Deep-sea movement patterns of the Patagonian toothfish

Abstract

Context Knowledge on movement patterns within marine fish populations are essential for understanding key aspects of their biology, distribution and stock structure. Many deep-sea fish species possess complex life-history patterns with distributions occurring across vast areas. The nature of connectivity at different life-history stages in a dynamic Patagonian toothfish population on the Patagonian Shelf, Slope and deep-sea plateau around the Falkland Islands remains speculative. Aims We aimed to elucidate the movement patterns as well as the extent that these are driving connectivity during the adult life-history stages of Patagonian toothfish in the region. Methods A 5+-year tag–recapture program was executed and data were analysed using generalised additive models. Key results The majority of individuals (77.59%) displayed high site fidelity (<50 km), suggesting that seasonal spawning migrations are uncommon. However, 9.91% of individuals undertook large-distance movements across oceanographic and physical boundaries. These were characterised by large (>120 cm) fish inhabiting the slope and deep-sea plains (north of 52°S) undertaking southward (direction = 150–240°) home-range relocations to spawning areas. Conclusions and implications The results provide compelling evidence to a single Patagonian toothfish metapopulation, with important considerations in terms of the spawning stock dynamics, and the development of regional management agreements across their Patagonian distribution.