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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 male and female ringed seals in the Gulf of Finland and Estonian coastal waters (pooled data).The proportion of time diving deeper than 2 m, time spent at surface, and time hauled out from figs 6, 8, and 11. “Shallow” denotes dives in the interval 1–2 m, and is given by 100% minus the sum of all other activities.
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pone-0002006-g009: Activity budget for male and female ringed seals in the Gulf of Finland and Estonian coastal waters (pooled data).The proportion of time diving deeper than 2 m, time spent at surface, and time hauled out from figs 6, 8, and 11. “Shallow” denotes dives in the interval 1–2 m, and is given by 100% minus the sum of all other activities.

Mentions: The sum of time spent diving, at surface and hauled out should add up to 100%, but since we defined the time spent diving as deeper than 2 m (Fig. 3), we lack information on the time spent in the depth interval from 1 m and up to 2 m. Assuming the difference between the sum of all other activities and the total amount of time was spent in this depth interval, the total activity patterns from moult to breeding can be estimated (Fig. 9). In males, the total time submerged was about 85% in May to July, which decreased to about 50% in September and October after which they spent 50 to 60% of their time under the surface up to March. Females spent about 70% of their time submerged from mid May to August after which a similar proportion was spent under water as in males. The main difference was seen in the summer when males spent about 10% of their time at the surface compared with 20 to 40% in females.


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 male and female ringed seals in the Gulf of Finland and Estonian coastal waters (pooled data).The proportion of time diving deeper than 2 m, time spent at surface, and time hauled out from figs 6, 8, and 11. “Shallow” denotes dives in the interval 1–2 m, and is given by 100% minus the sum of all other activities.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0002006-g009: Activity budget for male and female ringed seals in the Gulf of Finland and Estonian coastal waters (pooled data).The proportion of time diving deeper than 2 m, time spent at surface, and time hauled out from figs 6, 8, and 11. “Shallow” denotes dives in the interval 1–2 m, and is given by 100% minus the sum of all other activities.
Mentions: The sum of time spent diving, at surface and hauled out should add up to 100%, but since we defined the time spent diving as deeper than 2 m (Fig. 3), we lack information on the time spent in the depth interval from 1 m and up to 2 m. Assuming the difference between the sum of all other activities and the total amount of time was spent in this depth interval, the total activity patterns from moult to breeding can be estimated (Fig. 9). In males, the total time submerged was about 85% in May to July, which decreased to about 50% in September and October after which they spent 50 to 60% of their time under the surface up to March. Females spent about 70% of their time submerged from mid May to August after which a similar proportion was spent under water as in males. The main difference was seen in the summer when males spent about 10% of their time at the surface compared with 20 to 40% in females.

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