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Seasonal movements and diving of ringed seals, Pusa hispida, in the Western Canadian Arctic, 1999-2001 and 2010-11.

ABSTRACT. Satellite-linked time-depth recorders were deployed on 17 ringed seals in early summer in 1999, 2000, and 2010, near the Inuvialuit community of Ulukhaktok, Northwest Territories, Canada. The main objective was to investigate movements and diving behaviour of ringed seals in the Prince Albert Sound (PAS) and eastern Amundsen Gulf (EAG) regions in relation to season, sex, and age-class. Tags performed well on 16 of 17 tagged seals, with average tracking periods of 256 d (SD 69, range: 134-352). Adult and subadult ringed seals traveled considerable distances throughout the open water period (mean = 5844 km, range = 1232-9473 km), using vast home ranges during this season, shown with 90 Percent Volume Contours (90 PVC) averaging 122 854 [km.sup.2] for subadults, 76658 [km.sup.2] for adult females, and 21649 [km.sup.2] for adult males. Overall, adults spent 69.5% of the observed open water days in foraging/resident mode and 22.8% in traveling mode. The majority (75%) of total observed foraging/resident time was spent in PAS and EAG. Eleven of 12 adults made forays outside EAG and PAS to distant areas, including Prince of Wales Strait (7 seals), Viscount Melville Sound (6), Minto Inlet (4), western Amundsen Gulf (4), and six other zones. During open water season, subadults spent 36.8% traveling and 51.4% foraging/ resident, also mainly in EAG and PAS (61%), but they all traveled to distant zones, eight in total. During winter, all tagged adult females, five of seven adult males, and three of four subadults returned to PAS and EAG to occupy winter home ranges that were on average 15% of the size of the open water home range (mean winter ranges = 1299 [km.sup.2] for adult males, 3599 [km.sup.2] for adult females, and 30499 [km.sup.2] for subadults). The mean size of the winter home ranges varied by as much as a factor of 10 among the three winters examined. Seal movements were most restricted during the winters with extensive fast ice (1999-2000 and 2010-11) and least restricted during the winter (2000-01) when fast ice did not form in EAG. In winter, adult females made more long, deep dives than either adult males or subadults.

Key words: ringed seal; satellite telemetry; Amundsen Gulf; Prince Albert Sound; Beaufort Sea; sea ice; diving; foraging

RESUME. Des enregistreurs de profondeur temporelle en liaison avec un satellite ont ete deployes sur 17 phoques anneles au debut des etes 1999, 2000 et 2010 pres de la collectivite inuvialuite d'Ulukhaktok, dans les Territoires du Nord- Ouest, au Canada. L'objectif principal consistait a etudier les deplacements et les comportements de plongee des phoques anneles des regions du detroit de Prince-Albert (DPA) et de la partie est du golfe Amundsen (EGA) en fonction de la saison, du sexe et de la classe d'age. Les etiquettes ont donne des resultats valables dans le cas de 16 des 17 phoques etiquetes, les periodes moyennes de pistage ayant atteint 256 jours (SD 69, etendue : 134-352). Les phoques anneles adultes et jeunes adultes parcouraient des distances considerables pendant la periode des eaux libres (moyenne = 5 844 km, etendue = 1232-9473 km), dans de vastes domaines vitaux au cours de la saison. Les pourcentages du volume des contours de 90 (90 PVC) s'etablissaient en moyenne a 122854 [km.sup.2] pour les jeunes adultes, a 76658 [km.sup.2] pour les femelles adultes et a 21649 [km.sup.2] pour les males adultes. Dans l'ensemble, les adultes ont passe 69,5 % des journees observees en eaux libres en mode d'alimentation et de residence, et 22,8 % en mode de deplacement. La majorite (75 %) du temps total observe en mode d'alimentation et de residence etait dans le DPA et l'EGA. Onze adultes sur 12 se sont aventures en dehors du DPA et de l'EGA pour atteindre des endroits eloignes, dont le detroit du Prince-de-Galles (7 phoques), le detroit du Vicomte de Melville (6), l'anse Mintot (4), l'ouest du golfe Amundsen (4) et six autres zones. Pendant la saison des eaux libres, les jeunes adultes ont passe 36,8 % du temps en mode de deplacement et 51,4 % du temps en mode d'alimentation ou de residence, egalement principalement dans le DPG et l'EGA (61 %), mais ils se sont tous rendus dans des zones eloignees, huit en tout. Durant l'hiver, toutes les femelles adultes etiquetees, cinq males adultes sur sept et trois jeunes adultes sur quatre sont revenus dans le DPA et l'EGA pour occuper des domaines vitaux hivernaux qui correspondaient, en moyenne, a 15 % de la taille du domaine vital en eaux libres (etendues moyennes des domaines hivernaux = 1299 [km.sup.2] pour les males adultes, 3 599 [km.sup.2] pour les femelles adultes et 30 499 [km.sup.2] pour les jeunes adultes). La taille moyenne des domaines vitaux hivernaux a varie en fonction d'un facteur de 10 au cours des trois hivers a l'etude. Le deplacement des phoques etait plus restreint pendant les hivers ou la glace etait rapide (1999-2000 et 2010-2011) et moins restreint pendant l'hiver (2000-2001) ou la glace rapide ne s'est pas formee dans l'EGA. L'hiver, les femelles adultes faisaient plus de plongees longues et profondes que les males adultes ou les jeunes adultes.

Mots cles : phoque annele; telemesure satellitaire; golfe Amundsen; detroit de Prince-Albert; mer de Beaufort; glace de mer; plongee; alimentation

Traduit pour la revue Arctic par Nicole Giguere.


As apex predators, marine mammals provide a means to assess changes in the marine ecosystem (Moore et al., 2014). Knowledge of critical habitats used by marine mammals may help researchers to predict how seals will respond to climate change or other factors that alter habitat (Laidre et al., 2008). However, attempts to relate changes in the environment (Melling et al., 2005; Serreze et al., 2007; Walsh, 2008) to a marine mammal's responses to those changes, are often constrained by lack of baseline information about the species, its life history, prey, and critical habitats (Moore et al., 2014). Although the distribution, reproduction, and biology of the ringed seal (Pusa hispida) in the western Canadian Arctic have been the subject of scientific study for four decades (Stirling et al., 1977, 1982; Smith, 1987; Kingsley and Byers, 1998; Harwood et al., 2000, 2012b; Stirling, 2002), the seasonal movements and habitat use of ringed seals in Amundsen Gulf have not been explicitly examined to date.

The ringed seal is abundant throughout the circumpolar Arctic and feeds at several trophic levels (Dunbar, 1941; Lowry et al., 1978, 1980; Smith, 1987). Ringed seals are opportunistic predators, but adults prey mainly on Arctic cod, Boreogadus saida, throughout the Western Arctic at all times of the year (Johnson et al., 1966; Smith, 1987; Smith and Harwood, 2001). During the ice-free months, some adults travel considerable distances away from their fast ice breeding habitats in order to feed (Smith, 1987; Heide-Jorgensen et al., 1992; Teilmann et al., 1999; Freitas et al., 2008a), and ringed seals are well known to prey on zooplankton where they are abundant (e.g., Lowry et al., 1978, 1980; Harwood, 1989). There is growing evidence that adults are philopatric, returning annually to the same winter and breeding sites in the fast ice prior to freeze-up in the fall (Smith and Hammill, 1981; Kelly et al., 2010).

Subadult ringed seals in the Western Arctic population undertake extensive migrations during the fall, probably in response to food availability (Smith, 1987; Harwood et al., 2012a). In other areas, their migrations have been linked to advancing and retreating ice (e.g., Svalbard, Freitas et al., 2008a; Chukchi/Bering Seas, Crawford et al., 2011). Seasonal and age-specific prey preferences are known (Lowry et al., 1980; Thiemann et al., 2008; Young et al., 2010), as are patterns of habitat use, which differ within and among populations (Freitas et al., 2008a; Crawford et al., 2011; Carroll et al., 2013). In the Western Arctic, the less experienced subadults (< 6 y) appear to rely most heavily on invertebrates (Smith, 1987; Smith and Harwood, 2001; authors' unpubl. data), and occupy peripheral areas of the core breeding habitat in Prince Albert Sound (Smith, 1987).

The large bays with stable fast ice in eastern Amundsen Gulf (EAG), including northwest Prince Albert Sound (PAS), where the present study was staged, provide prime habitat for ringed seals of the Western Arctic (Smith, 1987). The stable fast ice provides ringed seals with a substrate for pupping, lactation, haul-out, and protection from weather and predators (Smith and Stirling, 1975, 1978; Smith, 1976, 1987; Stirling et al., 1982; Lydersen and Gjertz, 1987; Hammill and Smith, 1989; Hammill et al., 1991; Smith and Lydersen, 1991; Furgal et al., 1996). The availability of food during the winter is also paramount to their reproductive success (Smith, 1987; Lydersen, 1991). The crucial combination of suitable sea ice and abundant winter prey is what makes eastern Amundsen Gulf and western Prince Albert Sound a core breeding habitat for ringed seals in Canada's Western Arctic (Smith, 1987).

Satellite tracking of ringed seals from other areas has revealed seasonal differences in habitat use strategies, which have included relatively restricted movements in winter and early spring (Harwood et al., 2007; Kelly et al., 2010), forays to distant areas in summer (Teilmann et al., 1999; Born et al., 2004), and extensive migrations during fall and winter (Freitas et al., 2008a; Crawford et al., 2011; Harwood et al., 2012a). Given the circumpolar range of ringed seals, which occupy areas as diverse as lakes, pack ice, and fast ice (Finley et al., 1983; Smith et al., 1991; Born et al., 2004), the annual feeding strategies of this species are clearly diverse and adaptable to a variety of habitat types.

The objectives of the present study were to investigate movements, habitat use, and diving behaviour of ringed seals in relation to season, age-class, and sex. We accomplished this through the use of satellite telemetry and with the assistance of local Inuvialuit harvesters.


Capture and Tagging

In total, 17 ringed seals were captured, measured, weighed, and tagged with satellite-linked transmitters (SDR-10, SDR-16, SPLASH) in June and July of 1999, 2000, and 2010. The tags, manufactured by Wildlife Computers Ltd. (Redmond, Washington, USA), send data to polar orbiting satellites. Data are then retrieved via the Argos system (Harris et al., 1990). Tags collected and relayed information on movement (geographic positions) and diving data of the instrumented animals. Tags were applied after the moult, 7-14 days prior to breakup of fast ice in NW Prince Albert Sound.

The seals were captured from shore at a site known locally as "Orhohivik" (70[degrees]36' N; 117[degrees]18' W), which is located in NW Prince Albert Sound, 17 km east of the seal monitoring site (Harwood et al., 2012b) and approximately 25 km southeast of Ulukhaktok, NT (Fig. 1). They were captured using 229 mm (9") mesh cotton seal nets set perpendicular to shore (Smith et al., 1973) and monitored continuously during deployment. When a seal became entangled, it was immediately removed from the net and transported to the workstation on shore. Covering their heads with a tarp calmed the seals, and only gentle restraint was necessary. The pelage was cleaned with rubbing alcohol, and a tag was applied using approximately 150 mL of five-minute epoxy glue (Christensen and Jensen, 1977; Priede and French, 1991; Heide-Jorgensen et al., 1992; McConnell et al., 1992; Testa, 1994; Burns and Castellini, 1998; Teilmann et al., 1999; Harwood et al., 2007). Tags were attached to the back between the two front flippers. Both the glue and transmitter were warmed with a hair dryer before deployment to initiate hardening of the glue, which took about 20 min. Standard length, sex, weight, and claw age were determined for all seals that were live-captured. Seals were classified as adults or subadults in the field by external examination and estimation of claw age. Seals were classified as adults if their claw age was greater than six (Smith, 1987; Harwood et al., 2012b).

After the tag application process was completed and the glue had dried, the seals were released at the capture site. The Animal Care Committee of Canada's Department of Fisheries and Oceans approved all animal handling procedures used in this study. The tag and epoxy attachment is shed when the animal next moults, in this case in May or June of the following year, and regeneration of the pelage has been noted in seals observed after the moult (Testa, 1994).

The transmitters were cast in epoxy. SDR tags (1999, 2000) measured 15 cm x 10 cm x 3.5 cm, and weighed 170 g in seawater and approximately 600 g in air. SPLASH tags (2010) were 78 mm x 51 mm x 25 mm and weighed 32 g in seawater and 114 g in air. The 1999 transmitters were programmed to transmit at a maximum of 500 transmissions per day, whereas the 2000 and 2010 tags transmitted for a maximum of 300 transmissions per day. Tags in 2010 were duty cycled to transmit every second day in order to conserve battery life.

The transmission repetition rate was 45 s at sea and 90 s when the seal was hauled out. The tag's saltwater switch ensured that transmissions occurred when the tag was in the air (when the seal surfaced to breathe or was hauled out). The pressure transducer had a resolution of [+ or -]1 m and an accuracy of +1% of the depth reading. Time and pressure (depth) were sampled every 42.5 s and stored in user-defined six-hour bins (n = 10 in 1999 and 2000, n = 14 in 2010). Data collected included maximum depth and duration of each dive (sensor capability to 500 m in 1999 and 2000 and to 1000 m in 2010).

Data Processing and Analysis

Data about locations, dives, and transmitter status were collected via the Argos Location Service Plus system (Fancy et al., 1988; Harris et al., 1990). We used Satpak 3.0 in 1999-2001 and DAP 3.00.0143 (Wildlife Computers) in 2010-11 to download data received from Argos into Excel. SAS V.8.0 (1990) and XLStat 13.6 were used for statistical analyses.

To remove locations with suspect accuracy, all locations (quality B, A, 0, 1, 2, 3) were filtered using the sdafilter developed by Freitas et al, (2008b) in the package Argosfilter in R version 2.5.1 (R Development Core Team, 2014). The filter has separate velocity and angular components. First, locations that indicated swim speeds exceeding 2 m/s were removed, since 3.3 km/h (approximately 0.91 m/s) is the upper limit of observed rate of movement for ringed seals (Teilmann et al., 1999). The angular component of the filter is used to remove locations with a high degree of location error that fall far from the line of travel, but are still within the above threshold velocity. Using default settings, locations with angles less than 15[degrees] within 2.5 km of the track line were removed. Within 2.5 and 5 km of the track line, locations were removed if they resulted in angles of less than 25[degrees]. Finally, we removed any locations that fell on land.

Distance Traveled and Size of Seasonal Home Ranges

The minimum distance traveled was calculated as the distance between two successive filtered locations. The sum of these minimum distances was used to estimate distance traveled per seal and per season. A Kernel Density Estimator (KDE) was used to determine the spatial extent of home ranges used by adult and subadult seals in open water season and in winter (e.g., Silverman, 1986; Worton, 1989; Wand and Jones, 1995), and we refer to the 90 PVC as the "home range." The KDE is a non-parametric method for calculating the probability that an animal occurs within a defined area (Quakenbush et al., 2010). Smoothed cross-validation (SCV) was used for bandwidth selection (Quakenbush et al., 2010), separately for each seal and season, as described by Duong and Hazelton (2005) and using package "ks" (Duong, 2007) in R version 2.5.1. Percent Volume Contours (PVCs) used to visualize and compare the kernel densities (home ranges) of the tagged seals were derived from the KDE raster datasets (Sain et al., 1994; Seaman and Powell, 1996; Seaman et al., 1999; Gitzen and Millspaugh, 2003).

Since transmitters lasted different periods of time and did not transmit with equal frequency, we standardized the contributions made by individual seals over time for the kernel density estimation procedure. We did not want tags that contributed little information to have equal weight in the kernel densities; therefore, we weighted the contribution of individual seals according to the number of locations used to compute the kernel density for each seal. We selected the filtered location with the highest quality code from each of the four six-hour periods of each day. When multiple locations had the same location quality code, we selected the location that was transmitted the earliest within the time period. This procedure has the effect of spacing the accepted locations throughout the day and equalizing the contribution of information from tags that differed in transmission frequency.

Ice Conditions

The formation and persistence of fast ice is of particular interest in the study of ringed seals (Smith, 1987). The Canadian Ice Service maps fast ice weekly via satellite-image analysis to prepare regional ice charts (Environment Canada, 2013), on which fast ice is uniquely coded as 10/10 ice concentration. An area of ice is judged to be fast ice if the satellite reveals a flaw lead at its boundary with pack ice or no evidence of recently active leads. Correspondingly, we here judged breakup in the spring to have occurred when a lead (or area of generally light ice cover) at least 10 km wide persisted in EAG for one week or more. The number of days between the formation of fast ice in fall or winter, and the earliest date of breakup in spring was taken as the duration of the fast ice and referred to here as "winter." The (monthly) frequency of charting for the winters prior to 2004-05 would have the effect of negatively biasing these estimates of duration.

Using the annual estimated values of fast ice duration in EAG, we calculated the mean ([+ or -]SD) duration of fast ice for two decades, from 1991-92 to 2010-11. To examine the relationship between fast ice and the size of home ranges used by the tagged adult seals, we prepared a scatterplot and used a Pearson product moment correlation to compare the duration of fast ice in the winters for which we had tagged seals (1999-2000, 2000-01, 2010-11) to the individual home ranges used by those seals in the corresponding winters.

Behavioural State during Open Water

To distinguish areas where seals were in apparent foraging/resident mode, as opposed to making sustained, directional migrations, Bayesian state-space models (BSSMs) were run using the filtered location data (Hoenner et al., 2012). This type of model is commonly applied to animal movement ecology in terrestrial and aquatic ecosystems as a correlated random walk (Jonsen et al., 2013). The BSSM is a time-series method that consists of two stochastic models: (1) the process model (i.e., transition equation), which estimates the individual's current state such as geographic location and behavioural state given its previous state, and (2) the observation model, which relates the unobserved states estimated by the process model to the observed locations obtained from Argos data (Jonsen et al., 2005). Here, we fit a two-state switching BSSM, which allows movement parameters to "switch" between two behavioural state modes (e.g., traveling and foraging/resident), within a hierarchical framework (hBSSM) which improves parameter and location estimation and overall model fit (see Jonsen et al., 2005, 2006, and Mills Flemming et al., 2010 for further details). Before running the models, we classified ringed seals into six distinct groupings by age-class (i.e., adult and subadult) and year captured (i.e., 1999, 2000, and 2010). The hBSSM runs in discrete and regular time intervals to mitigate irregularity over time of observations obtained via ARGOS transmissions (Jonsen et al., 2005). A time step of 12 h was used for each model, which is a common approach with duty-cycled transmitters and in animals inhabiting ice-covered environments (Jonsen et al., 2007; Bestley et al., 2012), and 24 h periods are referred to here as "observed days." The mean estimates of behavioural state are continuous values between 1 (traveling) and 2 (foraging/resident); values of 1.35 or less were considered to represent traveling, values of 1.65 or more were deemed to represent residence or foraging, and values between 1.35 and 1.65 were considered uncertain. This approach, similar to that used by Jonsen et al. (2007), is considered conservative.

The hBSSM was implemented using the package bsam v0.44 (Jonsen et al., 2013) in R v3.0.3 (R Development Core Team, 2014), which runs Markov Chain Monte Carlo (MCMC) methods using Just Another Gibbs Sampler (JAGS). Each ringed seal grouping was run in two MCMC chains for 30000 iterations with a 20000 sample burn-in and thinned every 10 samples. Thus, every 10th sample from the remaining 10 000 was used for parameter estimation and to reduce autocorrelation. Chain convergence and autocorrelation for all hBSSM model runs were assessed visually via trace and autocorrelation plots and then estimated by Gelman and Rubin's potential scale reduction factor, which was less than 1.1.

Filtered locations were grouped into 13 geographic zones: EAG, western Amundsen Gulf, PAS, Coronation Gulf, Dolphin and Union Strait, Darnley Bay, Franklin Bay, Minto Inlet, Eastern Beaufort Sea, Prince of Wales Strait, Viscount Melville Sound, M'Clure Strait, and McClintock Channel (Fig. 2). Using hBSSMs, we tallied the number of days and type of modeled activity during the open water period for adults and subadults in each zone. The model interpolates estimates of behaviour and location for each 12 h period in the tracking period (Jonsen et al., 2005). During winter, uplinks were too sporadic for interpolation using hBSSMs, so filtered locations were tallied and plotted.


Because of the potential for sensor error in the upper 2 m of the water column, descents were considered dives only if they exceeded 4 m in depth and 1 min in duration. Data from the dive depth bins were pooled into five intervals (> 4-10 m, > 10-40 m, > 40-100 m, > 100-200, and > 200 m), as were data from the dive duration bins (> 1-5, > 5-10, > 10-18, > 18-24, and > 24 min). The mean ([+ or -] SD) proportion of dives in each interval for each six-hour diving record was calculated and plotted separately for open water and winter, and for adult males, adult females, and subadults, and presented in bar graphs. The mean proportion of dives in each time/depth interval of each six-hour record was compared among age/sex classes and seasons, using PROC GLM and a Duncan's Multiple Range test in SAS V.8 (1990).


Tag Performance and Sample Size

Seventeen seals were tagged near Ulukhaktok, NT (Fig. 1) during 28 June-1 July in 1999 (n = 4), 16-19 July in 2000 (n = 4), and 6-10 July 2010 (n = 9), immediately following breakup of the fast ice in EAG in those years (Table 1). Thirteen adults (6 females, 7 males) and 4 subadults (2 males and 2 females) were tagged and released. Tags performed well on 16 of 17 instrumented seals, and they were tracked during all four seasons. Fourteen tags transmitted for more than 200 days, and four of these transmitted for more than 300 days (Table 1). Battery voltages reported in the last transmissions indicated that battery power was not the reason for tag failure in any of the deployments (Kevin Ng, Wildlife Computers, pers. comm. 2013).

Animals were tracked from the time of tagging in June or July until October (no. of tags transmitting = 16), November (15), February (12), March (7), April (5), May (4) and June (3). We received only 13 transmissions from one of the adult females tagged (seal ID 15; Table 1), and those results are not included in any analyses (Table 1).

We obtained a total of 21 373 filtered positions, representing a minimum tracking distance of 93 507 km, from the 16 tagged seals (Table 1); the average was 1336 filtered locations per seal (range 338-2489). The proportion of all received locations accepted by the filtering procedure averaged 13% for the SDR tags (range 11%-31%) and 71% for the SPLASF1 tags (range 65%-78%; Table 1). Seals were tracked for an average of 256 days (SD 69, range 134-352). Overall, 81.5% of the filtered positions and 83.4% of the minimum distances tracked were in the open water period (Table 2). On average, open water locations were seven times as numerous as locations during periods of ice cover (range 1-17 times among individual tagged seals).

Movements and Size of Home Range, by Season

All but one of the tagged seals moved out of the capture area within days of tagging (Fig. 3a, b). The farthest distance that individual seals traveled from the tagging site ranged from 150 to 2383 km (average = 951 km; Table 1), and the minimum distance traveled during deployment averaged 5844 km (range = 1232-9473 km).

A subadult female (Fig. 3b, ID 44; Table 1) covered the longest distance between July 2010 and June 2011 by traveling north through Prince of Wales Strait, then circling Banks Island to the west, and eventually returning to overwinter less than 60 km from the tagging site (Fig. 3b). One adult female (2010, ID 46; Fig. 3a) followed a relatively linear track, starting in EAG. The seal moved in a northwestward direction for approximately 1000 km far into the offshore Beaufort Sea and then returned to EAG along an essentially identical route prior to freeze-up. At the end of the open water period, 13 tagged seals (10 of 12 adults and 3 of 4 subadults) eventually returned to PAS and EAG for wintering. The average distance between the tagging site and the last location in winter was 191 km (range 16-702 km; Table 1; Fig. 4a, b). Among all tagged individuals, the total distance tracked was lower during winter (average = 1037 km; range = 140-3302 km) than during the open water period (average = 4878 km; range = 1182-7503 km; Table 2).

During the open water season, tagged ringed seals used home ranges that were 6.6 times as large as winter home ranges (Table 2; mean 90 PVC winter = 9699 [km.sup.2]; mean 90 PVC open water = 64 141 [km.sup.2]). Open water home ranges were largest for subadults (n = 4, mean 90 PVC 122 854 [km.sup.2]), followed by adult females (n = 5, mean 90 PVC = 76658 [km.sup.2]), and smallest for adult males (n = 7; mean 90 PVC = 21 649 [km.sup.2]). In winter, the home ranges (mean 90 PVC) were smaller for every sex/age class (30499 [km.sup.2] for subadults, 3599 [km.sup.2] for adult females, and 1299 [km.sup.2] for adult males; Table 2).

The duration of the fast ice in eastern Amurtdsen Gulf averaged 51.4 d (61.8 SD; range 0-163 d) for the 20 winters between 1991-92 and 2010-11. Ice conditions in eastern Amundsen Gulf were variable during our three study years; fast ice persisted for 133 d in 1999-2000 and 98 d in 2010-11, but did not form at all in 2000-01. The size of winter 90 PVCs was negatively correlated with number of days of fast ice in winter ([R.sup.2] = -0.87094, df = 9, p < 0.05): seals used the smallest ranges in winters with persistent fast ice (Fig. 5) and the largest in 2000-01, when fast ice did not form.

During 1999-2000 and 2010-11, mean 90 PVCs were 432 [km.sup.2] and 695 [km.sup.2], respectively (Table 2). These figures contrast with those for the winter of 2000-01, when the mean 90 PVC was 4196 [km.sup.2], 10 times as large as in winter 1999-2000 and six times as large as in winter 2010-11. Ice was present in Amundsen Gulf in 2000-01, but never reached a solid sheet of 10/10 concentration. A shear zone remained active between Cape Parry and Cape Bathurst throughout the winter, and by 1 April, a large lead had formed off Ulukhaktok, which persisted until June. During that winter, two of the tagged seals (IDs 17 and 47) were tracked regularly within this lead.

Examining the behavioural mode of adults and subadults during the open water season revealed that adults spent 69.5% of the 1625 days observed in foraging/resident mode and 22.8% in traveling mode. Adults spent the majority (75%) of foraging/resident days in PAS and EAG (Fig. 3a, Table 3). Similarly, subadults spent 51.4% of 555 observed days foraging/resident, also mainly (61%) in PAS and EAG, and 36.8% of observed days traveling (Fig. 3b, Table 3). Eleven of 12 adults made forays to other zones during summer, traveling to distant areas most notably Viscount Melville Sound (6 of 12 seals) and the southern end of Prince of Wales Strait (7 of 12). There were also indications of seals in foraging/resident mode in McClintock Channel (1 of 12), Minto Inlet (4 of 12), Amundsen Gulf near Nelson Head (2 of 12), Darnley Bay (1 of 12), Dolphin and Union Strait (4 of 12), and offshore of Cape Bathurst (1 of 12) (Fig. 3a; Table 3). Subadults also used open water foraging areas located in Viscount Melville Sound (2 of 4 seals), offshore of the NW coast of Banks Island (1 of 4), southern Prince of Wales Strait (4 of 4), the Nelson Head area (3 of 4), Dolphin and Union Strait (4 of 4), and Coronation Gulf (2 of 4) (Fig. 3b, Table 3).

Most adults (12/14) overwintered in EAG and PAS (83% of all observed days, Fig. 6). They also used five other zones in winter, but the proportion of days in other areas was minor (16% in total). Three of four tagged subadults ultimately overwintered in EAG/PAS (31% of all observed days), but they also used six other zones during winter (28% in Coronation Gulf, and 40% in the other areas combined, Fig. 6).


Dive depth and duration records were available for 16 seals (> 10892 records), each record representing a six-hour interval with 6-10 bins of diving data. The diving records represented 239 041 dives, 84% during the open water period and 16% during the winter. Approximately half of the records were obtained from seven SDR tags deployed in 1999 and 2000 (113 015 dives) and half from the nine SPLASH tags deployed in 2010 (126026 dives). The deepest dives recorded ranged from 82 to 497 m for the SDR-tagged seals and from 156 to 542 m for those with SPLASH tags (Table 1). Three of nine 2010 tagged seals had recorded dives deeper than 500 m, although this involved very few records (< 0.7%).

Adult females dove to all depth intervals, but compared to adult males and subadults (Fig. 7), they had a significantly greater proportion of their dives in the 200-500 m depth interval in winter (32.7%; df = 2, 254, F = 20.33, p < 0.0001). There were no statistical differences detected between the dive depth patterns of adult males and subadults during the winter (df = 2, 770, F = 0.0582, p > 0.9511). In the open water period, however, subadults had a greater proportion of dives in the shallower (< 100 m) intervals (30.7% 10-40 m, df = 2,4046; F = 35.58, p < 0.0001; 31.1% in 40-100 m, df = 2, 4046; F = 9.28, p < 0.0001) than either adult males or adult females, as well as the fewest dives in the 200-500 m interval (13.6%, df = 2, 1644, F = 42.21, p < 0.0001).

Durations of adult female dives were mainly in the 1-5 min (36% open water, 26.7% winter) or 5-10 min intervals (50%, open water, 30.7% winter), with some dives in the 10-18 min interval (9.8% open water), but most often (16.8%) in winter (Fig. 8). The proportion of dives in the 10-18 min interval was significantly greater for adult females than for adult males (6.6%) or subadults (6.0%) during winter (df = 2, 539, F = 20.31, p < 0.0001). Adult males showed the same pattern as adult females in open water dive durations, which fell mainly in the 1-5 min (39.3%) and 5-10 min (27.3%) intervals. Subadults had statistically shorter dives than adult males or adult females during the open water period, with 49.2% in the 1-5 min interval (df = 2, 3982, F = 58.31 p < 0.0001) and 53.3 % in the 5-10 min interval (df = 2, 3089, F = 58.64, p < 0.0001).


This study brings together local expertise and knowledge with modern scientific methods to provide new information on the wide-ranging seasonal movements and diving behaviour of ringed seals in the Western Arctic. The extent of movements and the range of locations used by adult and subadult ringed seals during the open water season were much greater than had been previously thought for this population. The study also confirmed strong fidelity to core winter habitats for adults, and also to some extent for subadults. Our finding that adult females dive deeper and for longer periods than either males or subadults during winter suggests there are seasonal differences among sex/age classes. Although our sample size was not robust, particularly for subadults, and had temporal gaps in tag deployment years, the data collected in this study are unique and increase our understanding of the habitats used by this species in the western Canadian Arctic.

Movements and Diving: Open Water

Ringed seals fast during the annual spring moult, which occurs for several weeks during May-June or early July before the sea ice melts or degrades (Smith, 1987). During the open water period, which follows their moult, the seals do extensive foraging while they regain condition prior to the onset of winter and the next breeding season (Smith, 1987; Harwood and Stirling, 1992). In this study, all but one of the tagged seals used vast and variable ranges in the Western Arctic during the open water period, some making forays for thousands of kilometres to a multitude of geographic areas. Other studies have demonstrated the use of an extensive summer range by ringed seal adults (Teilmann et al., 1999; Gjertz et al., 2000; Born et al., 2004; Freitas et al., 2008a; Kelly et al., 2010), and our results show a similar pattern of habitat use in the Western Arctic.

During open water, PAS and EAG had the greatest proportion of observed days for both adults (75%) and subadults (61%), and both zones had indications that seals were mainly in foraging/resident mode. Tagged seals were also in foraging/resident mode in several other zones during open water (Fig. 2a, b). The diving activity of ringed seals in this and other studies was concentrated in the upper 200 m of the water column, with most dives lasting less than 10 minutes (e.g., Lydersen, 1991; Kelly and Wartzok, 1996; Gjertz et al., 2000; Born et al., 2004; Crawford et al., 2011).

We note that the tagged seals favoured some of the same geographic locations that bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas) use for feeding during late summer. Coincidence of bowhead whales and ringed seals has been documented previously for the Beaufort Sea (Flarwood, 1989; Flarwood and Stirling, 1992). Bowhead whales are well known for aggregating in later summer to feed on dense patches of zooplankton (Laidre et al., 2007; Walkusz et al., 2012), and in the present study, we observed adult and subadult ringed seals in foraging/resident mode in at least five of the same areas that bowheads use. These included Viscount Melville Sound (Heide-Jorgensen et al., 2011; ADFG, 2014), offshore of the NW coast of Banks Island (Harris et al., 2008), north of Cape Parry (Paulic et al., 2012), south of Nelson Head (Davis et al., 1982), and north of Cape Bathurst (Walkusz et al., 2012).

Tagged belugas, major consumers of Arctic cod (Quakenbush et al., in press), also made sustained and directional migrations to Viscount Melville Sound in late summer (Richard et al., 2001), remaining there for more than three weeks and making deep dives that indicated foraging. The coincidence of ringed seals, bowhead whales, and beluga whales in specific locations in this region contributes to an emerging picture of distant, offshore foraging habitats used by at least these three species. We urge further research and monitoring in such areas to identify oceanographic processes that produce and possibly sustain these habitats, so that regulators and managers are well positioned to ensure their protection given pending offshore developments (AANDC, 2012).

Movements and Diving: Winter

Following the open water period, 12 of 14 of our tagged adults and 3 of 4 of our tagged subadults returned to EAG and PAS areas, just prior to freeze-up. Fidelity to wintering areas has been indicated for adults in other populations (Smith and Hammill, 1981; Krafft et al., 2007; Kelly et al., 2010), although generally not to the same extent for subadults. While our sample size of subadults was small, those subadults tagged in the core habitats of EAG and PAS (Smith, 1987) did not disperse in fall to the same extent as has been observed in other studies (Bering/Chukchi, Crawford et al., 2011; Svalbard, Freitas et al., 2008a; Cape Parry, Harwood et al., 2012b). This finding may reflect the exceptionally productive character of EAG and PAS, which makes it a core habitat that is attractive to and capable of supporting subadults, as well as the breeding adults.

Within the wintering areas in EAG and PAS, the more restrictive movements of ringed seals appear moderated by the constraints of sea ice, a situation that has also been observed in other locations across the circumpolar Arctic (Teilmann et al., 1999; Gjertz et al., 2000; Born et al., 2004; Freitas et al., 2008a; Kelly et al., 2010). During winter 2000-01, the year when our tagged seals used the largest winter home ranges, persistent southeasterly winds pushed ice out of Amundsen Gulf and into the Beaufort Sea, and fast ice did not form. Our tagged seals used a feeding area that was approximately 10 times larger than that of the previous year and six times as large as in 2010-11. The winter conditions in 2000-01 indicated a tendency for open leads along the shear line on the southern side of Amundsen Gulf. This westward movement of pack ice would also have forced upwelling of nutrient-rich water from greater depth along the southern side of Amundsen Gulf, as discussed by Williams et al. (2006, 2008). Upwelling would be further strengthened to the east of Cape Bathurst because of the steep bottom gradient on the west side of Franklin Bay (Williams and Carmack, 2008). The consequent likelihood of higher primary and secondary productivity, combined with warm Atlantic-derived water here below 250 m depth, may have encouraged aggregations of Arctic cod near the seabed in Franklin Bay, such as the one observed during winter 2003-04 (Benoit et al., 2008). Born et al. (2004) also found the size of the winter home range varied among winters, in their case by a factor of three. The relationship of ice cover and its interaction with oceanographic features and bottom topography in governing the distribution of seal prey in winter is not understood. However, the ice apparently had a direct influence on the movements and distribution of ringed seals as evidenced by our variable results over three winters.

As long-lived and wide-ranging oceanic predators, marine mammals can provide clues to explain changes in the food web and ecosystem structure (Boyd, 2002; Moore, 2008; Williams et al., 2013; Moore et al., 2014). Since they respond to ecosystem variation with changes in body condition (Moore, 2008; Moore et al., 2014), trends in seal body condition are a direct and useful link to the year-to-year availability and quality of the seals' prey. More than 2500 harvested ringed seals were sampled from this area during 1971-79 (Smith, 1987) and 1992-2011 (Harwood et al., 2012b). That monitoring study found a significant and sustained temporal trend of decreasing body condition of ringed seals since 1994, occurring in all age/sex classes and measured in spring just after breakup. The results of the present tagging study allow the general inference that seals sampled in the Harwood et al. (2012b) monitoring study used winter habitats mainly in EAG and PAS. The present results, and spatial and temporal linkages between the tagging and monitoring studies, point to changes having occurred in the winter prey base of ringed seals in the EAG/ PAS area.

In our study, dives deeper than 200 m were infrequent in males and subadults during winter, although they occurred 33% of the time in adult females in winter. This pattern may represent the female's foraging efforts towards aggregations of Arctic cod in mid-water and demersal habitats and reflect the greater energetic demands of breeding females prior to pupping and nursing. Arctic cod are found in demersal, mid-water, and under-ice habitats (Dunbar, 1941; Gulliksen, 1984; Bradstreet et al., 1986; Mundy et al., 2009; Crawford et al., 2012). They can occur both as dense near-surface shoals (Welch et al., 1993; Benoit et al., 2008) and as non-schooling individuals (Bradstreet et al., 1986; Plop et al., 1997). The summer distribution of Arctic cod is not well documented in this or other regions, although two recent studies have advanced our knowledge of cod distribution in summer for the Beaufort and Chukchi Seas (Crawford et al., 2012; J. Reist, DFO, pers. comm, 2013). In August 2012, a near-bottom aggregation of Arctic cod was found at approximately 200-400 m depth, spanning the slope along the entire southern Canadian Beaufort Shelf (J. Reist, pers. comm. 2013). Also during late summer sampling, Crawford et al. (2012) report cod were abundant in the Beaufort and Chukchi Seas at 200-375 m depths, in demersal habitats, as well as in the upper 75 m of the water column.

Predicted and contemporary oceanographic and sea ice changes will influence the availability of seal prey and structuring of the food web (Tynan and DeMaster, 1997; Serreze et al., 2007; Bluhm and Gradinger, 2008; Comiso et al., 2008; Laidre et al., 2008; Walsh, 2008; Kovacs et al., 2011). Knowledge of habitats that the seals use for feeding in winter may contribute to our understanding of contemporary, sustained declines in seal body condition that have been observed in this area over the past two decades (Harwood et al., 2012b). We have as yet no detailed information about the distribution of Arctic cod in winter or the factors that control this distribution. The opportunity now exists, however, using satellite tags deployed on seals, to refine our understanding of the seasonal distribution of seals (Smith, 2001; Fedak, 2004; Lydersen et al., 2004), and at the same time study water masses that influence the distribution of cod. CTDs (recorders that measure conductivity, temperature, and depth) deployed on marine mammals have shown enormous potential for cost-effective, in situ oceanographic sampling in important foraging habitats used by the marine mammals (Lydersen et al., 2002). Well-funded, long-term research programs using ringed seals and other marine mammals as "educated oceanographic sampling platforms" could be a key to understanding the changes that are occurring in the Arctic marine ecosystem.


The efforts, experience and skills of the seal capture crew led to the successful conduct of this study. Special thanks to Diane Codere (EMC), and to Harold Wright, Roger Memorana, Jack Kataokyak, and David and Bella Kuptana, all of Ulukhaktok, Northwest Territories, for participating in the live capture of seals. Dr. Mike Hammill and Jean-Francois Gosselin, both of Canada's Department of Fisheries and Oceans (DFO), and Dr. John Citta, Alaska Department of Fish and Game, provided much appreciated advice and assistance with ARGOS, tags, and GIS. Funding for the fieldwork was provided by the Fisheries Joint Management Committee (FJMC), Devon Canada (Pete Millman), DFO, and the World Wildlife Fund (in 1999). DFO, Inuvik, NT provided support for delivery of the field program. The authors wish to thank Dr. Rick Crawford and three anonymous reviewers for providing constructive comments on the manuscript. The support of the Olokhaktomiut Hunters and Trappers Committee (HTC) was greatly appreciated throughout all aspects of the work.


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Lois A. Harwood, (1) Thomas G. Smith, (2) James C. Auld, (3) Humfrey Melling (4) and David J. Yurkowski (5)

(Received 2 October 2013; accepted in revised form 29 August 2014)

(1) Corresponding author: Department of Fisheries and Oceans, Science, 301 5204 50th Avenue, Yellowknife, Northwest Territories X1A 1E2, Canada;

(2) EMC Eco Marine Corporation, 5694 Camp Comfort Road, Garthby, Quebec G0Y 1B0, Canada

(3) CGIS Geomatic Solutions, 157 Adelaide, Lindsay, Ontario K9V 4M5, Canada

(4) Department of Fisheries and Oceans, Institute of Ocean Sciences, Sidney, British Columbia V8L 4B2, Canada

(5) University of Windsor, Great Lakes Institute for Environmental Research, Windsor, Ontario N9B 3P4, Canada

TABLE 1. Identifiers and platform transmitter terminal (PTT)
numbers, and biological and deployment data, for 17 ringed seals
instrumented with satellite-linked tags near Ulukhaktok following
breakup of the fast ice in 1999, 2000, and 2010.

Seal      PTT              Relative   Estimated age   Weight
id no.   number    Sex       age      (claw bands)     (kg)

12       5056     male     adult           7++        100.91
13       5092     male     adult           7++        84.55
14       11747    female   subadult        5          36.36
15       21212    female   adult           6++        52.27
16       23526    female   adult           6++        79.55
17       23527    male     adult           8          50.00
18       23528    male     subadult        2.5        36.36
19       23529    female   adult           6          50.45
41       44391    male     adult           6++        87.27
42       44392    female   adult           6++        74.09
43       44393    male     subadult        4+         41.36
44       44395    female   subadult        4+         47.73
45       44396    male     adult           6++        63.64
46       44397    female   adult           6++        61.82
47       44399    male     adult           6++        78.18
48       44400    female   adult           6++        69.09
49       44402    male     adult           6++        50.91

Seal      Standard      Axillary    Year tag    Type      Release
id no.   length (cm)   girth (cm)   deployed   of tag     date MDT

12           127          129         1999     SDR-10   20 June 1999
13           132          122         1999     SDR-10   08 June 1999
14           104          101         1999     SDR-10   01 July 1999
15           102          115         1999     SDR-10   28 June 1999
16           120          120         2000     SDR-16   19 July 2000
17           110           97         2000     SDR-16   17 July 2000
18           100           91         2000     SDR-16   16 July 2000
19           111          100         2000     SDR-16   16 July 2000
41           121          126         2010     SPLASH   09 July 2010
42           130          117         2010     SPLASH   06 July 2010
43           104           61         2010     SPLASH   04 July 2010
44           116           95         2010     SPLASH   10 July 2010
45           126          115         2010     SPLASH   06 July 2010
46           136          101         2010     SPLASH   06 July 2010
47           134          113         2010     SPLASH   06 July 2010
48           126          113         2010     SPLASH   10 July 2010
49           117          102         2010     SPLASH   05 July 2010

         Last                 Days from     Days with      No. of
Seal     transmission       first to last   filtered      filtered
id no.   date                 inclusive     positions     positions

12       05 March 2000           251           105           338
13       10 November 2000        136           106           421
14       02 February 2000        217           132           453
15       07 July 2000            10            5           na (1)
16       02 June 2001            319           170           840
17       15 June 2001            334           202          1287
18       21 February 2001        221           142          1454
19       26 October 2000         103           90            701
41       01 March 2011           236           158          1750
42       10 April 2011           279           182          1478
43       26 April 2011           297           184          2033
44       26 June 2011            352           224          1706
45       17 June 2011            347           221          2489
46       15 February 2011        225           146          1820
47       11 March 2011           249           161          1291
48       27 March 2011           261           170          1603
49       23 March 2011           262           161          1709
         Mean (2)                256           160          1336
         Total (2)                                          21373

         Last               Distance        %           Maximum
Seal     transmission       tracked     filtered        recorded
id no.   date                 (km)      location     dive depth (m)

12       05 March 2000        1232         11              82
13       10 November 2000     3707         14             465
14       02 February 2000     4391         13             443
15       07 July 2000          74          na              na
16       02 June 2001         6547         21             491
17       15 June 2001         6946         26             497
18       21 February 2001     4506         31             472
19       26 October 2000      4693         23             307
41       01 March 2011        5401         67             466
42       10 April 2011        6415         67             366
43       26 April 2011        8182         73             508
44       26 June 2011         9473         65             524
45       17 June 2011         8738         77             542
46       15 February 2011     7653         78             490
47       11 March 2011        4045         75             156
48       27 March 2011        6399         67             392
49       23 March 2011        5179         70             318
         Mean (2)             5844
         Total (2)           93507

         Last               Distance between   Farthest distance
Seal     transmission        first and last      from tagging
id no.   date                 signal (km)          site (km)

12       05 March 2000             34                 150
13       10 November 2000          79                 900
14       02 February 2000          16                 330
15       07 July 2000              48                 60
16       02 June 2001             167                 480
17       15 June 2001             166                 400
18       21 February 2001         457                 560
19       26 October 2000           95                 720
41       01 March 2011             85                 710
42       10 April 2011            248                1251
43       26 April 2011            245                1344
44       26 June 2011             102                1812
45       17 June 2011             280                1653
46       15 February 2011          82                2383
47       11 March 2011            702                 995
48       27 March 2011             61                 676
49       23 March 2011            378                 845
         Mean (2)
         Total (2)

(1) na = not available.

(2) Does not include seal 15 (PTT 21212).

TABLE 2. Filtered locations and size of individual 90 PVC for adult
females, adult males, and subadults during open water and ice-
covered periods.

                             Date ice
                  Seal    formed in east
Year tagged      id no.   Amundson Gulf

Adult females:
2000               16     23 October
2000               19     23 October
2010               42     15 November
2010               46     15 November
2010               48     15 November
Adult males:
1999               12     25 October
1999               13     25 October
2000               17     23 October
2010               41     15 November
2010               45     15 November
2010               47     15 November
2010               49     15 November
1999               14     25 October
2000               18     23 October
2010               44     15 November
2010               43     15 November

                                 Open water

                 No. filtered     Distance        90 PVC
Year tagged       locations     tracked (km)   ([km.sup.2])

Adult females:
2000                  510           4349          11729
2000                  701           4787          15819
2010                 1265           5448          89736
2010                 1698           7503         215770
2010                 1368           5795          50238
Adult males:
1999                  301           1182            954
1999                  381           3466          11795
2000                  630           3708           9382
2010                 1619           5257           8847
2010                 1729           7582          54049
2010                 1015           3192          30026
2010                 1612           5015          36492
1999                  377           3667          14632
2000                 1319           4227          18853
2010                 1078           6136         298620
2010                 1809           6738         159312

                 No. filtered     Distance        90 PVC
Year tagged       locations     tracked (km)   ([km.sup.2])

Adult females:
2000                 330            2198            3745
2000                  nd              nd              nd
2010                 213             956           10055
2010                 122             140             257
2010                 235             597             338
Adult males:
1999                  37              50             178
1999                  40             241             686
2000                 657            3238            4647
2010                 131             141              16
2010                 760            1127             509
2010                 276             850            3009
2010                  97             141              46
1999                  76             878            5003
2000                 135             314             842
2010                 628            3302           87640
2010                 224            1379           28512

TABLE 3. Number of days (% of total tracking days) in open water
period on which adult and subadult ringed seals were observed
foraging/resident (F/R) or traveling in each of 13 geographic zones.
No. of seals = number of seals contributing to all behaviour states
indicated for each zone. See Figure 2 caption for geographic area

                             Adults (n = 12)

Location       F/R       Traveling    Uncertain    No. seals

EBS            13 (1%)      13 (4%)       2 (1%)        2
MS              1 (0%)       0 (0%)       0 (0%)        1
MC             11 (1%)      24 (7%)       1 (1%)        2
VMS            37 (3%)     67 (19%)     16 (12%)        6
PWS            19 (2%)     53 (15%)       7 (5%)        7
CO              0 (0%)       0 (0%)       6 (4%)        1
DUS             3 (0%)      12 (3%)     31 (24%)        4
MI             62 (6%)      10 (3%)       4 (3%)        4
PAS          539 (48%)     63 (18%)     32 (24%)       12
EAG          305 (27%)    104 (29%)     31 (24%)       12
WAG            49 (4%)       9 (2%)       2 (1%)        4
FB             37 (3%)       4 (1%)       1 (1%)        2
DB             53 (5%)       3 (0%)       1 (1%)        1
Total      1129 (100%)   362 (100%)   134 (100%)

                           Subadults (n = 4)

Location       F/R       Traveling    Uncertain    No. seals

EBS          42 (15%)      15 (7%)       3 (5%)        1
MS             0 (0%)       4 (2%)       0 (0%)        1
MC             0 (0%)       0 (0%)       0 (0%)        0
VMS           12 (4%)      11 (5%)       5 (8%)        2
PWS            7 (2%)     33 (16%)       6 (8%)        4
CO            20 (7%)      12 (6%)       5 (8%)        2
DUS          27 (10%)     22 (11%)     10 (15%)        4
MI              4(1%)       1 (0%)       1 (2%)        2
PAS         111 (39%)     29 (14%)     16 (24%)        4
EAG          61 (22%)     61 (30%)     14 (22%)        4
WAG            1 (0%)      14 (7%)       4 (6%)        2
FB             0 (0%)       0 (0%)       0 (0%)        0
DB             0 (0%)       2 (1%)       2 (3%)        1
Total      285 (100%)   204 (100%)    66 (100%)

FIG. 6. Percentage of tracking days when adult and subadult seals were
observed in each zone during the winters of 1999-2000, 2000-01 and

             Adults (n = 12)   Subadults (n = 4)

EBS                0%                 10%
MS                 0%                  0%
MC                 0%                  0%
VMS                0%                  0%
PWS                0%                  1%
CG                 0%                 28%
DUS                2%                 16%
MI                 3%                  1%
PAS               28%                  7%
EAG               55%                 24%
WAG                8%                 12%
FB                 1%                  0%
DB                 2%                  0%

Note: Table made from bar graph.
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Author:Harwood, Lois A.; Smith, Thomas G.; Auld, James C.; Melling, Humfrey; Yurkowski, David J.
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Date:Jun 1, 2015
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