Influence of Environmental Factors on Prey Discrimination of Bait-Attracted White Sharks from Gansbaai, South Africa.

Autor: Reinero FR; Sharks Studies Center-Scientific Institute, 58024 Massa Marittima, Italy., Sperone E; Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy., Giglio G; Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy., Pacifico A; Sharks Studies Center-Scientific Institute, 58024 Massa Marittima, Italy.; Department of Political Science and CEFOP-LUISS, LUISS Guido Carli University, 00197 Rome, Italy., Mahrer M; W. M. Keck Science Department, Claremont McKenna College, Claremont, CA 91711, USA., Micarelli P; Sharks Studies Center-Scientific Institute, 58024 Massa Marittima, Italy.; Department of Physical Sciences, Earth and Environment, University of Siena, 53100 Siena, Italy.
Jazyk: angličtina
Zdroj: Animals : an open access journal from MDPI [Animals (Basel)] 2022 Nov 24; Vol. 12 (23). Date of Electronic Publication: 2022 Nov 24.
DOI: 10.3390/ani12233276
Abstrakt: The influence of environmental factors on prey discrimination of bait-attracted white sharks was studied over a six-year period (2008-2013) at Dyer Island Nature Reserve (Gansbaai, South Africa). Across 240 bait-attracted feeding events observed in this period, both immature and mature white sharks were attracted by the seal-shaped decoy rather than the tuna bait, except for the years 2008 and 2011. Tide ranges, underwater visibility, water temperature, and sea conditions were, in decreasing order, the factors which drove white sharks to select the seal-shaped decoy. High tide lowered the minimum depth from which sharks could approach seals close to the shore, while extended visibility helped the sharks in making predatory choices towards the more energy-rich prey source, the odorless seal-shaped decoy. On the contrary, warmer water is associated with an increase in phytoplankton that reduces underwater visibility and increases the diversity of teleosts including tuna-a known prey of white sharks-driving the sharks to favor the tuna bait. Overall, sea conditions were almost always slightly rough, ensuring a good average underwater visibility. Recommendations for future research work at this site are presented.
Competing Interests: The authors declare no conflict of interest.
Databáze: MEDLINE
Nepřihlášeným uživatelům se plný text nezobrazuje