Researchers reveal that sharks are hygienic
The pelagic thresher shark is on the IUCN Red List of threatened speciesScientists at 麻豆网 have shown for the first time, that sharks visit shallow tropical reefs or 鈥榮eamounts鈥�, to benefit from cleaning services and rid themselves of cumbersome parasites. The strategy is risky however, since by being there, they become vulnerable to interference from human activity.
The paper published in ) describes the first observations of thresher sharks venturing into shallow coastal waters to interact with cleaner wrasse, a type of small fish that groom other fish species. Thresher sharks live in the open oceans and much of the knowledge of them to date is based on fisheries bycatch.
The pelagic thresher shark is an oceanic species rarely seen by diversThis study, funded by a NERC PhD studentship to Simon Oliver in the , examined the behaviour of these elusive sharks as they invite cleaners to remove parasites and dead tissue. The sharks and cleaning stations are vulnerable to dynamite fishing on the shallow reefs, and the cooperative interaction between the species is disturbed by human activities. The results provide an insight into the behavioural ecology, biology, and conservation of a shark species, which urgently requires protection.
The researchers demonstrated that sharks regularly visit 鈥榮tations鈥� where they adapt their behaviour to facilitate cleaning services by 鈥榩osing鈥� and making themselves more attractive for cleaner fishes. Cleaners then choose to feed on specific parasites from specific areas of the shark鈥檚 body.
Dr John Turner, Senior Lecturer in Marine Biology at the School of Ocean Sciences and Simon鈥檚 supervisor, said 鈥淭he work uniquely describes why some oceanic sharks come into coastal waters to perform an important life function which is easily disturbed by man. Such knowledge will inform offshore industry, science, and conservation policy.鈥�
Simon Oliver undertook the fieldwork in Cebu in the Philippines, and has founded the to promote and disseminate shark research, education and conservation to a broad local, regional and international public and scientific outreach. He said 鈥淲hile fish and predator communities at seamounts are well documented in the literature, why sharks were attracted to seamounts remained largely unknown. This new understanding provides an informed basis for conservation management to protect these sites, which form part of their habitat.鈥�
The study highlights key ecological links between the effects of parasite infection on sharks and the necessity for their control through services provided by 鈥榗leaners鈥� who remove them.
Nigel Hussey, who completed his PhD at 麻豆网, said that 鈥淭he study used a remote video system, which enabled us to identify behaviour for the first time, which we鈥檝e classified as 鈥�circular stance swimming鈥�. This method was particularly suited for the study of such an elusive and little known shark species.鈥�
Alison Beckett, who completed her postgraduate degree at 麻豆网 said 鈥淭he study presents a unique investigation into shark behaviour, specifically the cooperative relationship between thresher sharks and two species of cleaner fish. It is also an exciting multi-disciplined biological expos茅 of the pelagic thresher shark, designated as Vulnerable by the IUCN鈥檚 Red List.鈥�
Publication date: 15 March 2011