Bioactive products in the production of halibut and cod larvae / Bioactive products in production of halibut and cod larvae




Jónína Þ. Jóhannsdóttir, Rannveig Björnsdóttir, Eydís Elva Þórarinsdóttir, Kristjana Hákonardóttir, Laufey Hrólfsdóttir

Supported by:

AVS, Matvælasetur HA

Bioactive products in the production of halibut and cod larvae / Bioactive products in production of halibut and cod larvae

The aim of the project was to find ways to improve the survival and quality of cod and halibut larvae and to use environmentally friendly methods. The aim was also to open up the possibility of utilizing saithe peptides that could increase the value of saithe. The results of a previous project in halibut farming were promising and indicated that it was most convenient to treat larvae with peptides through feed animals, in addition to which it was necessary to further investigate the concentration of treatment. In connection with the project, new facilities for animal husbandry have been developed and set up at Fiskey hf. for research into the different treatments of feed animals and thus contribute to increased stability in the production of halibut juveniles. Repeated experiments with bioactive substances in the cultivation of equidae have been carried out and they seemed to tolerate a certain concentration of the substances. The main results of experiments in the early stages of cod farming indicate that treatment with saithe peptides results in good growth, noticeably faster development of internal organs and a much lower incidence of larval defects. However, it is clear that the effects of different levels of treatment need to be further investigated. There is strong evidence that IgM and lysozyme are present in cod larvae soon after hatching or much earlier than previously claimed, and that treatment appeared to stimulate their production. Treatment with saithe peptides does not appear to affect the bacterial flora of larvae, but a specific species composition was detected in the gastrointestinal tract of larvae in pots where larval survival and quality were optimal. This gives evidence that a certain species composition of bacterial flora is favorable for cod larvae.

The main goal of this project was to increase viability and quality of cod and halibut larvae before and during the first feeding period by using bioactive products. The aim was also to increase the exploitation and value of pollock. The findings of previous projects in halibut culture were promising and indicated that treating live feed is a suitable method to carry bioactive products to the larval intestines during first feeding but the intensities of treatment needed to be further investigated. New facilities have been developed in relation to the project for research in the live feed culture at Fiskey Ltd. to promote increased stability in the production of halibut fingerlings. Repeated experiments have been conducted in the culture of rotifers and results indicate good tolerance towards treatment with bioactive products in certain intensities. The overall results of the project indicated that pollock peptides may promote increased growth and quality of cod larvae during first feeding. The results also indicate the presence of IgM and lysozyme early post hatching, but it has not been observed in cod larvae of this size before. Furthermore, results also indicate that hydrolysates from pollock can stimulate the production of these factors in cod larvae. Treatment using pollock peptides, did not affect the bacterial community structure of live feed or cod larvae, however a similar structure was observed in larvae from the most successful production units different from other tanks. The results therefore indicate a bacterial community structure that may be preferable to the cod larvae.

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