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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
Activity budget for female ringed seals in the Bothnian Bay.Data pooled for four animals. Percentages of time diving (>2 m) extracted from time-at-depth data, and proportions of time hauled out from the “SLR”.
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pone-0002006-g010: Activity budget for female ringed seals in the Bothnian Bay.Data pooled for four animals. Percentages of time diving (>2 m) extracted from time-at-depth data, and proportions of time hauled out from the “SLR”.

Mentions: Data is only available for months November to March in this region, and we summarize the activities of females in the Bothnian Bay in Fig. 10. Females in this area dived deeper in late autumn and winter than both females and males in the two southern areas (chi-square: p<0.0001 in both cases). Here 13% of dives in January were deeper than 40 m, a pattern maintained over the winter since 17% and 23% of dives exceeded 40 m in February and March, respectively. A significantly different pattern (chi-square: p<0.0001 compared with both males and females in the southern areas) was also seen in the duration of dives where only 52% (Jan) to 64% (Feb) of dives in the winter were shorter than 2 min. Here 27% and 16% of dives lasted longer than 5 min in January and February, respectively.


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)

Activity budget for female ringed seals in the Bothnian Bay.Data pooled for four animals. Percentages of time diving (>2 m) extracted from time-at-depth data, and proportions of time hauled out from the “SLR”.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0002006-g010: Activity budget for female ringed seals in the Bothnian Bay.Data pooled for four animals. Percentages of time diving (>2 m) extracted from time-at-depth data, and proportions of time hauled out from the “SLR”.
Mentions: Data is only available for months November to March in this region, and we summarize the activities of females in the Bothnian Bay in Fig. 10. Females in this area dived deeper in late autumn and winter than both females and males in the two southern areas (chi-square: p<0.0001 in both cases). Here 13% of dives in January were deeper than 40 m, a pattern maintained over the winter since 17% and 23% of dives exceeded 40 m in February and March, respectively. A significantly different pattern (chi-square: p<0.0001 compared with both males and females in the southern areas) was also seen in the duration of dives where only 52% (Jan) to 64% (Feb) of dives in the winter were shorter than 2 min. Here 27% and 16% of dives lasted longer than 5 min in January and February, respectively.

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