SARF043:  Improving understanding of species specific requirements for marine finfish cultivation

Start Date: 1st March 2008
End Date: 28th February 2011
Main Contractor(s): Viking Fish Farms Ltd, and Biomar Ltd
Other Sponsor(s): BMFA

Objectives

Objective 1. To review existing information available on current feeds, feeding practices for farmed cod, and the factors affecting the poor doer condition in fish generally.

Objective 2. To assess, through laboratory tank trials, the reaction of juvenile cod to feeds differing in moisture content, size and expected palatability, and to examine the pattern of feeding activity, and fish growth and population size distribution pattern with each diet tested. From this, to recommend the diets and feeding strategies which may give the best results in subsequent cage trials.

Objective 3. To field test, using feedback loop feeders, the optimum diet or diets determined in the laboratory against standard cod diets, first in 5 to 6 metre cages at commercial stocking densities, with fish of an initial average weight of 10-15g. The parameters to be assessed for each regime will include:- " Daily feed intake and feeding pattern, with the latter to be examined both during each day and between days " Fish growth and condition factor; " Feed conversion ratio " Overall population size distribution of the fish on each diet and feeding regime, and in particular the proportion of fish that are significantly below the average weight and condition factor; " Mortality rates and unaccountable losses.

Objective 4. To recommend a diet and feeding strategy for Atlantic Cod which will alleviate the current problem of poor growers.

Summary

The project will address the common problem of "poor doer" syndrome in cod stocked in sea cages by ascertaining feed preferences in demand feeding trials in tanks and by examining feeding regimes and practices. After assessment of optimum feed size, hardness and palatability, a new feed will be specially formulated and offered to fish in sea trial pens using feedback loop distribution systems. The results will be compared with the performance of fish fed on currently available diets. Other issues that may affect the feeding response will be examined using demand feeding systems to assess the timing, regularity and distribution of the feed and the role of these in the successful feeding response in sea cages. The effect of inter-fish competition will be assessed under various regimes by examining fish condition and population size frequency distribution at regular intervals, and by behavioural work conducted in tanks. The collated results from all the above trials will be used to recommend feeds, feeding strategies and management practices that should minimise the incidence of poor growers in cod grow-out cages.