[MARMAM] recent Cook Inlet beluga publication

Stephanie Norman whaledoctor at gmail.com
Tue Jan 7 18:35:48 PST 2020

Please find below information on a recent Cook Inlet beluga publication
that is Open Access at the journal Ecosphere.

Citation: Norman, S.A., R.C. Hobbs, L.A. Beckett, S.J. Trumble, and W.A.
Smith. 2019. Relationship between per capita births of Cook Inlet belugas
and summer salmon runs: age-structured population modeling. Ecosphere
11(1): e02955. 10.1002/ecs2.2955

Abstract. Anthropogenic disturbances may alter a population’s conservation
status if the ability of individuals to survive and breed is affected. We
used an adaptation of the Heligman-Pollard model to estimate survival at
age of Cook Inlet belugas (CIB; Delphinapterus leucas), an endangered
population in south-central Alaska. We developed an age-structured Leslie
matrix model, based on
the life history parameters sur- vival and fecundity probability, to
evaluate the sensitivity of population size and growth of CIB, to variation
in estimate values of Chinook and coho salmon abundance in the Deshka
River, a major tributary of the Susitna River. Birth effect (eb) was
regressed against Chinook and coho salmon levels for the year of, the year
before, and two years before a beluga calf birth. The effect of a range of
modifications of salmon availability was
illustrated in CIB with a series of simulations. The maximum annual
population growths (k) were set at 1.036 (3.6%). Ranges of CIB survival and
fecundity probabilities indicated small changes in survival probabilities
have a greater impact on population growth than similar changes in birth
probability. As either survival (es) or fecundity (eb) was reduced, the
annual growth declined, with either es = 0.961 or eb = 0.388, causing a
decreased annual growth of -0.4%.
Regressions of Chinook salmon for the year of, the year before, and two
years before a birth were all significant at the 5% level as was coho in the
year of and year prior to birth. The mechanism model with the best fit was
the sum of Chinook and coho in the year of birth and year prior to birth.
Simulations showed that if salmon runs remained at their current levels,
the CIB population
would likely continue its current slow decline and per capita births would
continue to be low. The results from this study suggest reproductive
success in CIB is tied to salmon abundance in the Deshka River. Current
management practices should consider this when setting research priorities,
designing new studies, and developing management actions to achieve CIB
recovery targets.

The paper can be downloaded at the following link:

Thank you,

Stephanie A. Norman, DVM, MS, PhD
Marine-Med: Marine Research, Epidemiology, and Veterinary Medicine
E-mail: stephanie at marine-med.com
Website: www.marine-med.com
Phone: 206-321-0249
Twitter: whaledocsteph
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