SEASONAL MOVEMENTS AND DIVE PATTERNS OF JUVENILE BAIKAL SEALS, <i>PHOCA SIBIRICA</i>

Stewart, Brent S.; Петров, Е. А.; Baranov, Eugene A.; Ivanov, A. M.

doi:10.1111/j.1748-7692.1996.tb00065.x

Cited by 42 publications

(13 citation statements)

References 34 publications

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“…The Baikal seals have been reported to migrate freely over large distances in the lake (Petrov 1997), and may indeed cover considerable distances in a short time (Watanabe et al 2004). The seals from the 2 locations in the present study cannot therefore be considered as belonging to 2 separate colonies foraging on different prey, as was the case for the grey seals in Scottish waters studied by Walton & Pomeroy (2003).…”

Section: Gender and Age Differencesmentioning

confidence: 99%

“…In 2000 the population was calculated at 75 800 seals of ≥1 yr of age (Petrov 2000). The seals have adapted to the unique conditions of the deep and cold Lake Baikal, with its extended periods of ice cover, stable food reserves and the specific spatial and vertical distribution of the seals' main prey (Stewart et al 1997). Adaptations at the ecological and physiological level have resulted in morphological changes to the Baikal seal, which can be distinguished from the ringed and Caspian seals by karyotype, structure of the skull and skeleton, and dimorphism of the sexes (Pastukhov 1993).…”

Section: Introductionmentioning

confidence: 99%

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Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

Grahl‐Nielsen

Halvorsen²,

Bodoev³

et al. 2005

Mar. Ecol. Prog. Ser.

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The fatty acid (FA) composition was determined in the blubber of 5 adult Baikal seals Phoca sibirica caught in July 2001, nine 1-mo old pups caught in April 2002, and 25 adults and fetuses from 3 of these, caught in October 2002, all along the SE shores of Lake Baikal, eastern Siberia. For comparison, FA in the blubber of ringed seals P. hispida, the closest marine relative of the Baikal seal, caught along the ice edge around Svalbard during 1999 and 2000 were also analyzed. The FA of the main prey of the Baikal and ringed seals, the endemic golomyanka Comephorus baikalensis and polar cod Boreogadus saida, respectively, were also studied. The same suite of FA was found in all samples. Saturated FA (SFA) with branched chains, all n6 polyunsaturated FA (PUFA) and 18:3n3 and 20:3n3 were more abundant in the blubber of the Lake Baikal seal and in the golomyanka than in the blubber of the marine ringed seal and marine fishes. In contrast, the relative levels of monounsaturated FAs (MUFA) with 20 and 22 carbons and polyunsaturated 20:5n3 were lower in the Baikal species than in the Svalbard species. The FA composition of the inner blubber was significantly different from the FA composition of the outer blubber in both species. Despite large differences in FA composition between Baikal and ringed seal blubbers, vertical differences were manifested in the same FA: MUFA with 14, 16 and 18 carbons were present in higher relative abundance in the outer than in the inner layer. In both species all the other quantitatively important FA had lower or equal relative values in the outer layer. The FA composition of the seals' blubber differed from that of their main prey. The difference was, however, smaller between prey and inner blubber than between prey and outer blubber. The FA composition of the inner blubber of adults showed temporal differences. Since the change from prey to blubber in relative concentration occurred in the same direction for all but 5 FA, the selection of FA during deposition in the inner blubber was similar for the 2 species, even though there was a large difference between the general FA composition of the freshwater and marine lipids. The FA composition in the blubber of adults, pups and fetuses differed.

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Section: Gender and Age Differencesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

Grahl‐Nielsen

Halvorsen²,

Bodoev³

et al. 2005

Mar. Ecol. Prog. Ser.

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“…In previous research, satellite-linked transmitters were deployed on four juvenile Baikal seals to obtain histograms of dive depth and duration, composed of six bins for each parameter (Stewart et al, 1996). The most frequent dive depth and duration bins were 10-50·m and 2-6·min, respectively.…”

Section: Diving Behavior Of Baikal Sealsmentioning

confidence: 99%

Body density affects stroke patterns in Baikal seals

Watanabe

Baranov

Sato

et al. 2006

Journal of Experimental Biology

104

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SUMMARY Buoyancy is one of the primary external forces acting on air-breathing divers and it can affect their swimming energetics. Because the body composition of marine mammals (i.e. the relative amounts of lower-density lipid and higher-density lean tissue) varies individually and seasonally,their buoyancy also fluctuates widely, and individuals would be expected to adjust their stroke patterns during dives accordingly. To test this prediction, we attached acceleration data loggers to four free-ranging Baikal seals Phoca sibirica in Lake Baikal and monitored flipper stroking activity as well as swimming speed, depth and inclination of the body axis(pitch). In addition to the logger, one seal (Individual 4) was equipped with a lead weight that was jettisoned after a predetermined time period so that we had a set of observations on the same individual with different body densities. These four data sets revealed the general diving patterns of Baikal seals and also provided direct insights into the influence of buoyancy on these patterns. Seals repeatedly performed dives of a mean duration of 7.0 min(max. 15.4 min), interrupted by a mean surface duration of 1.2 min. Dive depths were 66 m on average, but varied substantially, with a maximum depth of 324 m. The seals showed different stroke patterns among individuals; some seals stroked at lower rates during descent than ascent, while the others had higher stroke rates during descent than ascent. When the lead weight was detached from Individual 4, the seal increased its stroke rate in descent by shifting swimming mode from prolonged glides to more stroke-and-glide swimming, and decreased its stroke rate in ascent by shifting from continuous stroking to stroke-and-glide swimming. We conclude that seals adopt different stroke patterns according to their individual buoyancies. We also demonstrate that the terminal speed reached by Individual 4 during prolonged glide in descent depended on its total buoyancy and pitch, with higher speeds reached in the weighted condition and at steeper pitch. A simple physical model allowed us to estimate the body density of the seal from the speed and pitch(1027-1046 kg m-3, roughly corresponding to 32-41% lipid content,for the weighted condition; 1014-1022 kg m-3, 43-47% lipid content,for the unweighted condition).

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“…Baltic ringed seals (Härkönen et al 2008b), Arctic ringed seal (Gjertz et al 2000) and Baikal seal (Stewart et al 1996). In the shallow north Caspian the majority of dives appeared to make use of the full bathymetry.…”

Section: Individual Variation In Foraging and Diving Behaviourmentioning

confidence: 99%

Individual variation in seasonal movements and foraging strategies of a land-locked, ice-breeding pinniped

Dmitrieva¹,

Jüssi²,

Jüssi³

et al. 2016

Mar. Ecol. Prog. Ser.

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Marine mammal satellite telemetry studies can provide important tests of movement and foraging theory. Here we present the first satellite tracking study of Caspian seals Pusa caspica, an endangered, ice-breeding phocid seal, endemic to the Caspian Sea. The Caspian Sea is one of the most variable habitats inhabited by any pinniped species, and lacks competing large piscivores. Under such conditions foraging theory predicts that individual variation in foraging strategy may develop to reduce intra-species competition. We deployed 75 Argos satellite tags from 2009 to 2012 on adult seals of both sexes, and used state-space modelling to describe movement, and behavioural states. During winter in all years most individuals were mobile within the icepack, making repeated trips into open water outside the ice field, with only brief stationary periods that may have been related to breeding activity. During summer 2011, 60% of tagged animals migrated into the mid and southern Caspian, while the remainder spent the ice-free season in the north. Summer foraging locations were not restricted by proximity to haul-out sites, with animals spending more than 6 months at sea. Maximum dive depths exceeded 200 m, and maximum duration was greater than 20 min, but 80% of dives were shallower than 15 m and shorter than 5 min. Hierarchical cluster analysis identified 3 distinct groups of summer dive behaviour, comprising shallow, intermediate and deep divers, which were also spatially exclusive, suggesting potential niche partitioning and individual specialisation on prey or habitat types. The results can contribute to assessment of impacts from anthropogenic activities and to designation of protected areas encompassing critical habitats.

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SEASONAL MOVEMENTS AND DIVE PATTERNS OF JUVENILE BAIKAL SEALS, PHOCA SIBIRICA

Cited by 42 publications

References 34 publications

Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

Fatty acid composition of blubber of the Baikal seal Phoca sibirica and its marine relative, the ringed seal P. hispida

Body density affects stroke patterns in Baikal seals

Individual variation in seasonal movements and foraging strategies of a land-locked, ice-breeding pinniped

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