Dolphins deliberately killed for use as bait in global fisheries

June 07, 2018

Important new research released ahead of World Oceans Day exposes the widespread practice of killing aquatic mammals such as dolphins, sea lions, seals and otters for use as bait in global fisheries. Published in open-access journal Frontiers in Marine Science, the study shines a new light into what researchers say is an issue that has so far received little attention within the scientific and conservation communities.

Bycatch -- the incidental capture of dolphins, sea turtles, birds and other non-targeted species in fishing operations --- is a well-known problem. Less well-known is the widespread practice of acquiring and using aquatic mammals for bait. According to the researchers' new systematic review, more than 40 species of aquatic mammals have been utilized as bait since 1970 in at least 33 countries, with more than 80% of these species deliberately killed for use in at least one fishery. Dolphins, for example, are commonly killed and used as bait in shark fisheries. Geographically, the practice appears to be most common in Latin America and Asia.

The study's lead author, Dr. Vanessa J. Mintzer from the University of Florida, USA, says while the reviewed sources reveal that killing marine mammals for bait is widespread, there is little information on the status of the populations being killed and whether, or how fast, they are declining. However it is clear, based on a few locations where this information is available, that killing for bait can reach unsustainable levels and lead to population decline. Dr. Mintzer says witnessing this, first hand, prompted this latest scientific review.

"Killing for use as bait is a primary threat affecting Amazon river dolphins, known as botos -- the species and issue I have studied since my Ph.D. dissertation. With this global review we wanted to see whether, and where, other species were killed for bait, and learn about possible solutions to stop the problem," says Dr. Mintzer.

The killing of marine animals for bait is, in general, a clandestine activity. As a consequence, the level of killing and impact on the species identified in the review will likely remain largely unknown for the foreseeable future. Dr. Mintzer says obtaining better data should now become an urgent priority.

"For scientists already working on species and locations identified as "hot spots" in this review, organized efforts should begin right away to estimate these numbers," she says. "It took years to determine that the hunt for botos was unsustainable and now conservation actions need to be expedited. We need to identify other affected populations now to facilitate timely conservation actions."

The study's authors also urge a focus on the enforcement of existing laws that make it illegal to kill marine mammals as well as the involvement of local communities and fishers in education and sustainable fishing programs and policies, as opposed to top-down implementation, to ensure success.

One key limitation faced by the researchers was a lack of information on the magnitude of the problem -- that is, how many animals in a specific area or region are killed to procure bait and the impacts of this practice on the affected populations. While the authors' analysis was constrained accordingly, the researchers say that lack of data is a common challenge faced by fishery managers and indicates clearly the broader need for additional resources for monitoring and assessment.
-end-
Please include a link to the original research in your reporting: https://www.frontiersin.org/articles/10.3389/fmars.2018.00191/full

Frontiers is an award-winning Open Science platform and leading open-access scholarly publisher. Our mission is to make high-quality, peer-reviewed research articles rapidly and freely available to everybody in the world, thereby accelerating scientific and technological innovation, societal progress and economic growth. For more information, visit http://www.frontiersin.org and follow @Frontiersin on Twitter.

Frontiers

Related Dolphins Articles from Brightsurf:

Study finds high levels of toxic pollutants in stranded dolphins and whales
Researchers examined toxins in tissue concentrations and pathology data from 83 stranded dolphins and whales from 2012 to 2018.

Tracking humanity's latest toxins in stranded whales and dolphins
As humanity develops new types of plastics and chemicals, researchers are constantly trying to keep up with understanding how these contaminants affect the environment and wildlife.

Young dolphins pick their friends wisely
Strategic networking is key to career success, and not just for humans.

Dolphins learn foraging skills from peers
Dolphins can learn new skills from their fellow dolphins. That's the conclusion of a new study reported in the journal Current Biology on June 25.

Dolphins learn in similar ways to great apes
Dolphins learn new foraging techniques not just from their mothers, but also from their peers, a study by the University of Zurich has found.

Shelling out for dinner -- Dolphins learn foraging skills from peers
Dolphins use empty gastropod shells to trap prey. A new study demonstrates for the first time that dolphins can learn this foraging technique outside the mother-calf bond - showing that they have a similar cultural nature to great apes.

Good night? Satellite data uncovers dolphins on the move at nighttime
More than 1,000 bottlenose dolphins live in Florida's Indian River Lagoon year-round.

Cooperative male dolphins match the tempo of each other's calls
When it comes to working together, male dolphins coordinate their behavior just like us.

Dolphins gather in female family groups
Social clusters including mothers' groups play an important role in the life of southern Australian bottlenose dolphins, a new study shows.

Lights on fishing nets save turtles and dolphins
Placing lights on fishing nets reduces the chances of sea turtles and dolphins being caught by accident, new research shows.

Read More: Dolphins News and Dolphins Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.