From bycatch to main catch

Twenty-five scientists from ten countries and four regional fisheries management organisations (RFMOs) will meet in Rome this week to examine the options for a state-of-the art sustainable management strategy for the multi-million-dollar blue shark fishing industry.

Blue sharks, Prionace glauca, are found throughout the world’s ocean, migrating incredible distances across the high seas from tropical climates to temperate waters.

Once thought of as accidental catch in longline tuna fisheries, they are now a major commercial target species in many parts of the world and make up around 60 percent of global shark landings.

More valuable than bluefin

A 2022 study by Oceana, a marine conservation organisation, valued global blue shark fisheries at USD411 million, more than the total commercial value of the three species of the iconic bluefin tunas.

Using FAO and RFMO data, the Oceana study found that over seven million blue sharks were legally caught and landed in 2019. Some estimates put that figure today at up to 20 million.

©Jonas Gruhlke/Shutterstock

“While blue sharks are among the most productive shark species, and can sustain being a target catch, they still require careful management if the fisheries are to be sustainable,” said Shana Miller, Project Director for International Fisheries Conservation at The Ocean Foundation.  

Regional cooperation

The Rome meeting is hosted by The Ocean Foundation and The Pew Charitable Trusts, with support from the Common Oceans Tuna project, Oceankind and the Paul M. Angell Family Foundation.

It will be attended by blue shark scientists from the four relevant tuna RFMOs, the International Commission for the Conservation of Atlantic Tunas (ICCAT), the Indian Ocean Tuna Commission (IOTC), the Inter-American Tropical Tuna Commission and the Western and Central Pacific Fisheries Commission.

The Rome workshop will brainstorm how to advance management procedures: pre-agreed frameworks that guide fisheries decision-making, for blue shark stocks.

Otherwise known as harvest strategies, management procedures determine how much fishing can occur under different stock conditions to ensure that fish populations remain healthy over the long-term.

While there are many MPs in place for tuna and other international fisheries, there is not yet one for any shark species.

Large-scale commercial fleets, mainly longliners, harvest 90 percent of blue shark catches, with distant-water fishing nations, those that travel out onto the high seas, responsible for 74 percent of the global blue shark catch, the Oceana report found.

Bluefin tuna stocks were brought back from the brink of depletion by a concerted approach by the RFMOs to adopt panoceanic harvest strategies.

Atlantic to Pacific

The workshop will build the simulation tool used to develop and assess the performance of different MPs before they are implemented, known as Management Strategy Evaluation (MSE).

“ICCAT and IOTC already have mandates to develop MSE-tested management procedures for their blue shark stocks, but there is no similar initiative in the Pacific at this time,” said Miller.

“By gathering experts from all of the tuna RFMOs to explore potential collaborations and brainstorm solutions to shared challenges, the workshop is designed to make progress to conserve blue shark populations at sustainable levels as efficiently as possible.”