Japan study creates model showing potential threefold profit increase for fisheries

A new study has discovered that a model optimizing Japanese catch levels for profitability could see a 3.5-fold increase in annual profits and a 30 percent increase in biomass. 

The new study – “Alternative outcomes under different fisheries management policies: A bioeconomic analysis of Japanese fisheries” –will appear in the journal Marine Policy (October 2019, Article 103646) and compares modeled outcomes under different fishery management policies. The study is the first of its kind apply profit modeling to Japanese fisheries, and compares the model with a simply maximum sustainable yield (MSY) model. 

Most species in Japan have been managed through a total allowable effort (TAE) approach that limits seasons and gear. Eight species have been managed through a total allowable catch (TAC) approach that puts a cap on the amount of fish landed. Recent reforms in the Japanese fishery management system will see more species subject to TAC. The question then arises – how should the TAC be determined?

The study examines tradeoffs between allowing current fishing mortality levels to continue (business as usual) versus adopting fishing mortality levels intended to maximize either yield or profitability. Because stock status estimates exist for only 37 stocks in Japan, a data-limited model is used to estimate the MSY-based reference points for 95 commercially exploited fish stocks using landing data from 1964 to 2015, representing 84 percent of Japanese landings.

The results suggest that adopting an economically optimal fishery policy could reduce catches over the next two decades, but increase the total annual profits by 3.5-fold and biomass levels by 30 percent by 2065 compared with the business-as-usual scenario. Maximum sustainable yield would require less of a short-term decrease in catch, but ultimately result in lower profits than the economically optimal scenario.

There are some shortcomings to the model. The prices data used is a range of historical prices, and it is possible that a large increase in future harvests could drive prices down. The study also does not take into account the actions of other nations, such as those fishing squid, mackerel, and saury just outside of Japan’s exclusive economic zone (EEZ); or the effects of climate change. 

It is also likely that many of the fishermen who would have to sacrifice their income for the next 20 years would not live long enough to see the benefit, though their children or their villages might. Giving them an incentive to support an economic-optimization model might require a government subsidy or buyout in the short term. How to maintain processing capability when product volumes are sharply reduced is also a practical constraint.

SeafoodSource talked with two of the authors, Kanae Tokunaga and Kazuhiko Otsuka. Tokunaga said  he was surprised that there was actually an increase in the stock even with the “business as usual” model. Since overfishing has brought current harvest levels to a fairly low level for many species, maintaining that level would result in an increase. The amount of catch reduction needed for the MSY model is also surprisingly small, meaning that it would not entail the short-term economic dislocation of the economic-optimization model.

The analysis is not precise enough to be used to set actual TACs, but it is important because it illustrates the tradeoffs and potential fishery upsides possible through fishery management reforms. It can be a conversation starter to discuss different management approaches. The authors aim to apply their models next at the prefectural level.

Photo courtesy of Shutterstock


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