Resultat från övervakningen av kustfisk : Asköfjärden (Egentliga Östersjön) 2005–2024

This report presents the results from the coastal fish monitoring in Asköfjärden, which has been conducted annually in August since 2016. The study is a part of the regional environmental monitoring of coastal fish. Fish monitoring is carried out with Nordic coastal multimesh gillnets, and the species composition of the catch, diversity, trophic level, abundance of predatory fish and cyprinids, as well as the size and number of the fish are studied. Environmental variables are also noted during the sampling. Age determination of perch is carried out after the sampling is completed. The monitoring area is located in Trosa municipality in Södermanland County, and the coastal water type is Mellankustvatten i Östergötlands och Stockholms skärgård. The area is relatively deep and exposed, and contains few spawning and nursery areas for typical warm water species. Unlike several nearby monitoring areas, Asköfjärden is considered to be insignificantly affected by local human activity. The most common species in the catch are perch and roach, which together accounted for just over 58% of the total catch. The total catch per net and night has increased since the start of the survey and can largely be explained by the increased abundance of herring and sprat. The area has undergone a change in the age distribution of perch, towards a larger proportion of young individuals in the nets. Additionally, the perch caught in Asköfjärden have a higher condition index and are longer than those at the start of the time series. The increasing numbers of round goby encountered in the fish monitoring may indicate that the species is becoming more common in the area.