Effectiveness of harvest strategies in achieving multiple management objectives in a multispecies fishery

Abstract

Fisheries management is characterised by multiple objectives, some of which may be complementary, while others may require trade-offs between outcomes. Balancing these objectives is made more complex in the case of multispecies and multigear fisheries. In this paper, we develop a bioeconomic model that captures the key elements of such a fishery to test a range of potential harvest strategies to provide insights into how economic target reference points could lead to both desirable and undesirable management outcomes (e.g. discards). The model is developed as a longrun optimisation model to identify target reference points to achieve multispecies maximum economic yield, and a dynamic recursive optimisation model, which includes more realistic representation of fishers' behaviour, such as discards and trading of under-caught species quotas. The potential economic, social and ecological impacts are evaluated using data envelopment analysis (DEA). The results suggest that the use of proxy target reference points can result in short-term economic benefits at the cost of slower stock recovery and higher discarding. Limiting the number of species subject to quota controls may also prove beneficial in multispecies fisheries, while ensuring quota markets are efficient is likely to produce benefits irrespective of the harvest strategy adopted.

Exploring trade‐offs in mixed fisheries by integrating fleet dynamics into multispecies size‐spectrum models

“…In a multispecies context, biomass at maximum sustainable yield can exceed biomass at maximum economic yield for some species (Hoshino et al, 2018); thus, the forced decrease in effort is in contrast with the harvest control rule which aims at maintaining species biomass around biomass at maximum economic yield. Also, achieving this target reference point across most species may be unfeasible for mixed fisheries (Hoshino et al, 2018;Pascoe et al, 2020). While transitioning towards multispecies or ecosystem-oriented management rules has proven challenging, research on multispecies management frameworks is progressing fast and proposing new options, with a balanced consideration of the benefits and risks of such approaches (e.g.…”

“…While transitioning towards multispecies or ecosystem-oriented management rules has proven challenging, research on multispecies management frameworks is progressing fast and proposing new options, with a balanced consideration of the benefits and risks of such approaches (e.g. Pascoe et al, 2020;Thorpe & De Oliveira, 2019). Our future work aims at considering some of these options to allow comparison of fisheries outcomes across both fleet competition patterns and management frameworks to identify ecological and socio-economic trade-offs, including those emerging from a much-needed improvement to the management of mixed fisheries.…”

“…While managing a multispecies fishery based on single species criteria that do not consider species and fleet interactions is a limitation, it reflects the current management framework of the Australian Southern and Eastern Scalefish and Shark Fishery as of many other fisheries worldwide (e.g. Pascoe et al, 2020). The target biomass thresholds that are commonly in place relate to the species' Biomass at Maximum Sustainable Yield (B MSY ).…”

How did a network of marine protected areas impact adjacent fisheries? Evidence from Australia

“…Moreover, the Great Australian Bight sector is mostly a deepwater trawl fishery and does not overlap with other sectors either technically or biologically (Pascoe et al . 2020). Based on the geographical proximity of the SEMRN and the Commonwealth Trawl and Gillnet, Hook and Trap sectors, we take these two sectors and the species caught within as our treatment group of species, and the species caught within the Great Australian Bight sector as our control group (see Appendix ).…”

Resilience management for coastal fisheries facing with global changes and uncertainties

“…The level of the discount rate as described in Dichmont et al (2010) is a similar issue. Another threat which occurs in multispecies management is that a change in the management can modify the behavior of fishermen from a non-target species activity to a specialized activity (Pascoe et al, 2020).…”