Defining the stock structures of key commercial tunas in the Pacific Ocean II: sampling considerations and future directions

摘要: Delineating the stock structure of highly-mobile, wide-ranging fishes subject to exploitation is a challenging task, yet one that fundamental optimal fisheries management. A case in point are stocks skipjack tuna (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye obesus) and albacore alalunga) Pacific Ocean, which support important commercial, artisanal, subsistence, recreational fisheries, contribute roughly 70 % global commercial catches. Although some spatial temporal structuring recognised within these stocks, growing evidence from range approaches suggests each species more complex than currently assumed both assessment climate change models, management regimes. In move towards improving understanding skipjack, yellowfin, South tunas an international workshop was held Noumea, New Caledonia, October 2018 review knowledge about their movement region, define discuss main gaps uncertainties concerning structure, develop biological sampling provision this information. Here, we synthesise discussions latter component. For species, identify several general considerations needed reduce uncertainty, including i) need for broadscale space, ideally covering species’ distribution, targeting adults spawning condition adopting phased approach; ii) temporally-repeated same geographical areas assess stability observed patterns over time; iii) resolve dynamics, such as those resulting movements associated with seasonal extensions poleward flowing currents, underlying iv) importance multidisciplinary approach identification, v) careful planning logistics coordination efforts across agencies. Finally, present potential designs could be adopted help overcome around initial identification provenance, mixing proportional contributions individuals harvested assemblages, well how accounted via use strategy evaluation.