Evaluation of acoustic transmitter implantation and determination of post-translocation behaviour of largemouth bass Micropterus salmoides in a South African impoundment

Abstract

Largemouth bass Micropterus salmoides are an important angling species that are often displaced during catch-and-release fishing tournaments. The impact of acoustic transmitter implantation on this species and the effect of displacement distance on their behaviour were tested. In April 2010, 10 fish with surgically implanted dummy acoustic transmitters and 10 control individuals were kept for 20 weeks under laboratory conditions. Wound healing, hepatosomatic index, gonadosomatic index and viscerosomatic index did not differ between treatment and control groups. However, fish with implanted dummy transmitters lost weight more rapidly than control fish. In 2010, an array of passive data-logging receivers was used at Wriggleswade Dam, Eastern Cape, to record movements of 10 acoustically tagged bass that had been displaced for distances ranging from 0.1 to 4.3 km. Fish displaced by up to 3.5 km remained within 3–4 km of their release site, but fish displaced 4.3 km immediately returned to their capture locations. Seven weeks after the initiation of the experiment, with the onset of winter, fish that had been holding in the vicinity of their release site near the Kubusi River inlet moved into the deeper basin of the impoundment. The results suggest that largemouth bass displaced for up to 4.3 km during fishing tournaments return to their capture localities.