Spatial and temporal variation in the diet of the California sea lion (Zalophus californianus) in the Gulf of California, Mexico.
Abstract--Between June 1995 and May 1996 seven rookeries in the Gulf of California Noun 1. Gulf of California - a gulf to the west of the mainland of Mexico
Sea of Cortes
Mexico, United Mexican States - a republic in southern North America; became independent from Spain in 1810 were visited four times in order to collect scat samples for studying spatial and seasonal variability California sea lion prey. The rookeries studied were San Pedro Martir, San Esteban San Esteban (the Spanish-language name of Saint Stephen) may refer to:
Biological classification. It ranks below family and above species, consisting of structurally or phylogenetically (see level, and 10 to family level, of which the most important were Pacific cutlassfish (Trichiurus lepturus), Pacific sardine sardine: see herring.
Any of certain species of small (6–12 in., or 15–30 cm, long) food fishes of the herring family (Clupeidae), especially in the genera Sardina, Sardinops, and Sardinella. (Sardinops caeruleus), plainfin midshipman midshipman: see toadfish. (Porichthys spp.), myctophid no. 1, northern anchovy anchovy: see herring.
Any of more than 100 species of schooling saltwater fishes (family Engraulidae) related to the herring. Anchovies are distinguished by a large mouth, almost always extending behind the eye, and by a pointed snout. (Engraulis mordax), Pacific mackerel mackerel, common name for members of the family Scombridae, 60 species of open-sea fishes, including the albacore, bonito, and tuna. They are characterized by deeply forked tails that narrow greatly where they join the body; small finlets behind both the dorsal and (Scomber japonicus), anchoveta (Cetengraulis mysticetus), and jack mackerel (Trachurus symmetricus). Significant differences were found among rookeries in the occurrence of all main prey (P [less than or equal to] 0.04), except for myctophid no. 1 (P>0.05). Temporally, significant differences were found in the occurrence of Pacific cutlassfish, Pacific sardine, plainfin midshipman, northern anchovy, and Pacific mackerel (P<0.05), but not in jack mackerel ([chi square chi square (kī),
n a nonparametric statistic used with discrete data in the form of frequency count (nominal data) or percentages or proportions that can be reduced to frequencies. ]=2.94, df=3, P=0.40), myctophid no. 1 ([chi square]=1.67, df= 3, P=0.64), or lanternfishes ([chi square]=2.08, df=3, P=0.56). Differences were observed in the diet and in trophic trophic /tro·phic/ (tro´fik) (trof´ik) pertaining to nutrition.
Of, relating to, or characterized by nutrition. diversity among seasons and rookeries. More evident was the variation in diet in relation to availability of Pacific sardine.
The population of the California sea lion (Zalophus californianus), in the Gulf of California numbers approximately 23,000 individuals, 82% of which inhabit in·hab·it
v. in·hab·it·ed, in·hab·it·ing, in·hab·its
1. To live or reside in.
2. To be present in; fill: Old childhood memories inhabit the attic. the northern region of the gulf above latitude latitude, angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respectively. 28[degrees] (Aurioles-Gamboa and Zavala-Gonzalez, 1994). In this region are found the most important reproductive areas and the highest pup production of the Gulf. Aurioles-Gamboa and Zavala-Gonzalez (1994) suggested that the high concentration of animals in this region is related to high abundance of pelagic pelagic
living in the middle or near the surface of large bodies of water such as lakes or oceans. fish such as Pacific sardine (Sardinops caeruleus) (also known as South American pilchard The South American pilchard, Sardinops sagax, is a sardine of the Family Clupeidae, the only member of the genus Sardinops, found in the indo-Pacific oceans. Their length is up to 40 cm. , FAO FAO,
n See Food and Agriculture Organization. ), Pacific mackerel (Scomber japonicus), Pacific thread herring (Zool.) the gizzard shad. See under Gizzard.
See also: Thread (Opisthonema libertate), and anchoveta (Cetengraulis mysticetus) (Cisneros-Mata et al., 1987 (1); Cisneros-Mata et al., 1991 (2); Cisneros-Mata et al., 1997(3)).
Despite the importance of the northern gulf region, feeding studies of the California sea lion at Gulf of California rookeries have been few and have been conducted at different time periods. Researchers have studied sea lion diet in Los Islotes (Aurioles-Gamboa et al., 1984; Garcia-Rodriguez, 1995), Los Cantiles (Isla Angel de la Guarda), Isla Granito (Sanchez-Arias, 1992; Bautista-Vega, 2000), and Isla Racito (Orta-Davila, 1988). These studies have shown that sea lions consume a variety of prey and that differences exist between the diet of sea lions found at different rookeries within the Gulf of California. At Los Islotes, the most important prey were cusk eel cusk eel
Any of several bottom-dwelling, eellike, chiefly marine fishes of the family Ophidiidae. (Aulopus bajacali), bigeye big·eye
Any of several small tropical marine fishes of the family Priacanthidae, having large eyes and reddish scales.
Noun 1. bass Pronotogrammus eos), threadfin bass Pronotogrammus multifasciatus), and splitail bass (Hemanthias sp.) (Aurioles-Gamboa et al., 1984; Garcia-Rodriguez, 1995). At Los Cantiles and Isla Granito important prey were lanternfish (Diaphus sp.), northern anchovy (Engraulis mordax), Pacific cutlassfish (Trichiurus nitens), shoulderspot (Caelorinchus scaphopsis), and Pacific whiting (Merluccius productus) (Sanchez-Arias, 1992; Bautista-Vega, 2000), whereas at Isla Racito, important prey were Pacific sardine (Sardinops caeruleus), Pacific mackerel (Scomber japonicus), grunt (Haemulopsis spp.), rockfish rockfish, member of the large family Scorpaenidae (rockfishes and scorpionfishes), carnivorous fish inhabiting all seas and especially abundant in the temperate waters of the Pacific. Rockfishes are found among rocks and reefs. (Sebastes spp.), and Pacific whiting (Merluccius spp.) (Orta-Davila, 1988).
Some California sea lion prey are important fisheries resources in Mexico. The Pacific sardine, for example, is the target of a fishery begun in 1967 and which, along with the northern anchovy, contributed to most of the volume of the catch (200,870 t during the 1995-96 season) obtained in the Gulf (Cisneros-Mata et al. (3)). The central and northern regions of the Gulf of California harbor the greatest abundance of sea lions and schooling fishes, such as the sardine and anchovy. Because of this, knowledge of sea lion feeding habits and their temporal and spatial variability Spatial variability is characterized by different values for an observed attribute or property that are measured at different geographic locations in an area. The geographic locations are recorded using GPS (global positioning systems) while the attribute's spatial variability is is relevant to understanding the potential interaction between sea lions and fisheries in the area (Orta-Davila, 1988; Sanchez-Arias, 1992; Bautista-Vega, 2000).
In this article, we present the results of concurrent diet studies conducted at various rookeries and haulout areas of sea lions in the northern rookeries of the Gulf of California to examine the prey consumed, and spatial and temporal variability in their diet.
Materials and methods
Scat samples of California sea lions were collected at Isla San Pedro Martir (SPM SPM - Sequential Parlog Machine , 28[degrees]24'00"N, 112[degrees]25'3"W), Isla San Esteban (EST EST electroshock therapy.
electroshock therapy , 28[degrees]42'00"N, 112[degrees]36'00"W), Isla Rasito (RAS (1) See network access server.
(2) (Remote Access Service) A Windows NT/2000 Server feature that allows remote users access to the network from their Windows laptops or desktops via modem. See RRAS and network access server. , 28[degrees]49'30"N, 112[degrees]59'30"W), Isla Granite (GRA GRA Graphic Arts
GRA Grande Raccordo Anulare (circular highway surrounding Rome, Italy)
GRA Graduate Research Assistant
GRA Georgia Research Alliance
GRA Graduate Research Assistantship
GRA Guyana Revenue Authority , 29[degrees]34'30"N, 113[degrees]32'15"W), Isla Lobes (LOB, 30[degrees]02'30"N, 114[degrees], 28'30"W), and at two colonies of Isla Angel de la Guarda known as Los Machos (MAC, 29[degrees]20'00"N, 113[degrees]30'00"W), and Los Cantiles (CAN, 29[degrees]32'00"N, 113[degrees]29'00"W, Fig. 1). The total number of California sea lions in these seven rookeries was approximately 15,000 animals (that were hauled out) of which about 12.2% inhabit San Pedro Martir, 34.7% San Esteban, 2.8% El Rasito, 10.0% Los Machos, 8.7% Los Cantiles, 11.0% Isla Granite, and 20.6% Isla Lobes (Aurioles-Gamboa and Zavala-Gonzalez, 1994). All the animals were spread out along the shoreline of each island, except at Isla Angel de la Guarda, where they were clustered within two areas: Los Cantiles, on the eastern shoreline and Los Machos on the western shoreline.
[FIGURE 1 OMITTED]
Scat samples were obtained at reproductive and non-reproductive haulout areas between June 1995 and May 1996. At El Rasito, sampling was done only at one reproductive area; fresh and dried samples were collected (Fig. 2). If for any reason a scat was not collected (because it was found in pieces or in poor condition), it was destroyed and the site was cleared to avoid collection during subsequent trips. All fresh and dried samples collected were pooled to represent each sampling period. We assumed that the diet information corresponded to a time period close to the collection trip, but some dried scats could have been deposited shortly after the last collection.
[FIGURE 2 OMITTED]
Scats were stored in plastic bottles and then dried shortly thereafter to prevent decomposition decomposition /de·com·po·si·tion/ (de-kom?pah-zish´un) the separation of compound bodies into their constituent principles.
1. of fish otoliths and other hard parts (which were used in subsequent prey identification) until the scats could be processed at a later date. The samples were processed by soaking in a weak biodegradable biodegradable /bio·de·grad·a·ble/ (-de-grad´ah-b'l) susceptible of degradation by biological processes, as by bacterial or other enzymatic action.
adj. detergent detergent (dētûr`jənt, dĭ–), substance that aids in the removal of dirt. Detergents act mainly on the oily films that trap dirt particles. solution for 1 to 7 days before being sifted through nested sieves of 2.00-, 1.18-, and 0.5-mm mesh size. Fish bones and scales, eye lenses of fish and squid, otoliths, cephalopod beaks, and crustacean crustacean (krŭstā`shən), primarily aquatic arthropod of the subphylum Crustacea. Most of the 44,000 crustacean species are marine, but there are many freshwater forms. fragments were extracted from the samples. Cephalopod beaks were stored in 70% ethanol ethanol (ĕth`ənōl') or ethyl alcohol, CH3CH2OH, a colorless liquid with characteristic odor and taste; commonly called grain alcohol or simply alcohol. , and the other items were dried and stored in vials. Sagittal sagittal /sag·it·tal/ (saj´i-t'l)
1. shaped like an arrow.
2. situated in the direction of the sagittal suture; said of an anteroposterior plane or section parallel to the median plane of the body. otoliths and cephalopod beaks were used to identify teleost fish Noun 1. teleost fish - a bony fish of the subclass Teleostei
malacopterygian, soft-finned fish - any fish of the superorder Malacopterygii and cephalopods, respectively. Identifications were made by using photographs and diagrams from Clarke (1962), Fitch (1966), Fitch and Brownell (1968), and Wolff (1984), as well as voucher A receipt or release which provides evidence of payment or other discharge of a debt, often for purposes of reimbursement, or attests to the accuracy of the accounts. specimen material from the 1) Center Interdisciplinario de Marinas Ciencias (CICIMAR), 2) Institute Tecnologico y de Estudios Superiores de Monterrey, Guaymas, 3) Los Angeles County Museum Los Angeles County Museum, Los Angeles, Calif. The original museum opened in 1913. Among its important patrons was William Randolph Hearst, whose enormous collection brought the museum major status among the country's art houses. of Natural History, California, and 4) Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (CICESE CICESE Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Spanish) ), Baja California Baja California, state, Mexico
Baja California (Span.: bä`hä kälēfōr`nyä), state (1990 pop. 1,660,855), 27,628 sq mi (71,576 sq km), NW Mexico, on the Baja California peninsula. Mexicali is the capital. , Mexico. Prey species identifed to family level were coded by using the family name plus a sequential number. Otoliths from prey species that were not identified to species, genus, or family level were coded with "fish species" plus a number.
Three indices were used to describe the diet of sea lions. Percent number (PN) represents the percentage of the number of individuals for each prey taxon taxon (pl. taxa), in biology, a term used to denote any group or rank in the classification of organisms, e.g., class, order, family. over the total number of individuals found in all scat samples. Percent of occurrence (PO) represents the percentage of scats having a given prey taxon and indicates the percentage of the population that is consuming a particular prey species. The third index, index of importance (IIMP IIMP Integrated Information Management Protocol
IIMP Integrated Information Management Program ) incorporates PN and PO and is defined as
(1) IIM IIM Indian Institute of Management (main Management Institutes of India)
IIM Individual Indian Money (US Department of Interior)
IIM Industrial Information Management [P.sub.i] = 1/U[U.summation summation n. the final argument of an attorney at the close of a trial in which he/she attempts to convince the judge and/or jury of the virtues of the client's case. (See: closing argument) over j=1][X.sub.ij]/[X.sub.j],
where [x.sub.i] = number of individuals of taxon i in scat j;
[X.sub.j] = total number of individuals from all taxa found in scat j; and
U = total number of samples with prey.
The IIMP, developed for scat analysis (Garcia-Rodriguez, 1999), was used to determine the importance of prey species, their spatial and temporal variation in the diet, diversity of prey estimates, and measures of similarity among rookeries. Crustaceans were not incorporated into the IIMP index because it was not possible to quantify Quantify - A performance analysis tool from Pure Software. the number of individuals in the samples.
We used the IIMP Index because it is less sensitive to changes in the number of prey in an individual scat compared to PN. For example, if a scat contains a single prey taxon, the IIMP does not change regardless of the number of individuals of that taxon, in that scat. However, as one increases the number of individuals of a given prey taxon in the scat, the PN will also increase for that prey. The IIMP allows each scat to contribute an equal amount of information, whereas PN can be dominated by a few scats with a large number of a single prey-taxon otoliths. In this manner the IIMP is similar to the split-sample frequency of ocurrence (SSFO SSFO Software Support Field Office
SSFO Self-Storage Fractional Ownership ) index, developed by Olesiuk (1993), where each scat is treated as a sampling unit and does not assume, as does PN, that the distribution of prey hard parts between scats is uniform. However, with the SSFO index, each prey taxon in a given scat is given an equal weight for that scat. If only one species occurs in a sample, its occurrence is scored as 1, if two species occur, each occurrence is scored as 0.5, and so forth (Olesiuk, 1993). The IIMP index incorporates more information than the SSFO index, regardless of the number of individuals of each taxon in the scat. (4)
Percent number (PN) was used only to show differences between broad prey groups (fishes and cephalopods) and PO was used to review the temporal and spatial changes from each main prey (those with average IIMP of at least 10% at any rookery). For all estimations, a single otolith otolith /oto·lith/ (o´to-lith) statolith.
1. Any of numerous minute calcareous particles found in the inner ear of certain lower vertebrates and in the statocysts of many (right or left) or single cephalopod beak beak
Stiff, projecting oral structure of birds and turtles (both of which lack teeth) and certain other animals (e.g., cephalopods and some insects, fishes, and mammals). (upper or lower) represented one individual prey. We tested the hypothesis that the occurrence of the main prey was independent of the rookery and of the date collection using contingency tables and an estimator of chi-square ([chi square]) (Cortes, 1997).
Total length of the otoliths (mm) and the linear equation obtained by Alvarado-Castillo (5) were used to estimate the length of the Pacific sardine (total length mm=7.41+(47.24 x otolith length mm); r=0.85, n=2740). Insufficient data did not allow estimating the size of specimens from May. All estimated lengths were transformed using log10, followed by an ANOVA anova
see analysis of variance.
ANOVA Analysis of variance, see there among sampling periods. The size of Pacific sardine consumed by California sea lion was compared to those caught in the commercial fishery. We chose to estimate the size of Pacific sardines because of the broad information available concerning age and growth and other aspects about the fishery and because we found many sardine otoliths in good condition.
Spatial and temporal correlation in composition of diet was compared by using the Spearman spear·man
A man, especially a soldier, armed with a spear. rank correlation In statistics, rank correlation is the study of relationships between different rankings on the same set of items. It deals with measuring correspondence between two rankings, and assessing the significance of this correspondence. coefficient coefficient /co·ef·fi·cient/ (ko?ah-fish´int)
1. an expression of the change or effect produced by variation in certain factors, or of the ratio between two different quantities.
2. ([R.sub.S]) (Fritz fritz
A condition in which something does not work properly: Our television is on the fritz.
[Perhaps from German Fritz , 1974). Pairs of IIMP values were used for each prey taxon in a pair of sampling events (rookeries or sampling dates) to examine the correlation among them. This analysis was limited to prey that had an IIMP value of 10% or more. Cluster analysis Cluster analysis
A statistical technique that identifies clusters of stocks whose returns are highly correlated within each cluster and relatively uncorrelated across clusters. Cluster analysis has identified groupings such as growth, cyclical, stable, and energy stocks. of average IIMP data for the seven rookeries was used to assess the similarity of the diet among rookeries. The dendrogram A dendrogram is a tree diagram frequently used to illustrate the arrangement of the clusters produced by a clustering algorithm (see cluster analysis). Dendrograms are often used in computational biology to illustrate the clustering of genes. for the cluster analysis was based on relative Euclidean distances and unweighted pair-grouping methods (UPGMA UPGMA Unweighted Pair Group Method, Arithmetic Mean ) strategy (Ludwig and Reynolds, 1988). We included only prey that, for at least one occasion, had IIMP values [greater than or equal to] 10%.
Trophic diversity was evaluated by using diversity curves (Hurtubia, 1973) developed from IIMP index data. For each date and colony, the cumulative diversity was calculated for increasing numbers of sequentially numbered (but we assumed randomly deposited and collected) scat samples. The diversity curves also allowed us to evaluate sample size (Hurtubia, 1973; Hoffman, 1978; Magurran, 1988, Cortes, 1997) by identifying the point at which the curve flattens. The diversity was estimated by using the Shannon index The Shannon index (incorrectly the Shannon–Weaver index or also incorrectly known as the Shannon-Weiner Index ) is one of several diversity indices used to measure diversity in categorical data. :
(2) H' = -[S.summation over i=1][p.sub.i]ln[p.sub.i],
where H' = trophic diversity;
S = total number of prey taxa; and
[P.sub.i] = IIM[P.sub.i], and represents the relative abundance of taxon i obtained from each seat and pooled from scat 1 up to the total number of scats collected.
The values of trophic diversity were then plotted against the number of pooled seats.
Identification of prey
The 1273 scat samples collected during June 1995 through May 1996 (Table 1) yielded fish remains in 97.4% of the samples, cephalopod remains in 11.2%, and crustacean remains in 12.7%. Fish and cephalopods represented 95.3% and 4.7%, respectively, of the 5242 individual prey (excluding crustaceans). The occurrence and number of these prey groups changed temporally and spatially (Fig. 3). We identified 92 prey taxa to the species level, 11 to the genus level, and 10 to family level from 851 scats (Table 2). Remaining scats had damaged prey structures in a condition that prevented us from identifying species to the genus or family level.
[FIGURE 3 OMITTED]
We found nine main prey with IIMP average values [greater than or equal to] 10% (Table 3): the Pacific cutlassfish (Trichiurus lepturus), the Pacific sardine (Sardinops caeruleus), the plainfin midshipman (Porichthys spp.), myctophid no. 1, the northern anchovy (Engraulis mordax), Pacific mackerel (Scomber japonicus), the anchoveta (Cetengraulis mysticetus), jack mackerel (Trachurus symmetricus), and the lanternfish (unid. myctophid).
Spatial and temporal variability of the main prey
The importance (IIMP) of the Pacific cutlassfish was greater in Los Cantiles (28.4%), Isla Lobos (20.8%), and Isla Granito (48.5%) than at other sites (Fig. 4). The Pacific sardine was the dominant prey at Los Machos and to the south. There was a significant correlation across the seasons between Los Machos and El Rasito (r=0.998, P=0.04), but not between Los Machos and Isla Granito r=0.602, P=0.59). The IIMP of sardine was also correlated cor·re·late
v. cor·re·lat·ed, cor·re·lat·ing, cor·re·lates
1. To put or bring into causal, complementary, parallel, or reciprocal relation.
2. between El Rasito and San Esteban (r=0.95, P=0.04). The plainfin midshipman did not show a clear pattern, but its presence in the diet increased northeastward from Isla Angel de la Guarda. Lanternfishes, especially myctophid no. 1, were the dominant prey at San Pedro Martir, San Esteban, and El Rasito. The presence of Pacific mackerel was positively correlatcd with the presence of the Pacific sardine. The anchoveta was only found at Isla Lobes, and jack mackerel at El Rasito, San Pedro Martir, and Isla Granito.
[FIGURE 4 OMITTED]
The changes in the PO of the main prey coincided with the variations of the IIMP. The occurrence of Pacific cutlassfish, Pacific sardine, plainfin midshipman, northern anchovy, Pacific mackerel, and jack mackerel was significantly different (P<0.04) among rookeries. Myctophid no. 1 showed no significant difference in ocurrence ([chi square]=11.04, df=6, P=0.09); but when all lanternfishes were pooled, their occurrence among rookeries was significantly different ([chi square]=11.13, df=6, P=0.04). We found significant temporal differences in the occurrence of Pacific cutlassfish, Pacific sardine, plainfin midshipman, northern anchovy, and Pacific mackerel (P<0.05), but no significant differences were found among seasons in the occurrence of jack mackerel ([chi square]=2.94, df=3, P=0.40), myctophid no. 1 ([chi square]=1.67, df=3, P=0.6428), or lanternfish ([chi square]=2.08, df=3, P=0.5562).
Size of Pacific sardine consumed by sea lions
The estimated size of the Pacific sardine found in scat was between 101.8 mm and 179.7 mm (mean length of 150.4 mm [+ or -] 13.7 mm). Significant differences were found among sampling periods (F=4.79, df=2, P=0.01), specifically between June and January (Newman-Keuls test; P=0.04) and between September and January (Newman-Keuls test; P=0.01). The average size was 147.4 mm ([+ or -]16.1 mm) in June, 151.7 mm ([+ or -]13.0 mm) in September, and 136.5 mm ([+ or -]13.7 mm) in January (Fig. 5). A similar pattern was found in Los Cantiles, Los Machos, and Isla Granito.
[FIGURE 5 OMITTED]
Spatial and temporal correlation in diet
We identified 25 prey taxa that had an IIMP index value of [greater than or equal to] 10% (Table 3) for a given collection. The Spearman rank correlation coefficient of IIMP between any pair of rookeries during June, September, January, and May was not significant (P>0.08). There was no positive correlation Noun 1. positive correlation - a correlation in which large values of one variable are associated with large values of the other and small with small; the correlation coefficient is between 0 and +1
direct correlation among any pair of sampling periods for any rookery (P>0.14), except between January and May at San Pedro Martir ([R.sub.S]=0.64, P<0.05) and El Rasito ([R.sub.S]=0.66, P<0.05) and between January and June as well as between January and May at Isla Lobos ([R.sub.S]=0.56, P=0.05; and [R.sub.S]=0.59, P=0.05, respectively).
The similarity in diet was related to the distance between rookeries. A clustering for the seven rookeries was obtained from these 25 prey taxa (Fig 6). We arbitrarily used a "cutoff" distance of 0.3 and 0.4 on the dendrogram as reference points for identifying clusters. The group obtained by using the first distance (0.3) showed four feeding areas: one located in the south (area I: San Pedro Martir, San Esteban, and El Rasito), another in Canal de Ballenas (area II: Los Machos) and two in the north (area III: Los Cantiles and Isla Lobes; and area IV: Isla Granite). When the second distance (0.4) was used, the seven rookeries grouped into two clusters: 1) the southern region and Canal de Ballenas, and 2) the region north of Angel de la Guarda.
[FIGURE 6 OMITTED]
Spatial and temporal variability in trophic diversity
Temporal variability in trophic diversity was evident between the rookeries (Fig. 7). In general, two patterns could be differentiated: one in which the diversity varied little throughout the year and the other in which diversity was high in January and low in September. The rookeries San Pedro Martir and Isla Lobos showed the first pattern and Los Machos and Isla Granito (and to a lesser extent, San Esteban and El Rasito) showed the second pattern. In September, when diversity was low, the dominant prey at San Esteban, El Rasito, and Los Machos was Pacific sardine, whereas at Isla Granito, it was Pacific cutlassfish (Fig. 4). The curves obtained for Los Cantiles showed a clear pattern of diversity only in September, although the trend in the January curve would suggest a higher diversity in January than in September.
[FIGURE 7 OMITTED]
Stomach acids attack otoliths, affecting their size and number and consequently the estimate of prey occurrence and importance. Erosion of otoliths during digestion digestion
Process of dissolving and chemically converting food for absorption by cells. In the mouth, food is chewed, mixed with saliva, which begins to break down starches, and kneaded by the tongue into a ball for swallowing. has been analyzed in studies of pinnipeds in captivity. Bowen (2000) reviewed nine studies that estimated the proportion of otoliths recovered in scat samples to obtain a prey-number correction factor (NCF See National Cristina Foundation. ). He found that NCF is greater than 1.0 because many prey species are not recovered in the scat samples. Additionally, the erosion level can be significantly different among prey species (Bowen, 2000) because of differences in the shape and microstructure mi·cro·struc·ture
The structure of an organism or object as revealed through microscopic examination.
a structure on a microscopic scale, such as that of a metal or a cell of otoliths. Therefore, estimates of biomass based on scat analysis should be carefully interpreted because the consumption of some prey species can be under- or overestimated. Correction factors are needed to compensate for differential erosion for the prey species of each pinniped pinniped: see seal.
Any member of the three existing families of aquatic, fin-footed mammals that constitute the suborder Pinnipedia (order Carnivora; see carnivore). .
In this study the most important prey of California sea lions were pelagic fish with small, thin, and fragile otoliths (Nolf, 1993). The lanternfish also have small otoliths--perhaps smaller than those of any other prey taxa found in the scats. Their true importance in California sea lion feeding may be underestimated because of erosion caused by stomach acids (Da Silva sil·va also syl·va
n. pl. sil·vas or sil·vae
1. The trees or forests of a region.
2. A written work on the trees or forests of a region. and Neilson, 1985; Murie and Lavigne, 1985; Jobling and Breiby, 1986; Jobling, 1987; Tollit et al., 1997). Similarly, the presence of cephalopods may have been underestimated because their jaws are composed of chitin, which is harder to digest, and frequently are regurgitated (Pitcher, 1980; Hawes, 1983). However, the high resistance to digestion of cephalopod beaks allows recovery of them in good shape. Thus they are a good choice to use in such diet analyses (Lowry and Carretta, 1999).
A numerical index of prey species importance may over-or underestimate the dominance of prey species in the diet because it does not consider the weight of the prey. For IIMP, a numerical index that assumes a similar weight for all prey species, the true importance of the individual large prey in the diet can be underestimated and the importance of individual small prey can be overestimated. This problem is also present when the PO, PN, and the SSFO index are used because these are all based only upon the number and occurrence of otoliths and cephalopods beaks. As when using PN, and the SSFO, the IIMP does not work for species that cannot be enumerated This term is often used in law as equivalent to mentioned specifically, designated, or expressly named or granted; as in speaking of enumerated governmental powers, items of property, or articles in a tariff schedule. , such as crustaceans.
Given the tendencies of the trophic diversity curves, the sample size was suitable in almost all cases. However, at San Pedro Martir a few more samples would have been useful to fully depict de·pict
tr.v. de·pict·ed, de·pict·ing, de·picts
1. To represent in a picture or sculpture.
2. To represent in words; describe. See Synonyms at represent. the diet. At Los Cantiles, except during September 1995, the samplings should have been more intense because the flattened portion of the diversity curves are not clear. The information, therefore, that comes from those samples could be biased. However, the number of scats that we analyzed contained a high percentage of the consumed species, especially the main prey.
The results of this study indicate that the California sea lion consumed mainly fish and some crustaceans and cephalopods. According to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. the PN index, fish were more important than cephalopods in the diet of sea lions. In addition, fish were more frequent (PO) than crustacean and cephalopods.
Crustaceans were represented in a similar manner in scats from all rookeries. Cephalopods, however, were more important at San Pedro Martir and San Esteban, probably because they are more common towards the southern gulf. Species of the suborder suborder /sub·or·der/ (sub´or-der) a taxonomic category between an order and a family.
A taxonomic category ranking between an order and a family. Oegopsida, which includes oceanic species (Roper and Young, 1975), were most commonly found in scats from these rookeries. Orta-Davila (1988) and Sanchez-Arias (1992) have also noted the low consumption of cephalopods at the northern rookeries. Fish were the most diverse and commonly eaten prey. In contrast to cephalopods, fish were slightly less important in the southern region.
The availability and abundance of the various prey resources influenced the diet of the sea lions in the Gulf of California. The distribution pattern of Pacific sardine closely agrees with its importance in the sea lions diet. The Pacific sardine occurred in high concentrations around Angel de la Guarda and Isla Tiburon during the summer and along
the coast of southern Sonora during the winter, where spawning occurs (Cisneros-Mata et al. (3)). Sardines were consumed in the Canal de Ballenas region during the summer (September), when they are very abundant. Larger size Pacific sardines were consumed by sea lions most frequently during the summer when adult sardines occur more frequently in the Canal de Ballenas. As adult sardine left. Canal de Ballenas (Cisneros-Mata et al., 1997), the proportion of young individuals in the diet of sea lions increased. The fish eaten by sea lions were apparently smaller than those captured by the commercial fisheries. The average estimated size of the sardines consumed was 150.4 mm, whereas the average size of commercially caught fish during the 1995-96 season was 162.4 mm (Cisneros-Mata et al. (3)). This 7% difference in size may have been caused by an underestimation of otolith size because of digestive Ulcers (Digestive) Definition
In general, an ulcer is any eroded area of skin or a mucous membrane, marked by tissue disintegration. In common usage, however, ulcer usually is used to refer to disorders in the upper digestive tract. erosion (Jobling and Breiby, 1986). If this is so, then the size of Pacific sardines consumed by sea lions is similar to the size of those captured by the fishery.
Isla Lobos was the only rookery where Pacific sardine was not consumed. This finding differs from those of Cisneros-Mata et al. (3) which show the Pacific sardines present as far north as Isla Lobos. However, their study period was during the 1991-92 El Nino episode, whereas our study occurred during normal oceanographic conditios in 1995-96.
Less is known about the spatial and temporal availability of other important prey. As with commercial captures (Arvizu-Martinez, 1987), Pacific mackerel occurred together with Pacific sardine. Similar variations in occurrence for both species have been noticed from stomach content analyses of the giant squid (Dosidicus gigas) (Ehrhardt, 1991). Lanternfishes were abundant north of Isla Angel de la Guarda (Robison, 1972); however they were not important in the diet of the California sea lion in this region. Their greater importance in the diet at southern rookeries was probably due to the absence of more preferred prey such as Pacific sardine, Pacific cutlassfish, or anchoveta. The consumption of northern anchovy tended to be less important towards Canal de Ballenas, where Pacific sardine reached its maximum importance. The low spatial overlap of these two species has also been noted in other studies. The anchoveta was present only at Isla Lobos. This is an estuarine-lagoon species, typical of coastal lagoons of northern Sinaloa and Sonora (Castro-Aguirre et al., 1995). The presence of this prey in Isla Lobos is possibly due to the sandy coast (Walker, 1960), which is similar to that of the Sinaloa-Sonora coast.
The diet of California sea lions differed among rookeries, probably due to differences in feeding sites and prey availability. Antonelis et al. (1990) studied the foraging characteristics of the northern fur seal The Northern Fur Seal, Callorhinus ursinus, is an eared seal found along the north Pacific Ocean, the Bering Sea and the Sea of Okhotsk. It is the largest member of the fur seal subfamily (Arctocephalinae) and the only species in the genus Callorhinus (Callorhinus ursinus Callorhinus ursinus
northern fur seal. ) and the California sea lion at San Miguel Island San Miguel Island is the westernmost of California's Channel Islands and the sixth-largest of the eight at 9,325 acres (37.74 km²), including offshore islands and rocks. Prince Island, 700 m off the northeastern coast, measures 35 acres in area. and found differences between foraging areas among species. The northern fur seal was found most frequently foraging in oceanic water within 72.4 km from the island, whereas Califorinia sea lions forgaged more often in the shallower neritic zone Noun 1. neritic zone - the ocean waters from the low tide mark to a depth of about 100 fathoms
Davy Jones, Davy Jones's locker, ocean bottom, ocean floor, sea bottom, sea floor, seabed - the bottom of a sea or ocean , within 54.2 km from the island. Different foraging distances in California sea lions from San Miguel Island were found by Melin and DeLong (1999). During the nonbreeding season a higher percentage of foraging locations occurred at distances less than 100 km, whereas during the breeding season Breeding season is the most suitable season usually with favorable conditions and abundant food and water when wild animals and birds (wildlife) have naturally evolved to breed to achieve the best reproductive success. most of the foraging locations occurred at distances greater than 100 km. These differences are probably due to the increased California sea lion population in San Miguel San Miguel (sän mēgĕl`), city (1993 pop. 118,214), E El Salvador, at the foot of San Miguel volcano (6,996 ft/2,132 m). It has textile, rope, and dairy-products industries. The region produces cotton, henequen, and vegetable oil. ; this increase in population forces sea lions to exploit new areas as a density-dependent response to population growth. Although, these differences could also be due to variability in the distribution of' prey (Melin and DeLong, 1999), as suggested by Antonelis and Fiscus (1980), foraging areas might change with season and annual variations in prey availability and abundance.
Foraging areas in the Gulf of California could lie closer to rookeries than those recorded for San Miguel Island sea lions because the diet was different among rookeries in spite of the shorter distance between them (54.2 km). At Los Islotes, Baja California Sur Baja California Sur (sr), state (1990 pop. 317,764), 27,571 sq mi (71,428 sq km), NW Mexico, on the Baja California peninsula. La Paz is the capital. , adult females fed within 20 km of the colony (Duran-Lizarraga, 1998). Kooyman and Trillmich (1986a, 1986b) reported similar data in sea lion colonies of the Galapagos Islands. In the northern region of the Gulf of California, feeding range could be shorter than that at Los Islotes because of the higher concentration of food at high nutrient nutrient /nu·tri·ent/ (noo´tre-int)
1. nourishing; providing nutrition.
2. a food or other substance that provides energy or building material for the survival and growth of a living organism. concentrations (phosphate phosphate, salt or ester of phosphoric acid, H3PO4. Because phosphoric acid is tribasic (having three replaceable hydrogen atoms), it forms monophosphate, diphosphate, and triphosphate salts in which one, two, or three of the hydrogens of the , nitrate nitrate, chemical compound containing the nitrate (NO3) radical. Nitrates are salts or esters of nitric acid, HNO3, formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g., ammonium or ethyl). , nitrite nitrite
Any salt or ester of nitrous acid (HNO2). The salts are inorganic compounds with ionic bonds, containing the nitrite ion (NO2−) and any cation. , and silicate silicate, chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may be considered chemically as salts of the various silicic acids. ) in Canal de Ballenas that is associated with strong tidal tidal /ti·dal/ (ti´d'l) ebbing and flowing like the waters of the oceans.
Resembling the tides; alternately rising and falling. mixing (Alvarez-Borrego, 1983).
Four foraging zones were discerned from dietary differences in sea lions from the seven rookeries studied. Zone I, which included San Pedro Martir, San Esteban, and El Rasito, was characterized by the consumption of lanternfish; zone II, which included Los Machos was characterized by the consumption of Pacific sardine and Pacific mackerel; zone III, which included Isla Granito, by the consumption of Pacific cutlassfish and the northern anchovy; and zone IV, Los Cantiles and Isla Lobos, was characterized by the consumption of the plainfin midshipman and the Pacific cutlassfish. These four zones may indicate differences in habits used by sea lions or may indicate different oceanographic conditions exploited by sea lions. The eastern coast of the Gulf of California displays high photosynthetic pigment A photosynthetic pigment or antenna pigment is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis. concentrations, associated with upwelling up·well·ing
1. The act or an instance of rising up from or as if from a lower source: an upwelling of emotion.
2. induced by winds from the northwest in the winter. These conditions may make Canal de Ballenas one of the most important for the distribution of Pacific sardine during the summer.
Trophic diversity varied spatially and temporally. San Pedro Martir and Isla lobos sea lions seem to depend on a more stable feeding areas compared to sea lions at rookeries on Isla Granito and Los Machos, where changes in diversity of consumed species indicated that sea lions feed on fewer species during certain times of the year. Similar results in relation to the changes in diversity were also noticed in the rookeries of the Channel Islands and Farallon Islands The Farallon Islands are a group of islands and rocks found in the Gulf of the Farallones, off the coast of San Francisco, California, USA. They lie 27 miles (43 km) outside the Golden Gate, 20 miles (32 km) south of Point Reyes. They are visible from the mainland on clear days. , California (Bailey and Ainley, 1982; Antonelis et al., 1984; Lowry et al., 1990; Lowry et al., 1991). Perhaps the tendency to have the highest values of diversity and little seasonal variation at San Pedro Martir is the result of this rookery being located in a zone of transition between two biogeographical bi·o·ge·og·ra·phy
The study of the geographic distribution of organisms.
bio·ge·og areas. This geographical position confers greater environmental heterogeneity het·er·o·ge·ne·i·ty
The quality or state of being heterogeneous.
the state of being heterogeneous. and greater ecological diversity (Walker, 1960).
California sea lions in the upper region of the Gulf of California obtain the main portion of their diet from a relatively small number of species. The decrease in abundance of any of these food resources can seriously affect the population, particularly at Isla Granito and Los Machos because sea lions from these rookeries depend on a few species.
Table 1 Number of scats collected at each rookery for each sampling period. June 1995 September 1995 January 1996 San Pedro Martir (SPM) 22 33 88 San Esteban (EST) 50 66 91 El Rasito (RAS) 11 56 58 Los Cantiles (CAN) 20 58 47 Isla Granito (GRA) 24 20 41 Los Machos (MAC) 39 32 36 Isla Lobos (LOB) 72 139 72 Total 238 404 433 May 1996 Total San Pedro Martir (SPM) 29 172 San Esteban (EST) 67 274 El Rasito (RAS) 25 150 Los Cantiles (CAN) 35 160 Isla Granito (GRA) 19 104 Los Machos (MAC) 0 107 Isla Lobos (LOB) 23 306 Total 198 1273 Table 2 Prey of California sea lion identified from scat samples collected at Isla San Pedro Martir, Isla San Esteban, Isla El Rasito, Los Cantiles, Isla Granito, Los Machos and Isla Lobos from June 1995 through May 1996. n ind. = number of individuals in the sample; PN = percent number; n occurr = number of occurrences; PO = percentage of occurrence; IIMP = index of importance. Scientific name Common name n Ind. Trichiurus lepturus Pacific cutlassfish 306 Sardinops caeruleus Pacific sardine 358 Porichthys spp. midshipman 456 Myctophid no. 1 lanternfish 714 Engraulis mordax northern anchovy 430 Scomber japonicus Pacific mackerel 103 Cetengraulis mysticetus anchoveta 410 Loliolopsis diomedeae squid 77 Trachurus symmetricus jack mackerel 111 Merlaccius spp. Pacific whiting 55 Pontinus spp. scorpionfish 61 Enoploteuthid no. 1 squid 95 Caelorinchus scaphopsis shoulderspot 65 Octopus sp. no. 1 octopus 24 Sebastes macdonaldi Mexican rockfish 42 Citharichthys sp no. 1 sanddab 120 Fish species no. 1 -- 49 Haemulopsis leuciscus white grunt 176 Peprilus snyderi salema butterfish 163 Prionotus spp. searobin 12 Prionotus stephanophrys lumptail searobin 53 Argentina sialis Pacific argentine 19 Fish species no. 2 -- 55 Hemanthias peruanus splittail bass 60 Fish species no. 3 -- 9 Micropogonias ectenes slender croaker 13 Lepophidium spp. cusk-eel 9 Fish species no. 4 -- 10 Sebastes exsul buccanner rockfish 15 Cranchiid no. 2 Squid 20 Haemulon flaviguttatum yellowspotted grunt 11 Selar crumenophthalmus bigeye scad 24 Fish species no. 5 -- 33 Paralabrax sp. no. 1 sea bass 9 Synodus sp. no. 3 lizardfish 10 Lepophidium prorates prowspine cusk-eel 5 Fish species no. 6 -- 9 Synodus sp. no. 1 lizardfish 25 Octopus sp, no. 2 octopus 8 Gonatus berryi squid 5 Mugil cephalus striped mullet 1 Paranthias colonus Pacific creole-fish 1 Balistes polylepis finescale triggerfish 13 Physiculus nematopus charcoal mora 30 Hemanthias spp. sea bass 9 Fish species no. 7 -- 10 Uroconger varidens conger eel 8 Larimus spp. drum 8 Apogon retrosella barspot cardinalfish 5 Dosidicus gigas squid 8 Merluccius productus Pacific whiting 1 Fish species no. 8 -- 2 Synodus sp. no. 2 lizardfish 12 Scorpaena sonorae Sonora scorpionfish 2 Eucinostomus spp. mojarra 13 Fish species no. 9 -- 3 Cynoscion reticulatus striped weakfish 23 Fish species no. 10 -- 10 Caulolatilus affinis bighead tilefish 4 Paralabrax auroguttatus goldspotted sand bass 18 Fish species no. 11 -- 3 Cranchiid no. 5 squid 1 Bodianus diplotoenia mexican hogfish 1 Prionotus sp. no. 1 searonbin 2 Strongylura exilis california needlefish 1 Synodus spp. lizardfish 6 Fish species no. 12 -- 3 Fish species no. 13 -- 2 Fish species no. 14 -- 3 Fish species no. 15 -- 2 Fish species no. 16 2 Porichthys sp. 1 midshipman 1 Fish species no. 17 -- 5 Calamus brachysomus Pacific porgy 5 Fish species no. 18 -- 1 Fish species no. 19 -- 5 Ophididae no. 1 -- 1 Fish species no. 20 -- 5 Sebastes sinesis blackmouth rockfish 2 Symphurus spp. tonguefish 3 Fish species no. 21 -- 2 Pronotogrammus multifasciatus threadfin bass 8 Fsh species no. 22 -- 2 Fish species no. 23 -- 2 Orthopristis reddingi Bronze-striped grunt 16 Fish species no. 24 -- 2 Fish species no. 25 -- 1 Cranchiidae no. 4 squid 2 Fish species no. 26 -- 2 Histioteuthis heteropsis squid 1 Scorpaenidae no. 1 -- 1 Fish species no. 27 -- 3 Fish species no. 28 -- 1 Fish species no. 29 -- 1 Cranchiidae no. 3 squid 1 Bollmannia spp. goby 1 Fish species no. 30 -- 1 Cranchiidae no. 1 squid 1 Paralabrax maculatofasciatus spotted sand bass 1 Ophidion scrippsae basketweave cusk-eel 1 Physiculus spp. cod, codling, mora 2 Ophididae no. 2 -- 4 Unid. Carangidae jacks 8 Unid. Engraulidae anchovies 1 Unid. Haemulidae grunts 13 Unid. Labridae wrasses 1 Unid. Mycthophidae lanternifishes 216 Unid. Ophididae cusk-eel 2 Unid. Scianidae drums 13 Unid. Scorpaenidae scorpionfishes 30 Unid. Serranidae sea bass 13 Unid. Triglidae searobins 1 Unid. Fishes 39 Unid. Cephalopods 4 Unid. fishes (very eroded) 381 Remains of cephalopods Remains of crustaceans Scientific name Common name PN Trichiurus lepturus Pacific cutlassfish 5.837 Sardinops caeruleus Pacific sardine 6.829 Porichthys spp. midshipman 8.699 Myctophid no. 1 lanternfish 13.621 Engraulis mordax northern anchovy 8.203 Scomber japonicus Pacific mackerel 1.965 Cetengraulis mysticetus anchoveta 7.821 Loliolopsis diomedeae squid 1.469 Trachurus symmetricus jack mackerel 2.118 Merlaccius spp. Pacific whiting 1.049 Pontinus spp. scorpionfish 1.164 Enoploteuthid no. 1 squid 1.812 Caelorinchus scaphopsis shoulderspot 1.240 Octopus sp. no. 1 octopus 0.458 Sebastes macdonaldi Mexican rockfish 0.801 Citharichthys sp no. 1 sanddab 2.289 Fish species no. 1 -- 0.935 Haemulopsis leuciscus white grunt 3.357 Peprilus snyderi salema butterfish 3.110 Prionotus spp. searobin 0.229 Prionotus stephanophrys lumptail searobin 1.011 Argentina sialis Pacific argentine 0.362 Fish species no. 2 -- 1.049 Hemanthias peruanus splittail bass 1.145 Fish species no. 3 -- 0.172 Micropogonias ectenes slender croaker 0.248 Lepophidium spp. cusk-eel 0.172 Fish species no. 4 -- 0.191 Sebastes exsul buccanner rockfish 0.286 Cranchiid no. 2 Squid 0.382 Haemulon flaviguttatum yellowspotted grunt 0.210 Selar crumenophthalmus bigeye scad 0.458 Fish species no. 5 -- 0.630 Paralabrax sp. no. 1 sea bass 0.172 Synodus sp. no. 3 lizardfish 0.191 Lepophidium prorates prowspine cusk-eel 0.095 Fish species no. 6 -- 0.172 Synodus sp. no. 1 lizardfish 0.477 Octopus sp, no. 2 octopus 0.153 Gonatus berryi squid 0.095 Mugil cephalus striped mullet 0.019 Paranthias colonus Pacific creole-fish 0.019 Balistes polylepis finescale triggerfish 0.248 Physiculus nematopus charcoal mora 0.572 Hemanthias spp. sea bass 0.172 Fish species no. 7 -- 0.191 Uroconger varidens conger eel 0.153 Larimus spp. drum 0.153 Apogon retrosella barspot cardinalfish 0.095 Dosidicus gigas squid 0.153 Merluccius productus Pacific whiting 0.019 Fish species no. 8 -- 0.038 Synodus sp. no. 2 lizardfish 0.229 Scorpaena sonorae Sonora scorpionfish 0.038 Eucinostomus spp. mojarra 0.248 Fish species no. 9 -- 0.057 Cynoscion reticulatus striped weakfish 0.439 Fish species no. 10 -- 0.191 Caulolatilus affinis bighead tilefish 0.076 Paralabrax auroguttatus goldspotted sand bass 0.343 Fish species no. 11 -- 0.057 Cranchiid no. 5 squid 0.019 Bodianus diplotoenia mexican hogfish 0.019 Prionotus sp. no. 1 searonbin 0.038 Strongylura exilis california needlefish 0.019 Synodus spp. lizardfish 0.114 Fish species no. 12 -- 0.057 Fish species no. 13 -- 0.038 Fish species no. 14 -- 0.057 Fish species no. 15 -- 0.038 Fish species no. 16 0.038 Porichthys sp. 1 midshipman 0.019 Fish species no. 17 -- 0.095 Calamus brachysomus Pacific porgy 0.095 Fish species no. 18 -- 0.019 Fish species no. 19 -- 0.095 Ophididae no. 1 -- 0.019 Fish species no. 20 -- 0.095 Sebastes sinesis blackmouth rockfish 0.038 Symphurus spp. tonguefish 0.057 Fish species no. 21 -- 0.038 Pronotogrammus multifasciatus threadfin bass 0.153 Fsh species no. 22 -- 0.038 Fish species no. 23 -- 0.038 Orthopristis reddingi Bronze-striped grunt 0.305 Fish species no. 24 -- 0.038 Fish species no. 25 -- 0.019 Cranchiidae no. 4 squid 0.038 Fish species no. 26 -- 0.038 Histioteuthis heteropsis squid 0.019 Scorpaenidae no. 1 -- 0.019 Fish species no. 27 -- 0.057 Fish species no. 28 -- 0.019 Fish species no. 29 -- 0.019 Cranchiidae no. 3 squid 0.019 Bollmannia spp. goby 0.019 Fish species no. 30 -- 0.019 Cranchiidae no. 1 squid 0.019 Paralabrax maculatofasciatus spotted sand bass 0.019 Ophidion scrippsae basketweave cusk-eel 0.019 Physiculus spp. cod, codling, mora 0.038 Ophididae no. 2 -- 0.076 Unid. Carangidae jacks 0.153 Unid. Engraulidae anchovies 0.019 Unid. Haemulidae grunts 0.248 Unid. Labridae wrasses 0.019 Unid. Mycthophidae lanternifishes 4.121 Unid. Ophididae cusk-eel 0.038 Unid. Scianidae drums 0.248 Unid. Scorpaenidae scorpionfishes 0.572 Unid. Serranidae sea bass 0.248 Unid. Triglidae searobins 0.019 Unid. Fishes 0.744 Unid. Cephalopods 0.076 Unid. fishes (very eroded) 7.268 Remains of cephalopods Remains of crustaceans n Scientific name Common name Occurr. Trichiurus lepturus Pacific cutlassfish 128 Sardinops caeruleus Pacific sardine 88 Porichthys spp. midshipman 95 Myctophid no. 1 lanternfish 119 Engraulis mordax northern anchovy 43 Scomber japonicus Pacific mackerel 42 Cetengraulis mysticetus anchoveta 15 Loliolopsis diomedeae squid 35 Trachurus symmetricus jack mackerel 41 Merlaccius spp. Pacific whiting 25 Pontinus spp. scorpionfish 26 Enoploteuthid no. 1 squid 23 Caelorinchus scaphopsis shoulderspot 25 Octopus sp. no. 1 octopus 17 Sebastes macdonaldi Mexican rockfish 18 Citharichthys sp no. 1 sanddab 23 Fish species no. 1 -- 25 Haemulopsis leuciscus white grunt 21 Peprilus snyderi salema butterfish 33 Prionotus spp. searobin 9 Prionotus stephanophrys lumptail searobin 14 Argentina sialis Pacific argentine 13 Fish species no. 2 -- 27 Hemanthias peruanus splittail bass 22 Fish species no. 3 -- 6 Micropogonias ectenes slender croaker 9 Lepophidium spp. cusk-eel 3 Fish species no. 4 -- 3 Sebastes exsul buccanner rockfish 10 Cranchiid no. 2 Squid 12 Haemulon flaviguttatum yellowspotted grunt 3 Selar crumenophthalmus bigeye scad 12 Fish species no. 5 -- 19 Paralabrax sp. no. 1 sea bass 5 Synodus sp. no. 3 lizardfish 3 Lepophidium prorates prowspine cusk-eel 4 Fish species no. 6 -- 5 Synodus sp. no. 1 lizardfish 10 Octopus sp, no. 2 octopus 7 Gonatus berryi squid 5 Mugil cephalus striped mullet 1 Paranthias colonus Pacific creole-fish 1 Balistes polylepis finescale triggerfish 4 Physiculus nematopus charcoal mora 12 Hemanthias spp. sea bass 6 Fish species no. 7 -- 8 Uroconger varidens conger eel 5 Larimus spp. drum 6 Apogon retrosella barspot cardinalfish 4 Dosidicus gigas squid 5 Merluccius productus Pacific whiting 1 Fish species no. 8 -- 2 Synodus sp. no. 2 lizardfish 5 Scorpaena sonorae Sonora scorpionfish 1 Eucinostomus spp. mojarra 5 Fish species no. 9 -- 3 Cynoscion reticulatus striped weakfish 7 Fish species no. 10 -- 1 Caulolatilus affinis bighead tilefish 3 Paralabrax auroguttatus goldspotted sand bass 4 Fish species no. 11 -- 2 Cranchiid no. 5 squid 1 Bodianus diplotoenia mexican hogfish 1 Prionotus sp. no. 1 searonbin 2 Strongylura exilis california needlefish 1 Synodus spp. lizardfish 5 Fish species no. 12 -- 3 Fish species no. 13 -- 1 Fish species no. 14 -- 1 Fish species no. 15 -- 1 Fish species no. 16 2 Porichthys sp. 1 midshipman 1 Fish species no. 17 -- 3 Calamus brachysomus Pacific porgy 2 Fish species no. 18 -- 1 Fish species no. 19 -- 2 Ophididae no. 1 -- 1 Fish species no. 20 -- 3 Sebastes sinesis blackmouth rockfish 1 Symphurus spp. tonguefish 1 Fish species no. 21 -- 1 Pronotogrammus multifasciatus threadfin bass 2 Fsh species no. 22 -- 2 Fish species no. 23 -- 1 Orthopristis reddingi Bronze-striped grunt 1 Fish species no. 24 -- 1 Fish species no. 25 -- 1 Cranchiidae no. 4 squid 2 Fish species no. 26 -- 2 Histioteuthis heteropsis squid 1 Scorpaenidae no. 1 -- 1 Fish species no. 27 -- 2 Fish species no. 28 -- 1 Fish species no. 29 -- 1 Cranchiidae no. 3 squid 1 Bollmannia spp. goby 1 Fish species no. 30 -- 1 Cranchiidae no. 1 squid 1 Paralabrax maculatofasciatus spotted sand bass 1 Ophidion scrippsae basketweave cusk-eel 1 Physiculus spp. cod, codling, mora 1 Ophididae no. 2 -- 1 Unid. Carangidae jacks 3 Unid. Engraulidae anchovies 1 Unid. Haemulidae grunts 11 Unid. Labridae wrasses 1 Unid. Mycthophidae lanternifishes 71 Unid. Ophididae cusk-eel 1 Unid. Scianidae drums 9 Unid. Scorpaenidae scorpionfishes 18 Unid. Serranidae sea bass 6 Unid. Triglidae searobins 1 Unid. Fishes 16 Unid. Cephalopods 4 Unid. fishes (very eroded) 231 Remains of cephalopods 14 Remains of crustaceans 162 Scientific name Common name PO Trichiurus lepturus Pacific cutlassfish 15.041 Sardinops caeruleus Pacific sardine 10.341 Porichthys spp. midshipman 11.163 Myctophid no. 1 lanternfish 13.984 Engraulis mordax northern anchovy 5.053 Scomber japonicus Pacific mackerel 4.935 Cetengraulis mysticetus anchoveta 1.763 Loliolopsis diomedeae squid 4.113 Trachurus symmetricus jack mackerel 4.818 Merlaccius spp. Pacific whiting 2.938 Pontinus spp. scorpionfish 3.055 Enoploteuthid no. 1 squid 2.703 Caelorinchus scaphopsis shoulderspot 2.938 Octopus sp. no. 1 octopus 1.998 Sebastes macdonaldi Mexican rockfish 2.115 Citharichthys sp no. 1 sanddab 2.703 Fish species no. 1 -- 2.938 Haemulopsis leuciscus white grunt 2.468 Peprilus snyderi salema butterfish 3.878 Prionotus spp. searobin 1.058 Prionotus stephanophrys lumptail searobin 1.645 Argentina sialis Pacific argentine 1.528 Fish species no. 2 -- 3.173 Hemanthias peruanus splittail bass 2.585 Fish species no. 3 -- 0.705 Micropogonias ectenes slender croaker 1.058 Lepophidium spp. cusk-eel 0.353 Fish species no. 4 -- 0.353 Sebastes exsul buccanner rockfish 1.175 Cranchiid no. 2 Squid 1.410 Haemulon flaviguttatum yellowspotted grunt 0.353 Selar crumenophthalmus bigeye scad 1.410 Fish species no. 5 -- 2.233 Paralabrax sp. no. 1 sea bass 0.588 Synodus sp. no. 3 lizardfish 0.353 Lepophidium prorates prowspine cusk-eel 0.470 Fish species no. 6 -- 0.588 Synodus sp. no. 1 lizardfish 1.175 Octopus sp, no. 2 octopus 0.828 Gonatus berryi squid 0.588 Mugil cephalus striped mullet 0.118 Paranthias colonus Pacific creole-fish 0.118 Balistes polylepis finescale triggerfish 0.470 Physiculus nematopus charcoal mora 1.410 Hemanthias spp. sea bass 0.705 Fish species no. 7 -- 0.940 Uroconger varidens conger eel 0.588 Larimus spp. drum 0.705 Apogon retrosella barspot cardinalfish 0.470 Dosidicus gigas squid 0.588 Merluccius productus Pacific whiting 0.118 Fish species no. 8 -- 0.235 Synodus sp. no. 2 lizardfish 0.588 Scorpaena sonorae Sonora scorpionfish 0.118 Eucinostomus spp. mojarra 0.588 Fish species no. 9 -- 0.353 Cynoscion reticulatus striped weakfish 0.823 Fish species no. 10 -- 0.118 Caulolatilus affinis bighead tilefish 0.353 Paralabrax auroguttatus goldspotted sand bass 0.470 Fish species no. 11 -- 0.235 Cranchiid no. 5 squid 0.118 Bodianus diplotoenia mexican hogfish 0.118 Prionotus sp. no. 1 searonbin 0.235 Strongylura exilis california needlefish 0.118 Synodus spp. lizardfish 0.588 Fish species no. 12 -- 0.353 Fish species no. 13 -- 0.118 Fish species no. 14 -- 0.118 Fish species no. 15 -- 0.118 Fish species no. 16 0.235 Porichthys sp. 1 midshipman 0.118 Fish species no. 17 -- 0.353 Calamus brachysomus Pacific porgy 0.235 Fish species no. 18 -- 0.118 Fish species no. 19 -- 0.235 Ophididae no. 1 -- 0.118 Fish species no. 20 -- 0.353 Sebastes sinesis blackmouth rockfish 0.118 Symphurus spp. tonguefish 0.118 Fish species no. 21 -- 0.118 Pronotogrammus multifasciatus threadfin bass 0.235 Fsh species no. 22 -- 0.235 Fish species no. 23 -- 0.118 Orthopristis reddingi Bronze-striped grunt 0.118 Fish species no. 24 -- 0.118 Fish species no. 25 -- 0.118 Cranchiidae no. 4 squid 0.235 Fish species no. 26 -- 0.235 Histioteuthis heteropsis squid 0.118 Scorpaenidae no. 1 -- 0.118 Fish species no. 27 -- 0.235 Fish species no. 28 -- 0.118 Fish species no. 29 -- 0.118 Cranchiidae no. 3 squid 0.118 Bollmannia spp. goby 0.118 Fish species no. 30 -- 0.118 Cranchiidae no. 1 squid 0.118 Paralabrax maculatofasciatus spotted sand bass 0.118 Ophidion scrippsae basketweave cusk-eel 0.118 Physiculus spp. cod, codling, mora 0.118 Ophididae no. 2 -- 0.118 Unid. Carangidae jacks 0.353 Unid. Engraulidae anchovies 0.118 Unid. Haemulidae grunts 1.293 Unid. Labridae wrasses 0.118 Unid. Mycthophidae lanternifishes 8.343 Unid. Ophididae cusk-eel 0.118 Unid. Scianidae drums 1.058 Unid. Scorpaenidae scorpionfishes 2.115 Unid. Serranidae sea bass 0.705 Unid. Triglidae searobins 0.118 Unid. Fishes 1.880 Unid. Cephalopods 0.470 Unid. fishes (very eroded) 27.145 Remains of cephalopods 1.645 Remains of crustaceans 19.036 Scientific name Common name IIMP Trichiurus lepturus Pacific cutlassfish 16.392 Sardinops caeruleus Pacific sardine 10.020 Porichthys spp. midshipman 9.297 Myctophid no. 1 lanternfish 7.901 Engraulis mordax northern anchovy 5.199 Scomber japonicus Pacific mackerel 3.403 Cetengraulis mysticetus anchoveta 2.404 Loliolopsis diomedeae squid 2.399 Trachurus symmetricus jack mackerel 2.273 Merlaccius spp. Pacific whiting 2.206 Pontinus spp. scorpionfish 1.842 Enoploteuthid no. 1 squid 1.754 Caelorinchus scaphopsis shoulderspot 1.728 Octopus sp. no. 1 octopus 1.614 Sebastes macdonaldi Mexican rockfish 1.496 Citharichthys sp no. 1 sanddab 1.220 Fish species no. 1 -- 1.153 Haemulopsis leuciscus white grunt 1.093 Peprilus snyderi salema butterfish 1.025 Prionotus spp. searobin 0.855 Prionotus stephanophrys lumptail searobin 0.814 Argentina sialis Pacific argentine 0.754 Fish species no. 2 -- 0.737 Hemanthias peruanus splittail bass 0.602 Fish species no. 3 -- 0.592 Micropogonias ectenes slender croaker 0.547 Lepophidium spp. cusk-eel 0.532 Fish species no. 4 -- 0.511 Sebastes exsul buccanner rockfish 0.505 Cranchiid no. 2 Squid 0.501 Haemulon flaviguttatum yellowspotted grunt 0.468 Selar crumenophthalmus bigeye scad 0.431 Fish species no. 5 -- 0.384 Paralabrax sp. no. 1 sea bass 0.373 Synodus sp. no. 3 lizardfish 0.341 Lepophidium prorates prowspine cusk-eel 0.335 Fish species no. 6 -- 0.324 Synodus sp. no. 1 lizardfish 0.324 Octopus sp, no. 2 octopus 0.308 Gonatus berryi squid 0.274 Mugil cephalus striped mullet 0.265 Paranthias colonus Pacific creole-fish 0.265 Balistes polylepis finescale triggerfish 0.245 Physiculus nematopus charcoal mora 0.244 Hemanthias spp. sea bass 0.234 Fish species no. 7 -- 0.233 Uroconger varidens conger eel 0.189 Larimus spp. drum 0.174 Apogon retrosella barspot cardinalfish 0.173 Dosidicus gigas squid 0.171 Merluccius productus Pacific whiting 0.167 Fish species no. 8 -- 0.159 Synodus sp. no. 2 lizardfish 0.132 Scorpaena sonorae Sonora scorpionfish 0.130 Eucinostomus spp. mojarra 0.129 Fish species no. 9 -- 0.127 Cynoscion reticulatus striped weakfish 0.124 Fish species no. 10 -- 0.122 Caulolatilus affinis bighead tilefish 0.114 Paralabrax auroguttatus goldspotted sand bass 0.110 Fish species no. 11 -- 0.102 Cranchiid no. 5 squid 0.097 Bodianus diplotoenia mexican hogfish 0.087 Prionotus sp. no. 1 searonbin 0.087 Strongylura exilis california needlefish 0.083 Synodus spp. lizardfish 0.146 Fish species no. 12 -- 0.074 Fish species no. 13 -- 0.065 Fish species no. 14 -- 0.060 Fish species no. 15 -- 0.058 Fish species no. 16 0.056 Porichthys sp. 1 midshipman 0.052 Fish species no. 17 -- 0.049 Calamus brachysomus Pacific porgy 0.043 Fish species no. 18 -- 0.042 Fish species no. 19 -- 0.041 Ophididae no. 1 -- 0.040 Fish species no. 20 -- 0.039 Sebastes sinesis blackmouth rockfish 0.039 Symphurus spp. tonguefish 0.038 Fish species no. 21 -- 0.036 Pronotogrammus multifasciatus threadfin bass 0.029 Fsh species no. 22 -- 0.027 Fish species no. 23 -- 0.021 Orthopristis reddingi Bronze-striped grunt 0.020 Fish species no. 24 -- 0.020 Fish species no. 25 -- 0.016 Cranchiidae no. 4 squid 0.014 Fish species no. 26 -- 0.014 Histioteuthis heteropsis squid 0.014 Scorpaenidae no. 1 -- 0.011 Fish species no. 27 -- 0.011 Fish species no. 28 -- 0.010 Fish species no. 29 -- 0.008 Cranchiidae no. 3 squid 0.006 Bollmannia spp. goby 0.006 Fish species no. 30 -- 0.005 Cranchiidae no. 1 squid 0.004 Paralabrax maculatofasciatus spotted sand bass 0.003 Ophidion scrippsae basketweave cusk-eel 0.003 Physiculus spp. cod, codling, mora 0.003 Ophididae no. 2 -- 0.002 Unid. Carangidae jacks 0.141 Unid. Engraulidae anchovies 0.248 Unid. Haemulidae grunts 0.509 Unid. Labridae wrasses 0.005 Unid. Mycthophidae lanternifishes 4.895 Unid. Ophididae cusk-eel 0.098 Unid. Scianidae drums 0.643 Unid. Scorpaenidae scorpionfishes 1.078 Unid. Serranidae sea bass 0.176 Unid. Triglidae searobins 0.002 Unid. Fishes 1.819 Unid. Cephalopods 0.373 Unid. fishes (very eroded) Remains of cephalopods Remains of crustaceans Table 3 Prey of California sea lions having IIMP index values [greater than or equal to] 10% in at least one sampling period for seven rookeries in the Gulf of California, Mexico. Blank indicate that species were not recorded in diet; "--" means unavailable data. Prey species June 1995 San Pedro Engraulis mordax 29.7 Martir myctophid no. 1 29.0 Porichthys spp. 11.2 Prionotus stephanophrys 0.6 enopleoteuthid no. 1 Sebastes macdonaldi Haeumulopsis leuciscus San Esteban Trichiurus lepturus 24.9 Sardinops caeruleus 10.0 unid. Myctophidae 13.8 myctophid no. 1 2.8 enopleoteuthid no. 1 Sebastes macdonaldi fish species no. 1 El Rasito Porichthys spp. 26.2 unid. Myctophidae 16.4 Scomber japonicus 13.8 Pontinus spp. 11.5 Octopus sp. no. 1 11.5 myctophid no. 1 6.6 Sardinops caeruleus 1.6 Trachurus symmetricus Caelorinchus scaphopsis Los Machos Sardinops caeruleus 21.0 Scomber japonicus 19.0 Merluccius spp. 15.4 Trichiurus lepturus 11.7 Sebastes macdonaldi 1.8 Los Cantiles Porichthys spp. 66.7 Trichiurus lepturus 22.2 Engraulis mordax 3.7 myctophid no. 1 Sardinops caeruleus fish species no. 3 unid. Fishes unid. Scianidae Lepophidium spp. Loliolopsis diomedeae Isla Granito Engraulis mordax 49.3 Trichiurus lepturus 22.0 unid. Myctophidae 1.7 Sardinops caeruleus 0.9 Porichthys spp. 0.5 Cithartchthys sp. no. 1 Isla Lobos Cetengraulis mysticetus 32.7 Trichiurus lepturus 25.2 Porichthys spp. 9.0 Loliolopsis diomedeae 4.9 Peprilus snyderi Prey species September 1995 San Pedro Engraulis mordax Martir myctophid no. 1 10.5 Porichthys spp. 2.0 Prionotus stephanophrys 3.3 enopleoteuthid no. 1 27.3 Sebastes macdonaldi 10.4 Haeumulopsis leuciscus San Esteban Trichiurus lepturus 3.4 Sardinops caeruleus 34.1 unid. Myctophidae 3.4 myctophid no. 1 11.8 enopleoteuthid no. 1 16.9 Sebastes macdonaldi 2.1 fish species no. 1 El Rasito Porichthys spp. 4.0 unid. Myctophidae 1.5 Scomber japonicus 3.2 Pontinus spp. 5.1 Octopus sp. no. 1 myctophid no. 1 5.1 Sardinops caeruleus 40.1 Trachurus symmetricus 22.0 Caelorinchus scaphopsis 3.6 Los Machos Sardinops caeruleus 64.1 Scomber japonicus Merluccius spp. Trichiurus lepturus 5.4 Sebastes macdonaldi Los Cantiles Porichthys spp. 15.5 Trichiurus lepturus 38.2 Engraulis mordax 0.4 myctophid no. 1 17.6 Sardinops caeruleus 6.8 fish species no. 3 0.9 unid. Fishes 0.9 unid. Scianidae Lepophidium spp. Loliolopsis diomedeae Isla Granito Engraulis mordax 7.8 Trichiurus lepturus 70.1 unid. Myctophidae 1.1 Sardinops caeruleus Porichthys spp. 18.2 Cithartchthys sp. no. 1 Isla Lobos Cetengraulis mysticetus 0.1 Trichiurus lepturus 27.7 Porichthys spp. 10.3 Loliolopsis diomedeae 2.2 Peprilus snyderi 23.5 Prey species January 1996 San Pedro Engraulis mordax 2.1 Martir myctophid no. 1 9.0 Porichthys spp. 6.8 Prionotus stephanophrys 3.3 enopleoteuthid no. 1 0.8 Sebastes macdonaldi Haeumulopsis leuciscus 16.7 San Esteban Trichiurus lepturus Sardinops caeruleus unid. Myctophidae 4.3 myctophid no. 1 8.9 enopleoteuthid no. 1 Sebastes macdonaldi 9.7 fish species no. 1 1.7 El Rasito Porichthys spp. 2.3 unid. Myctophidae 8.1 Scomber japonicus 3.7 Pontinus spp. 4.1 Octopus sp. no. 1 2.9 myctophid no. 1 21.4 Sardinops caeruleus 0.9 Trachurus symmetricus 5.0 Caelorinchus scaphopsis 13.5 Los Machos Sardinops caeruleus 16.8 Scomber japonicus 10.9 Merluccius spp. 8.2 Trichiurus lepturus Sebastes macdonaldi 11.3 Los Cantiles Porichthys spp. Trichiurus lepturus Engraulis mordax 14.3 myctophid no. 1 4.8 Sardinops caeruleus 19.0 fish species no. 3 14.3 unid. Fishes 19.0 unid. Scianidae 14.3 Lepophidium spp. 14 Loliolopsis diomedeae Isla Granito Engraulis mordax Trichiurus lepturus 2.0 unid. Myctophidae 12.6 Sardinops caeruleus 18.7 Porichthys spp. 4.6 Cithartchthys sp. no. 1 21.7 Isla Lobos Cetengraulis mysticetus 6.8 Trichiurus lepturus 15.8 Porichthys spp. 23.2 Loliolopsis diomedeae 11.6 Peprilus snyderi 5.2 Prey species May 1996 San Pedro Engraulis mordax 0.5 Martir myctophid no. 1 20.5 Porichthys spp. 15.5 Prionotus stephanophrys 10.9 enopleoteuthid no. 1 Sebastes macdonaldi Haeumulopsis leuciscus 6.0 San Esteban Trichiurus lepturus 3.0 Sardinops caeruleus 4.2 unid. Myctophidae 10.9 myctophid no. 1 18.8 enopleoteuthid no. 1 Sebastes macdonaldi 1.4 fish species no. 1 11.0 El Rasito Porichthys spp. unid. Myctophidae 16.4 Scomber japonicus 2.5 Pontinus spp. 10.9 Octopus sp. no. 1 7.7 myctophid no. 1 6.8 Sardinops caeruleus 7.3 Trachurus symmetricus 23.4 Caelorinchus scaphopsis 10.5 Los Machos Sardinops caeruleus -- Scomber japonicus -- Merluccius spp. -- Trichiurus lepturus -- Sebastes macdonaldi -- Los Cantiles Porichthys spp. Trichiurus lepturus 53.1 Engraulis mordax myctophid no. 1 Sardinops caeruleus fish species no. 3 unid. Fishes unid. Scianidae Lepophidium spp. Loliolopsis diomedeae 21.1 Isla Granito Engraulis mordax Trichiurus lepturus 100.0 unid. Myctophidae Sardinops caeruleus Porichthys spp. Cithartchthys sp. no. 1 Isla Lobos Cetengraulis mysticetus 27.8 Trichiurus lepturus 14.3 Porichthys spp. 35.5 Loliolopsis diomedeae 3.5 Peprilus snyderi Prey species Average San Pedro Engraulis mordax 8.1 Martir myctophid no. 1 17.3 Porichthys spp. 8.9 Prionotus stephanophrys 4.5 enopleoteuthid no. 1 7.0 Sebastes macdonaldi 2.6 Haeumulopsis leuciscus 5.7 San Esteban Trichiurus lepturus 7.8 Sardinops caeruleus 12.1 unid. Myctophidae 8.1 myctophid no. 1 10.6 enopleoteuthid no. 1 4.2 Sebastes macdonaldi 3.3 fish species no. 1 3.2 El Rasito Porichthys spp. 8.1 unid. Myctophidae 10.6 Scomber japonicus 5.8 Pontinus spp. 7.9 Octopus sp. no. 1 5.5 myctophid no. 1 10.0 Sardinops caeruleus 12.5 Trachurus symmetricus 12.6 Caelorinchus scaphopsis 6.9 Los Machos Sardinops caeruleus 34.0 Scomber japonicus 10.0 Merluccius spp. 7.9 Trichiurus lepturus 5.7 Sebastes macdonaldi 4.4 Los Cantiles Porichthys spp. 20.6 Trichiurus lepturus 28.4 Engraulis mordax 4.6 myctophid no. 1 5.6 Sardinops caeruleus 6.5 fish species no. 3 3.8 unid. Fishes 5.0 unid. Scianidae 3.6 Lepophidium spp. 3.5 Loliolopsis diomedeae 5.3 Isla Granito Engraulis mordax 14.3 Trichiurus lepturus 48.5 unid. Myctophidae 3.9 Sardinops caeruleus 4.9 Porichthys spp. 5.8 Cithartchthys sp. no. 1 5.4 Isla Lobos Cetengraulis mysticetus 16.9 Trichiurus lepturus 20.8 Porichthys spp. 19.5 Loliolopsis diomedeae 5.6 Peprilus snyderi 7.2
We wish to thank Secretaria de Marina, Armada An earlier brand name for laptop computers from Compaq. The line was noted for its quality and innovative features. de Mexico, for its great support during the field activities, and the Consejo Nacional de Ciencia y Tecnologia (CONACYT CONACYT Consejo Nacional de Ciencia y Tecnología (National Board of Science and Technology; Mexico, Bolivia, Paraguay) ) for funding this study under grant number 26430-N. The Secretaria de Medio Ambiente, Recursos Naturales y Pesca (SEMARNAP SEMARNAP Secretaria del Medio Ambiente, Recursos Naturales y Pesca (México, Secretariat of the Environment, Natural Resources and Fisheries) ) provided permits for field work (DOO.-700-(2)01104 and DOO.-700(2).-1917). We would like to thank Robert Lavenberg and Jeff Siegel for allowing us the use of otoliths from the collection at the Natural Museum History of Los Angeles Los Angeles (lôs ăn`jələs, lŏs, ăn`jəlēz'), city (1990 pop. 3,485,398), seat of Los Angeles co., S Calif.; inc. 1850. County and also Lawrence Barnes for his logistical lo·gis·tic also lo·gis·ti·cal
1. Of or relating to symbolic logic.
2. Of or relating to logistics.
[Medieval Latin logisticus, of calculation support during the stay of first author at Los Angeles; we also thank Manuel Nava for allowing us the use of otoliths from the collection in Tecnologico de Monterrey, Campus Guaymas. We are also grateful to Unai Markaida for his assistance in prey identification based on the examination of cephalopods beaks. We thank Mark Lowry fur commenting on an earlier draft of the paper, Norman Silverberg for reviewing the manuscript in English, and two anonymous reviewers fur their valuable suggestions and criticism. The first author would like to thank Centro Interdisciplinario de Ciencias Marinas-IPN for a scholarship (PIFI, Programa Institucional para la Formacion de Investigadores) assigned for postgraduate postgraduate
after first degree graduation, the registerable degree in veterinary science.
may be a research degree, e.g. PhD, or a course-work masterate with a vocational bias, or any combination of these. studies.
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According to the United States Census Bureau, the CDP has a total area of 3.2 km² (1.2 mi²), all land. . Los Angeles County Mus Muş (msh), city (1990 pop. 44,019), capital of Muş prov., E Turkey. It is in a region with many vineyards. Founded c.400 B.C., it was an important town of Armenia. ., Cont. in Sci. (119):1-16.
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Any of the exclusively aquatic placental mammals constituting the order Cetacea. They are found in oceans worldwide and in some freshwater environments. Modern cetaceans are grouped in two suborders: about 70 species of toothed whales (Odontoceti) and 13 species of stomachs and their importance in interpreting feeding habits. J. Fish. Res. Board Canada. 25(12):2561-2574.
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Garcia-Rodriguez, F. J.
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1999. Cambios espaciales y estacionales en la estructura trofica del lobe marina de California, Zalophus caliornianus, en la region de la grande islas, Golfo de California. Tesis de Maestria, 73 p. CICIMAR. La Paz, B.C.S, Mexico.
1983. An evaluation of California sea lion scat samples as indicators of prey importance. Master's thesis, 50 p. San Francisco San Francisco (săn frănsĭs`kō), city (1990 pop. 723,959), coextensive with San Francisco co., W Calif., on the tip of a peninsula between the Pacific Ocean and San Francisco Bay, which are connected by the strait known as the Golden State Univ., San Francisco, CA.
1978. The use of Pielou's method to determine sample size in food studies. In Fish food habits studies: proceedings of the second Pacific Northwest technical workshop (S. J. Lipovsky and C. A. Simenstad, eds.), p 56-61. Washington Sea Grant Publication, Seattle, WA.
1973. Trophic diversity measurement in sympatric sym·pat·ric
Occupying the same or overlapping geographic areas without interbreeding. Used of populations of closely related species. predatory predatory
pertaining to predator.
the hunting of birds, mice and small reptiles by cats and the hunting and herding behavior of dogs, often facilitated in a pack. species. Ecology 54(4):885-890.
1987. Marine mammal A marine mammal is a mammal that is primarily ocean-dwelling or depends on the ocean for its food. Mammals originally evolved on land, but later marine mammals evolved to live back in the ocean. faeces samples as indicators of prey importance--a source of error in bioenergetics bioenergetics,
n 1. system in which natural healing is enhanced by creating harmony between the patient's body and the natural environment.
2. studies. Sarsia 72:255-260.
Jobling, M., and A. Breiby.
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1986a. Diving behavior of Galapagos fur seals. In Fur seals: maternal strategies on land and at sea (R. L. Gentry and G. L. Kooyman, eds), p. 186-195. Princeton Univ. Press, New Jersey, NJ.
1986b. Diving behavior of Galapagos sea lions. In Fur seals--maternal strategies on land and at sea (R. L. Gentry and G. L. Kooyman, eds.), p. 209-220. Princeton Univ. Press, Princeton, NJ.
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An island of southern California in the Santa Barbara Islands south of Santa Catalina Island. , California, 1981-86. Fish. Bull. 88:509-521.
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1991. Seasonal and annual variability in the diet of California sea lions Zalophus californianus at San Nicolas Island San Nicolas Island (sometimes shortened as San Nic or SNI) is the most remote of California's Channel Islands. It is part of Ventura County. The 14,562 acre (58.93 km² or 22. , California, 1981-86. Fish. Bull. 89:331-336.
Ludwig, J. A., and J. F. Reynolds.
1988. Statistical ecology: a primer prim·er
A segment of DNA or RNA that is complementary to a given DNA sequence and that is needed to initiate replication by DNA polymerase. on methods and computing computing - computer , 338 p. John Wiley John Wiley may refer to:
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of , NY.
Magurran, A. E.
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1999. At-sea distribution and diving behavior of California sea lion females from San Miguel Island, California. In Proceeding of the filth Filth
See also Dirtiness.
held 3,000 oxen, uncleaned for 30 years; Hercules’ fifth labor: washes out dung by diverting a river. [Gk. and Rom. Myth. California islands symposium (D. R. Browne, K. L. Mitchell, and H. W. Chancy chanc·y
adj. chanc·i·er, chanc·i·est
1. Uncertain as to outcome; risky; hazardous.
2. Random; haphazard.
3. Scots Lucky; propitious. , eds.), p. 407-402. Santa Barbara Museum of Natural History, Santa Barbara, CA.
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fisheating; said of birds. pinnipeds. J. Wildl. Manag. 49: 910-912.
1993. A survey of perciform Per´ci`form
a. 1. (Zool.) Pertaining to the Perciformes. otoliths and their interest for phylogenetic phy·lo·ge·net·ic
1. Of or relating to phylogeny or phylogenetics.
2. Relating to or based on evolutionary development or history. analysis, with an iconographic i·co·nog·ra·phy
n. pl. i·co·nog·ra·phies
a. Pictorial illustration of a subject.
b. The collected representations illustrating a subject.
2. synopsis A summary; a brief statement, less than the whole.
A synopsis is a condensation of something—for example, a synopsis of a trial record. of the Percoidci. Bull. Mar. Sci. 52(1):220-239.
Olesiuk, P. F.
1993. Annual prey consumption by harbor seals (Phoca vitulina Phoca vitulina
see harbor seal. ) in the Strait of Georgia Noun 1. Strait of Georgia - the strait separating Vancouver Island from the Canadian mainland , British Columbia British Columbia, province (2001 pop. 3,907,738), 366,255 sq mi (948,600 sq km), including 6,976 sq mi (18,068 sq km) of water surface, W Canada. Geography
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1988. Habitos alimentarios y censos globules del lobe marine (Zalophus californianus) en el Islote El Racito, Bahia de las Animus Animus - ["Constraint-Based Animation: The Implementation of Temporal Constraints in the Animus System", R. Duisberg, PhD Thesis U Washington 1986]. , Baja California. Mexico durante octubre 1986-1987. Tesis de Licenciatura, 59 p. Universidad Autonoma de Baja California. Ensenada, B.C.
Pitcher, K. W.
1980. Stomach contents and feces feces
or excrement or stools
Solid bodily waste discharged from the colon through the anus during defecation. Normal feces are 75% water. The rest is about 30% dead bacteria, 30% indigestible food matter, 10–20% cholesterol and other fats, as indicators of harbour seal harbour seal
Nonmigratory, earless seal (Phoca vitulina) found throughout the Northern Hemisphere. Harbour seals are whitish or grayish at birth, generally gray with black spots as adults. The adult male may reach a length of about 6 ft (1. , Phoca vitulina, foods in the Gulf of Alaska Noun 1. Gulf of Alaska - a gulf of the Pacific Ocean between the Alaska Peninsula and the Alexander Archipelago
Pacific, Pacific Ocean - the largest ocean in the world . Fish. Bull. 78:797-798.
Robison, B. H.
1972. Distribution of the midwater fishes of the Gulf of California. Copeia (1972):449-61.
Roper, C. F. E., and R. E. Young.
1975. Vertical distribution of pelagic cephalopods. Smithsonian Contribution to Zoology 209(51):31.
1992. Contribucion al conocimiento de los habitos alimentarios del lobo marino de California Zalophus californianus en las Islas Angel de la Guarda y Granito, Golfo de California, Mexico. Tesis de Licenciatura, 63 p. Universidad Nacional Autonoma de Mexico. Mexico, D.F.
Tollit, D. J., M. J. Steward, P. M. Thompson, G. J. Pierce, M. B. Santos, and S. Hughes.
1997. Species and size differences in the digestion of otoliths mid beaks: implications for estimates of pinniped diet composition. Call. J. Fish. Aquat. Sci. 54:105-119.
Walker, B. W.
1960. The distribution and affinities of the marine fish fauna fauna
All the species of animals found in a particular region, period, or special environment. Five faunal realms, based on terrestrial animal species, are generally recognized: Holarctic, including Nearactic (North America) and Paleartic (Eurasia and northern Africa); of the Gulf of California. System. Zool. 9(3):123-133.
Wolff, G. A.
1984. Identification and estimation of size from the beaks of 18 species of cephalopods from the Pacific Ocean. NOAA NOAA
National Oceanic and Atmospheric Administration
Noun 1. NOAA - an agency in the Department of Commerce that maps the oceans and conserves their living resources; predicts changes to the earth's environment; Tech. Rep. NMFS NMFS National Marine Fisheries Service
NMFS National Mortality Followback Survey
NMFS Network Multimedia File System
NMFS Nested Mount File System 17, 49 p.
Francisco J. Garcia-Rodriguez
Centro Interdisciplinario de Ciencias Marinas-Instituto Politecnico Nacional
Departamento de Biologia Marina y Pesquerias
Apdo. Postal 592
La Paz, Baja California Sur, Mexico
E-mail address (for F. J. Garcia-Rodriguez): firstname.lastname@example.org
Manuscript approved for publication 9 October 2003 by Scientific Editor.
Manuscript received 20 October 2003 at NMFS Scientific Publications Office.