Climate damage from fishing the mesopelagic zone exceeds its economic benefits.

Mesopelagic fish represent an opportunity for fishing companies and food production, but their exploitation carries substantial environmental risks related to these populations' role in the oceanic carbon pump. We assess the economic viability of mesopelagic fishing from a private economic perspective, focusing on costs and revenues accruing to the fishing industry, and a public economic perspective, considering impacts on society at large, notably climate change. We develop a stylized model, which we apply to four pelagic trawling fleets in the European Union. We find that a mesopelagic fishery operated with current excess capacity in the four fleets considered is profitable from a private perspective, but the climate impacts potentially outweigh the private economic benefits. This implies that strict governance arrangements are needed to safeguard the sustainability of the mesopelagic zone. Considering long-term dynamics, we explore potential natural limits to an expanding mesopelagic fishery. First, a growing fishery will reduce biomass level, affecting profitability. Second, an increase in mesopelagic production may lower the price, also limiting potential for expansion. For the time being, however, it is unlikely that the fishery will reach a scale level where such feedbacks can be expected, making effective governance arrangements even more crucial. [ABSTRACT FROM AUTHOR]