[OANNES Foro] Purse seine fishing nets may be set for tuna, but they trap whatever fish swim into them, including manta and devil rays.

[Mario Cabrejos]

Small steps aim to make a large ocean safer for rays

by  <https://news.mongabay.com/by/marianne-messina/> Marianne Messina 

24 February 2020 

https://news.mongabay.com/2020/02/small-steps-aim-to-make-a-large-ocean-safe
r-for-rays/

Purse seine fishing nets may be set for tuna, but they trap whatever fish
swim into them, including manta and devil rays. As the net tightens, rays
will panic and thrash. Trauma and death by suffocation in the crush of fish
are likely outcomes. But even those rays lucky enough to survive the net
face further challenges. Tuna fishers don't really want a 1,600-kilogram
(3,500-pound) oceanic manta (Mobula birostris) flopping around on deck, but
large mantas aren't easy to put back into the ocean. Crews might hoist a ray
overboard by hooking it through its gill plates or running a cable through a
hole punched in its fin. This may explain why a 2016 New Zealand
<https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.2641> study found that
less than half of rays released alive survive.

New rules that apply to a vast swath of the Pacific Ocean aim to improve
manta and devil rays' chances of surviving encounters with fishing boats. In
December 2019, the Western and Central Pacific Fisheries Commission (WCPFC)
<https://www.wcpfc.int/doc/cmm-2019-05/conservation-and-management-measure-m
obulid-rays-caught-association-fisheries-wcpfc> adopted a measure
prohibiting fishers from targeting the rays or keeping the ones they catch
accidentally, and mandating that they release living rays in a manner "that
will result in the least possible harm." The multilateral body manages
fisheries in the region and includes some of the world's largest
tuna-fishing nations among its members: Japan, Indonesia, and the
Philippines.

Manta and devil rays,
<https://academic.oup.com/zoolinnean/article/182/1/50/3886052> newly grouped
into eight species in the genus Mobula, are generally large-bodied
planktivores that live in tropical and temperate waters around the world.
Females usually give birth to a single pup every one to five years, making
mobulids vulnerable to overfishing. Growth in demand for their gill plates
and anecdotal reports of decreasing ray populations have scientists worried.

The WCPFC mobulid protection measure comes five years after its initial
introduction as a set of non-binding guidelines, according to biologist
Wetjens Dimmlich, director of fisheries management for the Pacific Islands
Forum Fisheries Agency (FFA). The FFA helped push the measure's adoption,
with support from all of the FFA's 17 member nations - half the entire WCPFC
membership. Passing the measure was an accomplishment because it represented
the commitment of major fishing nations such as Japan and the Philippines to
upholding its provisions at their ports and on ships flagged to them.

Several factors contributed to the measure's adoption, Dimmlich said. It
helped that the Indian Ocean's fisheries management body had just
implemented a similar measure; that the region encompasses some of the most
lucrative (and growing) manta tourism in the world; and that WCPFC's small
member country of Palau, a dive-tourism destination, had just preserved 80%
of its national waters
<https://www.pewtrusts.org/en/research-and-analysis/articles/2020/01/01/pala
u-national-marine-sanctuary-goes-into-effect> as a marine sanctuary.

Tuna boats will bear the brunt of the measure's stipulations. Guidelines for
getting trapped rays safely back into the sea include tending immediately to
live animals, careful handling (gripping fins not gills), untangling the
animals from gear, and using special equipment rather than the ubiquitous
hooks and gaffs. The measure also encourages fishers to work with
satellite-tagging programs that track the rays for research purposes.

The eastern Pacific's fisheries management body, the Inter-American Tropical
Tuna Commission (IATTC), enacted similar protections for mobulids in 2015.
All IATTC member tuna boats of more than 363 tons (which is most commercial
boats) have onboard observers, so the fishery is poised to collect useful
scientific and compliance data.

The IATTC has been honing its conservation protocols since the 1960s, mainly
to protect dolphins. Boats are set up with conveyors at the sorting point
that conduct unwanted animals directly back to sea. But for many boats under
the WCPFC, where the work of conveyors is still done by humans and
efficiency has been a higher priority than rescuing bycatch, implementation
remains a work in progress.

"Most fishery measures take considerable time to implement," said Daniel
Fernando, a director of Blue Resources Trust, a Sri Lankan NGO that
supported the mobulid regulations in the Indian Ocean.

The devil ray in the details

Many individual islands and states in the western and central Pacific had
their own protections for the charismatic reef manta (M. alfredi), beloved
by tourists. But devil rays don't generally draw tourism revenue like mantas
do, according to Guy Stevens, founder and chief executive of the U.K.-based
NGO Manta Trust, who said he was encouraged by their inclusion in the new
WCPFC measure.

Stevens said he hopes tourism will eventually foster the same widespread
love for mobulids that dolphins receive, where a single undercover photo of
abuse can cause a Twitter cyclone of outrage. He said manta and devil rays
need the same stringent level of protection that the IATTC has provided for
dolphins: Dolphins have bycatch quotas, and onboard observers document each
ship's compliance. Fishing boats steer clear of dolphins when planning
routes. Crew members jump into the water to guide trapped dolphins over the
top of purse seine nets because they know that tuna will go low, but
dolphins will stay near the top - the kind of information yet to be gathered
about manta and devil rays.

As a result of the IATTC's 1999 dolphin conservation agreement, the
<https://www.iattc.org/DolphinSafeENG.htm> management body says bycatch
rates for dolphins dropped from 132,000 in 1986 to less than 1,000 in recent
years.

But to duplicate that level of success for mantas and devil rays, scientists
and fishers have much to learn about them. For instance, scientists don't
have much data on mobulids' migratory paths, or the locations of their
feeding grounds and cleaning stations that could help fishing boats avoid
them. Any increase in tagging and documentation resulting from the new
measure will help scientists fill those and other information gaps, as well
as understand what's working and what isn't in the safe-handling guidelines.

As long as fisheries management bodies show a willingness to work with the
science, Stevens said he expects the various regional manta and devil ray
protection measures to undergo continuous refining as the data come in. So
far, according to Stevens, managers are willing. The IATTC has already
scheduled a meeting with manta scientists, a year from now, to assess and
refine the mobulid protection measures it implemented in 2015.

The WCPFC measure is a doorway to answers. Will more gently handled and
quickly released rays have any better chances of surviving getting caught?
What kind of compliance, observation and enforcement practices are realistic
for the western and central Pacific?

The measure will take effect in January 2021. While it could be a long wait
for manta and devil rays, it gives scientists and NGOs a year to gather more
data. According to Dimmlich, the commission requested a report on mobulids
based on observer-gathered data later this year, and if feasible, a detailed
assessment of the region's mobulid stock by 2023.

"We have to go through the scientific process," Stevens said.

And if the measure doesn't look like it is saving mobulids?

"We go back to them and say this is not good enough."

 



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