The necessity of a holistic approach when managing marine mammal–fisheries interactions: Environment and fisheries impact are stronger than seal predation

Abstract

Seal populations are recovering in many regions around the world and, consequently, they are increasingly interacting with fisheries. We used an Ecopath with Ecosim model for the offshore Central Baltic Sea to investigate the interactions between the changes in fish stocks and grey seal ( Halichoerus grypus ) population under different fishing and environmental scenarios for the twenty-first century. The assumed climate, eutrophication and cod ( Gadus morhua ) fisheries scenarios modified seal predation impacts on fish. Fish biomass and catches are more affected by fishing mortality and the environment than by seal predation. Our results highlight that the impacts of the increasing seal population on lower trophic levels are complex; thus, we emphasize the need to consider a range of possible ecosystem contexts when evaluating potential impacts of top predators. Finally, we suggest that an increasing seal population is not likely to hinder the preservation of the main Baltic fish stocks. Electronic supplementary material The online version of this article (10.1007/s13280-018-1131-y) contains supplementary material, which is available to authorized users.

Variation in predator diet and prey size affects perceived impacts to salmon species of high conservation concern

“…Multi-species models used to evaluate management alternatives in marine realms include a broad spectrum of approaches, ranging from multiple linear regression (Walters et al 1986;Minto and Worm 2012), to fisheries assessment models of intermediate complexity ("MICE" models) (Plagányi et al 2014;Punt et al 2016), to large ecosystem models that include dozens, if not hundreds, of species (Lessard et al 2005;Costalago et al 2018). Increasing demand for ecosystem-based fisheries management means more complex multi-species approaches will probably be used with increasing frequency.…”

Disconnects in global discourses—the unintended consequences of marine mammal protection on small-scale fishers

“…For these and other reasons, the Food and Agricultural Organization (FAO) has highlighted the importance of the small-scale fisheries sector as a target for improving income and food security in developing countries (11). Worryingly, increases in the abundance of some marine mammals are generating tension with fisheries, particularly small-scale coastal fisheries (12,13). For example, in South America, pinniped depredation of catch is estimated to occur in ~56% of catches (14,15), and lead to average economic losses of ~30 per cent (16).…”

“…Peru and Chile are the 5 th and 12 th biggest countries worldwide for fisheries landings (22), and their small-scale fisheries are highly integrated with world fisheries markets (23). These fisheries also overlap with pinniped foraging areas, increasing the potential for interactions between this sector and marine mammals (8,12,13). Peru's small-scale fishing fleet contains an estimated 18,000 vessels and 67,000 fishers, distributed over 106 ports and landing sites (Castillo et al 2018).…”

Use of Ecoacoustics to Characterize the Marine Acoustic Environment off the North Atlantic French Saint-Pierre-et-Miquelon Archipelago

“…For example, one of the main threats for Southern Resident killer whales is the lack of food [74]. By gaining knowledge on these preys, new insights could be used in marine management strategies [75]. In our work, only sound pressure was analyzed, which may be inadequate to study the acoustics of fish and invertebrates as they mostly rely on particle motion [76,77].…”