Community Research and Development Information Service - CORDIS

Comparative analysis of signature behaviours in cod (Gadus morhua L.)

The purpose of this work was to test whether structural features in the otolith can be used to identify and understand behaviours recorded by DST tags. The basic premise is that significant changes in the fish's behaviour are likely to involve changes in the extrinsic and intrinsic factors that influence otolith microstructure. To achieve our objectives, patterns of behaviour of DST-tagged cod were identified and quantified to determine the frequency and timing of key behavioural phases such as migration, spawning and residence on feeding grounds.

In combination with the DST temperature record, the daily increments of recovered otoliths were examined to relate changes in growth conditions with changes in behaviour at scales from days to months. Experiments were conducted with adult cod to parameterise the effects of temperature, size and age for comparison with the long-term natural otolith signal from returned DST-tagged cod. A model predicting how signature behaviour influences otolith accretion to produce structures that are identifiable at the macrostructure level was applied to DST tagged individuals of the Baltic Sea and the North Sea to evaluate output of otolith macrostructure with actual observations of these individuals. Correlation of otolith microstructure with cod behaviour did not help to identify consistent patterns within ecosystems, although major biological drivers were identified that primarily influence otolith macrostructure between ecosystems.

Reported by

CENTRE FOR THE ENVIRONMENT, FISHERIES & AQUACULTURE SCIENCE
LOWESTOFT LABORATORY, PAKEFIELD ROAD
NR 33 0HT LOWESTOFT
United Kingdom
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