An easy, cheap, and versatile method to trap turtles, with calibrated sampling effort

Abstract

A novel method (hookless trot line) to trap freshwater turtles in aquatic environments from the Pampas region on southern South America is presented. Cost, functioning, effectiveness, biases, maintenance, and constraints of the hookless trot line are analyzed compared to three other methods (two variants of funnel traps and a trawl net) commonly used in studies dealing with freshwater turtle ecology. Fieldwork was carried out from 2005-2015 in streams that drain the northeast of Buenos Aires province, Argentina. The beef-baited, single-mouthed funnel trap with drift fences was the method that captured the most turtles. It was closely followed by the hookless trot line, whereas the other two methods obtained a small portion of captures. Nevertheless, we conclude that the best method to trap turtles in the region was the hookless trot line because it adapts to a wide range of environments, does not injure the turtles, is easy to build and transport, requires little maintenance, and its materials are cheaper and more durable than those of the other methods. Further, a calibration for the trot line is provided in order to minimize effort and maximize captures: in cost/benefit terms, the best result was achieved by employing 1 bait/1.5 m of shoreline.