[MARMAM] New publication: sea lion entanglements and haulout abundance trends in Washington state

Liz Allyn liz.allyn at makah.com
Wed Aug 26 13:04:17 PDT 2020


Dear MARMAM community,

Jonathan Scordino and I would like to announce the publication of our paper
in the journal PLoS ONE titled "Entanglement rates and haulout abundance
trends of Steller (*Eumetopias jubatus*) and California (*Zalophus
californianus*) sea lions on the north coast of Washington state".

Open access:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237178

Allyn EM, Scordino JJ (2020) Entanglement rates and haulout
abundance trends of Steller (*Eumetopias jubatus*) and California (*Zalophus
californianus*) sea lions on the north coast of Washington state. PLoS ONE
15(8): e0237178. https://doi.org/10.1371/journal.pone.0237178

Abstract:  Entanglements affect marine mammal species around the globe, and
for some, those impacts are great enough to cause population declines. This
study aimed to document rates and causes of entanglement and trends in
local haulout abundance for Steller and California sea lions on the north
coast of Washington from 2010–2018. We conducted small boat surveys to
count sea lions and document entangled individuals. Rates of entanglement
and entangling material occurrence were compared with records of stranded
individuals on the Washington and Oregon coast and with packing bands
recorded during beach debris surveys. The rate of entanglement for
California sea lions was 2.13%, almost entirely composed of adult males,
with a peak rate during June and July potentially due to some entangled
individuals not migrating to their breeding grounds. For Steller sea lions,
the rate of entanglement was 0.41%, composed of 77% adults (32.4% male,
63.3% female), 17.1% juveniles, 5.9% unknown age, and no pups. Steller sea
lions exhibited a 7.9% ± 3.2 rate of increase in abundance at the study
haulouts, which was similar to that seen in California sea lions (7.8% ±
4.2); both increases were greater than the population growth rates observed
range-wide despite high rates of entanglement. Most entanglements for both
species were classified as packing bands, followed by entanglement scars.
Salmon flashers were also prevalent and only occurred from June–September
during the local ocean salmon troll fishery. Packing band occurrence in
beach debris surveys correlated with packing band entanglements observed on
haulouts. However, no packing band entanglements were observed in the
stranding record and the rate of stranded animals exhibiting evidence of
entanglement was lower than expected, indicating that entanglement survival
is higher than previously assumed. Future studies tracking individual
entanglement outcomes are needed to develop effective, targeted management
strategies.

Please send questions and requests to liz.allyn at allyn.org.

 Best,

Liz Allyn
Marine Mammal Program
Makah Fisheries Management
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