Field Season Report: Center for Cetacean Research & Conservation

Prepared for
Department of Fisheries, Government of The Bahamas
October 21, 2001

Project Title
Opportunistic survey for beaked whales and other marine mammals off of Central Abaco

Submitted by
Nan Hauser

Research scientists
Nan Hauser, Colin MacCleod & Hoyt Peckham

Background: One quarter of the world's 80 whale and dolphin species belong to the family of beaked whales, but because they favor deepwater habitat, study and knowledge of these cetaceans is in its infancy. Sightings of these elusive creatures at sea are extremely rare due to their long dive times and unobtrusive surfacing behavior. Based on strandings data and limited observations at sea, beaked whales are thought to be some of the deepest and longest diving of all marine mammals. Beaked whales appear to have an anomalous sensitivity to anthropogenic sound, as evidenced by several recent stranding events in the wake of naval sonar testing operations in the Mediterranean, the eastern Atlantic, and the waters of The Bahamas. The conservation status of these cetaceans is unknown.

Objective

(1) document population of beaked whales off of central Abaco (ongoing project of BMMS since 1991, to which CCRC researchers have contributed since 1996).
(2) photo-identify all individuals encountered using 35mm still- photography and digital video, both surface and underwater
(3) opportunistically collect sloughed skin and fecal samples for genetic analysis
(4) evaluate future prospects for instrumenting beaked whales with suction-cup-attached acoustic recording tags which would provide unprecedented data such as beaked whale dive depth, dive time, velocity, dive aspect, vocalization profiles, and sounds received.
(5) involve and engage Abaconians in research process to further their understanding of and commitment to marine conservation through public outreach sessions offered to schools and community groups.

Methods

Opportunistic surveys were undertaken in the waters offshore (east) of Great Abaco, up to ten nautical miles offshore from Whale Cay to Little Harbour. On days with sea state lower than Beaufort Force 3, researchers traveled offshore from Central Abaco to search for beaked whales. Routes varied according to opportunistic encounters with beaked whales and sightings reported by boaters in the area. When sea conditions did not permit offshore work, opportunistic surveys were carried out along leeward (protected) shorelines.

Photo-ID: Identification photographs (photo-IDs) will be taken of the unique markings of each whale encountered. Photo-IDs will be acquired using 35mm still cameras equipped with telephoto and zoom lenses. Distinctive markings and behavior of whales will be recorded with digital video cameras on the surface, and when necessary, underwater. Field data, including behavioral mode, individuals present, geographic position, date, time, etc. are collected with voice recorders. All images will be digitized and data transcribed and subsequently integrated into databases. Photo-IDs and video stills will be entered into a Dense-beaked whale Photo-ID Catalog to monitor individual whales' residence and patterns of association. Waypoints are recorded at the beginning and end of every encounter.

Genetics: Genetic material (DNA) coded with individual whales' attributes can be gleaned from samples of their skin. Skin sloughed off as whales dive or exhibit high-energy behavior will be collected whenever possible. Samples will be logged with a unique access number, allowing cross-referencing of photo-ID and field data recorded simultaneously. Samples will be preserved and stored according to established protocols for later analysis. DNA will be analyzed to determine the species, sex and relatedness of individuals. On a larger scale, samples will be compared with those in existing databases to assess population identity and genetic diversity in beaked whales worldwide.
Fecal samples will be collected if observed in water.

Results

Total offshore survey time was 103 hours, 21 minutes over the 17 days spent on the water from May 13th to June 5th 2001.

A total of twenty two marine mammal sightings were made of eight species.

Mesoplodon densirostris (Dense-beaked whales) were sighted 5 separate times. ID photographs were obtained including one large male during the last encounter. Group sizes were between 2 and 4 individuals.
One floating fecal sample was collected from a Mesoplodon densirostris and frozen for further analysis.

Stenella frontalis (Spotted dolphins) were encountered five separate times.
1st encounter: Large pod extending over at least 2 miles. 90 to 100 animals with one very large offshore Tursiops truncatus (Bottle nose dolphin) swimming among them and bow riding the boat.
2nd encounter: Large pod (approx. 30-40) spread out over 4 miles. Towards the end of the encounter a hammerhead shark was noticed swimming among 5 of the dolphins and moving in synchrony with them. He was at the surface for at least 6 minutes that our boat was with him. At one point he swam in towards the front of our vessel and was "bow riding" with the dolphins. The encounter was filmed on digital video.
3rd encounter: Large pod consisting of adults, juveniles and many calves.
4th encounter: Five adult animals with 2 young calves.
ID shots of the dorsal fins were taken.
5th encounter: 60 to 100 animals for 43 minutes. Video and ID's obtained.

Tursiops truncatus (Bottlenose dolphins) were encountered on four occasions, in groups of 6, 1, 15, 9, and 1 individuals. Inshore animals were seen twice (one single animal during the first sighting just outside Man O War harbor and 12 animals coming through the south Man O War pass early one the morning. The larger groups consisted of all adults. Two sightings were of offshore Tursiops. The first being a solitary animal among a large group of spotted dolphins and the second consisting of between 160 and 200 animals traveling rapidly approximately 5 miles off shore. We spent one hour and fifty minutes traveling with the pod and covered 5.4 nautical miles in a straight line going North to South. At this date, analysis has not been completed, but many ID photos of individuals were obtained.

Kogia Simus (dwarf sperm whale) and Kogia breviceps (Pygmy sperm whale) were observed on 4 days.
These group sizes ranged from 2 to 15 animals. It is difficult to differentiate these 2 species of Kogia. We had animals of both species due to the difference in their dorsal fin size and placement. We could not distinguish if there were any mixed groups.

Peponocephala electra (Melon headed whales) 80 to 100 animals were around our boat for approximately 4 hours. Many photographs and video were obtained. They displayed curious surface behavior and chose to stay with us the entire encounter as we moved among the pod.

Physeter macrocephalus (Sperm Whales) Three sightings were very exciting to us having never seen them as far North in the Abacos and especially so close to the shore. The last day they were 5 miles off of Man O War Cay. From May 27th to May 31st we saw group sizes of 6 to 18 animals. Underwater and surface footage was obtained. One of the animals that we filmed had a severe deformity of its lower jaw. With closer examination it appeared that the mandible had been broken so critically that the jaw dragged to the side and behind the animals mouth. The whale looked healthy and was of normal size and weight. Due to the amount of scar tissue and what looked like keloid tissue the injury appeared to be old.

Miscellaneous sightings
2 hammerhead sharks on 2 occasions
1 bull shark
1 blue stingray
12 spotted stingrays
1 mahi- mahi

The students and teachers of the Man O War School enthusiastically received an educational enrichment program.

Discussion

With the amount of research time (103 hours, 21 minutes) in the 17 days spent on the water from May 13th to June 5th 2001 we were very pleased with the results of the survey. The good weather allowed us to sight the beaked whales and learn more about their identity and behavior. We videotaped and photographed a beaked whale tail slapping at the surface, which we had never observed before.

The total of twenty-two marine mammal sightings (eight species) was very encouraging. We are glad to see that in our small study site that sea life is teaming and there is much more for us to learn about the elusive beaked whales and other marine mammals. We very much look forward to another survey of the area in May of 2002.

Acknowledgments

Funding was supplied by the Center for Cetacean Research and Conservation. Many thanks to Joan Daeschler and Helen Hauser Jordan. We are indebted to Anne and Peter Heinemann, and Derek & Margot Lee for generously providing lodging for the researchers during this project. Special thanks to Rudy Engholm, who volunteered his airplane, time and effort to the expedition. Many thanks also to boat operator Kaisa Joy. They both offered their unwavering support. Thanks to volunteer observers Anne Heinemann, Peter Heinemann, Kaisa Joy, Joan Daeschler, Ali Haible, and Annemarie Trethewey.

Thanks are also due to the Government of The Bahamas, especially Michael T. Braynen and Mr. Roland Albury of Bahamas Department of Fisheries, for granting us permission to conduct this study, and to the Bahamas National Trust for their support and interest.

Respectfully submitted by Nan Hauser
Center for Cetacean Research and Conservation
800 Mere Point, Brunswick, Maine 04011 USA

P.O. Box 3069
Avarua, Rarotonga
Cook Islands, South Pacific
nan@whaleresearch.org