The Shark human conflict
Shark human conflict
Some facts about the human and shark conflict:
- From 2011 to 2016 there have been 491 registered shark attacks worldwide (43 fatal) 1
- For reducing the number of shark-human encounters the most used system have always been to cull the sharks by using shark nets and drumlines 2,3 .
- Culling technologies don’t provide a physical separation between beach-users and sharks, in fact in New South Wales (Australia) 65% of shark bites occur at netted beaches. Shark nets also resulted in large scale unjustified killing of marine animals (3944 in NSW over the past 20 years, 40% of these weren’t sharks, but whales, turtles and dolphins) 4.
- The loss of sharks proved to also cause an imbalance in the prey/predator distribution: smaller sharks and marine mammals increase in number and, by eating smaller fish and crustaceans have a negative impact on local fishery and the health status of the marine ecosystem. 5–7
- A reduction in the number of sharks also result in a loss for the shark eco-tourism businesses, valued at an excess of 314 Mil US$ a year worldwide 8,9
- In Durban, South Africa, seven gill nets were deployed in 1952 (each 130 m long) and in the first year of operation 552 elasmobranches were caught in these nets 3. Since 1989, some live sharks were released from the nets but it is estimated that only 12,5% of the sharks captured in anti-shark nets survive 10,11.
- To date this problem, mostly in poorly developed countries, has not been addressed. As a response to an incident in Mozambique involving a bull shark (22/10/2015), “The Mozambican Maritime Administration has deployed a team of around 60 fishermen, biologists and local officials to hunt and kill a dangerous shark which attacked and killed a woman in the Bay of Inhambane in the south of the country” (source: http://en.starafrica.com/news/mozambique-hunts-to-kill-deadly-shark.html).
REFERENCES and SOURCES
- International Shark Attack File. Available at: https://www.qt.com.au/news/every-shark-attack-ever-recorded-captured-map/2674734/.
- O’Connell, C. P. et al. Effects of the Sharksafe barrier on white shark (Carcharodon carcharias) behavior and its implications for future conservation technologies. J. Exp. Mar. Bio. Ecol. 460, 37–46 (2014).
- Kwazulu Natal Shark Board. KNSB Website. Available at: http://www.shark.co.za/Pages/ProtectionSharks-NetsDrumlines.
- Report into the NSW Shark Meshing Program. (2016).
- Rosenblatt, A. et al. The Roles of Large Top Predators in Coastal Ecosystems: New Insights from Long Term Ecological Research. Oceanography 26, 156–167 (2013).
- Baum, J. K. & Worm, B. Cascading top-down effects of changing oceanic predator abundances. J. Anim. Ecol. 78, 699–714 (2009).
- Heithaus, M. R., Frid, A., Wirsing, A. J. & Worm, B. Predicting ecological consequences of marine top predator declines. Trends Ecol. Evol. 23, 202–210 (2008).
- Gallagher, A. J. & Hammerschlag, N. Global shark currency: The distribution frequency and economic value of shark ecotourism. Curr. Issues Tour. 14, 797–812 (2011).
- Cisneros-Montemayor, A. M., Barnes-Mauthe, M., Al-Abdulrazzak, D., Navarro-Holm, E. & Sumaila, U. R. Global economic value of shark ecotourism: implications for conservation. Oryx 47, 381–388 (2013).
- Cliff, G., Elst, R. P. Van Der, Govender, A., Witthuhn, T. K. & Bullen, E. M. First Estimates of Mortality and Population Size of White Sharks on the South African Coast. in Great White Shark, the biology of Carcharodon carcharias (1995).
- Dudley, S. F. J. & Simpfendorfer, C. A. Population status of 14 shark species caught in the protective gillnets off KwaZulu-Natal beaches, South Africa, 1978-2003. Mar. Freshw. Res. 57, 225–240 (2006).
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