Diet composition and seasonal feeding patterns of a freshwater ringed seal (Pusa hispida saimensis)

作者：Auttila Miina^*; Sinisalo Tuula; Valtonen Mia; Niemi Marja; Viljanen Markku; Kurkilahti Mika; Kunnasranta Mervi

来源：Marine Mammal Science, 2015, 31(1): 45-65.

DOI：10.1111/mms.12133

• Phoca
• stable isotopes
• digestive tract analysis
• seal-fishery interaction
• nutritional status
• conservation
• Saimaa ringed seal

The Saimaa ringed seal (Pusa hispida saimensis) is one of the few freshwater seal populations worldwide. The major conservation issue of this critically endangered population is bycatch mortality. We used digestive tract content and stable isotopes (C-13 and N-15) to estimate the diet and seasonal feeding patterns for gaining better understanding of the seals feeding habits and potential conservation implications. The diet was similar across age groups. Altogether 15 fish species were identified and the most important were smelt (Osmerus eperlanus), ruff (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula) and cyprinids. The high N-15 values suggested that the seals lose weight during winter and spring. Additionally the drop in N-15 values indicated that pups start to recover from postweaning stress and gain weight around the age of 6 mo. The isotope values differed regionally, which emphasizes that samples from consumers and prey should be collected from the same regions to improve interpretation of the stable isotopic results. Overall, diet composition suggests minimal to nonexistent competition with commercial or recreational fishing. However, observed weight loss of pups during summer may be related to higher risk of bycatch and this should be taken into account when planning temporal fishing closures.

• 出版日期2015-1