Alarming Decline in Shark Populations Points to Need for Stricter Conservation Measures

Despite years of calls to better protect oceanic sharks and rays, a recent study in the journal Nature reveals that, since 1970, the global abundance of these predators has declined more than 70 percent, largely because of increased fishing pressure. In what the authors called an “unprecedented increase in the risk of extinction,” half of these species now are classified as endangered or critically endangered on the International Union for Conservation of Nature Red List of Threatened Species.

In particular, the concerning status of the oceanic whitetip and the shortfin mako shark demonstrates how the regional fisheries management organizations (RFMOs) have failed to do enough to stop the incidental catch and killing of sharks. If these species are going to have a chance at survival, RFMOs must significantly reduce shark mortality this year – either by requiring fleets to use less harmful gear or by limiting the use of gear associated with shark bycatch and deaths.    

Across ocean basins, management is falling short

The Western and Central Pacific Fisheries Commission (WCPFC) and the International Commission for the Conservation of Atlantic Tunas (ICCAT) are the RFMOs responsible for managing the western Pacific oceanic whitetip and north Atlantic shortfin mako, respectively – both of which are overfished. And although WCPFC and ICCAT have taken different approaches to conservation efforts, neither has done enough to curb declines.

The oceanic whitetip was once one of the most widespread and abundant sharks in the open ocean but is now among the most threatened because of a combination of indiscriminate fishing and RFMOs’ failure to fully address the shark’s long-term decline. In 2012, WCPFC adopted a ban on retention for the species, meaning even sharks accidentally caught by gear targeting other species cannot be kept. 

Although the measure has helped reduce the economic incentive to catch oceanic whitetip, the most recent stock assessment suggests that the population could go extinct in the Pacific if the current mortality rate continues. As a result, WCPFC scientists are recommending additional mitigation and safe handling measures to reduce mortality and help the population recover.

In the North Atlantic, shortfin makos have been mismanaged for decades, and catch and mortality resulting from swordfish and tuna fisheries, particularly of juveniles, remains too high. With so few reproductively mature sharks in the water, ICCAT scientists say the population will continue to decline even if fishermen don’t kill a single shortfin mako in the next 15 years.

At the past two meetings of ICCAT, a number of governments have proposed adoption of a “no retention, with no exceptions” measure, as recommended by ICCAT scientists and similar to the oceanic whitetip shark measure at WCPFC. But ICCAT members have consistently failed to come to consensus on this much-needed first step toward shortfin mako rebuilding, making its recovery even harder to achieve.

Bryan Toro

Retention and bycatch measures could help

Fortunately, there are additional measures that WCPFC and ICCAT can put in place that can change the trajectory for these vulnerable shark species. According to the Nature study, the most at-risk species cannot withstand additional pressure from fishing. One of the primary drivers of shark overfishing comes from longline gear, in which thousands of baited hooks are set. This method usually targets tunas and swordfish, but sharks often end up on the lines. Although “no retention” measures are an important starting point for conservation and sustainable management, additional measures are needed to help avoid shark bycatch altogether, or at least allow those accidentally caught to be released alive.

These could include gear modifications such as: changing wire leaders to nylon monofilament to allow easier escape for sharks, closing areas where sharks are abundant to fishing and improving live-release practices. WCPFC’s action on oceanic whitetip was an important first step, but it shows that “no retention” isn’t enough. ICCAT managers should take stronger action and couple a strict “no retention” measure with additional mitigation and safe handling rules to help recover these sharks faster.

All RFMOs, including ICCAT and WCPFC, should also adopt increased observer coverage for longline fisheries to verify implementation of any bycatch mitigation measures. New electronic monitoring technology makes it easier to gather data on catch, bycatch and compliance with existing rules and, when used, increases compliance and self-reporting by vessel crews and reduces misreporting of catch.

Although getting effective mitigation measures and increased longline observer coverage in place is challenging, the alarm bells are ringing. WCPFC, ICCAT, and other RFMOs must immediately commit themselves to following the science so that oceanic whitetip, shortfin mako and other threatened shark species around the world have a chance to recover. If fisheries managers continue to avoid necessary actions to control bycatch, the only options left will be to significantly reduce the amount of longline hooks in the water – or risk losing these sharks forever.  

Rachel Hopkins is a senior manager and KerriLynn Miller is an officer with Pew’s international fisheries program.