North Slope Borough Department of Wildlife Management scientists gather data from a harvest.
2016 Spring Hunt, Barrow, AK
The subsistence harvest of bowhead whales by Alaskan Eskimos is managed under an agreement between the Alaska Eskimo Whaling Commission (AEWC) and the National Oceanic and Atmospheric Administration (NOAA) under the broader umbrella of the International Whaling Commission (IWC) treaty. This agreement establishes a quota, originating from the IWC, which sets limits on how many whales can be taken in a given period of time. Under present IWC practices, the Scientific Committee of the IWC may review the level of quota and supporting documentation annually to make recommendations. Additionally, the United States must request a renewal of the quota every six years.
Providing current and accurate scientific information on the bowhead whale is a pre-requisite to the request for a quota and requirement by the IWC. Supporting scientific data must be provided by the AEWC at the very least on: (1) population size; (2) harvest (catch); and (3) population structure. The burden of collecting and analyzing the required data falls on the AEWC and is accomplished through the following studies.
Bowhead Whale Abundance Survey
An essential pre-requisite to maintaining and renewing the quota is the submission of an accurate estimate of the size and growth trend of the Bering-Chukchi-Beaufort seas (BCB) stock of bowheads, which is called an abundance survey. There are two approaches to developing abundance surveys: the first is an ice-based spring migration survey and the second is an aerial photoID “capture-recapture” survey. While the ice-based census is more precise, it has a lower probability (<50%) of a survey being successful due to “normal” periodic lead closures, recent warming trends and lack of adequate and safe ice - all of which are out of AEWC’s control.
Abundance surveys, whether ice-based or aerial, take approximately five years to complete; one year to collect data and three to four years to analyze data. Both an ice-based visual-acoustic and aerial photoID (capture-recapture) survey were conducted in 2011 with the intent of producing two independent abundance estimates. The process of collecting and analyzing a ‘huge’ dataset like that from the 2011 ice-based census is a major undertaking. The analysis and manuscript preparation must be careful and painstaking to withstand external review by the IWC Scientific Committee. For the analysis of the 2011 ice-based survey data, sophisticated new statistical methods had to be invented. The initial data was utilized by the IWC Scientific Committee in 2013, and the final analysis of the ice-based survey was published and will be used by the IWC Scientific Committee in discussion and management models for quota recommendations. The next abundance survey must be completed by 2021 via the IWC agreement. The AEWC collaborates with the North Slope Borough Department of Wildlife Management to complete this survey.
Genetics Study to Determine Stock Structure
Another requirement of IWC whale management procedures is to provide data on the population structure of the bowhead whale. The NSB genetics program was developed in 2002 as a result of the blockage of the IWC quota renewal of the bowhead whale. The scientific basis used by Japan to vote against the quota was the possibility that multiple subpopulations existed within the Bering Chukchi Beaufort Seas (BCBS) stock of bowhead whale. As a result, an interim quota was established contingent on a major stock-structure program being conducted. Again, the burden of developing a program fell on the NSB/AEWC program. Approximately a million dollars later, the AEWC was able to provide evidence that the BCBS bowhead whales were functionally one stock in 2007. The North Slope Borough Department of Wildlife Management has continued to gather and analyze genetic data, and has published numerous papers on stock structure and similar genetic questions.
Bowhead Whale Harvest, Health, Life History and Reproduction
The AEWC is also required to provide information on the harvest (catch) of the bowhead whale, including estimated mortality, health and reproduction rates. This information is gathered during the hunts through scientists participation through sampling of the bowhead whales landed. Much of this work has not been covered through previous NOAA funding; however, it is important to note the requirement of providing this information to the IWC.
The bowhead life history research on reproduction and age is underway with the University of Alaska Fairbanks, Ohio School of Medicine and other institutions. This work is critical for studies including: contaminant analysis, health assessment, growth rates, population assessment modeling, and other studies. The 2016 work funded by a grant from the U.S. Fish and Wildlife Service Coastal Impact Assessment Program (CIAP).
NSB DWM RESEARCH TOPICS