[MARMAM] New paper on mysid shrimp as a prey item for gray whales in Washington, USA

Liz Allyn liz.allyn at makah.com
Tue Jan 16 11:15:54 PST 2024


Dear MARMAMers,

My co-authors and I are pleased to announce the publication of a new
article titled "Distribution and demographics of mysids (Crustacean:
Mysida) as prey for gray whales (Eschrichtius robustus) in northwest
Washington state."

Allyn EM, Scordino JJ, Akmajian AM. 2024. Distribution and demographics of
mysids (Crustacea: Mysida) as prey for gray whales (*Eschrichtius robustus*)
in northwest Washington state. PeerJ 12:e16587
https://doi.org/10.7717/peerj.16587

Abstract:

The movement and distribution of gray whales (*Eschrichtius robustus*)
during the feeding season is likely dependent on the quality of foraging
opportunities and the distribution of prey species. These dynamics are
especially important to understand for the Pacific Coast Feeding Group
(PCFG) of gray whales which spend the feeding season along the coast from
northern California, USA through northern British Columbia, Canada. In
Washington state, no previous work has been done to describe available gray
whale prey. The main goal of this research was to initiate studies on an
important gray whale prey item in northwest Washington, mysid shrimp
(Mysida), by establishing a baseline understanding of mysid swarm
demographics in the area and investigating patterns in gray whale and mysid
presence. Prey samples were collected during June through November 2019 and
June through September 2020 using a vertically-towed plankton net at seven
sites in the Strait of Juan de Fuca and seven sites in the Pacific Ocean in
areas where gray whales were known to feed. Mysids collected in the samples
were counted and the sex, length, species, maturity, and gravidity were
documented. Patterns in gray whale and mysid co-occurrence were explored
through data visualization. Seven species of mysids were observed in the
survey area. In 2019, the number of mysids per tow increased steadily
through the season, the most abundant species of mysids were *Holmesimysis
sculpta* and *Neomysis rayii*, and sampled mysids averaged 4.7 mm in
length. In 2020, mysids were abundant in tow samples in June and July but
were not abundant in the remaining months of the sampling season. The
average length of mysids in 2020 was 13.3 mm, and a large portion were
sexually mature males and brooded females identified as *H. sculpta*.
Throughout the survey area, the majority of whale sightings occurred later
in the season in 2019 and earlier in the season in 2020, coinciding with
the trends of sampled mysids. This study provides the first description of
mysid swarm composition and temporal variation in northwest Washington.
Tows were dominated by a similar assemblage of mysid species as what is
observed in other areas of the PCFG range. The differences in sampled mysid
assemblages between years, and the presence of whales in the survey area in
times and at sites where samples with high mysid counts were collected,
suggest evidence for interesting predator-prey dynamics that warrant
further investigation.

The article is open access and can be found at the link: Distribution and
demographics of mysids (Crustacea: Mysida) as prey for gray whales
(Eschrichtius robustus) in northwest Washington state [PeerJ]
<https://peerj.com/articles/16587/>

-- 
Liz Allyn (She/Her)
Marine Mammal Technician II
Makah Fisheries Management
&
Graduate Student
Marine Conservation and Ecology Group <https://sites.uw.edu/essing/>
School of Aquatic and Fishery Sciences
University of Washington
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