Trophic impact of Atlantic bluefin tuna migrations in the North Sea

Research output: Contribution to journalJournal articleResearchpeer-review

492 Downloads (Pure)

Abstract

Large highly migratory predators can have major impacts on local marine ecosystems by reducing prey populations and leading to trophic cascades that affect the entire fish community. These trophic interactions are typically non-linear and can alter both the migratory behaviour of the predator and the stability of the fish community. The impact of a migrating top-predator is investigated here for Atlantic bluefin tuna in the North Sea. Bluefin tuna has been absent from the region for half-century, but recent years have seen recovery of migrations and a return of bluefin tuna in the area. We use a size spectrum model to analyse the trophic impact of the returning tuna on the entire fish community, under scenarios with varying levels of tuna consumption and fishing mortality on the prey. We show that with high level of prey fishing mortality in the North Sea, the effect of a tuna re-colonization results in only limited trophic cascades. However, high tuna consumption or changes in fishing mortality may result in a sudden recruitment failure of small-pelagic fish due to cascading effects on the fish community. In present-day conditions, the level of tuna consumption that triggers recruitment failure is lower at increasing fishing mortalities on their prey, providing indications for the future sustainable management of both small-pelagics and bluefin tuna in the area.
Original languageEnglish
JournalICES Journal of Marine Science
Volume74
Issue number6
Pages (from-to)1552-1560
ISSN1054-3139
DOIs
Publication statusPublished - 2017

Keywords

  • fish community
  • long distance migration
  • size spectrum model
  • trophic cascade

Cite this