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Atlantic cod

Scientific name: Gadus morhua

Diet and feeding of juvenile cod in a recirculating system

The combined effect of feeding regime and photoperiod on the growth of juvenile Atlantic cod Gadus morhua in land-based recirculating aquaculture systems (RAS) was examined using three different commercial diets. Fish of 8-10 g were reared in 1 m³ tanks at an initial density of 10 kg m-³ for 78 d.

Three RAS units were used to simultaneously test three feed/photoperiod regimes that might be encountered in the wild or aquaculture; LightDark (LD) 24:0, LD12:11 (+1 h crepuscular periods) and LD6:6 (+12 h crepuscular periods). Feed was administered during the light period every 30 min for a 3 min feeding duration. In each RAS unit three diets (A, B and C) were tested, which were broadly similar in composition but from different manufacturers. Water exchange rate averaged 10-19% in the three recirculation systems, and key water quality parameters such as NH4+ and CO2 remained at low effect concentrations (<0.4 and <3 mg L-1, respectively). Final stocking densities were 45-60 kg m-³.

The figure above shows that there was a significant influence of both feed/photoperiod regime and diet on specific growth rate (SGR). Fish receiving the LD12:11 and LD6:6 regimes and Diet A grew best (SGR 2.59 and 2.54 % d-1 respectively). Fish fed Diet B and C also grew best under the LD12:11 and LD6:6 feed/photoperiod regimes (SGR range of 2.41 – 2.46 % d-1). Conversely, fish kept in the LD24:0 feed/photoperiod regime grew relatively slowly irrespective of diet type (SGR range of 2.26 – 2.32 % d-1). The feed conversion performance of the feed/photoperiod regimes and diets followed the same pattern.

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This work was carried out by M Fülberth as part of his MSc thesis. My participation in this work was made possible by a postdoc fellowship from the NZ Foundation for Research Science and Technology.

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This research has been published and is available as follows:

Fülberth, M., Moran, D., Jarlbæk, H., Støttrup, J.G., (2009). Growth of juvenile Atlantic cod Gadus morhua in land-based recirculation systems. Effects of feeding regime, photoperiod and diet. Aquaculture, 292: 225-231.

doi:10.1016/j.aquaculture.2009.04.028 ------- get PDF of paper