by Minling Pan
If you ever wondered how much it costs a fishery to save a sea turtle, check out this new study conducted by Dr. Minling Pan of the Pacific Islands Fisheries Science Center (PIFSC) Socioeconomic program and Dr. Shichao Li, formerly of the Joint Institute for Marine and Atmospheric Research of the University of Hawaiʻi.
According to their study, the answer to this question is quite straightforward: a fishery’s cost of saving a turtle depends on the rate of sea turtle bycatch (unintended and unwanted catch) in the fishery. In short, the higher the bycatch rate, the lower the cost to save one sea turtle (through regulating the fishery to reduce sea turtle interactions).
This finding suggests that it would be more cost effective if sea turtle conservation efforts or regulations — such as seasonal or area closures, sea turtle caps, or effort caps — take place in fisheries where bycatch rates are high. Given the transboundary nature of sea turtle and swordfish populations, these results provide insights into opportunities for fishery managers to explore win-win solutions in promoting sea turtle conservation while maintaining sustainable fisheries.
Measuring the cost of saving sea turtles
To measure the cost of saving one sea turtle in a fishery, Drs. Pan and Li developed a spatial and temporal model of sea turtle interactions the Hawaiʻi swordfish fishery. This model enables prediction of sea turtle interaction rates associated with each unit of swordfish fishing effort and the economic returns of the fishing effort by area and time.
They used a Generalized Additive Model approach, developed by PIFSC colleagues Kobayashi and Polovina (2005), to estimate sea turtle interactions associated with fishing effort in various seasons and locations. They added to the model economic returns associated with fishing effort by estimating a fishing trip cost function using ongoing trip cost data collected through a collaborative effort between the PIFSC Socioeconomics Program and the Pacific Islands Regional Office (PIRO) Observer Program.
The analysis compares the costs of saving one sea turtle across international fisheries with various sea turtle bycatch rates, and the team examined the trade-offs between saving one sea turtle and the economic returns of fishing operations in different seasons and different areas.
The study found that between 1994 and 2003, the Hawaiʻi swordfish fishery interacted with one loggerhead sea turtle for every 23,000 pounds of swordfish caught. This swordfish catch would be valued at approximately $50,000 in 2015 swordfish prices. After NOAA Fisheries imposed new regulations on gear and bait in April 2004, the sea turtle bycatch rate for the fishery dropped significantly.
Thus, in recent years, the fishery has interacted with one loggerhead for every 238,000 pounds of swordfish caught. This amount of catch is worth $520,000 in 2015 swordfish prices. Consequently, the marginal cost to a fishery, in terms of lost revenues, for saving an additional sea turtle is higher when the sea turtle bycatch rate is low, the researchers found.
If you are interested in finding out more detailed information, click the link below to read the newly published paper: