Tag: Halibut farming

Reports

Leit að bætibakteríum / Searching for putative probionts in the production system of halibut larvae

Published:

01/09/2008

Authors:

Jónína Þ. Jóhannsdóttir, Eyrún Gígja Káradóttir (MS student), María Pétursdóttir, Jennifer Coe, Heiðdís Smáradóttir, Rannveig Björnsdóttir

Supported by:

Tækniþróunarsjóður Rannís (2006-2008) / Technology Development Fund of Rannís, the Icelandic Center for Research (2006-2008)

Leit að bætibakteríum / Searching for putative probionts in the production system of halibut larvae

The overall goal of the project is to improve the survival and quality of halibut larvae in starter feeding using supplementary bacteria. In the composition of supplementary bacteria for fish, the breeding of warm-water species has often been considered, and the bacterial species that have been used have proved to have a poor foothold in the environmental conditions involved in the breeding of cold-water species, such as halibut. This project seeks out and identifies bacteria that are prevalent in halibut larvae from breeding units that have been successful in terms of larval performance and metamorphosis. Studies were performed on the properties of isolated bacterial strains in terms of growth inhibitory effects on known pathogens for fish as well as predominant bacterial species from halibut larvae in breeding units where the performance and quality of larvae were below average. The predominant bacteria were isolated from larvae in all breeding units of Fiskey hf. in two different periods in addition to which samples were taken from juveniles in export size. The results of studies on the growth inhibitory effect of isolated strains revealed 18 bacterial strains that were found to inhibit the growth of known pathogens and / or bacterial strains that had been isolated from the larval rearing environment. Sequencing results showed a good correlation with 6 different bacterial species. Subsequently, it will be treated with a selected mixture of additive bacteria in the early stages of halibut farming.

The overall aim of this project is to use probiotic bacteria to promote increased survival of halibut larvae during first feeding. Previous studies indicated that the microbial load of larvae and their environment represents a problem and the objective of this project was to search for possible candidates for probiotic bacteria to promote survival and growth of larvae use during the first and most sensitive phase of production. Potential probiotic strains were selected on the basis of dominance in the gut of larvae from production units with successful growth, development and survival. The growth inhibiting activity was tested against known fish pathogens as well as bacteria dominating the intestinal community of larvae from production units with poor overall success. We isolated dominating bacteria in the gut of larvae from all production units of two different spawning groups at Fiskey Ltd. and also from export-size fingerlings. Growth inhibition studies revealed 18 bacterial isolates that inhibited growth of known fish pathogens and / or dominating bacterial isolates from the gut of larvae of an overall poor quality. 16S rRNA sequencing revealed a reasonable correlation to 6 bacterial species and presently. As a next step, halibut eggs and larvae will be treated with selected strains to test their potential as probionts during the first production stages of halibut aquaculture.

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Reports

Treatment of halibut (Hippoglossus hippoglossus L.) eggs and larvae using putative probions isolated from the production system

Published:

01/09/2008

Authors:

Jónína Þ. Jóhannsdóttir, Heiðdís Smáradóttir, Eyrún Gígja Káradóttir, Eydís Elva Þórarinsdóttir, María Pétursdóttir, Rannveig Björnsdóttir

Supported by:

Tækniþróunarsjóður Rannís (2006-2008) / Technology Development Fund of Rannís, the Icelandic Center for Research (2006-2008)

Treatment of halibut (Hippoglossus hippoglossus L.) eggs and larvae using putative probions isolated from the production system

The aim of the project as a whole is to improve the survival and quality of halibut larvae in starter feeding and use environmentally friendly methods where eggs and larvae are treated with a new mixture of additive bacteria that have been isolated from the halibut breeding environment. There will be great losses in the first stages of halibut farming and therefore it is important to create an optimal environment during these first and most sensitive stages of farming. The use of supplemental bacteria is one way of doing this, but supplementary bacteria can in various ways have a positive effect on their host, such as preventing unwanted bacteria from gaining a foothold in its digestive tract, stimulating the immune response and improving the balance in its digestive tract. Three separate experiments were carried out in the fish farm of Fiskey hf. where it was treated with a mixture of additive bacteria at different stages of the culture. The effect of the treatment was assessed in terms of the performance and quality of the eggs and larvae, but the composition of the bacterial flora of the farm was also examined. Supplementary bacteria were added to the breeding environment of eggs, but larvae were treated through the feed animals. The main results suggest that treatment with a new mixture of additive bacteria can affect the composition of the bacterial flora of eggs, larvae and their feed animals, but that treatment needs to be done more frequently than was done in the study if long-term effects are to be maintained. Repeated treatment at the egg stage seemed to reduce the incidence of defective peritoneal larvae, in addition to which treatment from the beginning of the initial feeding seemed to have a positive effect on the larval performance at the end of the initial feeding.

Poor survival of larvae during the first feeding phases calls for measures to create optimal environmental conditions during the first and most sensitive phases of the larval production. The overall aim of the project was to promote increased survival and quality of halibut larvae, using putative probionts isolated from halibut production units. Probiotic bacteria can affect their host in various ways, eg by preventing the attachment of unfavorable bacteria, stimulating the immune system and promoting increased stability in the gastrointestinal tract. In this project three separate experiments were carried out at a commercial halibut farm, Fiskey Ltd. in Iceland. Different treatment schedules were used for treatment of eggs from fertilization and larvae throughout first feeding. A mixture of equal concentration of three selected strains was added to the tank water environment of eggs or through grazing of the live feed. The effects of treatment were evaluated with respect to the overall success of eggs and larvae as well as with respect to chances in the bacterial community structure. The results indicate that treatment may affect the bacterial community of eggs, larvae and live feed but more frequent treatments seem to be needed than examined in the present study. Repeated treatment of eggs resulted in reduced incidence of jaw deformation (gaping) amongst yolk sac larvae and treatment from the onset of exogenous feeding resulted in improved survival of larvae compared to sibling tank units.

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Reports

Use of bioactive substances in halibut farming

Published:

01/12/2007

Authors:

Jónína Þ. Jóhannsdóttir, Heiðdís Smáradóttir, Jennifer Coe, Rut Hermannsdóttir (MS student), María Pétursdóttir, Rannveig Björnsdóttir

Supported by:

Líftækninet HA (2005-2007), KEA University Fund (2006)

Use of bioactive substances in halibut farming

The main goal of the project was to promote the increased performance of halibut in fire and use environmentally friendly methods. Bioactive substances were used that were easy to obtain, contributed to the increased value of seafood and also had some of the desired activity, ie. bactericidal / inhibitory, prebiotic or immunostimulatory activity. Experiments were made with various materials in the project, ie. chitosan derivatives as well as peptides derived from blue whiting, cod and saithe. The effect of treatment with the substances was assessed in terms of the growth and performance of larvae and forage animals as well as in terms of the composition of the bacterial flora and the stimulation of a non-specific immune response in larvae. The main results indicate that the most suitable method for introducing substances into larvae is to use feed animals (Artemia) and a method was developed in the project to treat them. The bioactive substances did not appear to have a bactericidal effect in the rearing environment of the feed animals, but did contribute to a change in the composition of the bacterial flora. Bioactive substances seemed to be used primarily as supplements as feed animals were plump and playful. The performance and quality of larvae in the breeding units of Fiskey hf. is very different and there is no obvious relationship between the performance of the peritoneal stage and the performance and quality of the larvae at the end of the initial feeding. The composition of bacterial flora was also found to be very different in peritoneal larvae and larval feeding larvae. Three separate experiments were carried out in the Fiskey juvenile farm where the larvae in the initial feeding were treated with bioactive substances. The main results showed that it is important to treat with the right concentration of substances and for a reasonably long time as too much concentration can have a negative effect on the growth and metamorphosis of larvae. Treatment with blue whiting peptides was thought to give promising results and have a beneficial effect on larval metastasis. Bioactive substances did not appear to have a decisive effect on the number of bacterial bacteria in the gastrointestinal tract of larvae, but treatment with blue whiting and cod peptides could potentially alter the composition of the flora. Studies on the non-specific immune response of halibut larvae revealed the presence of C3 and Lysozyme from the end of the peritoneal stage, but IgM production does not begin until about 28 days after the start of feeding. Higher levels of IgM were detected during the first weeks in larvae treated with saithe peptides and this may indicate an immunostimulatory effect. The results of the project as a whole indicate that the bioactive substances studied did not have a decisive effect on the bacterial flora of the farm, but the treatment of larvae in starter feeding with the right concentration of bioactive substances could have a good effect on larval performance and stimulate larval immune response. of the farm when they have not yet developed a specialized immune response.

The aim of this project was to promote increased survival of halibut larvae during first feeding by using bioactive products. The bioactive products were selected by the criterion that they were easily accessible and induced any of the desired effects ie inhibiting bacterial growth, prebiotic effects or immunostimulants. The products studied are chitosan and peptide hydrolysates from blue whiting, cod and saithe. The effects of treatment were evaluated with respect to growth and survival of larvae and the live feed (Artemia) as well as effects on bacterial numbers or the community structure of the intestinal microbiota of larvae and stimulation of the innate immune system of the larvae. The results indicate that treating live feed (Artemia) is a suitable method to carry the bioactive products to the larval intestines during first feeding and a new technique has been standardized for treatment of the live feed with the products. The bioactive products did not affect the total bacterial count in the Artemia but the composition of the bacterial community may be changed as a result of the treatment. The Artemia seems to use the bioactive products as a food supplement and was well suited to be used as live feed. A significant variation in overall success of larvae was observed without any obvious correlation between survival of larvae at the end of the yolk sac stage and at the end of first feeding. A different bacterial pattern was observed in the intestine at the yolk sac stage compared to first feeding larvae. Three separate experiments were carried out in the halibut production units at Fiskey Ltd. where larvae were treated with various bioactive products. The results emphasize the importance of treating larvae with the appropriate concentrations of the products, as elevated concentrations can negatively affect growth and metamorphosis of the larvae. Treatment with peptides from blue whiting resulted in relatively good survival of larvae with similar success of metamorphosis compared to control units. The bioactive products did not affect bacterial growth but there were indications that peptides from blue whiting and cod may affect the composition of the intestinal community of bacteria in the larvae. Results from studies of the immunological parameters indicate the presence of C3 and Lysozyme already from the end of the yolk sac stage and the initialization of IgM production after approximately 28 days in feeding. Production of IgM was stimulated in larvae treated with peptides from saithe, indicating immunostimulating effects of this product. The overall results indicate that the bioactive products studied did not affect the bacterial flora during the first production stages of halibut larvae. However, if used in the appropriate quantities and at the right time, the products may promote survival and growth and stimulate the innate immunity of larvae.

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