A synthesis of a coastal northern pike (Esox lucius) fishery and its social-ecological environment in the southern Baltic Sea: Implications for the management of mixed commercial-recreational fisheries

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We synthesize a large body of literature involving peer-reviewed work, grey literature and novel data analyses about the small-scale northern pike (Esox lucius) fishery in lagoon ecosystems in the southern Baltic Sea. Based on our comprehensive review that synthesizes ecological as well as social, economic and governance-related literature we derive implications for the management of mixed commercial-recreational fisheries in coastal areas. The interconnected shallow and biologically highly productive meso- to polytrophic lagoons (extension about 2000 km2) bordered by the peninsula of Fischland-Darß and the islands of Hiddensee, Rügen and Usedom in the southern Baltic Sea of Germany constitute an oligo- to mesohaline transitional habitat suitable for colonization by a range of freshwater fishes, including pike. In the Rügen area, pike successfully recruits in the mesohaline lagoons, but anadromous subpopulations and freshwater residents also exist in tributaries, forming a connected meta-population. The stock is co-exploited by a small-scale commercial fishery and a largely tourism-dominated recreational fishing sector that, depending on the angler type, values the pike for both consumption as well as for its trophy size. The recreational sector has risen in economic and social relevance since the German reunification in 1990 and today removes similar amounts of biomass than commercial fisheries. Pike is a prime target species of anglers, and recreational pike angling in the lagoons today generates a larger economic impact in terms of jobs created compared to the commercial pike fishing, where pike is typically one target among many freshwater fish. Stock assessments and stakeholder reports have revealed that the stock size and size of pike in the catch have been falling since 2010, fueling conflicts among fishers and anglers for space and fish. Reasons for the current decline of the pike stock involve multiple pressures operating jointly and possibly synergistically, such as local overharvest, loss of stock structure through past blocking of freshwater streams, eutrophication and macrophyte loss, predation mortality by natural predators, reduced availability of marine prey through declines of western Baltic spring-spawning herring (Clupea harengus), and poorly understood impacts of climate change. The assessment of current fishing mortality suggests a the stock stock is size/quality-overfished from the perspective of anglers, and fully exploited to slightly growth-overfished when judged against the reference point of maximum sustainable yield. The current biomass trend is negative. The current instantaneous fishing mortality rate, F, is estimated to range between 0.2 and 0.4 yr-1. Hence, fishing cannot be the sole culprit of the current stock decline because the current fishing mortality rates are too high for the underlying productivity, but not exessive. Because the current fishery no longer meets the expectations of recreational anglers, and angler numbers have recently declined, if the aim is to also suit anglers, reductions of fishing mortality would be useful in recovering the stock and fishing quality, coupled with restoration of access to flooded wetlands as spawning and nursery grounds, and control of other mortality sources of pike (e.g., cormorants). However, whether such actions indeed rebuild the fishery remains uncertain because of the potential for compensatory natural and fisheries mortality and other environmental changes affecting recruitment and abundance negatively. Policy makers may want to solve the allocation problem among commercial and recreational fisheries, install a robust monitoring system and a management framework that is inclusive of multiple perspectives and objectives and adaptive to novel productivity regimes and further structural changes in the mixed fishery. Further research on climate change impacts, food web changes, impacts of natural predators such as seals, cormorants or stickleback, and the behavioral and socio-economic aspects of commercial and recreational fisheries is warranted.

Arlinghaus et al. 2023. A synthesis of a coastal northern pike (Esox lucius) fishery and its social-ecological environment in the southern Baltic Sea: Implications for the management of mixed commercial-recreational fisheries. Fisheries Research, 263, 106663.

Veröffentlicht : 2023
Erschienen in : Fisheries Research, 263, 106663