[MARMAM] New publication: Natural history, population dynamics, and habitat use of humpback whales over 30 years on an Alaska feeding ground

Neilson, Janet janet_neilson at nps.gov
Tue Jan 17 11:17:03 PST 2017

Dear MARMAM community,

My co-authors and I are pleased to announce the following open access

Gabriele, C. M., J. L. Neilson, J. M. Straley, C. S. Baker, J. A.
Cedarleaf, and J. F. Saracco. 2017. Natural history, population dynamics,
and habitat use of humpback whales over 30 years on an Alaska feeding
ground. Ecosphere 8(1):e01641. 10.1002/ecs2.1641


The rigorous program of monitoring humpback whales (*Megaptera novaeangliae*),
implemented by Glacier Bay National Park and Preserve in 1985, augmented by
additional data collected in southeastern Alaska since 1968, constitutes
one of the longest studies of living whales in the world. This monitoring
program, now a National Park Service (NPS) Inventory and Monitoring Program
Vital Sign, employed consistent methods for summer surveys from 1985 to
2014 to document the number of whales and gather longitudinal records on
individuals in Glacier Bay and Icy Strait. Survey effort averaged 355.4
h/yr (SD = 45.8), resulting in 9485 encounters with 662 individual whales,
including 276 calves. The population increased at a rate of 5.1%/yr, from
41 individuals in 1985 to 239 individuals in 2013, primarily due to
long-term site fidelity and local recruitment. We documented sighting
histories of >30 yr in southeastern Alaska, for 54 whales, including one
45-yr sighting history. Almost half of the whales first identified as calves
returned in subsequent years, at a mean age of 3.2 yr (SE = 0.28, range =
1–17 yr). Over 75% of females had their first calf by age 13. The maximum
female reproductive span was 32 yr, and the maximum number of calves was
11. We estimated mean effective calving rate with a simple ratio and used
logistic regression to estimate calving probability. Both methods resulted
in similar maximal estimates that were somewhat lower than previously
published values for this species: 0.324 (95% CL: 0.28–0.36) calves/ female
/ yr vs. calving probability of 0.319 (95% CL: 0.29–0.35). Minimal
estimates, in which the first calf of each known-aged female was omitted,
were 0.302 (95% CL: 0.27–0.34) calves/mature female / yr vs. calving
probability of 0.305 (95% CL: 0.27–0.34) calves/mature female/ yr. This
monitoring program has guided Park management actions and documented this
once critically endangered population’s trajectory toward recovery, often
through collaboration with other agencies and organizations, fostering the
continued protection and understanding of this distinctive species. Our
findings highlight the value of marine protected areas for migratory species
with strong seasonal site fidelity and the role of long-term monitoring in
interpreting population-level responses to changing marine ecosystems.


Janet Neilson
Humpback Whale Monitoring Program
Glacier Bay National Park & Preserve
PO Box 140
Gustavus, Alaska 99826
Janet_Neilson at nps.gov
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