1 (4.1)
                                            8.2-12.3        3.5-11.3
                           E. Bering        8.9 (NA)         4.5(NA)

Cottidae
    Arctic staghorn        Beaufort        17.9 (1.2)      56.8(11.3)
      sculpin                               16.1-18.9       40.7-66.3
    Belligerent sculpin    E. Bering       23.0 (2.7)     125.2 (45.0)
                                            20.5-26.9      84.9-194.3
    Shorthorn sculpin      Beaufort        16.2 (2.0)      43.0 (14.3)
                                            12.1-18.5       17.0-62.1
                           E. Bering       20.2 (2.3)      83.7 (27.8)
                                            17.3-22.1      50.6-106.8
Stichaeidae
    Stout eelblenny        E. Bering
    Slender eelblenny      Kotzebue
                           E. Bering

Liparidae
    Variegated             E. Bering
      snailfish
Zoarcidae
    Canadian eelpout       E. Chukchi

Ammodytidae
    Pacific sand lance     Beaufort         9.9 (1.6)       3.9 (1.7)
                                            8.1-11.3         22-5.5
                           E. Chukchi      10.1 (0.6)       4.0 (0.6)
                                            9.7-10.5         3.6-4.5
                           Kotzebue         15.0 (NA)       12.0 (NA)
                           E. Bering        8.9 (NA)        2.8 (NA)
Pleuronectidae
    Longhead dab           E. Bering

    Arctic flounder        E. Bering

Fish                       Beluga stock   Source of equation

Clupeidae                                 Harvey et al., 2000
    Pacific herring        E. Bering

Osmeridae
    Pond smelt             Bristol Bay    No conversion available

    Rainbow smelt          Kotzebue       Harvey et al., 2000

                           E. Bering      Harvey et al., 2000

                           Bristol Bay    Harvey et al., 2000

                           Bristol Bay    Length measured
                                          Weight Harvey et al., 2000
                           Bristol Bay    Measured
    Eulachon               Cook Inlet     Harvey et al., 2000

    Capelin                E. Bering      Harvey et al., 2000

Salmonidae
    Coho salmon            Cook Inlet

                           Cook Inlet     Measured

                           Cook Inlet     Measured

    Sockeye salmon         Bristol Bay    Measured

Gadidae
    Arctic cod             Beaufort       Frost and Lowry, 1981

                           E. Bering      Frost and Lowry, 1981

    Saffron cod            Beaufort       Frost and Lowry, 19811

                           E. Chukchi     Frost and Lowry, 19811

                           Kotzebue       Frost and Lowry, 19811

                           E. Bering      Frost and Lowry, 19811

                           Bristol Bay    Frost and Lowry, 1981
                           Cook Inlet     Harvey et al., 2000

    Walleye pollock        Beaufort       Frost and Lowry, 1981

                           E. Bering      Frost and Lowry, 1981

Cottidae                                  Seaman et al., 19822
    Arctic staghorn        Beaufort
      sculpin
    Belligerent sculpin    E. Bering      Seaman et al., 19822

    Shorthorn sculpin      Beaufort       Seaman et al., 19822

                           E. Bering      Seaman et al., 19822

Stichaeidae
    Stout eelblenny        E. Bering      No conversions available
    Slender eelblenny      Kotzebue       No conversions available
                           E. Bering      No conversions available
                                          No conversions available
Liparidae
    Variegated             E. Bering
      snailfish
Zoarcidae
    Canadian eelpout       E. Chukchi     No conversions available

Ammodytidae                               Harvey et al., 2000
    Pacific sand lance     Beaufort

                           E. Chukchi     Harvey et al., 2000

                           Kotzebue       Harvey et al., 2000
                           E. Bering
Pleuronectidae
    Longhead dab           E. Bering      No conversions available

    Arctic flounder        E. Bering

(1) There are two different length regressions in Frost and
Lowry (1981) for this species depending on otolith size.

(2) The length and weight regressions from Seaman et al.
(1982) are the same for all Cottidae species.

Table 6.--Number and type of prey identified from stomach
contents of five belugas from the eastern Bering Sea stock
collected in Hooper Bay, Alaska, on 27 October 2012.

                                                   Beluga stomach

                                             1       2          3
Gender                                     Male    Female     Female
Taxon Color                                White   White    White-gray

Fishes
  All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron              3                  2
      camtschaticum
  All Osmeridae
    Rainbow smelt, Osmerus mordax           41      174        128
  Capelin, Mallotus villosus                         4          9
    All Gadidae
  Arctic cod, Boreogadus saida              78      347        399
    Saffron cod, Eleginus gracilis          181     242        390
  All Cottidae
    Sculpin species, Hemilepidotus spp.              1
    Belligerent sculpin, Megalocottus                4          9
      platycephalus
    Sculpin species, Myoxocephalus spp.      1       2
  All Liparidae
    Variegated snailfish, Liparis                    1          4
      gibbus
  All Zoarcidae
    Eelpout species, Lycodes spp.                               2
  All Stichaeidae
    Stout eelblenny, Anisarchus medius       1       1          1
      Slender eelblenny, Lumpenus
      fabricii
  All Ammodytidae
    Pacific sand lance, Ammodytes                    1          2
      hexapterus
  All Pleuronectidae
    Longhead dab, Limanda proboscidea                4          2
    Arctic flounder, Pleuronectes                    1          3
      glacialis
  All Unidentified fish
Minimum no. of fish eaten                   305     782        951

Invertebrates
  All Polychaeta
    Polynoidae                              18       11         19
    Nereididae, Nereis spp.                 11
  All Bivalvia                                       3
  All Mysidae
    Mysis oculata                            1       9          12
    Neomysis rayii                                   5          3
  All Isopoda
    Saduria entomon                          1       3          4
  All Amphipoda
Gammaridea                                   3
    Gammarus spp.                                               10
  Melitidae, Melita spp.                             1
  All shrimp
    Crangon alaskensis or septemspinosa      1       50         60
    Shrimp spp.                             20
  All Ascidiacea, tunicates
    Pelonaia corrugata                               1
Minimum no. of taxon eaten                  13       20         18

                                                     Beluga stomach

                                               4            5
Gender                                       Female       Female
Taxon Color                                White-gray   White-gray

Fishes
  All Petromyzontidae, lamprey spp.
    Arctic lamprey, Lethenteron                2            11
      camtschaticum
  All Osmeridae
    Rainbow smelt, Osmerus mordax             200          203
  Capelin, Mallotus villosus                   7            1
    All Gadidae
  Arctic cod, Boreogadus saida                440          380
    Saffron cod, Eleginus gracilis             83          147
  All Cottidae
    Sculpin species, Hemilepidotus spp.
    Belligerent sculpin, Megalocottus          4            5
      platycephalus
    Sculpin species, Myoxocephalus spp.                     2
  All Liparidae
    Variegated snailfish, Liparis              1
      gibbus
  All Zoarcidae
    Eelpout species, Lycodes spp.
  All Stichaeidae
    Stout eelblenny, Anisarchus medius        1 4           1
      Slender eelblenny, Lumpenus
      fabricii
  All Ammodytidae
    Pacific sand lance, Ammodytes              1            2
      hexapterus
  All Pleuronectidae
    Longhead dab, Limanda proboscidea          2            1
    Arctic flounder, Pleuronectes
      glacialis
  All Unidentified fish                        4
Minimum no. of fish eaten                     749          753

Invertebrates
  All Polychaeta
    Polynoidae                                 8            8
    Nereididae, Nereis spp.                    2
  All Bivalvia
  All Mysidae
    Mysis oculata                              10           9
    Neomysis rayii                             2            1
  All Isopoda
    Saduria entomon                            1            1
  All Amphipoda
Gammaridea
    Gammarus spp.                                           5
  Melitidae, Melita spp.
  All shrimp
    Crangon alaskensis or septemspinosa        40           35
    Shrimp spp.
  All Ascidiacea, tunicates
    Pelonaia corrugata
Minimum no. of taxon eaten                     18           16

Table 7.--Fish and invertebrate prey diversity by
stock of beluga whales in Alaska.

                                     No.
                      No. fish   invertebrate
Stock                 species      species        Month

Beaufort                 8            16           4-6
E. Chukchi               5            15           6-8
Kotzebue                 6            9          6,7,10
E. Bering                25           22        5-7, 9,10
Bristol Bay              14           4          5-8, 10
Cook Inlet (<2002)       2            01          4-10
Cook Inlet (>2002)       12           8         3,6-9,11

(1) No invertebrates were recorded during this
time period likely due to field methods.

Article Details

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Author:	Quakenbush, Lori T.; Suydam, Robert S.; Bryan, Anna L.; Lowry, Lloyd F.; Frost, Kathryn J.; Mahoney,
Publication:	Marine Fisheries Review
Geographic Code:	1U9AK
Date:	Jan 1, 2015
Words:	14917
Previous Article:	Assessment of remote video for monitoring beluga whales, Delphinapterus leucas, of cook Inlet, Alaska.
Next Article:	Errata.
Topics:	Animal feeding behavior Research Beluga (Whale) Food and nutrition Varieties Cetacea Endangered species Fishes Whales White whale Food and nutrition Varieties Zoological research