A just-released study suggests that fisheries may be more profitable under different climate change scenarios, with the caveat that current management practices must change for this positive future to be realized.
The study, released on Wednesday, 29 August, in the journal Science Advances, was co-authored by 12 researchers, including scientists from the Environmental Defense Fund; the University of California, Santa Barbara; Hokkaido University; and Imperial College London.
It models four different climate change scenarios ranging from mild to extremely severe for fisheries under four different management strategies and arrives at the conclusion that global fisheries may have a bright future under climate change.
The researchers said the results “show that the future of global fisheries could actually be more prosperous than today, but only if management reforms addressing current mismanagement and looming challenges from climate change are implemented in the near future across a wide range of fisheries.”
On the other hand, the impact of climate change could be much worse than prior projections suggest “if appropriate adaptations to potential productivity changes and climate-driven movement of species across management boundaries are not made," the researchers found. "Maladaptive responses to the pending loss of a fishery or the arrival of a new fishery could exacerbate the previously projected direct effects of climate change."
These findings are timely, Kristin Kleisner, senior scientist for Environmental Defense Fund’s Oceans program and co-author of the paper, told SeafoodSource, “because we show that it is imperative to continue our efforts to hold climate change in check following the Paris Accord, and we also need to put in place the best management possible to ensure our fisheries are sustainable and continue to provide benefits that humans rely on.”
Fisheries management strategies, including full adaptation, productivity adaptation, range shift adaptation, and no adaptation, were modelled under climate change scenarios with a particular focus on “the moderately high-emission scenario, RCP 6.0, under which global mean temperature is expected to increase by 2.2°C by 2100.”
The study found that “adopting proactive and adaptive fishery management approaches today would lead to substantially higher global profits (154 percent), harvest (34 percent), and biomass (60 percent) in the future compared to No Adaptation. Simultaneously addressing both range shift and productivity changes generates much greater benefits in profits, harvest, and biomass than focusing on either challenge alone... Productivity or Range Shift Adaptation alone produces intermediate benefits.”
The study notes that range shift of species brought about by climate change makes effective management of fisheries particularly challenging, as “changes in species distributions can move stocks into and out of management jurisdictions, such as countries’ exclusive economic zones (EEZs), altering management jurisdiction and incentives for those stocks.”
For these reasons, Kleisner told SeafoodSource via email, there is need for a sea change in the way global fish stocks are managed.
“Currently the majority of fisheries (roughly 80 percent) are not managed or under poor management due to lack of resources and capacity. Additionally, in areas with relatively good management plans, much of this management is focused on single species and assuming relatively constant environmental conditions," Kleisner said.
“We can do better by instituting management that is both adaptive and responsive to climate change, that takes into account overall ecosystem (e.g., multi-species and habitat) changes, and that involves inter-jurisdictional management - that is both across management borders within a country and between different countries,” she added.
Kleisner said there are organizations engaging with the thorny issue of range shift.
“Regional fisheries management organizations (RFMOs) were established to manage highly migratory and straddling stocks, and this is a good start," she said. "But to date, there has been little to no cooperation on how to handle future shared stocks, and this is something that will need to improve. One exception is with the Commission for the Conservation of Antarctic Marine Living Resources or CCAMLR, which is an RFMO that has established collaborative arrangements with neighboring RFMOs to monitor the movement of stocks across regulatory borders and to understand what shifting stocks and associated fishing pressure changes means for the ecosystem in the future.”
Additionally, “there are international obligations such as the United Nations Convention on the Law of the Sea (UNCLOS),” Kleisner said.
But, the study notes, even with the best management in place some fisheries will become extinct under the moderately high emissions scenario, whereas under the most extreme climate scenario both profit and harvest will decline relative to today.
"While some stocks essentially go extinct (MSY declines by 100 percent), others increase by more than 35 percent under [the moderately high emissions scenario] RCP6.0,” states the study.
Kleisner explained, “Given the area where species are currently found and the temperature changes that are predicted, we see contrasting outcomes for some species in terms of future range size. Some will experience range expansions as the total area of suitable habitat increases, while others will experience range contractions as the total area of suitable habitat decreases. We translate these changes in range size into projected changes in productivity, which affects MSY. For species where productivity decreases due to climate change effects, we see a decrease in MSY, and vice versa for species where productivity increases.”
The authors of the study concluded their report by stressing the need to reduce greenhouse gas emissions, so that fisheries can achieve their potential for increased profitability, while wryly admitting that “for about half of the world’s individual fisheries, this better future appears unattainable."
"Even under the most optimistic scenario for human responses, roughly half of the world’s fisheries are projected to decline under a moderate climate change scenario. Most latitudes in the tropics are not expected to obtain higher profits in the future compared to today,” according to the study.
