Acronym NA
Category
Aquaculture
Title Control of malformations in the production of Atlantic cod (Gadus morhua L.) by optimizing temperature and light conditions Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National Coordinator Kristian Prytz Coordinator email kristian.prytz@fhf.no
Coordinator institution
FHF - Norwegian Seafood Research Fund (Norway)
Institutions involved
NA
Start year 2005 End year 2006 Funding (€) € NA Website NA Summary In order to clarify how molecular markers associated with the development of bone deformities are affected by temperature, experiments were carried out in collaboration with NFR project 59672 with different temperatures (4, 6 and 8 °C) from fertilization to initial feeding.
Temperature affected the activity of proteins important for cell differentiation and for the development and maturation of the skeleton, and the effect was most severe at the beginning of segmentation and organ formation.
In cod, the formation and mineralization of bone continues into the initial feeding period. Because temperature affects both development speed and growth, experiments were carried out with different temperatures during the initial feeding period. The lowest proportion of deformities was achieved with a gradual increase from 6-12 °C over 7 weeks compared to a constant 8 or 12 °C. At a size of 50 grams, all fish were X-rayed, and the deformities were divided into axis errors or deformed whorls. A gradual increase in temperature over a long period clearly gave the best result with regard to deformities, and neck cracking was most affected by unfavorable high temperature. In some species, the light regime during the initial feeding can have an impact on the development of the fish larvae. Experiments were therefore carried out in which the effect of day/night regime was investigated, and the effect of ceiling light versus light source on the vessel edge. Choice of light regime or location of light source had no effect on the incidence of bone deformities. Growth was best with 24 hours of light compared to 16 hours of light and 8 hours of night. Light from the roof gave better growth than light on the edge of the vessel.
In collaboration with the EU project FineFish, the effect of water speed on the development of lordosis was investigated. 60 days after initial feeding, cod fry were split into two groups, one of which was exposed to a behaviorally regulated current that was so strong that the fish changed direction after 5-10 seconds, while the fish in the control group experienced no current. The time for the start of the experiment was chosen because the water demand then increases with regard to self-cleaning of vessels and oxygen. At this age, the spine behind the swim bladder consists mainly of cartilage, and can therefore be sensitive to mechanical stress. At the end (13 grams), 13% of the fish in the control vessels had lordosis, while a full 32% of the fish that received high water velocity had the same deformity.
Fish from the experiment with different spawning temperatures were marked and placed in cages in the sea at a size of 50 g to investigate how different deformities develop over time. The fish were X-rayed when released in January, and twice more the following year. Both the proportion of fish with neck fractures and the degree of severity increased over time. It seems that an early recorded curvature of the neck will not normalize, but often worsens. The course of lordosis is more unclear than that of a neck fracture. Less severe lordosis detected early seems to be able to normalize, but lordosis can also occur at later stages.
Keywords
Fish;
Fish health;
Cod;
Disease;
Marine Region
76
Not associated to marine areas
0
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