Problem crocodiles, Crocodylus porosus, at Nhulunbuy, Northern Territory: an assessment of relocation as a mangaement strategy

Abstract

Since 1986 the Conservation Commission of the Northern Territory has operated a programme to remove 'problem' saltwater crocodiles from waters in and adjoining the township of Nhulunbuy. Over a period of five years, 52 different saltwater crocodiles (44 male) were captured. Most (48) were released at remote sites designated by the traditional Aboriginal owners of the surrounding lands. Release distances from the township varied from 17 to 282 km (by coastline). Many crocodiles (47.9%), including those released at the most distant sites, returned to, and were subsequently recaptured at, the township. Total capture rates (initial captures and recaptures pooled) varied seasonally, with fewer crocodiles being caught in the cooler dry season. During the wet season capture rates remained high, but relatively fewer 'new' crocodiles were caught. Probability of recapture could not be related to distance and direction of release from the township, nor size and sex of the released crocodile. Frequency of capture of individual crocodiles (1-8 times) was also unrelated to these variables. The high rates of return indicate that relocation is unlikely to be an effective strategy for managing humancrocodile interactions, at least in areas where potential release sites already support saltwater crocodile populations near carrying capacity.