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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
Maximum depths of dives from status messages given as maxima for each month and average monthly maximum values.Standard errors indicated by bars.
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pone-0002006-g005: Maximum depths of dives from status messages given as maxima for each month and average monthly maximum values.Standard errors indicated by bars.

Mentions: The reliability of the depth sensors was confirmed, since none of the recorded dives of ringed seals exceeded the maximum depth (120 m) of the sea bed in all three areas of the Baltic. The maximum depth of dives, over the previous 24 hour period, indicated that both male and female maximum dives were about 100 m in most months of the year. However, these deep dives were relatively rare, since the average daily maximum dive depths were about 40 m for males and 25 m for females. Monthly maximum depths were relatively shallow between December and February for females and in March for males (Fig. 5).


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)

Maximum depths of dives from status messages given as maxima for each month and average monthly maximum values.Standard errors indicated by bars.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0002006-g005: Maximum depths of dives from status messages given as maxima for each month and average monthly maximum values.Standard errors indicated by bars.
Mentions: The reliability of the depth sensors was confirmed, since none of the recorded dives of ringed seals exceeded the maximum depth (120 m) of the sea bed in all three areas of the Baltic. The maximum depth of dives, over the previous 24 hour period, indicated that both male and female maximum dives were about 100 m in most months of the year. However, these deep dives were relatively rare, since the average daily maximum dive depths were about 40 m for males and 25 m for females. Monthly maximum depths were relatively shallow between December and February for females and in March for males (Fig. 5).

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