2019 Aerial Surveys of Arctic Marine Mammals - Post 6

October 11, 2019

How many bowhead whales are in the Bering-Chukchi-Beaufort (BCB) stock? This year the ASAMM team got the very special chance to help answer this question!

Bering-Chukchi-Beaufort Bowhead whale.

A Bering-Chukchi-Beaufort Bowhead whale surfaces for air.

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Prior to starting the ASAMM Bowhead Abundance surveys, teams were trained on lessons learned from previous research, methodologies that would be implemented during the August surveys, and what the collected data will be used for.

The International Whaling Commission (IWC) requires a population abundance estimate to be submitted for the BCB bowhead whale stock every 10 years.  In years past, the scientific and local community of northern Alaska have conducted ice-based visual and acoustic surveys, with the survey team stationed on shorefast sea ice, to census the population.  But deteriorating Arctic spring sea ice conditions have increased the safety risks for scientists, and lowered the chances of success, of conducting these ice-based surveys. Predicted changes in Arctic climate are likely to exacerbate this trend.  To compensate for the rapidly changing Arctic environment, aerial photo-identification methods have been implemented, but the subsequent data analysis is very time-intensive.

To derive a new BCB bowhead abundance estimate in a more timely manner, the ASAMM Bowhead Abundance project (aka: ABA) was conceived. 

With the assistance of the international collaboration between the National Oceanic and Atmospheric Administration, Bureau of Ocean Energy Management, Alaska Eskimo Whaling Commission, North Slope Borough, Department of Fisheries and Oceans Canada, Inuvialuit Game Council, and Fisheries Joint Management Council, ABA surveys were conducted across the Beaufort Sea and in Amundsen Gulf during the month of August. 

Planned transects are shown in blue; actual transect effort is shown in brown.

Planned transects are shown in blue; actual transect effort is shown in brown.

Survey Effort

  • Flights: 40
  • Flight Hours: 167
  • Kilometers Flown: 43,320
  • Transect Flight Hours: 76
  • Transect Kilometers Flown: 15,990

Most bowhead whales were in four general areas in the eastern Beaufort Sea: 1) Franklin Bay in western Amundsen Gulf; 2) near Cape Bathurst; 3) off the Tuktoyaktuk Peninsula; and 4) north of Herschel Island.  Far fewer bowhead whales were seen in the western Beaufort Sea, with sightings as far west as Cape Halkett.  Sixty-five bowhead whale calves were seen.

Franklin Bay, Cape Bathurst, offshore of the Tuktoyaktuk Peninsula, and north of Herschel Island were the areas of greatest sightings. Calves were sighted in all of these high density areas, except Franklin  Bay.

Franklin Bay, Cape Bathurst, offshore of the Tuktoyaktuk Peninsula, and north of Herschel Island were the areas of greatest sightings. Calves were sighted in all of these high-density areas, except Franklin Bay.

Data collected during ABA will be further analyzed over the next year, and a report on the new BCB bowhead abundance estimate will be submitted to the IWC in spring 2020.

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Sometimes when flying over the ocean, ASAMM’s survey plane is surrounded by nothing but blue, extending to the horizon, in every direction. And sometimes, when focusing your gaze out towards the horizon the vaporous spouts and black backs of bowhead whales can be seen against the blue watery backdrop.

The study area for the ABA surveys was selected for a number of reasons, including the highest potential to encounter areas of substantial bowhead whale sightings.  Most sightings of bowhead whales trickle in at a manageable pace, but occasionally we encounter high density areas of aggregating bowheads. For these situations, we are equipped with special protocols — the Cetacean Aggregation Protocols (aka: CAPs).

CAPs were first initiated by ASAMM in 2018 and have been successfully utilized during high density aggregations of not just bowhead whales but gray whales, fin whales, and humpback whales, too. In August 2019, we had the chance to put CAPs into action once again during ABA. 

Under the midnight sun, a group of five bowhead whales lounge at the surface, floating atop deep blue waters for a moment before diving into the depths below.

Under the midnight sun, a group of five bowhead whales lounge at the surface, floating atop deep blue waters for a moment before diving into the depths below.

This map depicts a CAPs survey through an area of high-density bowhead sightings.

This map depicts a CAPs survey through an area of high-density bowhead sightings.

Observers photograph sightings to gather images for identification of individual whales and mark- recapture analysis, which can be used in abundance estimates and life history studies.

Observers photograph sightings to gather images for identification of individual whales and mark-recapture analysis, which can be used in abundance estimates and life history studies.

When one of these high-density whale aggregations is encountered, the survey team flies straight and level through the aggregation without any circling, and sighting-specific data are collected for all large whales within 3 km of each side of the plane to estimate the number of sightings encountered per length of transect.

Once the edge of the aggregation is reached, the team diverts from the transect to circle and collect data on as many groups of whales as possible within the overarching aggregation area. For each group, we gather additional details about the whales, including a number of whales, calves, and behaviors, and sometimes photographs for further documentation and individual identification.  During these sessions many behaviors may be recorded, including surface-active groups, breaching, tail slapping, rolling, feeding, and log play.  CAPs require the entire survey team, including observers, data recorder, and pilots, to work together seamlessly and efficiently!

A bowhead whale-sized THANK YOU goes out to everyone who was involved and who contributed their time, energy, knowledge, expertise, resources, assistance, and warm thoughts to make the ASAMM Bowhead Abundance surveys a success!!

In addition to bowhead whales and other marine mammals, the ASAMM Bowhead Whale teams also saw spectacular sights in the Northwest Territories, Canada. The view above the village of Ulukhaktok (top). Sheer cliff faces of Banks Island (top left). Smoking Hills (right). Fiery fall tundra (bottom left). The  Canadian Arctic was bathed in never-ending beauty to behold.

In addition to bowhead whales and other marine mammals, the ASAMM Bowhead Whale teams also saw spectacular sights in the Northwest Territories, Canada. The view above the village of Ulukhaktok (top). Sheer cliff faces of Banks Island (top left). Smoking Hills (right). Fiery fall tundra (bottom left). The Canadian Arctic was bathed in never-ending beauty to behold.

ABA Central and East Teams with their survey platforms (Aero Commander and Twin Otter)

ABA Central and East Teams with their survey platforms (Aero Commander and Twin Otter)

 

 

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