Effects of female spawning experience and larval size on feeding and growth of cod larvae Gadus morhua L. reared in mesocosms

Abstract

The viability, defined in terms of growth and feeding success, of cod larvae from first-time and repeat spawners of similar sizes was studied in two mesocosms. The growth rate of larvae from first-time and repeat spawners were similar from hatching through to 41 days old, when the experiment was terminated. Larvae from first-time spawners were heavier throughout the experiment than larvae of repeat spawners, a difference that might be explained by a difference (although non-significant) in egg size between the two groups. There was a significant difference in growth rate between the two mesocosms, which may be explained by the difference in temperature between the mesocosms. In both mesocosms larvae fed mainly on copepod nauplii during the first weeks of life and started to actively select copepodites at age 20 days post hatch. There was no significant difference in the energy content of the ingested prey at a given age between offspring of first-time and repeat spawners, although there was a significant difference between the two mesocosms. The dry mass of the ingested prey items compared to larval dry mass increased until age 17–27 days post hatch and decreased thereafter.

Keywords:

• Maternal effects
• feeding success
• fish larva
• microsatellites
• temperature-dependent growth
• energy content

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank the staff at Flødevigen Research Station for their assistance during the experiment. Thanks to Torild Johansen for skilful help in the laboratory. This experiment was funded by the EU project MACOM (Demonstration of Maternal Effects of Atlantic Cod: Combining the Use of Unique Mesocosms and Novel Molecular Techniques), under the programme ‘Quality of life and living resources’ (QLRT-PL1999-0167).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark