Background/Aims
Most global seafood is harvested by multispecies fisheries. In Australia, the Northern Prawn Fishery (NPF) is a multispecies tropical prawn trawl fishery that has been operating since the late 1960s, primarily in the Gulf of Carpentaria. The fishery is one of Australia’s most valuable and catches eight prawn species across two distinct fishing seasons.
Methods
Here, we highlight how the NPF’s established history of extensive monitoring programs, detailed knowledge of species-specific biology and life history dynamics, and adaptive management developed through MSE testing has resulted in the long-term sustainability of these short-lived, highly variable northern Australian prawns.
Results
The NPF is managed to achieve Maximum Economic Yield (MEY) by regulating effort controls, including limitations on season length, number of vessels and operational gear. Despite MEY as an overarching goal, various harvest strategies have been developed to accommodate species-specific traits. For example, the reliance of common banana prawn recruitment success on environmental drivers, specifically monsoon rainfall, outweighs the effects of any stock-recruitment relationship. Consequently, this species is managed using an MEY-based catch rate trigger. In contrast, tiger prawns are assessed biennially using a multispecies, weekly sex- and size-structured population model that is combined with a bio-economic model to estimate the levels of effort required to achieve MEY in the long-term. The former has relatively low data requirements and there is no formal stock assessment, while the latter is data-intensive and includes information from extensive fishery-independent surveys that separately target recruitment and spawning stocks, as well as an annual economic survey of the fishery.
Conclusion
The diverse harvest strategies used to manage the NPF resources highlight the inherent difficulty of managing multispecies fisheries. Climate change is adding a new layer of complexity to multispecies fisheries management, and research focus has shifted toward flexible and adaptive management strategies that account for species interactions and differential species responses to environmental variability. In this context, the NPF may serve as an instructional case study for other fisheries facing an increasingly uncertain future.