New research pinpoints 'blue corridors' for highly migratory fish

Date:
May 9, 2022
Source:
University of British Columbia
Summary:
New research has pinpointed four high-traffic areas in the Pacific
Ocean that should be considered of high priority if conservation
efforts focused on large pelagic fishes such as tuna, blue marlin
and swordfish are to be successful.



FULL STORY ==========================================================================
New research has pinpointed four high-traffic areas in the Pacific Ocean
that should be considered of high priority if conservation efforts focused
on large pelagic fishes such as tuna, blue marlin and swordfish are to
be successful.


==========================================================================
By studying the tendency of fish to return to their place of birth to
reproduce -- a concept known as philopatry that is often, and falsely,
thought to apply only to salmon species -- and pairing such knowledge
with catch distribution maps and tagging and genetic sequencing studies, researchers at UBC's Sea Around Us initiative identified the tentative migration routes of 11 tuna and other large pelagic fish in the Pacific
Ocean and determined that certain areas should be considered as of 'high'
and 'very high' priority when it comes to maintaining their populations.

"We applied the concept of philopatry to the movements extracted from
tagging studies of species such as the near-threatened Pacific bluefin
tuna and the heavily-fished yellowfin tuna, and we also combined this information with the links between populations inferred from genetic
studies. This allowed us to identify tentative annual migration cycles,"
said Veronica Relano, a doctoral candidate with the Sea Around Us and
lead author of thestudy that presents these findings.

"The interesting thing is that when we compared our proposed migration
routes and the mapped catch data from 1950 to 2016 available on the Sea
Around Uswebsite, we found many coincidences. Clearly, the accuracy of
these routes is reinforced by considering philopatry, although they are
still tentative," she said.

After analyzing the seasonal migration paths of each of the 11 fish
species individually, the researchers superposed them and noticed that
several species and populations of these large pelagic fishes use the
same migration routes.

"Those high-traffic areas, two of which are in northeastern and central sections of the Pacific Ocean and two in the southwestern and central
sections, should become parts of blue corridors, which are routes where
strict fisheries management measures or partial bans of industrial fishing ought to be enforced to allow for increased connectivity of habitats
and thus allow populations of marine species to maintain themselves,"
said Dr. Daniel Pauly, co-author of the study and the Sea Around Us
principal investigator.

"But before setting up any protected area to support the rebuilding
of diminished fish populations, it is important to consider the
entire body of knowledge available on the migrations and movements of
different species. This is what we set out to do with this study. Our
findings suggest in which areas such efforts would be more effective,
but as stated in our title, the closed migration cycles we propose are tentative, and thus it would be nice if other researchers set out to
test their validity," he said.


========================================================================== Story Source: Materials provided by University_of_British_Columbia. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Veronica Relano, Daniel Pauly. Philopatry as a Tool to Define
Tentative
Closed Migration Cycles and Conservation Areas for Large Pelagic
Fishes in the Pacific. Sustainability, 2022; 14 (9): 5577 DOI:
10.3390/ su14095577 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220509191545.htm

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