Unintended capture of sharks in commercial fisheries is a major source of mortality for many shark species worldwide. The International Union for Conservation of Nature (IUCN) lists 79 shark species as threatened, ranging from Critically Endangered (10) and Endangered (20) to Vulnerable (49). 

High levels of shark bycatch have been reported in longline fisheries that target tuna and swordfish, where up to one-quarter of the total catch in some fisheries is made up of shark species. Although longlines are the primary threat to sharks, they can also be caught in purse seine fisheries, where they can become entangled in fish aggregating devices (FADs), and in gillnet fisheries. 

The loss of sharks has been shown to negatively impact ocean environments, where decreasing numbers of sharks can lead to changes in the abundance of their prey species, triggering a cascade of other impacts in the ecosystem. 

The following are best practices for reducing the unintended capture and harm of sharks in longline fisheries. (As our initiative develops, we will expand this list to include best practices for reducing impacts from other types of fishing gear:

  • Avoiding hotspots where sharks are found in large numbers
  • Setting longline gear and hooks deeper, to avoid capturing sharks in shallower depths
  • Reducing the amount of time fishing gear is left in the water
  • Prohibiting the use of wire leaders that prevent sharks from being able to bite through lines and escape and/or shark lines that attract more sharks to the gear
  • Promptly and safely releasing any incidentally captured sharks
  • Using fish instead of squid for bait, which will reduce interactions with some shark species
  • Increasing observer coverage on fishing vessels to 100 percent, ideally comprised of a minimum of 20-percent human observer coverage, with the remainder covered by electronic monitoring. 

Fishery improvement projects (FIPs) in Costa Rica, Ecuador, and Peru, the main mahi-mahi producer countries in the Eastern Pacific Ocean, are implementing measures to reduce incidental captures of sharks. For example, in Ecuador, the use of wire leaders has been completely banned, while in Costa Rica, the vessels are not allowed to use wire leaders for three consecutive months. Fishers and processors from these three countries have formed a group called the Mahi-Mahi Regional Committee (COREMAHI) to work together pre-competitively to resolve regional-level sustainability challenges in the mahi fisheries. COREMAHI is currently developing a code of conduct with voluntary commitments to mitigate the impact of mahi fisheries on shark stocks and other species. It is expected that this code will be approved and launched at the end of this year.