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Clarke C.R.,Marine Research Facility | Clarke C.R.,University of London | Lea J.S.E.,Marine Research Facility | Lea J.S.E.,University of Plymouth | And 2 more authors.
Marine and Freshwater Research | Year: 2013

There is a lack of studies on how provisioning may influence shark numbers and behaviour. The effects of long-term provisioning were investigated at a Red Sea reef, where both grey reef shark (Carcharhinus amblyrhynchos) and silky shark (Carcharhinus falciformis) occurred. Initially, grey reef sharks outnumbered silky sharks, but over 6 years, silky shark numbers increased almost 20-fold, whereas grey-reef sightings decreased >90%. Following this, silky-shark sightings also declined considerably (>80%). It is suggested that these declines could relate to local overfishing. Many silky sharks were identified individually through distinctive markings or conventional tagging. Some individual silky sharks were recorded regularly over 2 years or more, but most appeared to be transient visitors. Sighting records indicated that provisioning extended the residency of transient individuals. If visiting silky sharks were drawn from a larger regional population, this would explain both their initial accumulation and why, to begin with, sightings were sustained despite local fishing pressure. Conversely, the site fidelity typical of grey reef sharks would have made them more susceptible to local depletion. Silky sharks were recorded as behaving more boldly when present in greater numbers, but the decline in grey reef sharks appears to be unrelated to the initial increase in the numbers of silky shark. © 2013 CSIRO.


Gore M.A.,Marine Conservation International | Gore M.A.,Heriot - Watt University | Frey P.H.,Marine Conservation International | Frey P.H.,Heriot - Watt University | And 5 more authors.
PLoS ONE | Year: 2016

Following centuries of exploitation, basking sharks (Cetorhinus maximus) are considered by IUCN as Endangered in the Northeast Atlantic, where they have now been substantially protected for over two decades. However, the present size of this population remains unknown.We investigated the use of photo-identification of individuals' dorsal fins, combined with mark-recapture methodology, to investigate the size of populations of basking shark within the west coast of Scotland. From a total of 921 encounters photographed between 2004 and 2011, 710 sharks were found to be individually identifiable based on dorsal fin damage and natural features. Of these, only 41 individuals were re-sighted, most commonly both within days of, and close to the site of, the initial encounter. A smaller number were re-sighted after longer periods of up to two years. A comparison of the distinguishing features of individuals on first recording and subsequent re-sighting showed that in almost all cases these features remained little changed, suggesting the low re-sighting rate was not due to a loss of distinguishing features. Because of the low number of re-sighting we were not able to produce reliable estimates for the long-term regional population. However, for one 50 km diameter study area between the islands of Mull, Coll and Tiree, we were able to generate closed-population estimates for 6-9 day periods in 2010 of 985 (95% CI = 494-1683), and in 2011 of 201 (95% CI = 143-340). For the same 2011 period an open-population model generated a similar estimate of 213 (95% CI = 111-317). Otherwise the low rate and temporal patterning of re-sightings support the view that such local basking shark populations are temporary, dynamic groupings of individuals drawn from a much larger regional population than previously supposed. The study demonstrated the feasibility and limitations of photo-identification as a non-invasive technique for identifying individual basking sharks. © 2016 Gore et al.


Gore M.A.,Marine Conservation International | Gore M.A.,University Marine Biological Station Millport | Kiani M.S.,University of Karachi | Ahmad E.,WWF Pakistan | And 5 more authors.
Journal of Cetacean Research and Management | Year: 2012

This paper reports the findings of a project (Cetacean Conservation Pakistan) launched in 2004 with a view to: (a) undertaking quantitative surveys to determine the variety and abundance of species present; (b) working with local fisher communities to collate local knowledge and promote public awareness; and (c) promoting a marine cetacean conservation strategy and measures. Boat-based surveys for live animals and shore surveys for beachcast specimens have confirmed the presence of twelve species of whale and dolphin. Among these bottlenose dolphins (Tursiops sp.) occur both inshore along the coasts of Sindh and Balochistan, and offshore in parts of Balochistan; these two populations possibly representing different sub-species. Indo-Pacific humpback dolphins (Sousa chinensis) are common inshore around the mouth of the Indus Delta and in large sheltered bays in Balochistan, where finless porpoise (Neophocaena phocaenoides) also occur. Spinner dolphins (Stenella longirostris) were observed in very large schools (up to 2,000) around the shelf edge in eastern Balochistan, as were Risso's dolphins (Grampus griseus) in smaller numbers. Common dolphins (Delphinus capensis) were recorded even further offshore. There were two sightings of humpback whales (Megaptera novaeangliae), and one of a killer whale (Orcinus orca). Bryde's whales (Balaenoptera edeni), sperm whales (Physeter macrocephalus) and Cuvier's beaked whales (Ziphius cavirostris) were recorded only during beach surveys, while skeletal remains in institutions also supported the occurrence of blue whales (Balaenoptera musculus). Work with local fisher communities supported this picture of species distribution and provided information on threats to local cetaceans. These are principally occasional entanglement in fishing gear and opportunistic exploitation for use as food, as bait, as medicine or for other purposes. The project incorporated policy development and the preparation of a marine cetacean biodiversity action plan that included the listing of species in provincial conservation legislation, the designation of a marine protected area in Balochistan, the establishment of a national whale and dolphin conservation society, and trials of whale and dolphin watching as a means of raising public awareness and providing alternative economic value.


Richards K.,University of York | O'Leary B.C.,University of York | Roberts C.M.,University of York | Ormond R.,Marine Conservation International | And 2 more authors.
Marine Pollution Bulletin | Year: 2015

Shark tourism is a popular but controversial activity. We obtained insights into this industry via a global e-mailed questionnaire completed by 45 diving/snorkelling operators who advertised shark experiences (shark operators) and 49 who did not (non-shark operators). 42% of shark operators used an attractant to lure sharks and 93% stated they had a formal code of conduct which 86% enforced "very strictly". While sharks were reported to normally ignore people, 9 operators had experienced troublesome behaviour from them. Whilst our research corroborates previous studies indicating minimal risk to humans from most shark encounters, a precautionary approach to provisioning is required to avoid potential ecological and societal effects of shark tourism. Codes of conduct should always stipulate acceptable diver behaviour and appropriate diver numbers and shark operators should have a moral responsibility to educate their customers about the need for shark conservation. © 2014 Elsevier Ltd.

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