Acronym NA
Category
Aquaculture
Title Pigmentflekker i muskulatur og organer hos atlantisk laks - Pigment spots in muscles and organs of Atlantic salmon 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 Erling Olaf Koppang Coordinator email Erling.olaf.koppang@veths.no
Coordinator institution
NMBU - Norwegian University of Life Sciences (Norway)
Institutions involved
NA
Start year 2004 End year 2005 Funding (€) € NA Website https://www.fhf.no/prosjekter/prosjektbasen/541014/ Summary This is a preliminary project at the Norwegian School of Veterinary Science to investigate the cause of melanin spots in the muscles and organs of farmed salmon.
Occurrence and significance
A survey of the extent of the problem has been conducted. Pigment spots in the muscles are often deep and are not detected by standard quality control after slaughter, therefore three filleting/smoking plants were contacted, one foreign and two in Norway. The foreign producer received raw materials from 44 suppliers last year and could report 4% rejects of total volume due to pigment spots. Rejects below 1% of the delivery were not registered. Nationally, the occurrence of pigment spots in fillets was 10-20% in one and 8-10% in the other producer. Partial rejection was carried out as needed. This extra trimming was time-consuming and costly, and additionally, the trimmed fillets had to be used in other specially adapted production. Roughly estimated, 4% or higher rejection of fish amounts to 2000 tons out of 500,000 tons of fish produced in Norway. This results in significant loss of value. In addition, there are extra production costs.
Pigment spots in muscles
Filleted salmon with pigment spots were collected on the filleting line to study and describe the pathological changes, as well as to explore causal relationships and factors affecting melanin formation. A detailed description of this material was published in the Journal of Fish Diseases in January 2005 (Koppang et al. 2005). In brief, oil/fat droplets surrounded by granulomatous inflammation were observed. This inflammation gathered pigment-containing cells that caused the black pigment spots observed in the fillets visually. Injected oil as a cause of these changes is discussed in the article and is associated with the development of autoimmunity and general inflammatory conditions in mammals.
Melanomacrophages/pigment cells
To study the mechanisms and functions of melanomacrophages found in the inflammatory processes, we have used genetic and electron microscopic examinations to study melanogenesis in these cells in cell culture. We have cloned and sequenced genes specific for melanin formation in salmon. We have shown that these genes are expressed in a salmon cell culture consisting of presumptive macrophages. Further examination of these cells in electron microscopic studies showed that they produced melanin that was sent out through channels in the cells' surface. Furthermore, the cells were positive for CD83, which is a marker for special cells in the immune system (Haugarvoll et al. 2006).
Conclusions:
The following conclusions can be drawn from the preliminary project:
- The problem of melanization is extensive in Norwegian fish farming.
- Melanin spots in muscles seem to be associated with the use of oil-based vaccines.
- The melanin spots consist of inflammatory cells and melanomacrophages that often surround drops of fat, presumably vaccine components.
- It is not known how the oil component in vaccines is distributed and metabolized in fish, but it is likely to be localized in fatty tissue such as muscles over time and may cause damage there.
- Melanized inflammatory cells in fish can produce their own melanin.
- Melanized inflammatory cells in fish appear to consist of a specific leukocyte population with unknown mechanisms.
Keywords
Fish quality;
Salmon;
Fish;
Fish products;
Fish health;
Marine Region
76
Not associated to marine areas
0
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