”Integrated fish monitoring in coastal reference areas” consists of an ecological and a physiological/biochemical project following all organizational levels from cell to community, associated to a contaminant monitoring programme. This report treats the ecological project.
The main objectives are to:
1. Provide references for locally polluted areas.
2. Follow changes in the coastal ecosystems due to impact from land and the open sea.
3. Indicate large-scale changes in the seas surrounding Sweden due to natural processes, toxic substances, plant nutrients, global warming and resource exploitation. In many cases this can be done cheaper and more efficiently than in the open sea.
4. Follow the development of archipelagoes, due to their internationally unique character. Sweden has a special responsibility in this respect.
To fulfil the objectives, the investigations must be made in areas free from local human impact and representing important Swedish coastal systems. Basic studies for integrated monitoring have been running for three years in one Baltic and one Skagerrak archipelago. Besides this, ecological fish monitoring is carried out in eight other reference areas, four of them in Finland and Estonia.
The programme is directed towards demersal coastal fish communities. It is based on a stratified monitoring of abundance with gill and fyke nets minimizing variations within year and between stations. A view of the health conditionis gained by checking external disease symptoms on every fish caught. Modelspecies, stationary during all their life cycle, were selected for the combined physiological and ecological studies. Perch is studied at the east and viviparousblenny at the west coast.
For the model species, year-class size, mortality and growth are studied through age-analyses. Age at maturity, frequency of females with developing gonads, and relative weight of the gonad indicating reproductive capacity are recorded. The studies are made in combination with clinical health tests, alsousing biomarkers. The blenny offers special possibilities as it carries its fry in the ovary for 4—6 months after hatching. The number of fry and their growth and mortality are recorded. The physiological and biochemical analyses on perch provide a solid background for monitoring. In viviparous blenny, the results so far are promising, but some development is still required.
This report mainly presents the statistical variations of the test fishing results.The variations are reasonably low and the catches at different stations covariate closely between years. Trends at 3—5% per year can be detected in the common species.
For the future we suggest that a fish programme comprising ecological and physiological variables, including a biomarker approach, should be run together with contaminant analyses in four national reference areas
Göteborg, 1992. , p. 24