SOME ASPECTS OF INTERACTION BETWEEN INDO-PACIFIC HUMPBACK DOLPHINS (SOUSA CHINENSIS) AND HUMANS AT TIN CAN BAY, QUEENSLAND, AUSTRALIA
Australian Whale Conservation Society,
P.O. Box 12046, Elizabeth Street,
Brisbane, Queensland 4127, Australia
Cases of interaction between humans and wild dolphins have been well documented from various parts of the globe and more often than not depict instances involving bottlenose dolphins, (Tursiops truncatus). Accounts of other delphinid species interacting with humans are less common and include common dolphins, (Delphinus sp.), Atlantic spotted dolphins, (Stenella frontalis), spinner dolphins, (S. longirostris), and the dusky dolphin, (Lagenorhynchus obscurus).
Here we report the interaction between Indo-Pacific humpback dolphins, (Sousa chinensis), and humans at a small town on the east coast of Queensland, Australia. Anecdotal evidence suggests the interaction may have commenced as early as circa 1974. A number of key issues pertaining to the interaction are presented and a brief account given of some of the data accumulated during our study.
Key words: Indo-Pacific humpback dolphin, (Sousa chinensis), human/dolphin interaction, provisioning, Tin Can Bay.
Records of dolphins interacting with humans are numerous in the published literature ranging from ancient mythology, through to contemporary records of physical contact, cooperative fishing and hand-feeding (Alpers 1963; Doak 1988; Hall 1984; Lockyer 1990). The majority of documented cases involve bottlenose dolphins, (Tursiops truncatus) (Lockyer 1990; Doak 1995), therefore any interaction involving other species must surely arouse considerable interest.
For some years the initial contact between a bottlenose dolphin and human at Monkey Mia in Western Australia evolved into the situation which is well known throughout the world today (Edwards 1987). That situation has created a good deal of opportunity for study of "wild" dolphins (Wilson 1994).
Some years after the commencement of interaction at Monkey Mia a relationship began forming at almost the same latitude on the opposite side of Australia. Approximately 1974 fisherfolk began feeding an Indo-Pacific humpback dolphin, (Sousa chinensis), from small craft on the waters of Tin Can Inlet and the Great Sandy Strait (L. Franz, pers. comm.).
The shallow estuarine waterway in the vicinity of the interaction area is well sheltered from all but the worst weather conditions, the nearest opening to the Pacific Ocean being approximately 10 kilometres to the north-north-east.
Humpback dolphins and, to a greater extent, bottlenose dolphins, (Tursiops sp.), are known to opportunistically feed by following trawlers in the region (J. McLoud, pers. comm.); indeed both have been observed behaving in this manner in Moreton Bay approximately 150 kilometres to the south (P. Garbett, pers. obs.).
Anecdotal evidence suggests that local residents have recognised this same individual dolphin, given the name of "Scar" due to its distinguishing features, since 1974 (L. Franz, pers. comm.). In more recent years, both recreational and commercial fisherfolk have parted with some of their catch in feeding this and other dolphins in the region (M. Machen, pers. comm.).
At about the time "Scar" was first observed with a neonate in late 1992 she began frequenting the Snapper Creek public boat ramp at Tin Can Bay and before long began accepting fish offered in shallow water near the water's edge from the hands of locals and tourists alike (Figure 1).
Fish for the purpose of hand-feeding the dolphins may be purchased from a kiosk adjacent to the interaction area. No controls exist to monitor the quality or quantity of fish dispensed for provisioning. Indeed, there are no controls on site managing the interaction and provisioning such as those which exist in other locations where dolphins are provisioned (Wilson, 1994; Orams, 1994; 1995). For this reason, grave concerns are held by conservation organisations about the situation. A number of parties have expressed commercial interest in the dolphin interaction. Some of the business ventures which already have capitalised on the phenomenon conduct coach tours and helicopter flights. A male Rottweiler dog belonging to a nearby business proprietor was renowned for regularly swimming with "Scar" and her calf "Junior" for a number of years until his sudden disappearance in November 1996.
Figure 1. Indo-Pacific humpback dolphin (Sousa chinensis), "Scar" accepting an offering of fish at Snapper Creek boat ramp, Tin Can Bay, Queensland.
During 1994 we began an investigation into the history of the dolphins of Tin Can Bay and from 1 January 1995 monitored on a daily basis the regularity of visits by dolphins to the interaction area. Help was enlisted from a number of areas in this regard not the least of which being from the volunteer staff of the Coast Guard Tin Can Bay whose radio control room overlooks the interaction area.
For the ensuing 731 day period dolphins were present on a minimum of 87.5% of days. Dolphins were usually first observed at the boat ramp during the hour between 0700h and 0800h. On less than 6% of days dolphins arrived during the afternoon.
Whilst some available literature reveals tidal influence over some movements of dolphins (Green & Corkeron 1991) the arrival times of the study animals were seemingly unaffected by positions of the tide.
During January 1995 two other dolphins visited the boat ramp in the company of "Scar" and "Junior". The greatest number of dolphins observed by us at the boat ramp at a single time was six. Eight dolphins have been identified by us entering the provisioning area at different times. In April 1996 a pair of dolphins known as "Beaky" and "Little Beaky" visited the boat ramp, the former (larger and with a deformed upper jaw) accepting fish. This pair visited irregularly until November 1996 from which time their presence became significantly more frequent.
In April 1995 the calf "Junior" commenced accepting fish from human hands and in the ensuing weeks was able to be touched. Children were observed riding the dolphin by holding onto the dorsal fin. An adult was observed trying unsuccessfully to climb onto the back of the dolphin. These sorts of human behaviour raise concerns for the safety of both dolphins and humans, especially in light of incidents in South America in recent years where the death of a human resulted from injuries sustained when a dolphin reacted to irresponsible actions on the part of humans (Anon. 1994).
In early January 1997 "Junior" visited the provisioning area alone for three days. During this period anecdotal evidence was received by us that "Scar" was seen with a neonate of a length no greater than 75 centimetres. Whilst the report was unconfirmed this was the first period of such a length that "Scar" and "Junior" had not been observed in each other's company. "Scar" returned after a three day absence and was not accompanied by a neonate.
Considering the proximity to civilisation and the relative ease with which studies of the humpback dolphins from the Tin Can Inlet and Great Sandy Strait could be conducted, at the time of writing (February 1997) no research projects other than our own have been conducted using the Tin Can Bay humpback dolphins as subject matter.
The phenomenon continues to become more widely known through word of mouth, tourist brochures, souvenir sales, radio advertising, newspaper and magazine articles, and televised news reports and wildlife segments. Some other dolphin/human interaction sites such as Monkey Mia and Tangalooma are relatively remote; the former isolated by sheer distance from civilisation whilst the latter, being on an island, is accessible only by boat or aircraft. Tin Can Bay, with no controlling body managing the interaction, is only two hundred kilometres from the state capital of Brisbane and susceptible to escalating numbers of unsupervised persons. Clearly, the greater the delay in the necessary legislation, the greater the potential for associated problems exacerbating.
During the course of our investigation into the history of the habituation of dolphins at Tin Can Bay, a number of persons and organisations were approached for assistance. Those to whom we extend a most sincere thanks are Commander Bevan Thoroughood and volunteers of Coast Guard Tin Can Bay, Marc Darguisch of the Rainbow Beach office of the Queensland National Parks and Wildlife Service, Mark and Bruce Machen and Rodney Mackenzie of Fraser Island Houseboat Hire, Beverley Petersen and residents of Tin Can Bay, and numerous commercial and recreational fisherfolk. We also thank Guy Bedford for comments on an earlier draft of this document.
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© February 1997
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