Linda Pedersen
POP levels found in farm associated saithe from Masfjorden were in general low compared with levels from studies from coastal and open sea area in Norway. However, due to risk for POPs to enter the food chain and to bioaccumulate to detrimental concentrations in top predators, monitoring discharged levels from fish farming should continue.
Hovedinnhold
Aquaculture in Norway is a steadily growing industry with Atlantic salmon (Salmo salar) as the main cultivated species. In the recent years, both aqua feed and farmed fish around the world have been reported to contain lipophilic persistent organic pollutants (POPs), and the safety of consuming farmed fish have been questioned. The large scale production, combined with open net pen system, has highlighted the importance of monitoring the environment close to fish farms. Excess aqua feed pellets attract a large number of wild fish and this shift from natural to aqua feed diet may affect both physiology and chemical body burden in the wild fish. As part of a research project at the Institute of marine research this study analyzed the liver of various wild farm associated (FA) fish for levels of certain PCBs, PBDEs, DDTs, HCHs, HCB and TNC. One of the species, Saithe (Pollachius virens), were the main focus of the study. In addition to chemical analysis, saithe were analyzed for biochemical markers for POP exposure (EROD activity and CYP1A levels by ELISA), for changes in gene expressions of selected gene transcripts, fatty acid profile and condition indices. FA saithe was compared to a group of saithe caught from an assumable unaffected area (REF).Total POP levels were measured to be almost four times higher in the REF saithe, while expression levels of most gene transcripts, both related to toxic defenses, and to lipid metabolism, were up regulated in the FA saithe. HSI was higher in the FA saithe and fatty acid profile differed between the two saithe groups, reflecting intake of more plant derived fatty acids in the FA saithe.
POP levels found in farm associated saithe from Masfjorden were in general low compared with levels from studies from coastal and open sea area in Norway. However, due to risk for POPs to enter the food chain and to bioaccumulate to detrimental concentrations in top predators, monitoring discharged levels from fish farming should continue. Such monitoring may also assist to discover whether farm associated wild fish is affected from feeding on discharges from net pens.
