Diets of gray (Halichoerus grypus) and harp (Pagophilus groenlandicus) seals in Newfoundland waters using hard-part and molecular analyses

Foley, Jessica E. (2018) Diets of gray (Halichoerus grypus) and harp (Pagophilus groenlandicus) seals in Newfoundland waters using hard-part and molecular analyses. Masters thesis, Memorial University of Newfoundland.

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Abstract

I examined the diet of gray (Halichoerus grypus) and harp (Pagophilus groenlandicus) seals using: hard-part analysis (HPA; subdivided into stomach and intestine) and a multiplex Polymerase Chain Reaction (PCR) technique. Through these methods, I looked at harp and gray seal diet in Newfoundland waters, investigated otolith passage rates within the digestive tract, and developed a multiplex PCR technique to compare with HPA to further investigate biases associated with diet reconstruction based on HPA. Both techniques provided evidence for retention of large prey and faster passage of smaller pray. I conclude that otoliths of different sizes and thicknesses are affected by digestion differently; I suggest that HPA should be conducted using samples from both the stomach and intestine, and that it should be used in conjunction with other methods of diet analysis like PCR as this may give a better idea of the diet, and prey sizes consumed.

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