Reports

TOPCOD, OPTILAR / Long live the first model. Preferred breeding processes in larval and juvenile farming of cod

Published:

01/04/2011

Authors:

Jónína Jóhannsdóttir, Agnar Steinarsson, Rannveig Björnsdóttir

Supported by:

Technology Development Fund and AVS R&D Fund of Ministry of Fisheries in Iceland

TOPCOD, OPTILAR / Long live the first model. Preferred breeding processes in larval and juvenile farming of cod

Recent research has shown that the best conditions for the production of larvae produce juveniles of better quality and that the growth advantage in the early stages of rearing pays off to some extent in the later stages of growth. The main goal of this project is to define the best conditions for cod cod farming in Iceland and to that end use various methods to solve the main problems associated with the production of cod larvae today. This report discusses the work components that Matís ohf. participated in, among other things, researching the effects of enrichment of feed animals with supplementary bacteria and protein digestion on the growth, development, immune stimulation and digestive flora of larvae, as well as research on the effects of different primary feeds on muscle growth carried out in collaboration with the MRI. The results indicate that the start of dry feed feeding late or around 50 dph does not give the larvae a growth advantage and that it is sufficient to feed Artemia up to 40 dph. Dry feed from 30 dph led to lower growth and an increased incidence of structural defects. Enrichment of feed animals with a lyophilized mixture of two complementary bacterial strains did not affect the composition of bacterial flora larvae and strains did not gain a foothold in treated larvae. However, poor roe quality can be expected to have affected treatment outcomes. The results of experiments confirm previous results on the positive effect of enrichment of feed animals with protein digestion on the performance and development of larvae.  

Recent research has demonstrated that production optimization during the larval and juvenile phase will to some extent be reflected in the performance of the fish during the ongrowing phase. The objectives of the project are to optimize the larval production of Atlantic cod in Iceland by applying a multidisciplinary approach to solve central bottlenecks related to larval production. This report presents tasks where Matis ohf. was involved, including analyzes of the effects of live prey enrichment using putative probionts and a fish protein hydrolyzate on larval survival quality immune stimulation and intestinal bacterial community of larvae. The study also involved an analysis of the effect of startfeeding protocols on muscle growth in collaboration with MRI. The results indicate that late weaning around 50 dph may be excessive and produce no significant advantage. An intermediate weaning strategy, with brine shrimp feeding up to 40 dph, appears to be sufficient to convey important advantages in terms of growth and anatomy. Early weaning at 30 dph produced slow ‐ growing juveniles and a higher deformity ratio. Using the freeze dried preparations of the probionts did not affect the bacterial community structure of larvae and the probionts were not found to be established within the bacterial community of treated larvae. Poor quality egg may, however, partly explain the lack of effects as a result of treatment. The present study confirms the results of previous studies where live prey enrichment using a fish peptide hydrolyzate significantly improved larval survival and development. 

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Reports

Production of wheeled animals for cod farming / Production of quality rotators for breeding cod fry

Published:

01/03/2009

Authors:

Jónína Þ Jóhannsdóttir, Agnar Steinarsson, Rannveig Björnsdóttir

Supported by:

Nordic-Atlantic co-operation (NORA)

Production of wheeled animals for cod farming / Production of quality rotators for breeding cod fry

There is great interest in finding ways to control farming conditions at all stages of aquaculture. The control of microbial flora in the environment and the gastrointestinal tract of larvae is, among other things, thought to be able to reduce losses that occur in the early stages of marine fish farming. A large number of bacteria usually accompanies feed animals in cod farming, but the use of recycling systems in the breeding of equidae has, among other things, the advantage that a smaller number of bacteria gain a foothold in the systems compared to batch farming. The use of bacterial flora for bacterial flora control has increased significantly in recent years and has in some cases contributed to increased growth and quality of larvae. In addition to strengthening co-operation between cod juvenile producers in the Nordic countries, the aim of the project is to develop methods that increase stability and efficiency in the production of feed animals. It is based on a recycling system designed by Sintef in Norway and this section investigates the effects and presence of selected beneficial bacteria in the system. The main results of treatment with two selected bacterial strains showed that the wheeled animals tolerated the treatment well and an increased crop of animals was obtained when treated with the bacteria in lyophilized form. There was a significant decrease in the number of bacteria in the purgatory during treatment with liquid bacterial culture and the number of bacteria in the purgatory did not reach the initial number during the experiment, but there was some increase in the number of lactic acid bacteria. Although the amount of lactic acid bacteria in equidae only increased after treatment, the bacterial strains did not gain a foothold in the system or lead to changes in the composition of the bacterial flora when treated at this concentration. The project is funded by Nordisk Atlantsamarbejde (NORA) and worked in collaboration with Matís, the Marine Research Institute, SINTEF, Fiskaaling, IceCod and Stofnfisk as well as Nordland Marin Yngel.

There is an increasing interest in controlling environmental parameters during the first production stages of aquaculture and controlling bacterial numbers is among various environmental parameters that are believed to promote increased survival of larvae. Elevated bacterial numbers are introduced into the system through the live feed, but numbers of bacteria have been found to be greatly reduced by the use of recirculation culturing system as compared with batch culturing systems. Furthermore, the use of potentially probiotic bacteria in aquaculture has increased over the past years and has in some cases contributed to increased growth and quality of marine larvae. In addition to promoting collaboration between cod producers within the Nordic countries, the main goal of the current project is to develop methods for stable and advantageous production of live feed animals (rotifers). The project is based on a recirculation culturing system engineered by SINTEF and the present part of the project deals with the effect of treatment and persistence of selected probiotic bacterial strains in the system. The overall results indicate that the rotifer cultures were not negatively affected by the bacterial treatment and treatment using freeze-dried preparations of the two probiotic strains even resulted in improved harvesting of the live feed. A drop in bacterial numbers within the bio-filter unit was, however, observed following the addition of liquid bacterial cultures, indicating negative effects of the bacteria on the bacterial community of the bio-filter unit. An increase in the numbers of lactic acid bacteria was observed in the rotifer cultures following treatment, but the probiotic bacterial strains were neither found to become established as a part of nor affect the dominating bacterial community of the system using the concentrations applied. The project was supported by the Nordisk Atlantsamarbejde (NORA) and is a collaboration between Matís, Hafrannsóknastofnun, SINTEF, Fiskaaling, IceCod, Stofnfiskur and Nordland Marin Yngel.

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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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