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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
Seasonal changes in diurnal haul-out behaviour as given by the proportion of “dry” transmissions.Data given for night (2100-0300) day (0900-0300), and mean values for all hours of day (All). Standard errors of estimates given by error bars. N = 7066 for females and 3061 for males.
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pone-0002006-g008: Seasonal changes in diurnal haul-out behaviour as given by the proportion of “dry” transmissions.Data given for night (2100-0300) day (0900-0300), and mean values for all hours of day (All). Standard errors of estimates given by error bars. N = 7066 for females and 3061 for males.

Mentions: Complementary data on haul-out patterns was provided from the ratio of dry/wet transmissions (SLR), which was available from all transmitters. Also here it is evident that, over most of the year, both sexes spent nearly all their time in the water during the day (Fig. 8), a pattern which changed dramatically for females in the pupping season in February and March, when females seem to haul out 40% of their time during the day. Males spent up to 40%, and females up to 50%, of the night on the reefs in August and September. The nocturnal haul out time decreased substantially for both sexes in November, but increased again in January, when 60% of the time was spent out of water. In February and March night-time haul-out decreased substantially for females but not 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)

Seasonal changes in diurnal haul-out behaviour as given by the proportion of “dry” transmissions.Data given for night (2100-0300) day (0900-0300), and mean values for all hours of day (All). Standard errors of estimates given by error bars. N = 7066 for females and 3061 for males.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0002006-g008: Seasonal changes in diurnal haul-out behaviour as given by the proportion of “dry” transmissions.Data given for night (2100-0300) day (0900-0300), and mean values for all hours of day (All). Standard errors of estimates given by error bars. N = 7066 for females and 3061 for males.
Mentions: Complementary data on haul-out patterns was provided from the ratio of dry/wet transmissions (SLR), which was available from all transmitters. Also here it is evident that, over most of the year, both sexes spent nearly all their time in the water during the day (Fig. 8), a pattern which changed dramatically for females in the pupping season in February and March, when females seem to haul out 40% of their time during the day. Males spent up to 40%, and females up to 50%, of the night on the reefs in August and September. The nocturnal haul out time decreased substantially for both sexes in November, but increased again in January, when 60% of the time was spent out of water. In February and March night-time haul-out decreased substantially for females but not 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