Agreenstrategy for shark attack mitigation off Recife, Brazil

Abstract

Shark attacks on humans have prompted the implementation of shark control programs aiming at reducing local populations of potentially aggressive species using mostly gillnets. However, shark meshing produces ecological disturbances by inflicting severe mortality not only to sharks but also to several harmless, frequently endangered taxa, including cetaceans, sirenians and chelonids. A different methodological approach to mitigate shark peril off Recife combines bottom longlining and drumlines with comparably better results. This region has been experiencing an abnormally high shark attack rate since 1992, but the protective fishing strategy was developed in 2004 only. Unlike traditional shark control programs, the Shark Monitoring Program of Recife (SMPR) aims at removing dangerous sharks not from their populations but from the hazardous area instead, which is achieved by capturing, transporting and releasing sharks offshore. During 8 years, the SMPR caught fish and turtles only and showed high selectivity for sharks compared with shark meshing. Target species comprised carcharhinids and sphyrnids and accounted for 7% of total catch. The fishing mortality of abundant taxa was generally low except for Carcharhinus acronotus and Gymnothorax spp., and protected species had ∼100% survival. The shark attack rate diminished about 97% while fishing operations were being conducted (W = 1108.5, P < 0.001), whereas no-fishing periods and the period prior to the implementation of the SMPR had similar shark attack rates. Overall, the SMPR seems to be less detrimental than shark meshing strategies while clearly contributing for enhancing bather safety; thus, it may provide an effective, ecologically balanced tool for assisting in shark attack mitigation.

Three decades of longlining in Bimini, Bahamas, reveals long‐term trends in lemon shark Negaprion brevirostris (Carcharhinidae) catch per unit effort

“…Each set, five lines of 15 hooks were set for a 24‐h period. Individual longlines could not be considered independent sampling, due to their potential effect on each other during the survey (Hazin & Afonso, ). Unit effort was calculated as the number of fishing days multiplied by the number of hooks: hook days, D H .…”

Seasonal variability of bull and tiger shark presence on the west coast of Reunion Island, western Indian Ocean

“…Coastal communities often demand intervention to reduce the risk of further attacks, especially if an unusually high number of incidents have occurred in a short space of time (Curtis et al 2012). A wide range of mitigation measures to decrease the risks of shark attack have been implemented, including short-term targeted shark fishing, long-term deployment of shark-fishing devices such as gillnets or drumlines, use of shark repellents and, more recently, scientific studies to understand better the biology, ecology and behaviour of sharks (Cliff and Dudley 1992;Wetherbee et al 1994;Nel and Peschak 2006;Beschta and Ripple 2009;Cliff and Dudley 2011;O'Connell et al 2011O'Connell et al , 2014Hazin and Afonso 2014). In general, knowledge of apex shark predators remains scarce compared to their terrestrial counterparts (Beschta and Ripple 2009).…”

Mobulid ray by-catch in longline fisheries in the south-western Atlantic Ocean

“…In the north-western Atlantic, Beerkircher et al (2008) reported that of the total combined catches of mobulids and dasyatids by the US pelagic longline fishery, 97% were released alive. A somewhat higher mortality in longlines was reported by Hazin and Afonso (2014) in north-eastern Brazil for devil rays (Mobula sp. ), but their sample size was small (n ¼ 6, 50% dead).…”