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Abstract

Healthy coastal fish stocks and communities comprise an important part of the environmental targets of the Marine Strategy Framework Directive and Baltic Sea Action Plan, both in Sweden and the Baltic Sea as a whole. As such, the status of fish communities along our coasts should be assessed and Good Environmental Status (GES) should be achieved in 2020 by using a suite of selected indicators.
Many coastal fish stocks in the Baltic Sea are typically local in their appearance and response to environmental conditions. In spite of a well-developed coastal fish monitoring program in Sweden, there are still spatial gaps in its coverage limiting the potential for a full comprehensive status assessment of coastal fish.
Within the commercial fishery, all fishermen are obliged to report the catches and effort of their fishery to the European Commission via daily logbooks. To date, however, the information gathered from the small-scale coastal fisheries has not been used to assess the status and development of coastal fish stocks and communities. In this report we assess the potential for using data collected within the small-scale coastal fishery for indicator development and status assessments of coastal fish by 1) screening the species targeted and gears used in the commercial fishery, 2) comparing the temporal development of indicators derived from the commercial fishery and fishery independent coastal fish monitoring, and 3) comparing the outcome of status assessments derived from indicators developed using the two sources of data.
Our results show that the commercial coastal fishery in Sweden is mainly targeting cod, herring, whitefish, flounder and perch, and to a minor extent also pike and pike-perch. These species are mainly caught using gillnets, but in some areas traps or trap-nets are of importance. Catches of species of noncommercial value as roach and breams and other members of the carp family are very low or not registered, and the data is hence limited to a few species of commercial importance.
We found an overall weak match and substantial variation across coastal areas between indicators derived from the commercial fishery and fisheries independent monitoring data. There was, however, a reasonable concordance between the Abundance of large perch (above 25 cm) from monitoring data and catch-per-unit-effort (CPUE) of perch in the commercial fishery. When assessing the environmental status of the fish communities based on indicators derived from the two sources of data, there was a rather good overall match in GES for the indicators Abundance of perch, Abundance of large perch and Abundance of piscivores and CPUE based indicators from the commercial fishery. The match was lower for the indicator Abundance of large piscivores and indicators ignoring effort data in the commercial fishery.
Our results suggest that CPUE data from the coastal commercial fishery could potentially be used as a complement and give additional support for status assessments of coastal fish in Sweden, particularly for the indicator Abundance of large perch. Since no information on size structure or the abundance of species of low commercial value could be obtained from the coastal commercial fisheries statistics, the data reported is in its current form of limited use for more detailed assessments of coastal fish communities. This regards important parameters such as size structure and the abundance of important functional groups as carp fishes. The fisheries statistics includes many sources for potential errors, but there are some means that can be used to increase the value of this data for assessments. The quality of the reporting can be improved, a selected number of coastal fishermen can be contracted for more detailed self-reporting of their catches and efforts. It is especially important to focus on registration of by-catch (both undersized fish of focal species and species of non-commercial value), subsampling for length and age estimates, and improved resolution of the effort and fishing location. This would be especially valid for those species and stocks that we have limited information on in the fishery independent gillnet monitoring programs as for example whitefish, pike-perch, pike and flatfishes.