Reports

Gæðasalt í saltfiskverkun / Quality salt for curing of salted fish

Published:

01/02/2013

Authors:

Ásbjörn Jónsson, Aðalheiður Ólafsdóttir, Helgi Sigurjónsson, Egil Þórir Einarsson, Kristín Anna Þórarinsdóttir, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund (R 11 088‐11) and Tækniþróunarsjóður Ísl. A former user Italy (110667‐0611)

Contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

Gæðasalt í saltfiskverkun / Quality salt for curing of salted fish

The main goal of the project was to use the geothermal sea in Reykjanes for the production of salt that can be used to produce high quality salted fish. A process will be developed to produce the salt with geothermal energy on site and to be able to control its chemical composition so that the correct effect of salted fish can be ensured. Salt extracted from the geothermal sea was compared with imported salt from the Mediterranean during the production of salted cod fillets with brine as pre-salting stage and dry salting at the end. The results showed that higher utilization was obtained in the salted fish processing with salt extracted from the geothermal sea, and that the processing took less time as the uptake of salt into the cod muscle was higher compared to the imported salt. Salt extracted from the geothermal sea was comparable in quality to the imported salt.

The aim of the project was to utilize raw material and energy from a geothermal brine to produce salt which can be used to increase the value in production of salted fish. Imported salt from Tunis was compared with the salt from geothermal brine, by producing salted cod from pickle salting followed by dry salting. The results showed that higher yield was observed in production of salted fish, by using salt produced from geothermal brine. Also curing took less time where the penetration of salt in the cod muscle was faster compared to the imported salt. The salt produced from geothermal brine is comparable with the imported salt.

Report closed until 01.02.2015

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Reports

Monitoring of the marine biosphere around Iceland 2010 and 2011 / Pollution monitoring in the marine environment around Iceland 2010 and 2011

Published:

01/07/2012

Authors:

Hrönn Jörundsdóttir, Natasa Desnica, Þuríður Ragnarsdóttir, Helga Gunnlaugsdóttir

Supported by:

Ministry of the Environment and Ministry of Fisheries and Agriculture

Contact

Natasa Desnica

Research Group Leader

natasa@matis.is

Monitoring of the marine biosphere around Iceland 2010 and 2011 / Pollution monitoring in the marine environment around Iceland 2010 and 2011

This report presents the results of an annual monitoring project funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The purpose of this monitoring is to fulfill Iceland's obligations under the Oslo and Paris Agreements (OSPAR), as well as the AMAP (Arctic Monitoring Assessment Program). The data is part of Iceland's contribution to the International Council for the Exploration of the Sea (ICES) database. The Marine Research Institute collects samples and Matís oversees the preparation of samples and measurements of trace elements in the marine environment. The samples are measured at Matís and at the University of Iceland Laboratory of Pharmacology and Toxicology. Various inorganic trace elements and chloro-organic substances were measured in cod caught in Hafró's annual spring rally in March 2011 and in mussels collected at 11 locations around the country in August / September 2010. Monitoring in the marine environment around Iceland began in 1989 and samples are collected once a year. for a year and worked according to international sampling instructions. The data is collected in a database, the report provides overview images for some of the materials monitored. Cadmium is regionally higher in Icelandic mussels compared to mussels from other countries. The results show changes in the pattern of chlorine organic matter in mussels collected near Hvalstöðin in Hvalfjörður in September 2010 which are comparable to results from the same place since 2009. There were no visible changes in the concentration of these substances at the mussel collection point at Hvammsvík in Hvalfjörður or at any another collection site around the country that was studied in 2010. It is important to monitor these changes in the pattern of the concentration of chloro-organic substances in mussels in the monitoring project in the coming years to see if they are still present. A detailed statistical analysis of the data is in progress, i.e. Scientific methods can be used to estimate the increase or decrease of pollutants in the marine environment in Iceland.  

This report contains results of the annual monitoring of the biosphere around Iceland in 2010 and 2011. The project, overseen by the Environmental and Food Agency of Iceland, is to fulfill the OSPAR (Oslo and Paris agreement) and AMAP (Arctic Monitoring Assessment Program) agreements. The project was funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The data obtained is a part of Iceland´s contribution to the ICES databank (ices.dk). The collection of data started 1989. Matís is the coordinator for marine biota monitoring and is responsible for methods relating to sampling, preparation and analysis of samples. The samples were analyzed at Matís and the Department of Pharmacology and Toxicology at the University of Iceland. Trace metals and organochlorines were analyzed in cod (Gadus morhua) caught in March 2011 and in blue mussel (Mytilus edulis) collected from 11 sites in August / Sept 2010. Marine monitoring began in Iceland 1989 and the sampling is carried out according to standardized sampling guidelines. Changes were observed in the organochlorine concentration patterns in blue mussels collected year 2010 at the sampling site Hvalstod in Hvalfjordur which are in line with results obtained year 2009. No noteworthy increase in organochlorine concentrations was however observed in blue mussels obtained at Hvammsvík in Hvalfjordur nor any of the other sample sites studied year 2010. These results need to be followed up in the annual monitoring of the biosphere around Iceland next year to see if this change in contaminant concentration pattern continues. A thorough statistical evaluation is on ‐ going on all the available data from this monitoring program to analyze spatial and temporal trends of pollutants in the Icelandic marine biosphere.

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Reports

Seasonal variation of fatty acid composition of cod flesh

Published:

01/03/2012

Authors:

Kristín Anna Þórarinsdóttir, Helga Gunnlaugsdóttir, Jónas R. Viðarsson, Sigurjón Arason

Supported by:

Fisheries Project Fund

Seasonal variation of fatty acid composition of cod flesh

The report summarizes the results of measurements of the chemical content of the liver and cod muscles according to the season and fishing area. The results indicate that seasonal fluctuations in muscle fat content are relatively small. Another issue is the liver, its fat content was found to be lowest in the latter part of winter and in spring. At the same time, the water content was highest. Changes in the chemical composition of the liver were thought to be related to the fluctuations in the behavioral patterns and physical activity of the fish around spawning.

The report summarizes the results from measurements on chemical composition of liver and muscle of cod as affected by fishing grounds and seasonal variation. The results indicate that seasonal fluctuations in fat content of the muscle are relatively low. On the contrary, fat and water content in liver, varied with season. The fat content was lowest late winter and in spring. At the same time, the highest water content in liver was observed. These changes were explained by changes in behavior and physiological functional of the fish in relation to the reproductive cycle.

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Reports

Monitoring of the marine biosphere around Iceland 2009 and 2010 / Pollution monitoring in the marine environment around Iceland 2009 and 2010

Published:

01/09/2011

Authors:

Helga Gunnlaugsdóttir, Natasa Desnica, Þuríður Ragnarsdóttir, Hrönn Jörundsdóttir

Supported by:

Ministry of the Environment and Ministry of Fisheries and Agriculture

Monitoring of the marine biosphere around Iceland 2009 and 2010 / Pollution monitoring in the marine environment around Iceland 2009 and 2010

This report presents the results of an annual monitoring project funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The purpose of this monitoring is to fulfill Iceland's obligations regarding the Oslo and Paris Agreement (OSPAR), as well as the AMAP (Arctic Monitoring Assessment Program). The data have been sent to the International Council for the Exploration of the Sea (ICES) database. The Marine Research Institute collects samples and Matís oversees the preparation of samples and measurements of trace elements in the marine environment. The samples are measured at Matís and at the University of Iceland Laboratory of Pharmacology and Toxicology. Various inorganic trace elements and chloro-organic substances were measured in cod caught in Hafró's annual spring rally in March 2010 and in mussels collected at 10 locations around the country in August / September 2009. Monitoring in the marine environment near Iceland began in 1989 and samples are collected once a year. for a year and worked according to international sampling instructions. The data is collected in a database, the report provides overview images for some of the materials monitored. Cadmium is regionally higher in Icelandic mussels compared to mussels from other countries. The results show changes in the pattern of chlorine organic matter in mussels collected near Hvalstöðin in Hvalfjörður in September 2009, there were no visible changes in the concentration of these substances at the mussel collection site at Hvammsvík in Hvalfjörður or at any other collection site around the country studied in 2009. Important is monitoring these changes in the pattern of concentration of chlorinated organic substances in mussels in the monitoring project in the coming years to see if they are still present. A detailed statistical analysis of the data is in progress, i.e. Scientific methods can be used to estimate the increase or decrease of pollutants in the marine environment in Iceland.

This report contains results of the annual monitoring of the biosphere around Iceland in 2009 and 2010. The project, overseen by the Environmental and Food Agency of Iceland, is to fulfill the OSPAR (Oslo and Paris agreement) and AMAP (Arctic Monitoring Assessment Program) agreements. The project was funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The data has been submitted to the ICES databank (ices.dk). The collection of data started 1989. Matís is the coordinator for marine biota monitoring and is responsible for methods relating to sampling, preparation and analysis of samples. The samples were analyzed at Matís and the Department of Pharmacology and Toxicology at the University of Iceland. Trace metals and organochlorines were analyzed in cod (Gadus morhua) caught in March 2010 and in blue mussel (Mytilus edulis) collected in August / Sept 2009. Marine monitoring began in Iceland 1989 and the sampling is carried out according to standardized sampling guidelines. Changes were observed in the organochlorine concentration patterns in blue mussels collected year 2009 at the sampling site Hvalstod in Hvalfjordur, no noteworthy increase in organochlorine concentrations was however observed in blue mussels obtained at Hvammsvík in Hvalfjordur nor any of the other sample sites studied year 2009. These results need to be followed up in the annual monitoring of the biosphere around Iceland next year to see if this change in contaminant concentration pattern continues. A thorough statistical evaluation is ongoing on all available data from this monitoring program to analyze spatial and temporal trends of pollutants in the Icelandic marine biosphere.

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Reports

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

Published:

01/06/2011

Authors:

Hélène L. Lauzon, Kolbrún Sveinsdóttir, Magnea G. Karlsdóttir, Eyjólfur Reynisson, Björn Margeirsson, Emilia Martinsdóttir

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

The aim of the experiment was to compare the freshness, quality and shelf life of sub-chilled (CBC) cod necks in air storage and in aerated packages (MAP) at controlled temperatures to simulate temperature fluctuations during transport and distribution in the European market. Changes in the composition of the gas in the packages were monitored and sensory assessments and microbial and chemical measurements were performed. The fish was caught in bottom trawls in the spring and processed three days after fishing. There was a two-day prolongation during the freshness period and one day for the shelf life of fish in aerated packages (2.7 kg in a tray) compared to air (3.1 kg) in foam plastic, despite a 0.5 ° C difference in the average temperature of the groups and the air group was stored at lower temperatures (‐0.3 ± 0.9 ° C). The greatest temperature fluctuations led to the greatest shortening of the freshness time in air-conditioned packages. Cod saddles stored subcooled at -1.1 ± 0.1 ° C had a shelf life of 13 days. The results of microbial counts and chemical measurements showed the importance of Photobacterium phosphoreum in the formation of TMA in the process of damaging cod necks during both air and air exchange packaging. MAP and subcooling slowed down and changed the damage process. MAP increased drip by 2% in the later stages of storage.

The aim of this study was to compare freshness, quality deterioration and shelf life of CBC (combined blast and contact) ‐treated cod loins packaged in bulk under different atmospheres (air or modified atmosphere, MA) and stored under different temperature profiles to mimic temperature changes during transport and distribution to European markets. Sensory, chemical, microbial and headspace gas composition analyzes were performed regularly. The fish was caught by trawler in the spring and processed 3 days post catch. Following simulation of current sea freight conditions and distribution to European markets, a 2 ‐ day and 1 ‐ day increase in freshness period and shelf life of MA ‐ packaged fish (2.7 kg in trays), respectively, was observed compared to air ‐ stored loins (3.1 kg in EPS boxes). This is despite a mean product temperature difference of 0.5 ° C between the products, being lower (‐0.3 ± 0.9 ° C) for air ‐ stored fish. Abusive conditions had the greatest impact on the reduction of the freshness period for MAP fish. Superchilled storage of MAP loins (‐1.1 ± 0.1 ° C) resulted in a 13 ‐ day shelf life. Evaluation of microbial and chemical indicators emphasized the importance of Photobacterium phosphoreum and TMA formation in the deterioration of cod loins stored in air or MA, while superchilled MAP storage delayed as well as modified the spoilage pattern. MAP increased drip loss by about 2% at late storage.

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Reports

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

Published:

01/05/2011

Authors:

Kristín Anna Þórarinsdóttir, Hannes Magnússon, Irek Klonowski, Ásbjörn Jónsson, Frank Hansen, Egil Olsen, Sigurjón Arason

Supported by:

NORA

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

The effect of added gelatin extracted from fish was investigated on the utilization, chemical composition and quality of chilled, frozen and salted cod fillets. The gelatin was mixed into brine which was then injected into the fillets. Salted fillets were pickled after injection, then salted dry for 3 weeks and finally dehydrated. For comparison, fillets were sprayed only with brine. The main results were that the effect of gelatin on utilization and chemical composition was insignificant. Changes were mainly due to increased salt content. Another issue was the damage processes in chilled products. Microbial growth and degradation formation were higher in the fillets injected with gelatin. However, no visual difference in fillet appearance could be detected by brine composition. 

The effects of added fish gelatin on yield, chemical composition and quality of chilled, frozen and salted cod fillets were evaluated. The gelatin was mixed with salt brine and injected to the fillets. Salted fillets were brined after injection, dry salted for 3 weeks and finally rehydrated. Fillets injected only with salt brine were used as control. Effects of added gelatin on yield and chemical composition were not significant. Alterations were primarily due to the increased salt content by injection. Conversely, the growth of microorganisms and degradation within chilled fillets was accelerated by addition of gelatin. However, no significant differences were observed in visual appearance of the fillets. 

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Reports

Functionality testing of selected Chill ‐ on technologies during a transport ‐ simulation study of palletized cod boxes: qPCR for fish spoilage bacteria, SLP model and QMRA to evaluate pathogen growth in spiked cod

Published:

01/11/2010

Authors:

Hélène L. Lauzon, Björn Margeirsson, Kolbrún Sveinsdóttir, Eyjólfur Reynisson, María Guðjónsdóttir, Emilia Martinsdóttir (Matís); Radovan Gospavic, Nasimul Haque, Viktor Popov (WIT); Guðrún Ólafsdóttir, Tómas Hafliðason, Einir Guðlaugsson, Sigurður Bogason (UoI)

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Functionality testing of selected Chill ‐ on technologies during a transport ‐ simulation study of palletized cod boxes: qPCR for fish spoilage bacteria, SLP model and QMRA to evaluate pathogen growth in spiked cod

In this study, tests were carried out on technical solutions developed in the EU project Chill ‐ on, where a simulation experiment was set up to simulate the actual transport of fish from Iceland to Europe. The temperature fluctuations experienced by the fish were aimed at mimicking transport from Iceland to France by ship. Pallets of cod fillets in foam plastic boxes were transported to the Westman Islands by ship and back to Matís in Reykjavík. Samples from these pallets were then compared with control samples that had been stored in Matís' refrigerated conditions. Cod nuggets were also packed in consumer packs (trays) immediately after processing and then after 6 days and were stored in subcooled or refrigerated conditions. Microbial growth experiments were also performed in which Listeria monocytogenes, Escherichia coli and Salmonella Dublin were added to cod necks stored in foam boxes in conditions similar to the storage and transport processes during export. Temperature measurements, sensory evaluation, microbial and chemical measurements were used to present data to test and verify the QMRA / SLP models and quantification of Pseudomonas bacteria using qPCR technology.

The aim of the cod wet trials and the corresponding shelf life study was to include scenarios to test and demonstrate the functionality of some Chill ‐ on technologies in a simulated cod supply chain. Temperature fluctuations were induced according to the actual scenario in the supply chain of cod from Iceland to France via sea freight. The study included sample groups created at the point of processing after packaging in EPS boxes. The reference group was stored at Matís under superchilled conditions. Simulation trials for downward distribution were performed at Matís upon receipt of the pallets shipped to the Westman Isles from Reykjavik (Iceland ‐ Europe freight simulation) and compared with the reference group. Repackaging of loins in retail trays was performed on days 0 and 6 with storage under superchilled and chilled conditions, respectively. In addition, a pathogen challenge trial was performed by spiking loins (5 kg) with Listeria monocytogenes, Escherichia coli and Salmonella Dublin, followed by storage in EPS boxes under temperature conditions simulating export and distribution. Temperature recordings along with microbial, chemical and sensory analyzes from the groups evaluated provided necessary data to test and validate the QMRA / SLP models and the quantitative molecular (qPCR) method to estimate counts of pseudomonads.

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Reports

Pollution monitoring in the marine environment around Iceland 2008 and 2009 / Monitoring of the marine biosphere around Iceland 2008 and 2009

Published:

01/09/2010

Authors:

Hrönn Ólína Jörundsdóttir, Natasa Desnica, Sonja Huld Guðjónsdóttir, Þuríður Ragnarsdóttir, Helga Gunnlaugsdóttir

Supported by:

Ministry of the Environment and Ministry of Fisheries and Agriculture

Contact

Natasa Desnica

Research Group Leader

natasa@matis.is

Pollution monitoring in the marine environment around Iceland 2008 and 2009 / Monitoring of the marine biosphere around Iceland 2008 and 2009

This report presents the results of an annual monitoring project funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The purpose of this monitoring is to fulfill Iceland's obligations regarding the Oslo and Paris Agreement (OSPAR), as well as the AMAP (Artic Monitoring Assessment Program). The data has been sent to the International Council for the Exploration of the Sea (ICES) database. The Marine Research Institute collects samples and Matís oversees the preparation of samples and measurements of trace elements in the marine environment. The samples are measured at Matís and at the Laboratory of Pharmacology and Toxicology. Various inorganic trace elements and chloro-organic substances were measured in cod caught in Hafró's annual spring rally in March 2009 and in mussels collected at 11 locations around the country in August / September 2008. Monitoring in the marine environment around Iceland began in 1989 and data is collected in database. The report provides overview images for some of the topics covered. Cadmium is regionally higher in Icelandic mussels compared to mussels from other countries. There are small changes between years in the concentration of inorganic and organic substances, but a detailed statistical analysis of the data is needed in order to be able to assess with scientific methods the increase or decrease of pollutants in the marine environment in Iceland.

This report contains results of the annual monitoring of the biosphere around Iceland in 2008 and 2009. The project, overseen by the Environmental and Food Agency of Iceland, is to fulfill the OSPAR (Oslo and Paris agreement) and AMAP (Arctic Monitoring Assessment Program) agreements. The project was funded by the Ministry of the Environment and the Ministry of Fisheries and Agriculture. The data has been submitted to the ICES databank (ices.dk), collection of data began in 1989. Matís ohf is the coordinator for marine biota monitoring and is responsible for methods relating to sampling, preparation and analysis of samples. The samples were analyzed at Matís and at the Department of Pharmacology and Toxicology at the University of Iceland. Trace metals and organochlorines were analyzed in cod (Gadus morhua) caught in March 2009 and in blue mussel (Mytilus edulis) collected in August / Sept 2008. Marine monitoring began in Iceland 1989. Cadmium is higher in some locations in Iceland compared to other countries . No significant changes were observed in the concentration of organic or inorganic pollutants investigated. However, a thorough statistical evaluation has to be carried out on the available data to analyze spatial and temporal trends of pollutants in the Icelandic marine biosphere.

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Reports

Let's look at the yellow from fishing in the stomach - a study of factors that affect the value of cod / Factors influencing the quality and value of the Icelandic cod; a value chain perspective

Published:

01/09/2010

Authors:

Helga Gunnlaugsdóttir, Jónas R. Viðarsson, Ásta M. Ásmundsdóttir, Cecilia Garate, Hrönn Jörundsdóttir, Ingibjörg G. Jónsdóttir, Sigurjón Arason, Vordís Baldursdóttir, Þorsteinn Sigurðsson, Sveinn Margeirsson

Supported by:

Increased value of seafood (AVS), HB ‐ Grandi, Guðmundur Runólfsson hf, Fiskistofa, Hafrannsóknastofnunin, Matís

Let's look at the yellow from fishing in the stomach - a study of factors that affect the value of cod / Factors influencing the quality and value of the Icelandic cod; a value chain perspective

The aim of this project was to gather more detailed information than has previously been done on the chemical composition, processing properties and value of cod in the value chain. The main results of the study are:

• There was not much difference in the carcass of cod by season, but the carcass coefficient was slightly higher in December than around the spawning season (February-May) when it was lowest. No association was found between fish body and liver fat content.

• There was a positive relationship between hepatic index and liver fat content (R2 = 0.55). However, the relationship was not linear, but the fat content increased rapidly at a low liver factor but less as the liver factor increased. Likewise, the fat content of the liver increased with length and age in both hens and females.

Liver fat content, fish weight or body mass index do not provide conclusive evidence of fillet utilization. Likewise, the water content and water resistance of the fillets had little or no effect on production efficiency or emissions.

• The summary result of the assessment of the effect of sex, sexual maturity and age on fillet utilization is that there is a difference in fillet utilization between individual fishing trips, this difference seems to be somewhat dependent on the maturity of the fish and is according to available data lowest at maturity stage 4 (ie fish in spawning or spawning). It should be noted, however, that there is a considerable imbalance in the database regarding the distribution of puberty in individual fishing trips and there are relatively few samples of fish from stages 3 and 4 compared to stages 1 and 2.

A comparison was made of the concentration of PCB7 in cod directly from the sea on the one hand and after processing, ie in frozen fillets, on the other. There was no significant difference in the concentration of PCB7 in whole fish and frozen cod fillets, so fish processing does not seem to affect the concentration of these substances in the fillets.

• There was no statistically significant relationship between iron concentration (Fe), selenium (Se), lead (Pb) or PCB7 and gender, age or puberty. There is a statistically significant relationship between the concentration of mercury in the flesh of cod (ie in fillets) and age, length and sexual maturity. Mercury is known to accumulate in the flesh of fish with age and the results of this study are consistent with and based on these results.

The aim of this project is to collect more detailed data about the factors influencing the quality and value of the Icelandic cod during processing, were the end product is frozen fillet. Data were collected from 2007 to 2008 on fillet yield, water content, water capacity, gaping, parasites as well as the chemical composition (nutrients & undesirable substances). These variables are important for the quality and profitability of the cod industry. Emphasis has been laid on connecting these variables to data about fishing ground, season of fishing, sex, sexual maturity in order to increase our understanding on how it is possible to maximize the value of the catch. In addition, the liver from each individual cod was collected and the fat and water content analyzed. The results from this study show that there is a nonlinear relationship (R2 = 0,55) between the liver condition index and the fat content of the liver.

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Reports

Photoperiod and genetics of growth and maturity in cod (Gadus morhua)

Published:

01/04/2010

Authors:

Guðmundur Óli Hreggviðsson, Ólafur H. Friðjónsson, Þorleifur Ágústsson, Sigríður Hjörleifsdóttir, Kjell Hellman, Filipe Figueiredo, Helgi Thorarensen

Supported by:

Technology Development Fund, The Icelandic Center for Research

Contact

Guðmundur Óli Hreggviðsson

Strategic Scientist

gudmundo@matis.is

Photoperiod and genetics of growth and maturity in cod (Gadus morhua)

One of the main problems of cod farming is premature puberty, which results in slower growth and a much longer rearing period. Preliminary studies carried out in pots on land indicated that a new type of light, the so-called CC light, which emits light of one wavelength (green light) had a much greater effect on growth (up to 60% growth increase) and timing of puberty than conventional halogen light. This study examined the role of genotype and expression of certain key genes in response to light cycles, the determination of premature puberty and the association with increased cod growth in aquaculture. It was investigated whether, body size, weight and premature puberty were familial traits. At the end of a six-month indoor spawning season with two types of lighting, one with white halogen light and the other with continuous CC light, the cod was warlike in sea cages. In the sea cages he was also subjected to different light cycle treatments on the one hand with continuous CC light and on the other hand with natural light. After two years of sea farming, the fish were slaughtered, the phenotype of growth and sexual maturity was determined and it was divided into sibling groups, a total of approx. 2000 fish from each treatment separately. It was found that CCL light had a clear effect on delaying puberty and was much more noticeable in hens. The gonads developed much more slowly and not at all to the full compared to cod raised during the natural light cycle at the same time. There was also some variation between sibling groups in the effect of light on the development of gonads. On the other hand, this delay in puberty did not lead to such a sensitive growth rate. The familial similarity of growth patterns was also examined and a clear difference in mean weight was found between sibling groups. Responses to CCL treatment, however, were very divergent and appeared to vary between sibling groups. CCL treatment appeared to increase growth rate in some groups but slow growth rate in others. This could vary by gender. It was also investigated whether pretreatment of broths with CCL light during the coastal spawning season made the cod more sensitive to the effects of CCL light at sea level. That did not turn out to be the case. Certain key genes in growth and puberty control were isolated, along with some or all of their infiltrates. These were growth hormone (GH) genes, growth hormone receptors, growth hormone releasing factor (GHRF) receptors and insulin-like growth factor receptor2 (IGF2) receptors. In the sequences of three of these genes, GH, GHR and IGF2, variable mutations were found and a method for genetic marking was developed based on these sequences. The effect of light cycles on growth expression was also assessed by measuring the expression of two of these genes, GH and GHR. The relative expression of GHR was not found to be greater in larger fish and no association was found between CCL delayed puberty and GHR expression. GH expression was also examined in fish at sea level. Significant differences in GH expression were measured at only one sampling point, early in the first year in the sea cages in the CCL-treated group. This increase did not occur in the corresponding changes in the staging characteristics of growth and puberty measured at the same time.

Light and photoperiod is a powerful environmental regulator of growth and sexual maturation in fish. Initial studies had indicated that a new type of lights, Cold Cathode ‐ lights (CCL), had much greater effect on growth and sexual development than white halogen light traditionally used in fish farming. In this study we investigated selected candidate gene expression in cod in response to CC ‐ light photoperiod treatment and possible genetic contribution to this response. This effect was evaluated by quantitatively comparing phenotypic traits under the different treatments. On December 2008 (“*”), significant differences were found fish farmed under natural light, in combination with gene expression studies and genotypic family assignments. After hatching the fish was reared from 6 months in indoor tanks under two different light regimes, white halogen light and CC ‐ light. The fish was then transported to sea cages and divided into two groups, one that received continuous CC ‐ light and another that received only natural light treatment. The fish was reared in these sea cages for an additional two years until harvesting. Approximately 2000 individuals from each treatment were genotyped and assigned to different full sib groups. Total body weight, length and gonadal weight were also measured for all individuals. Physiologically, the fish responded clearly to CCL treatment regarding maturity related traits, with less gonadal development in the CCL treated fish. The difference was substantial and the same trend could be observed in all families. The degree of response however differed somewhat between families to some which may signify underlying genetic differences. The effect of CCL treatment on growth related traits was less clear. Apparent growth responses to CCL treatment varied greatly between families and they appeared to be either negative or positive, depending on family and sex. Opposite effects were even observed within families on different sexes. In this project genes associated with growth and maturity were retrieved partly or completely from cod (Gadus morhua). These genes were: Growth hormone (GH), growth hormone receptor (GHR), growth hormone releasing factor (GHR F) and insulin like growth factor 2 receptor (IGF2R). A number of their introns were also obtained and variable microsatellite regions could be identified in intron regions of three of these genes, GH, GHR F, and IGF2R. A method was developed based on the GH and GHR gene sequences to amplify and evaluate expression of these genes in different tissues of cod. GHR expression levels were measured at different sampling points both during the indoor stage where different size groups and treatments were compared and at the outdoor stage where different light treatments were mainly compared. Differences in expression levels between different size groups and between different light treatment groups were insignificant. The light influence is on the GH gene expression, was only observed in the beginning of March early at the sea cage stage and could not be associated with increased growth or delayed reproductive development. The CCL (Cold ‐ Cathode Light) has a single green wavelength that diffuses more effectively throughout the water column than white light. It may therefore mask natural light more efficiently. Still it may be necessary to train fish for the CCL lights and at the indoor stage one half of the juveniles received CCL treatment before transportation to the sea cages. When imprinted and not imprinted were compared negligible difference in gonadal development were, however, observed strongly indicating that prior imprinting to sea cage rearing had no effect.  

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