VISUAL/PHOTO IDENTIFICATION AND BIOPSY PROGRAM

Deborah Thiele and Debra Glasgow

Visual survey was conducted in daylight hours throughout the cruise, when visibility and weather conditions permitted. Over 200 hours of visual survey effort was conducted. Humpback whales made up the majority of sightings (Table 1). The main objectives of the cruise were to recover SIO and WHOI moorings and redeploy one SIO mooring on the northern LTER transect line. In addition, ship time was allocated to the visual survey, photo identification and biopsy program. The objectives of this program were to: conduct visual survey throughout the SO GLOBEC study area in the Western Antarctic Peninsula; focus ship time effort on geographical areas and/or at physically defined features (i.e., the ice edge, Matha Strait, southern Adelaide Island, waters over deep troughs, NE end of Alexander Island) where whales had been found in concentrations and/or feeding during the previous spring, autumn and winter SO GLOBEC cruises; to obtain photo identification records and tissue biopsies from whales in these areas.

Humpbacks were numerous, as usual in the Bransfield and Gerlache Strait, and around Palmer Station. After leaving Palmer Station the ship worked offshore, just over the shelf break to recover moorings. Sighting conditions were not good throughout this part of the cruise due to sea and wind conditions, and hardly any sightings were made. One notable exception occurred during the recovery of the SIO ARP (acoustic recording package) #2. More than 20 sei whales in 5 groups were observed in the area, very active at the surface and feeding (side lungeing observed). Sonobuoys were deployed, and the ship remained stationary and declutched to reduce interference. A wide range of calls were recorded over the next two hours (see acoustics report). These high quality recordings are exceptional because acoustic detections from this species have rarely been made, and this species is generally believed to be infrequent callers.

The next part of the cruise was conducted within Marguerite Bay (northern end). WHOI and SIO moorings were retrieved, detected or dragged for over a number of days. During transits around the Faure Shallows (22 February) many humpbacks and minkes were detected visually (see maps). Most humpbacks sighted here were in the region of the shallows that abuts the eastern end of the deep trough that runs in to the bay around the southern end of Adelaide Island. Feeding behaviour was frequently observed here.

On the 24^th February we surveyed what was left of the sea ice by following the outer ‘ice edge’ from well NE of the tip of Alexander Island in a SW direction, crossing the major trough which bisects Marguerite Bay and George VI Sound. Killer whales, humpbacks and minke whales were recorded here, with humpbacks dominating. Individual photo identification records and tissue biopsy samples were collected from humpback and minke whales along the ice edge during the day. The ship then transited back to the northern end of Marguerite Bay for drifter and mooring work.

Ship time was again made available to the marine mammal survey program on 26^th February. We chose to head for Matha Strait – an area of consistently high whale and krill concentrations throughout the 2001–2002 SO GLOBEC surveys. As the ship broke through ridge and rafted sea ice into the southern end of Laird Island, humpbacks were again found in abundance. The ice edge here provided a rich feeding area for over 50 humpbacks and a small number of minke and killer whales. Zodiac work (photo id, biopsy, feeding behaviour observations and photo records) was carried out throughout the afternoon.

Humpback groups were also concentrated outside Deception Island on 1 March, and on the transit from the island to Palmer Station through the Straits that afternoon and evening. This species were also abundant as we crossed Dallman Bay, headed for the Drake Passage on the 3^rd March. At the northern end of the bay we observed three humpbacks (including a calf) surrounded by a very large, but also very spread out, group of killer whales. A few of the killer whales were closely shadowing the humpbacks, but did not appear to be seriously intending to attack. Some of the killer whale group was observed tail slapping in unison for some time. This group appeared to be the small ‘fish-eating’ type, rather than the mammal-eating type of killer whale. Excellent survey condition were experienced on the first day of transit back across the Drake Passage and an entire afternoon of constant fin whale sightings kept everyone busy as we sailed across uncharted shoals and ridges. Many fin and a couple of blue whales were recorded on sonobuoys here.

Table 1. Cetacean sightings/no. of animals LMG 03-02

Species – common name	sightings	animals
Fin whale, like fin whale	23	65
Sei whale	5	22
Minke, like minke	17	36
Killer whale	3	38
Unidentified cetaceans	13	26
Hourglass dolphin	3	13
Humpback, like humpback	116	320
TOTAL	180	520