Prey preferences of sympatric fin (Balaenoptera physalus) and humpback (Megaptera novaeangliae) whales revealed by stable isotope mixing models |
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Authors: | Conor Ryan Simon D Berrow Brendan McHugh Ciarán O'Donnell Clive N Trueman Ian O'Connor |
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Institution: | 1. Marine and Freshwater Research Centre, Department of Life Science, Galway‐Mayo Institute of Technology, , Galway, Ireland;2. Marine Biodiversity Research Group, Department of Life Science, Galway‐Mayo Institute of Technology, , Galway, Ireland;3. Irish Whale and Dolphin Group, , Kilrush, Co. Clare, Ireland;4. Marine Institute, , Oranmore, Co. Galway, Ireland;5. Ocean and Earth Science, University of Southampton, National Oceanography Centre, , Southampton, SO14 3ZH United Kingdom |
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Abstract: | Over‐exploitation of top predators and fish stocks has altered ecosystems towards less productive systems with fewer trophic levels. In the Celtic Sea (CS), discards and bycatch levels have prompted concern about some fisheries, while fin and humpback whales are recovering from centuries of over‐exploitation. A lack of empirical evidence on the preferred diet of some predators such as whales in the CS has hindered the implementation of effective conservation measures using an ecosystem‐based approach to fisheries management. Using a Bayesian framework (SIAR), stable carbon (δ13C) and nitrogen (δ15N) isotope mixing models were used to assign proportionate diet solutions to fin and humpback whales (skin biopsies) and putative prey items: herring (Clupea harengus), sprat (Sprattus sprattus), and krill (Meganyctiphanes norvegica and Nyctiphanes couchii) in the CS. Krill was the single most important prey item in the diet of fin whales, but one of the least important for humpback whales (albeit based on a small sample of humpback whale samples). Age 0 sprat and herring comprised a large proportion of the diet of both species, followed by older sprat (age 1–2) and older herring (age 2–4). An ecosystem based approach to fisheries management will be required in the CS if we seek effective conservation of both fin and humpback whales, and sustainable fisheries. |
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Keywords: | diet
SIAR
Bayesian mixing model biopsy Balaenopteridae |
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