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Alaska Ecosystems Program

By Land, Sea, and Air: A Collaborative Steller Sea Lion Research Cruise in the Aleutian Islands

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figure 1, '=24', see caption
Figure 1.  Adult female Steller sea lion (=24), with a head-mounted satellite tag, 18 March 2012, at Petrel Point, Semisopochnoi Island.  This animal was captured, instrumented, and branded on 1 November 2011 on Ulak Island.  Photo by V. Burkanov.  (NMFS MMPA research permit 14326-03).

The Alaska Ecosystems Program (AEP) of the National Marine Mammal Laboratory (NMML) conducted a joint research cruise in the Aleutian Islands, 4-25 March 2012, with the Geophysical Institute (GI), University of Alaska Fairbanks, to study the winter diet of Steller sea lions (Eumetopias jubatus) and test the feasibility of using unmanned aircraft as a survey platform. Both Lowell Fritz (AEP) and Gregory Walker (GI) received grants from the North Pacific Research Board (NPRB) to study Steller sea lions in the Aleutian Islands -- Fritz to examine the relationship between diet and population trend (NPRB project #1114) and Walker to test the use of unmanned aircraft (NPRB project #1120).

Discussions began in fall 2011 to conduct the field operations necessary for both projects during a jointly-funded cruise in winter 2012, with the added benefit to NMML scientists of observing the operation of unmanned aircraft for survey purposes and to the GI team of learning more about sea lion biology and ecology.

As Fritz and Walker obtained the necessary permits from the NMFS Office of Protected Resources, the Federal Aviation Administration (FAA), and the NOAA Aircraft Operations Center, it became clear that including representatives from these groups could help educate them in the operation of small unmanned aircraft for marine mammal surveys.

Thus, on 4 March, the following group of 11 scientists, managers, engineers, pilots, and NOAA Corps officers boarded the RV Norseman in Adak, Alaska, to begin a 3-week Aleutian Islands research cruise: Fritz, Carey Kuhn, Sara Finneseth, Vladimir Burkanov, and Yura Burkanov (invited volunteer) from the AEP; Walker and David Giessel from the GI; Jay Skaggs from the FAA; Taylor Nobles from AeroVironment, LLC (makers of the "Puma," one of the unmanned aircraft tested on this trip); and CDR Nancy Hann and LTJG Van Helker (currently at NMML) from the NOAA Corps.

figure 2, see caption
Figure 2.  Movement of an adult female Steller sea lion (=24) between at-sea and on-land locations, 3-6 April 2012.  The easternmost cluster of dive locations (stars) on northern Petrel Bank is where near-simultaneous sea lion diving and prey sampling by the FV Seafisher (AFSC cruise) occurred on 4 April 2012.  Petrel Point is the northernmost point on Semisopochnoi Island.

In total, 54 Steller sea lion terrestrial haulout sites were visited, and almost 3,000 Steller sea lions were observed. The AEP group collected nearly 350 diet samples from 14 sites spanning the entire Aleutian Island chain from Cape Wrangell on Attu Island (172°E) to Adugak Island near Samalga Pass (169°W). In addition, they installed six cameras that will take pictures, every 30 minutes during daylight hours, of the rookery beaches at Cape Wrangell and Gillon Point on Agattu Island in the western Aleutian Islands.

figure 3, see caption
Figure 3.  Steller sea lions on East Cape, Amchitka Island, 9 March 2012.  This photo was taken with the Aeryon Scout quad-copter by Gregory Walker and David Giessel, Geophysical Institute, University of Alaska Fairbanks, with a GoPro Hero (11 mega pixels) camera equipped with a 170° fisheye lens.  The legs of the quad-copter are visible in the upper right and left of the image.  (NMFS MMPA research permit 14326-03).

Unlike populations in the Gulf of Alaska, sea lion populations in the western Aleutian Islands continue to decline. To help promote their recovery, NMFS closed (beginning in 2011) directed fishing for two of the primary sea lion prey species (Atka mackerel and Pacific cod) in this area (NMFS regulatory area 543).

Photographs at these two rookeries will provide information on the seasonal use of these terrestrial sites by sea lions and provide sightings of sea lions branded as pups on both Russian and U.S. rookeries, which will help scientists estimate survival and reproductive rates and track the movement of animals across the international boundary.

During this cruise, 15 branded sea lions were observed, 11 of which were positively identified by their unique numbers: 5 were 9-month-old juveniles born and branded on Gillon Point in 2011, 3 were older animals branded as pups on rookeries as far as 1,400 nmi (nautical miles) from where they were observed, and 3 were animals captured as either juveniles or as an adult.

The marked adult seen on this trip, "=24," was a lactating female that was captured on 1 November 2011 on Ulak Island (179°W) and instrumented with a satellite tag to obtain information on her movements, dive locations, and diving behavior. On this cruise, she was seen on both 7 and 18 March at Petrel Point on Semisopochnoi Island (179°E; Fig. 1), a location she had frequently hauled out on during winter 2011/12 between feeding trips to the north and east on Petrel Bank and neighboring slope habitats. AEP scientists confirmed that =24 had a dependent juvenile offspring when she was observed on 18 March. This sea lion spent considerable time diving (and presumably eating) during the winter on the northern edge of Petrel Bank (starred locations furthest to the right (east) in Fig. 2), approximately 50 km northeast of Petrel Point.

figure 4, see caption
Figure 4.  Steller sea lions on East Cape, Amchitka Island, 9 March 2012.  This photo was taken with the Puma fixed-wing unmanned aircraft by Taylor Nobles, AeroVironment.  The infrared image shows warm animals (black) on colder rock substrate (white).  (NMFS MMPA research permit 14326-03).

In late March 2012, the catcher-processor FV Seafisher began an Atka mackerel tag-recovery cruise on Petrel Bank for the Alaska Fisheries Science Center under the direction of Susanne McDermott. On 4 April 2012, the Seafisher used both hydro-acoustics and bottom trawls to sample the fish community at approximately the same time and location where =24 was diving (starred locations in Fig. 2). To accomplish this, the AEP sent near real-time position updates for =24 to the Seafisher, which found that she was likely feeding on Pacific ocean perch, walleye pollock, and Atka mackerel located at the head of a canyon.

The GI, NOAA Corps, AeroVironment, and FAA unmanned aircraft team conducted 39 flights surveying Steller sea lion terrestrial haulouts in the Aleutian Islands. Missions were flown under 525 ft in altitude when over land and generally under 300 ft on approach to the sea lion haulout. Animals on haulouts were photographed obliquely from just offshore, and island haulouts were often circled.

Two types of unmanned aircraft were tested during this cruise: the "Aeryon Scout," a small battery-powered quad-copter, with a flight duration of 20 minutes, equipped with a GoPro high resolution real-time video/still camera on a gimbaled mount; and the Puma, a fixed wing (10-ft wingspan) battery-powered aircraft, with a flight duration of 2 hours, equipped with real-time video as well as infrared and visual still-photo capability.

The Scout flew 30 missions on 10 days over 12 sea lion sites and was launched and retrieved from both the vessel and from land. It took thousands of photos of sea lions (e.g., Fig. 3) and was able to take enough overlapping photos at several important summer breeding locations to produce three-dimensional maps. The Puma flew nine missions on 7 days over nine sea lion sites (Fig. 4). This aircraft was hand-launched from the vessel and was retrieved by landing it in the water. The flights during this cruise were the most extensive to date to test the use of unmanned aircraft to survey Steller sea lions, and they provided valuable baseline information on animal response, survey techniques, and flight operations from land and vessels in the Aleutian Islands.

By Lowell Fritz.

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