The impact of the sandeel fishery closure on seabird food consumption, distribution, and productivity in the northwestern North Sea

Abstract

Abstract:In the North Sea, the lesser sandeel (Ammodytes marinus) is the target of an industrial fishery and the principal prey of many top predators. Because of concerns about potential effects on predators, the sandeel fishery off eastern Scotland was closed in 2000, and local sandeel abundance increased subsequently. To examine whether closure benefitted sandeel-dependent seabirds, we compared summer sandeel consumption, at-sea distributions, and breeding success of seven species with fishery removals and abundance of older (1+ group) and young-of-the-year (0 group) sandeels from 1996 to 2003. Breeding success of black-legged kittiwake (Rissa tridactyla), a species that has declined in recent decades, was related to abundance of both 1+ group (the age class targeted by the fishery) and 0 group sandeels. The proportion of 0 group consumed by kittiwakes and proportion of the kittiwake population foraging in the area were linked to 0 group abundance. None of these parameters in the other seabird species were associated with sandeel abundance. Our results suggest that fishery closure can have a beneficial impact on top predators sensitive to variation in abundance of the target species, although environmental conditions before and after closure are also likely to be critically important.Résumé : Dans la mer du Nord, le lançon équille (Ammodytes marinus) fait l'objet d'une pêche industrielle et il constitue la principale proie de plusieurs prédateurs supérieurs. À cause de préoccupations concernant les effets potentiels sur les prédateurs, la pêche commerciale aux lançons équilles au large de la côte est de l'Écosse a été fermée en 2000 et l'abondance locale des lançons a alors augmenté. Afin de vérifier si cette fermeture a été bénéfique aux oiseaux marins dépendants des lançons, nous avons comparé la consommation de lançons pendant l'été, la répartition en mer et le succès de la reproduction chez sept espèces en fonction des retraits de la pêche et de l'abondance des lançons de l'année (groupe 0) et des lançons plus âgés (groupe 1+) de 1996 à 2003. Le succès de la reproduction de la mouette tridactyle (Rissa tridactyla), une espèce en déclin au cours des dernières décennies, est relié à l'abondance des lançons, tant ceux du groupe 1+ (la classe d'âge ciblée par la pêche) que ceux du groupe 0. La proportion des lançons d'âge 0 consommée par les mouettes et la proportion de la population de mouettes qui recherche sa nourriture dans la région sont reliées toutes deux à l'abondance du groupe 0. Aucune de ces variables chez les autres espèces d'oiseaux marins n'est reliée à l'abondance des lançons. Nos résultats indiquent que la fermeture de la pêche peut avoir un effet béné-fique sur les prédateurs supérieurs qui sont sensibles à la variation de l'abondance de l'espèce ciblée, bien que les conditions du milieu avant et après la fermeture puissent être aussi vraisemblablement d'importance primordiale.[Traduit par la Rédaction] Daunt et al. 381

Observed and predicted effects of climate change on species abundance in protected areas

“…Although seabirds might be more directly affected by sea temperature than the measures of air temperature we used, our models nonetheless had good ability to explain recent large-scale population trends in this group. The apparent sensitivity of seabirds to warming matches empirical observations which describe how recent increases in sea-surface temperature have reduced the abundance and condition of fish prey species for many seabirds 26 . As a result, the productivity of seabirds has declined in relation to warmer temperatures 27,28 and they may also be vulnerable to more direct negative effects of warming through heat stress 29 .…”

Bottom-up effects of a no-take zone on endangered penguin demographics

“…MPA networks) [2]. In summary, our results support the use of small-scale fishing closures to conserve marine predators [4][5][6] but highlight the importance of integrating them into holistic, ecosystem-based management regimes. D, expected deviance; P opt , optimism penalty applied to model; PED, penalized expected deviance ( D þ P opt ); DPED, difference in PED; s.e., standard error associated with DPED; ratio of DPED/s.e., indicating model support; AB, anchovy biomass; SB, sardine biomass; SC, sardine catch; AC, anchovy catch; C, closure status.…”

“…Marine protected areas (MPAs) are increasingly designated to protect benthic habitats and species, but their efficacy for highly mobile species is unclear [2,3]. This problem is exacerbated when fisheries closures are designed to benefit mobile, upper trophic level predators by protecting their prey [4]. In particular, behaviourally mediated change or unrelated natural fluctuations in prey may mask population-level responses to closures [4][5][6].…”

Identifying Risk: Concurrent Overlap of the Antarctic Krill Fishery with Krill-Dependent Predators in the Scotia Sea

“…This is supported by our maps of overlap, which identified areas where concurrent occupation by predator and fisheries occurred repeatedly over time. A concentration of fishing effort in such localized areas may negatively impact predators, particularly central-place foragers like numerous breeding seabird and pinniped species [2, 3, 67, 68]. To mitigate potential negative effects of fisheries on predators in critical foraging areas, it thus seems necessary to specify not only relatively low harvest rates for forage fish fisheries, but to identify areas where the risk to predators may be greatest and implement management measures that account for high-risk areas.…”