Spawning patterns and retention and dispersal of early life stages of Atlantic cod (Gadus morhua) in a Newfoundland fjord

Knickle, David Craig (2009) Spawning patterns and retention and dispersal of early life stages of Atlantic cod (Gadus morhua) in a Newfoundland fjord. Masters thesis, Memorial University of Newfoundland.

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Abstract

Ichthyoplankton and hydroacoustic surveys were used to examine Atlantic cod (Gadus morhua) distribution and behaviour as well as cod egg abundance and distribution during spring and summer 2006 and 2007 to infer on cod spawning activity in Smith Sound, a known overwintering area on Newfoundland's northeast coast. In the first section of the thesis, estimated spawning times from egg abundance and distribution patterns and environmental data suggested a prolonged spawning period with spring and summer spawning peaks. Spring egg distribution indicated dispersal of eggs out of the Sound. In summer, egg and larval densities were highest within the innermost portion of the Sound, suggesting significant retention and local development. In the second part of the thesis, acoustic measurements of cod behaviour were closely linked with egg production times adding further support that vertical shoaling behaviour is associated with reproduction of cod in the wild.

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