Investigating diet, distribution, and growth of silver hake (Merluccius bilinearis) in their northernmost extent in the Gulf of St. Lawrence

Zhu, Liang (2020) Investigating diet, distribution, and growth of silver hake (Merluccius bilinearis) in their northernmost extent in the Gulf of St. Lawrence. Masters thesis, Memorial University of Newfoundland.

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Abstract

Changing ocean conditions are driving distribution shifts in many marine species on a global scale, which will have major ecological implications for marine environments. I investigated the recent trend of increased silver hake (Merluccius bilinearis) abundances within the Gulf of St. Lawrence to characterize their biology in their northernmost extent. I assessed the diet and distribution of silver hake, as well as the overlap between the diet and distribution of silver hake with those of two resident species, Greenland halibut (Reinhardtius hippoglossoides) and redfish (Sebastes sp.). Silver hake’s diet in the Gulf was primarily benthic, with smaller contributions from pelagic prey than in diets reported along other parts of their range. Overlaps of diet and distribution between silver hake and the two highly abundant resident species were also high. I analyzed otoliths from the silver hake samples to investigate the age structure and growth of hake in the Gulf of St. Lawrence. Hake’s age structure in the Gulf is similar to that of nearby regions where most individuals are age four or younger, while von Bertalanffy growth rates showed higher rates of growth and lower asymptotic lengths in the Gulf compared to hake from the Scotian Shelf and Northeast United States Shelf. My results provide some of the first descriptions of silver hake biology within the Gulf of St. Lawrence.

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