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Seasonal activity budget of adult baltic ringed seals.

Harkonen T, Jüssi M, Jüssi I, Verevkin M, Dmitrieva L, Helle E, Sagitov R, Harding KC - PLoS ONE (2008)

Bottom Line: Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks.Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn.The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.

View Article: PubMed Central - PubMed

Affiliation: Swedish Museum of Natural History, Stockholm, Sweden. tero.harkonen@nrm.se

ABSTRACT
Although ringed seals are important components in oceanic and fresh water ecosystems at high latitudes, little is known about how they exploit these harsh environments. Seasonal activity and diving behaviour of 19 adult Baltic ringed seals were studied by satellite telemetry. We elaborated an activity budget for ten months of the year, extending over the period from moult to the breeding season. Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks. Both the mean duration and the mean depth of dives peaked in June and July. Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn. Less than one percent of dives exceeded 10 min in females, while 10% of male dives lasted longer than 10 min in June to September. Less than one percent of dives lasted for more than 25 min. Both females and males were most active during day time and hauled out predominantly during the night. Activity patterns during the summer are suggested to be correlated to energy accumulation and prey availability. The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.

Show MeSH
Diurnal haul-out behaviour of male and female ringed seals in the Gulf of Finland and Estonian coastal waters.Data from “Timelines” pooled for main seasons: Summer (May–Aug), Autumn (Sep–Nov) and Winter (Dec–March).
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pone-0002006-g007: Diurnal haul-out behaviour of male and female ringed seals in the Gulf of Finland and Estonian coastal waters.Data from “Timelines” pooled for main seasons: Summer (May–Aug), Autumn (Sep–Nov) and Winter (Dec–March).

Mentions: Estimates of time spent hauled out on land was provided by two partly independent alternatives; Timelines and the SLR (“dry & wet” transmissions). Timelines provide fine-scale data on the proportion of time spent in water over a 24 hour period, but only the last six transmitters deployed had this option. As shown by time-line data, seals of both sexes spent more time at sea during the light hours of day in all seasons, and they hauled out predominantly at night (Fig. 7). In winter (Dec–Feb) females hauled out more than 40% of their time during the night, compared with 25% of the time for males.


Seasonal activity budget of adult baltic ringed seals.

Harkonen T, Jüssi M, Jüssi I, Verevkin M, Dmitrieva L, Helle E, Sagitov R, Harding KC - PLoS ONE (2008)

Diurnal haul-out behaviour of male and female ringed seals in the Gulf of Finland and Estonian coastal waters.Data from “Timelines” pooled for main seasons: Summer (May–Aug), Autumn (Sep–Nov) and Winter (Dec–March).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2289877&req=5

pone-0002006-g007: Diurnal haul-out behaviour of male and female ringed seals in the Gulf of Finland and Estonian coastal waters.Data from “Timelines” pooled for main seasons: Summer (May–Aug), Autumn (Sep–Nov) and Winter (Dec–March).
Mentions: Estimates of time spent hauled out on land was provided by two partly independent alternatives; Timelines and the SLR (“dry & wet” transmissions). Timelines provide fine-scale data on the proportion of time spent in water over a 24 hour period, but only the last six transmitters deployed had this option. As shown by time-line data, seals of both sexes spent more time at sea during the light hours of day in all seasons, and they hauled out predominantly at night (Fig. 7). In winter (Dec–Feb) females hauled out more than 40% of their time during the night, compared with 25% of the time for males.

Bottom Line: Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks.Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn.The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.

View Article: PubMed Central - PubMed

Affiliation: Swedish Museum of Natural History, Stockholm, Sweden. tero.harkonen@nrm.se

ABSTRACT
Although ringed seals are important components in oceanic and fresh water ecosystems at high latitudes, little is known about how they exploit these harsh environments. Seasonal activity and diving behaviour of 19 adult Baltic ringed seals were studied by satellite telemetry. We elaborated an activity budget for ten months of the year, extending over the period from moult to the breeding season. Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks. Both the mean duration and the mean depth of dives peaked in June and July. Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn. Less than one percent of dives exceeded 10 min in females, while 10% of male dives lasted longer than 10 min in June to September. Less than one percent of dives lasted for more than 25 min. Both females and males were most active during day time and hauled out predominantly during the night. Activity patterns during the summer are suggested to be correlated to energy accumulation and prey availability. The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.

Show MeSH