Earlier migration and distribution changes of albacore in the Northeast Atlantic

Abstract

Marine species have exhibited trends in their geographic distribution and phenology in recent decades, and these changes are triggered by climate variability or anthropogenic pressures. Northeast Atlantic albacore has recently been identified to show changes of this nature, although the underlying causes are still uncertain. The aim of this work was to analyse the Northeast Atlantic albacore distribution shifts and phenological changes during the trophic migration that juveniles undertake from late spring to autumn and to identify potential causes of such variability. Specifically, time series of albacore catches of the Basque trolling fleet were studied and compared with trends derived from a null ecological niche model using very large number of catch observations (27,982). The results showed an earlier albacore migration of 2.3 days per decade during the period of 1981–2017, which was partly associated with the recent warming of the sea. The trend analysis of the catch distribution also detected a significant north‐westward trend in catch observations and a northward trend in species habitat. In contrast, both latitudinal trends were uncorrelated. This result suggests that interannual species distribution shifts are mainly related to factors other than oceanic‐climatic variability, such as fleet behaviour or prey changes.

The Role of Climate, Oceanography, and Prey in Driving Decadal Spatio-Temporal Patterns of a Highly Mobile Top Predator

“…Such productivity and diversity, however, might be altered by climate change in the near future, as rising temperatures (0.26 • C per decade; Costoya et al, 2015) are expected to increase ocean stratification and reduce primary production and zooplankton biomass in the area (Chust et al, 2014a). In recent years, losses in fisheries production have already been reported (Free et al, 2019), together with changes in the composition, distribution, and phenology of fish species (Blanchard and Vandermeirsch, 2005;Chust et al, 2019;Baudron et al, 2020). Cetacean spatiotemporal variability, in contrast, has been mainly assessed by exploring changes in their relative abundance (Hemery et al, 2007;Castège et al, 2013;Authier et al, 2018), although both abundance and distribution are considered key criteria by the European Marine Strategy Framework Directive (MSFD; Directive 2008/56/EC) aiming to assess the environmental status of species and ecosystems in European Union waters.…”

Changes to the structure and function of an albacore fishery reveal shifting social‐ecological realities for Pacific Northwest fishermen

“…Indeed, fishermen reported albacore “pushing north” during recent warm‐water oceanographic anomalies (Interviews 5, 20), with schools of fish observed off Southeast Alaska (Cavole et al., 2016). A northward shift in fishing opportunities could coincide with future projections of favourable thermal habitat (Christian & Holmes, 2016), but studies conducted in other ocean basins have shown that albacore distributions are highly variable and do not always correspond with shifts in oceanographic habitat (Chust et al., 2019). Though more research is required to determine how interactions between climate, feeding, migration and spawning throughout the range of the species in the North Pacific are likely to mediate fishable biomass, we would suggest asymmetric impacts are likely across the different segments of North American fishing fleets.…”

Multisatellite-Based Feeding Habitat Suitability Modeling of Albacore Tuna in the Southern Atlantic Ocean

“…In reality, despite the dynamicity of marine fisheries, climatic change, global warming, and various biotic and abiotic factors could alter tuna migration, food availability, catch rate, and stock indices, all of which are related to habitat [45,56,58,60,80]. Determining the precise mechanism(s) underlying suitable habitat is challenging; additionally, whether the interannual distribution shifts of species are mainly associated with other ocean-climate factors, prey abundance, or even another factor like fleet behavior [81] remains unclear. Hence, indirect habitat modeling using diet composition indicators (e.g., small pelagic fish, crustacean, and squid) and historical changes in hotspot habitat resulting from empirical habitat suitability models, such as that of the present study, and advanced modeling of population dynamics [82] could also be suggested as further research areas for the implementation of regional EBFM in the SAO.…”