Competition for the fish – fish extraction from the Baltic Sea by humans, aquatic mammals, and birds

Abstract

Seals and fish-eating birds have increased in the Baltic Sea and there is concern that they compete with fisheries. Using data from around year 2010, we compare consumption of different fish species by seals and birds to the catch in the commercial and recreational fishery. When applicable this is done at the geographical resolution of ICES subdivisions. Predation by birds and mammals likely has limited impact on the populations of the commercially most important species (herring, sprat, and cod). In the central and southern Baltic, seals and birds consume about as much flatfish as is caught by the fishery and competition is possible. Birds and seals consume 2-3 times as much coastal fish as is caught in the fishery. Many of these species are important to the fishery (e.g. perch and whitefish) and competition between wildlife and the fishery is likely, at least locally. Estimated wildlife consumption of pike, sea trout and pikeperch varies among ICES subdivisions and the degree of competition for these species may differ among areas. Competition between wildlife and fisheries need to be addressed in basic ecosystem research, management and conservation. This requires improved quantitative data on wildlife diets, abundances and fish production.

Top‐down pressure on a coastal ecosystem by harbor seals

“…This pattern is also evident in other regions, like the Baltic (Hansson et al. ). However, locally near the coast with high densities of central‐place foraging predators, the impact of these predators may exceed that of fishing (Hansson et al.…”

“…, Hansson et al. ). This is challenging though, since they target different size classes, and the estimated removals are based on different methodologies.…”

“…However, locally near the coast with high densities of central‐place foraging predators, the impact of these predators may exceed that of fishing (Hansson et al. ). In the Dutch coastal zone, the fisheries specifically targeting demersal fish species are rather small compared to the other predators (i.e., landing 723 tons, including 99 tons in the Wadden Sea; van Kooten et al.…”

Biodiversity and ecosystem services in Nordic coastal ecosystems

“…Recent studies however point out that information on the actual impact of fishing pressure is lacking (ICES, 2011;Havs-och Vattenmyndigheten, 2015) and that the ultimate cause of weak trout populations is not known (ICES, 2011). In recent years, the sea trout populations in the Bothnian Bay have increased from 60% of expected maximum in 2001 to a mean of 74% 2012(Havs-och Vattenmyndigheten, 2018.…”

Predator recovery, shifting baselines, and the adaptive management challenges they create

“…, Hansson et al. ). This emotionally charged issue arguably stems from a relatively narrow ecological view of pinnipeds—primarily as predators of commercially valuable natural resources.…”