Movements and area use by small spotted grunter (Pomadasys commersonnii) in the Great Fish Estuary (South Africa): implication for management

Abstract

Næsje, T.F., Childs, A.R., Cowley, P.D., Thorstad, E.B., Økland, F., Weerts, S., and Buthelezi, P. 2005. Movements and area use by small spotted grunter (Pomadasys commersonnii) in the Great Fish Estuary (South Africa): implication for management. - NINA Report 55. 46 pp. Great Fish Estuary Programme: Behaviour and management of important estuarine fishery species A project within the South Africa / Norway Programme on Research Cooperation The aim of the programme is to investigate the movement behaviour, migrations and habitat use of important estuarine fishery species (spotted grunter and dusky kob) and local exploitation from fisheries to contribute to the development of a sustainable utilisation strategy. Background The utilisation of estuarine fish resources plays a major role in the local economy and food supply in many parts of South Africa. Many fish species that spend parts of their life in estuaries, such as the spotted grunter (Pomadasys commersonnii) and dusky kob (Argyrosomus japonicus), are exploited for both food (subsistence and small scale fisheries) and recreation. Such estuarine species may also form an important component of commercial coastal fisheries. Due to the poor status of many of the estuarine associated fish stocks, the sustainability of these fisheries is in question. It is therefore urgent to develop sound management practices based on adequate knowledge of the migratory behaviour, population biology, and habitat use of the targeted species. Project purpose The purpose of this project is to investigate the movement behaviour of two of South Africa’s most important estuarine fishery species, the spotted grunter and dusky kob, the exploitation of these species in estuaries and its implications for management. The movements and activity patterns of the spotted grunter and dusky kob are recorded by making use of acoustic telemetry methods, while the fisheries data are collected using structured visual surveys and on-sight direct contact roving creel (interview) surveys. Results from the project will contribute significantly to ensure sustainable utilization of these heavily targeted species. movement behaviour, Pomadasys commersonnii, area use, fisheries, management