Long-term decline in northern pike (Esox lucius L.) populations in the Baltic Sea revealed by recreational angling data

The role of chemical communication in the predator-prey role reversal of northern pike (Esox lucius) and three-spined stickleback (Gasterosteus aculeatus)

“…Stickleback predation on pike eggs and larvae have been proposed as a main cause to recent declines in pike abundances and the failure of populations to recover despite extensive management (Bergström et al, 2022;Eklöf et al, 2020;Nilsson et al, 2019). With sticklebacks frequently aggregating in pike recruitment habitats, it has been debated whether this may be due to sticklebacks actively migrating to forage on pike larvae or whether it is rather a consequence of that increasing numbers of sticklebacks end up in these habitats as part of their life-cycle.…”

“…The Baltic Sea provides an excellent example emphasizing the important role of a predator-prey role reversal in structuring the fish community. The coastal fish community has changed drastically along large parts of the Baltic Sea including pronounced declines of the toppredators northern pike (Esox lucius, hereafter pike) and Eurasian perch (Perca fluviatilis, hereafter perch) (Bergström et al, 2022;Ljunggren et al, 2010;Nilsson et al, 2004;Olsson, 2019). Multiple reasons have been linked to the decline, among them habitat degradation (Sundblad and Bergström, 2014), fisheries (Bergström et al, 2019), eutrophication (Bergström et al, 2016;Lehtonen et al, 2009), and increased predation pressure by seals (Halichoerus grypus) (Bergström et al, 2022;Hansson et al, 2018) and cormorants (Phalacrocorax carbo sinensis) (Heikinheimo et al, 2021;Östman et al, 2012).…”

“…The coastal fish community has changed drastically along large parts of the Baltic Sea including pronounced declines of the toppredators northern pike (Esox lucius, hereafter pike) and Eurasian perch (Perca fluviatilis, hereafter perch) (Bergström et al, 2022;Ljunggren et al, 2010;Nilsson et al, 2004;Olsson, 2019). Multiple reasons have been linked to the decline, among them habitat degradation (Sundblad and Bergström, 2014), fisheries (Bergström et al, 2019), eutrophication (Bergström et al, 2016;Lehtonen et al, 2009), and increased predation pressure by seals (Halichoerus grypus) (Bergström et al, 2022;Hansson et al, 2018) and cormorants (Phalacrocorax carbo sinensis) (Heikinheimo et al, 2021;Östman et al, 2012). Recently, there has also been increasing support to the hypothesis that rapidly increasing abundances of the three-spined stickleback (Gasterosteus aculeatus, hereafter stickleback) negatively impact the abundances of pike and perch, which in sub-adult and adult life-stages are main predators on sticklebacks in the coastal habitat, both by resource competition and direct predation on their young (Bergström et al, 2015;Eklöf et al, 2020;Nilsson et al, 2019;Olin et al, 2022).…”

Corroborating age with oxygen isotope profiles in otoliths: consequences for estimation of growth, productivity and management reference points in northern pike (Esox lucius)in the southern Baltic Sea

“…Baltic Sea pike stocks have traditionally been exploited by commercial fisheries, but in recent years a strong recreational fishery has developed that often has different objectives to commercial fisheries, e.g., favoring the catch of trophy fish or catch rate over biomass yield (Ahrens et al, 2020; Arlinghaus et al, 2019). Over the last decade, pike stocks have declined in many areas of the Baltic (Berggren et al, 2021; Bergström et al, 2022; Lehtonen et al, 2009; Olsson, 2019; Tibblin et al, 2015). To align fishing mortality rates with shifts in resource abundance, assessment of contemporary growth rates and derivation of fisheries reference points that suit commercial and recreational fisheries is important (Ahrens et al, 2020).…”

Temperature moderates eDNA-biomass relationships in northern pike

“…In the Baltic Sea, large scale patterns indicate that the pike populations on the east coast of Sweden have drastically declined. The reasons are multifaceted but likely a consequence of increased predation on adults from grey seals and cormorants (Hansson et al 2017, Svensson 2021), predation on juvenile stages by three-spined stickleback (Eklöf et al 2020, Donadi et al 2020), loss of recruitment habitats (Sundblad and Bergström 2014), and also a period of high recreational fishing mortality during the early 1990s (Bergström et al 2022). For stationary species which form genetically stable distinct populations over rather small geographical areas (Laikre et al 2005, Wennerström et al 2016, Möller et al 2021, Diaz-Suarez et al 2022) management needs to be regional and there is a need for monitoring methods which are able to accurately assess the status of pike populations on a local scale.…”