[MARMAM] New paper on abundance of cetaceans in Hawaiian waters

Amanda Bradford - NOAA Federal amanda.bradford at noaa.gov
Thu Feb 23 11:44:42 PST 2017


Aloha MarMam community -

My coauthors and I would like to let you know that the following paper has
recently been published in Fishery Bulletin:

Bradford, A. L., K. A. Forney, E. M. Oleson, and J. Barlow.  2017.
Abundance estimates of cetaceans from a line-transect survey within the
U.S. Hawaiian Islands Exclusive Economic Zone.  Fishery Bulletin
115:129–142.

*Abstract*: A ship-based line-transect survey was conducted during the
summer and fall of 2010 to obtain abundance estimates of cetaceans in the
U.S. Hawaiian Islands Exclusive Economic Zone (EEZ). Given the low sighting
rates for cetaceans in the study area, sightings from 2010 were pooled with
sightings made during previous line-transect surveys within the central
Pacific for calculating detection functions, which were estimated by using
a multiple-covariate approach. The trackline detection probabilities used
in this study are the first to reflect the effect of sighting conditions in
the central Pacific and are markedly lower than estimates used in previous
studies. During the survey, 23 cetacean species (17 odontocetes and 6
mysticetes) were seen, and abundance was estimated for 19 of them (15
odontocetes and 4 mysticetes). Group size and Beaufort sea state were the
most important factors affecting the detectability of cetacean groups.
Across all species, abundance estimates and coefficients of variation range
from 133 to 72,528 and from 0.29 to 1.13, respectively. Estimated abundance
is highest for delphinid species and lowest for the killer whale (*Orcinus
orca*) and rorqual species. Overall, cetacean density in the Hawaiian
Islands EEZ is low in comparison with highly productive oceanic regions.

You can download a PDF of the paper here
<http://fishbull.noaa.gov/1152/bradford.pdf>, or I'm happy to send you one
directly upon request.

I know that abundance estimation, while important, is generally not the
most exciting of topics!  If you'd like to ease into learning more about
our line-transect surveys in Hawaiian waters and how we use the resulting
abundance estimates, I've posted a non-technical summary of the published
paper on our blog
<https://pifscblog.wordpress.com/2017/02/23/counting-whales-and-dolphins-in-hawaiian-waters/>
.

Kind regards,
amanda

-- 
*Amanda L. Bradford, Ph.D.*
Research Ecologist, Cetacean Research Program
Pacific Islands Fisheries Science Center, NOAA Fisheries
(808) 725-5714

Mailing address:
NOAA IRC
NMFS/PIFSC/PSD/Amanda Bradford
1845 Wasp Blvd., Building 176
Honolulu, HI 96818
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