2017 Aerial Surveys of Arctic Marine Mammals - Post 5

September 28, 2017

The kids are alright – Bowhead whale calves in the Alaskan Arctic.

ASAMM, Marine Mammals Aerial survey

A Bowhead whale mother and calf.

There are some who might think that baby bowhead whales, known as calves, do not qualify as “cute” or “adorable”. Rubbish! Although they may not appear as cuddly as polar bear or walrus babies, bowhead whale calves still pass the “awwwww” test. The universal appeal of baby animals is not the only reason the Aerial Surveys of Arctic Marine Mammals (ASAMM) project expends extra effort to document the presence or absence of bowhead whale calves. Calf data is also used to assist with the general health assessment of a population by determining calving interval (e.g., how often do adult females have calves), measuring calf growth rate over time (e.g., how fast do calves grow), estimating an annual ratio of calves to adults, and calculating calf sighting rates. Some of these assessments require specialized photography methods that ASAMM is not able to incorporate into survey protocol, but many of the assessments directly benefit from data collected by ASAMM.

Most bowhead whale calves are born during the spring migration from wintering areas in the Bering Sea to summering grounds in the Beaufort Sea, usually between the beginning of April and end of May. Calves may be born as early as March and as late as August. Calves-of-the-year that are seen by ASAMM in July and August in the western Beaufort Sea are therefore probably about 3-6 months old. Bowhead whale calves are generally (but not always) light gray and uniformly mottled, with a narrow head in relation to the width of the body, and a stout or rotund body in relation to overall length. Most calves-of-the-year are observed in close association with an adult, who is presumably the mother (or cow). ASAMM also regularly records very small whales, assumed to be calves-of-the-year, alone at the surface, presumably hanging out there while mom feeds subsurface. As calves get older, they spend less time closely associated with their mothers, their skin darkens from light gray to darker gray, and their heads appear proportionately larger and bodies slimmer. Several of these features can be seen in the images in Figures 1 and 2.


Figure 1. Selection of bowhead whale cow-calf pairs photographed during summer (July-August) months in the western Beaufort Sea during ASAMM. Of note, the cows in the 19 July 2014 and 7 August 2017 images are likely older females because white on the tail becomes more pronounced with increasing age.  Photo Credit (left to right, top to bottom): Corey Accardo, Heather Foley, Lisa Barry, Laura Ganley, Lisa Barry, Vicki Beaver, NOAA Fisheries.


Figure 2. Selection of bowhead whale cow-calf pairs photographed during fall (September-October) months in the western Beaufort Sea during ASAMM. Calves are noticeably longer and leaner than those observed in summer. Photo Credit: Lisa Barry, Suzie Hanlan, Cynthia Christman, NOAA Fisheries.


Figure 3. Bowhead whale calf-of-the-year distribution, western Beaufort Sea, July-August, 2012-2017.

In some years, in fact, the calf ratio (number of calves observed divided by the total number of whales observed) was actually higher in summer (July-August) than fall (September-October). Bowhead whale cow-calf pair occurrence during summer months in the western Beaufort Sea may be indicative of a change in bowhead whale habitat use in this area or may be due to the increased survey effort in this area since 2012. Summer 2017, in particular, has been more extraordinary than previous summers for bowhead whale calves - both calf ratio and calf sighting rate (number of calves sighted per km surveyed) were higher in summer 2017 than in the previous five years (Figure 4).


Figure 4. Bowhead whale calf ratio (no. calves per total whales) (A) and sighting rate (no. calves per km surveyed) (B), summer, 2012-2017.

While it is possible that some of the calves sighted in summer 2017 were sighted more than once, the high calf ratio and sighting rate strongly suggest that calf production was high. And calf sightings have continued into September, with 89 bowhead whale calves observed so far, representing the highest number of calves in September since this project began! High calf production is one positive indicator of the overall health of the Western Arctic stock of bowhead whales. Bowhead whale body condition is another indicator, and that increased from 1989-2011 (George et al., 2015) in correlation with summer sea ice loss in the western Beaufort Sea. The loss of summer sea ice may be increasing bowhead whale food production, known as secondary productivity.

And well-fed mama bowhead whales are more likely to successfully produce healthy (and, yes, adorable) calves!


  • George, J.C., M.L. Druckenmiller, K.L. Laidre, R. Suydam, and B. Person. 2015. Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea. Progress in Oceanography 136: 250-262.
  • Koski, W.R. and G.W. Miller. 2009. Habitat use by different size classes of bowhead whales in the central Beaufort Sea during late summer and autumn. Arctic 62(2): 137-150.

Additional Resources

Meet the Bloggers

Amelia Brower.png

Amelia Brower is a NOAA Fisheries affiliate with the NOAA Fisheries Alaska Fisheries Science Center through the Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington (UW).

Amelia began working with marine mammals in 2006. She has participated in marine mammal necropsies, seal, sea lion, and fur sea lion rehabilitation and diet and life history studies, bone preservation, monitoring for manatees and other marine life from dredges, oceanographic sampling, small boat surveys for toothed whales off Hawaii, and seal, sea lion, and North Atlantic right whale aerial surveys.

Amelia Brower joined the Aerial Surveys of Arctic Marine Mammals (ASAMM) project in 2009 as a seasonal observer and as a year-round core team member in 2010. Amelia is a team leader during the field season and spends the rest of the year error-checking and analyzing data and photos and assisting with and producing reports, presentations, and scientific publications. Amelia’s work within the ASAMM data has focused on gray whale feeding in the northeastern Chukchi Sea and humpback, fin, and minke whale distribution in the Chukchi Sea. She also serves as the ASAMM polar bear data liaison.


Christy Sims.png

Christy Sims is a NOAA Fisheries affiliate through the Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington (UW).

Christy started as a photo-identification volunteer at the Alaska Fisheries Science Center in 1998, and has been working with the Cook Inlet beluga whale project since completing her Masters of Marine Affairs at the UW in 2001.

Christy has worked as observer and videographer on the Cook Inlet beluga aerial surveys since 2003 as well as working on photo-id projects on humpback and bowhead whales. She has also participated in Aerial Survey of Alaska Marine Mammals (ASAMM) as a team leader since 2012.

When she isn't flying around in Alaska in a small plane, Christy is in Seattle analyzing data or designing and managing databases.


Amy Willoughby.png

Amy Willoughby is a marine mammal biologist at NOAA Fisheries’ Alaska Fisheries Science Center.

Amy began her career on the sandy beaches of Florida’s Atlantic coast where she conducted sea turtle nesting surveys. She took to the skies in 2009 as an aerial survey observer for the Florida Fish and Wildlife Conservation Commission’s North Atlantic right whale Early Warning System project.

Since then she has logged hundreds of flight hours searching for protected marine species in the Gulf of Mexico and coastal waters from New Jersey to South Carolina.

Amy has been involved in numerous field projects, conducting research on a range of species including salmon, marbled murrelets, bottlenose dolphins, ice-associated seals, and polar bears.

In 2014, Amy headed to the Alaskan Arctic for a seasonal position with the Aerial Surveys of Arctic Marine Mammals (ASAMM) project as a marine mammal observer and was fortunate to have the project invite her on as a full-time employee. Since then, she has worked for ASAMM year-round on fieldwork logistics, data management and analysis, and reports, and she serves as team leader and walrus data liaison during field operations.



Janet Clarke is a contractor with Leidos who supports the Aerial Surveys of Arctic Marine Mammals (ASAMM) project through a contract with NOAA Fisheries Alaska Fisheries Science Center.

Janet began studying Arctic marine mammals in 1982, and her first project as a young naïve college graduate was as a biologist on these same aerial surveys. She logged about 1,500 aerial survey hours from 1982-1991, most of which were flown in Grumman Goose aircraft and often over large expanses of sea ice. From 1991-2007, Janet supported several Navy exercises as a marine mammal (and occasionally sea turtle) Subject Matter Expert, both in the field and as a co-preparer of environmental impact statements and environmental assessments. The Arctic remained her geographic area of interest, however, and she was delighted to return to the area in 2007 as the Project Lead for ASAMM.

As Project Lead, Janet’s responsibilities extend to field project management, data analyses, report and manuscript writing, formal and information presentations, producing garishly colored maps, being the keeper of ASAMM “corporate” knowledge, and (best of all) occasionally being a team leader on ASAMM surveys.