Cage diving is the most important activity for the sustainable use of white sharks (Carcharodon carcharias). However, information related to their behaviour during ecotourism is scarce. This study provides useful information for monitoring C. carcharias during cage-diving activities around Guadalupe Island, Mexico. Surface behaviour of 106 white sharks was recorded for 87 days on-board six cage-diving boats in 2012, 2013, and 2014. Of the observed sharks, 63% were immature specimens (n = 67) and 37% were considered mature (n = 39). Seventy-one per cent were males (n = 75) and 29% were females (n = 31). Interactions were classified into one of the 11 behaviours: parading, close inspection, horizontal attack, vertical attack, bait catching, feeding, not feeding, buoy catching, encounter, escape, and staying. Parading, close inspections, and horizontal attacks were performed more often by mature males, whereas immature females performed more vertical attacks, with no differences between mature and immature males. A total of 1,542 ethograms were registered. Each ethogram consisted on average of 6.3 ± 5.6 behaviours with a significant transitional pattern from horizontal attacks to parading and close inspections, and from vertical and horizontal attacks to bait being caught. A pattern related to feeding in a simple stimulus response reflex was observed. The shark's length seems to play an important role in the efficiency of the attacks, presumably resulting from the experience of mature individuals. Intentional feeding should be avoided to prevent negative effects related to ecotourism. This study constitutes a baseline for future research on white shark behaviour. It can be applied in other regions regardless of environmental conditions, quantity and size of the boats, and types of bait. Using this standard method could improve the monitoring, management, and conservation of this vulnerable species.

The surface behaviour of white sharks during ecotourism: A baseline for monitoring this threatened species around Guadalupe Island, Mexico

Sperone E.
2019

Abstract

Cage diving is the most important activity for the sustainable use of white sharks (Carcharodon carcharias). However, information related to their behaviour during ecotourism is scarce. This study provides useful information for monitoring C. carcharias during cage-diving activities around Guadalupe Island, Mexico. Surface behaviour of 106 white sharks was recorded for 87 days on-board six cage-diving boats in 2012, 2013, and 2014. Of the observed sharks, 63% were immature specimens (n = 67) and 37% were considered mature (n = 39). Seventy-one per cent were males (n = 75) and 29% were females (n = 31). Interactions were classified into one of the 11 behaviours: parading, close inspection, horizontal attack, vertical attack, bait catching, feeding, not feeding, buoy catching, encounter, escape, and staying. Parading, close inspections, and horizontal attacks were performed more often by mature males, whereas immature females performed more vertical attacks, with no differences between mature and immature males. A total of 1,542 ethograms were registered. Each ethogram consisted on average of 6.3 ± 5.6 behaviours with a significant transitional pattern from horizontal attacks to parading and close inspections, and from vertical and horizontal attacks to bait being caught. A pattern related to feeding in a simple stimulus response reflex was observed. The shark's length seems to play an important role in the efficiency of the attacks, presumably resulting from the experience of mature individuals. Intentional feeding should be avoided to prevent negative effects related to ecotourism. This study constitutes a baseline for future research on white shark behaviour. It can be applied in other regions regardless of environmental conditions, quantity and size of the boats, and types of bait. Using this standard method could improve the monitoring, management, and conservation of this vulnerable species.
fish
marine reserve
ocean
protected species
recreation
sustainability
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/308037
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