Relative impacts of fishing and eutrophication on coastal fish assessed by comparing a no-take area with an environmental gradient

Lena Bergström,Ulf Bergström,Martin Karlsson,Leif Pihl,Patrik Kraufvelin

doi:10.1007/s13280-018-1133-9

Lena Bergström, Ulf Bergström + Show 3 more

Open Access

https://doi.org/10.1007/s13280-018-1133-9

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Abstract

Understanding the relative impacts of pressures on coastal ecosystems is central for implementing relevant measures to reach environmental management objectives. Here, survey data on the species and size composition of coastal fish are evaluated in relation to fishing and eutrophication, by comparing a long-standing no-take area to an environmental gradient in the Baltic Sea. The no-take area represents an intermediate eutrophication level, but the species composition resembles that seen at low eutrophication in areas with fishing. The catch biomass of piscivores is 2–3 times higher in the no-take area than in the other areas, while the biomass of Cyprinids, generally benefitted by eutrophication, corresponds to that of areas with low eutrophication. The results support that fishing may generate eutrophication-like effects, and, conversely, that no-take areas may contribute to improving environmental status in impacted areas by enhancing piscivores, which in turn may contribute to further improvement in the food web.

Highlights

Coastal fish provide important services to humans, such as food production and recreation, but are recognized as central to ecosystem function (Holmlund and Hammer 1999)
This study aims at exploring the relative impacts on coastal fish from pressures exerted by fishing and eutrophication in a coastal region of the Baltic Sea
The study corroborates that no-take areas can enable an enhanced biomass and size structure of target species for fisheries (Lester et al 2009; Fenberg et al 2012), and, further, that they may contribute to improving the status of coastal fish in areas affected by eutrophication

Summary

Introduction

Coastal fish provide important services to humans, such as food production and recreation, but are recognized as central to ecosystem function (Holmlund and Hammer 1999). Impacts on coastal ecosystems from human activities are, long-lasting and increasing today, with associated negative effects on the environmental status of species and habitats (Airoldi and Beck 2007; Andersen et al 2015), and there is a continued need to protect biodiversity and enhance restoration measures. This issue is highly relevant for coastal fish in the Baltic Sea (Bergstrom et al 2016a; Kraufvelin et al 2018). Management may often be hampered by limited knowledge on the relative extent to which different human-induced pressures are affecting the environmental status

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