Swedish Agency for Marine and Water Management

Kustlaboratoriets övervakning av kustfiskbestånd startade för över 30 år sedan och bedrivs huvudsakligen med provfisken efter standardiserade rutiner i en handfull områden utmed svenska kusten. Delar av detta program ingår i ett internationellt miljöövervakningssystem. Det yrkesmässiga fisket följs genom det licensierade fiskets loggboksstatistik. I laboratoriets första resursöversikt, 1997, omfattade redovisningen i första hand de viktigaste sötvattenarterna. I årets upplaga presenteras även kustfisket på de marina arterna. Sedan ett antal år tillbaka ger Kustlaboratoriet prognoser för abborre i Östersjön och för torsk och havslekande sik i Bottniska viken. Detta sker i samarbete med Vilt- och Fiskeriforskningsinstitutet (VFFI) inom ramen ”Samarbetsorganet för fisk i Bottniska viken”. Ett utvecklingsarbete pågår för att förbättra metoderna och även ge prognoser för fler arter. Årets översikt har koncentrerats på förutsättningarna att genomföra fångstprognoser.

The Institute of Coastal Research monitors the most important fish stocks for the professional and leisure fishing in the coastal zone. The first report on resource monitoring in the Swedish coastal zone, issued last year, was an overview of the present situation concerning the possibilities to make stock assessments for coastal species. However, traditional methods for assessing these stocks were considered not adapted for coastal conditions and could only be used in a few cases. Special criteria requested for, e. g., VPA, like a defined unit stock and variable fishing mortality, are seldom met. As coastal species often appear as hundreds different separate stocks such analyses are complicated or unreasonably expensive which has been an incentive for developing new methods better adapted to coastal conditions.

The stock assessment procedures have progressed far enough for analysing the general status of the major coastalstocks. A few species are overexploited or close to, e.g. vendace and cod, but some species are considered under exploitedand could sustain a higher fishing mortality, e.g. perch, pike and flounder. For other species the basis for statements are weaker. The prerequisites for making catchprognoses are discussed and for some species prognoses are presented.

The Institute of Coastal Research also is engaged in environmental monitoring. Coastal fish communities are studied at nuclear power plants and pulpmills. Reference areas coupled to an international system also engaging Finland and Estonia provide background data. Impacts on fish are also studied in the Öresund area at the site of the constructions of a bridge between Denmark and Sweden. Test fishing data produced by the monitoring programmes also provide an important input for the stock prognosis.

Chemical contamination is a problem restricting consumption of Baltic fish. Concentrations have, however, dropped considerably, and the recommendations may be reconsidered in the near future at least for the coastal species. Many local impacts of coastal eutrophication on fish are evident. Strong stocks of mainly cyprinids develop, but the recruitment of many predatory fish can be negatively affected. Although many improvements have been seen, effluents from pulp and paper mills continue to cause negative influence on fish reproduction and recruitment. The responsible substances are still unknown. Fish attracted to heated areas at nuclear power plants may suffer from severe reproductive disorders. Recently, a parasitic microsporidian was detected in roach and pike eggs, sometimes causing total destruction of the fish gonads.

Coastal fishing generally has small impacts on the environment. The risk of by catches of seals and birds constitute the main problem. An inquiry among fishermen was recently made, showing that by catches depend upon gears as well as the behaviour of the seals. The results point to a need of improving fishery techniques.