Study

Recovery of saltwater crocodiles following unregulated hunting in tidal rivers of the Northern Territory, Australia

  • Published source details Fukuda Y., Webb G., Manolis C., Delaney R., Letnic M., Lindner G. & Whitehead P. (2011) Recovery of saltwater crocodiles following unregulated hunting in tidal rivers of the Northern Territory, Australia. Journal of Wildlife Management, 75, 1253-1266.

Actions

This study is summarised as evidence for the following.

Action Category

Regulate wildlife harvesting

Action Link
Reptile Conservation

Legally protect reptile species

Action Link
Reptile Conservation
  1. Regulate wildlife harvesting

    A before-and-after study in 1975–2009 in 12 tidal rivers in the Northern Territory, Australia (Fukuda et al. 2011) found that after introducing regulated egg harvests and legal protection, saltwater crocodiles Crocodylus porosus increased in population density and average crocodile size increased over time. After saltwater crocodile harvests were regulated, relative population density of crocodiles (excluding hatchling crocodiles <0.6 m in length) increased by >three times (2009 estimate: 5 crocodiles/km; 1975 estimate: 2 crocodiles/km). The proportion of larger crocodiles (>1.8 m in length) increased over time in all rivers (most common size in 2007–2008: 2.7 m long, and in 1978–1979: 1.5 m long). Saltwater crocodiles were legally protected in the Northern Territory in 1971. Harvest of non-hatchling crocodiles was limited to <200/year and commercial fishing was banned on most rivers. A managed egg harvest was introduced in 1984–2009 (harvests in 1983–1986: 994–3,470 eggs, increasing to <50,000 in 2009–2010, see original paper for details). Saltwater crocodiles were surveyed in 12 large tidal rivers using a standardized approach (spotlight surveys at night by boat) in June–October in 1975–2009 (11–29 survey years/river, 33–138 km long surveys/river, 682 km total river length surveyed). Crocodile size was estimated when possible and only crocodiles >0.6 m (‘non-hatchlings’) were reported. Relative non-hatchling crocodile population densities were estimated using the sightings data divided by the length of river surveyed.

    (Summarised by: Katie Sainsbury)

  2. Legally protect reptile species

    A before-and-after study in 1975–2009 in 12 tidal rivers in the Northern Territory, Australia (Fukuda et al. 2011) found that after legal protection and regulated harvests, saltwater crocodile Crocodylus porosus increased in density and average crocodile size recorded increased over time. After saltwater crocodiles were legally protected and harvests regulated, relative density of non-hatchling crocodiles increased by >three times (2009 estimate: 5.3 crocodiles/km; 1975 estimate: 1.5 crocodiles/km). The proportion of larger crocodiles (>1.8 m in length) increased over time in all rivers (most common size in 2007–2008: 2.7 m long, and in 1978–1979: 1.5 m long). Saltwater crocodiles were legally protected in the Northern Territory in 1971. Harvest of non-hatchling crocodiles was limited to <200/year and commercial fishing was banned on most rivers. A managed egg harvest was introduced in 1984–2009 (see original paper for details). Crocodiles were surveyed in 12 large tidal rivers using standardized approach (spotlight surveys at night by boat) in June–October in 1975–2009 (11–29 survey years/river, 33–138 km long surveys/river, 682 km total survey length). Crocodile size was estimated when possible, and only crocodiles >0.6 m (‘non-hatchlings’) were reported. Relative non-hatchling crocodile densities were estimated using the sightings data divided by the length of river surveyed.

    (Summarised by: Katie Sainsbury)

Output references
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