Diet of harbor porpoises along the Dutch coast: a combined stable isotope and stomach contents approach

peer reviewed High stranding frequency of porpoises, Phocoena phocoena, along the Dutch coast since 2006 has led to increased interest in the ecology of porpoises in the North Sea. Stranded porpoises were collected along the Dutch coast (2006–2008) and their diet was assessed through stomach content...

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Bibliographic Details
Published in:Marine Mammal Science
Main Authors: Jansen, Okka, Michel, Loïc, Lepoint, Gilles, Das, Krishna, Couperus, A.S., Reijnders, Peter
Format: Article in Journal/Newspaper
Language:English
Published: Blackwell Publishing 2013
Subjects:
harbour porpoise
stable isotopes
Phocoena phocoena
marine mammals
SIAR
mixing models
Life sciences
Aquatic sciences & oceanology
Sciences du vivant
Sciences aquatiques & océanologie
Harbour porpoise
Online Access:https://orbi.uliege.be/handle/2268/134572
https://orbi.uliege.be/bitstream/2268/134572/1/2013%20Jansen%20MMS%2029-%20E295.pdf
https://doi.org/10.1111/j.1748-7692.2012.00621.x
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Summary:peer reviewed High stranding frequency of porpoises, Phocoena phocoena, along the Dutch coast since 2006 has led to increased interest in the ecology of porpoises in the North Sea. Stranded porpoises were collected along the Dutch coast (2006–2008) and their diet was assessed through stomach content and stable isotope analysis (d13C and d15N) of porpoise muscle and prey. Stable isotope analysis (SIAR) was used to estimate the con- tribution of prey species to the porpoises’ diet. This was compared to prey composi- tion from stomach contents, to analyze differences between long- and short-term diet. According to stomach contents, 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod, and sprat. Stable isotope analysis revealed that 70-83% of the diet consisted of poor cod, mackerel, greater sandeel, lesser sandeel, sprat, and gobies, highlighting a higher importance of pelagic, schooling species in the porpoises’ diet compared to stomach contents. This could be due to prey distribution as well as differ- ences in behavior of porpoises and prey between the coastal zone and offshore waters. This study supports the need for multi-method approaches. Future ecological and fishery impact assessment studies and management decisions for porpoise conservation should acknowledge this difference between the long- and short-term diet.

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