Tiger shark migrations altered by climate change
New migration patterns leave sharks more vulnerable to fishing

Date:
January 13, 2022
Source:
University of Miami Rosenstiel School of Marine & Atmospheric
Science
Summary:
A new study has revealed that the locations and timing of tiger
shark movement in the western North Atlantic Ocean have changed
from rising ocean temperatures. These climate-driven changes have
subsequently shifted tiger shark movements outside of protected
areas, rendering the sharks more vulnerable to commercial fishing.



FULL STORY ==========================================================================
A new study led by scientists at the University of Miami (UM) Rosenstiel
School of Marine and Atmospheric Science revealed that the locations and
timing of tiger shark movement in the western North Atlantic Ocean have
changed from rising ocean temperatures. These climate-driven changes have subsequently shifted tiger shark movements outside of protected areas,
leaving the sharks more vulnerable to commercial fishing.


==========================================================================
The movements of tiger sharks, (Galeocerdo cuvier) the largest
cold-blooded apex predator in tropical and warm-temperate seas, are
constrained by the need to stay in warm waters. While waters off the
U.S. northeast coastline have historically been too cold for tiger
sharks, temperatures have warmed significantly in recent years making
them suitable for the tiger shark.

"Tiger shark annual migrations have expanded poleward, paralleling rising
water temperatures," said Neil Hammerschlag, director of the UM Shark
Research and Conservation Program and lead author of the study. "These
results have consequences for tiger shark conservation, since shifts
in their movements outside of marine protected areas may leave them
more vulnerable to commercial fishing." Hammerschlag and the research
team discovered these climate-driven changes by analyzing nine years of tracking data from satellite tagged tiger sharks, combined with nearly
forty years of conventional tag and recapture information supplied by
the National Oceanic and Atmospheric Administration (NOAA) Cooperative
Shark Tagging Program and satellite derived sea-surface temperature data.

The study found that during the last decade, when ocean temperatures were
the warmest on record, for every one-degree Celsius increase in water temperatures above average, tiger shark migrations extended farther
poleward by roughly 250 miles (over 400 kilometers) and sharks also
migrated about 14 days earlier to waters off the U.S. northeastern coast.

The results may have greater ecosystem implications. "Given their role
as apex predators, these changes to tiger shark movements may alter predator-prey interactions, leading to ecological imbalances, and more
frequent encounters with humans." said Hammerschlag.

The study, titled "Ocean warming alters the distributional range,
migratory timing, and spatial protections of an apex predator, the tiger
shark (Galeocerdo cuvier)" was published January 13, 2022 in the journal
Global Change Biology.

The study's authors include: Neil Hammerschlag, Laura McDonnell, Mitchell Rider, Ben Kirtman from the UM Rosenstiel School; Garrett Street and
Melanie Boudreau from Mississippi State University; Elliott Hazen, Lisa Natanson, Camilla McCandless from NOAA Fisheries; Austin J. Gallagher
from Beneath the Waves; and Malin Pinsky from Rutgers University.

The Batchelor Foundation, Disney Conservation Fund, Wells Fargo,
Guy Harvey Ocean Foundation, the Herbert W. Hoover Foundation, the International Seakeepers Society, Oceana, Hoff Productions for National Geographic, and the West Coast Inland Navigation District provided
support for the study.

Video: https://youtu.be/vyLbf7KSXAk ========================================================================== Story Source: Materials provided by University_of_Miami_Rosenstiel_School_of_Marine_&
Atmospheric_Science. Original written by Diana Udel. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Neil Hammerschlag, Laura H. McDonnell, Mitchell J. Rider, Garrett M.

Street, Elliott L. Hazen, Lisa J. Natanson, Camilla T. McCandless,
Melanie R. Boudreau, Austin J. Gallagher, Malin L. Pinsky,
Ben Kirtman.

Ocean warming alters the distributional range, migratory timing,
and spatial protections of an apex predator, the tiger shark
( Galeocerdo cuvier ). Global Change Biology, 2022; DOI:
10.1111/gcb.16045 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220113092131.htm
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