The forgone benefits of discarding fish in the Gulf of California shrimp fishery

Fish discards represent a large share of harvested biomass in shrimp fisheries. The aim of this paper is to propose a methodology for valuing discards of both commercial and non-commercial fish species discarded in the Gulf of California shrimp fishery, by estimating the monetary value of forgone fish biomass. The value of commercial fish species was carried out by using growth and population models, in order to simulate the biomass that, if left in the ocean instead of being harvested at Age 0, could reach an optimal fishing size. Using deflated ex-vessel prices, the present value of commercial species hypothetically harvested at an optimal age, was computed. The value of non-commercial fish species represented the forgone benefits of not using discarded biomass for producing fishmeal. Hence, the estimated value of fish diversity discarded in trawling operations in 2013 would range between USD 60.80 million and USD 103.4 million. This estimate is one of the first attempts to give an economic value to both commercial and non-commercial discarded fish biomass. Hopefully, the methodology here proposed will serve as inspiration for further research in economic valuation of marine biodiversity.