Fisheries long term monitoring program : Preliminary Assessment of Juvenile Mangrove Jack around Weipa, May 2004

This report is a summary of the data collected in the Fisheries Long Term Monitoring Program freshwater fish surveys from 2000 to 2005. Queensland’s freshwater reaches contain a diverse array of freshwater fish fauna. Over 130 native species are recognised in north eastern Australia which is approximately half of the freshwater fish fauna of the Australian continent (Pusey et al. 2004). The sustainability of freshwater fish is highly dependent on suitable riverine habitat as species diversity and populations are closely linked to habitat conditions. Exotic fish species including carp (Cyprinus carpio), tilapia (Tilapia, Oreochromis spp.) and mosquitofish (Gambusia spp.) may compete with, or prey on, the eggs and juveniles of native species. The Department of Primary Industries and Fisheries (DPI&F) Long Term Monitoring Program (LTMP) has monitored the freshwater fish of 10 river systems in Queensland since 2000. The program uses electrofishing sampling techniques to collect annual information on populations of key recreational, commercial and exotic fish species. The program also collects ancillary information on water quality and habitat conditions that may help to correlate changes in fish community structure. Species diversity in most rivers has remained fairly stable throughout the period of the study. Six exotic fish species have been encountered, with goldfish, European carp and tilapia being of major concern to state agencies. The six years of sampling has been successful in obtaining a baseline dataset of the fish resources for the ten rivers monitored under the freshwater component of the LTMP

Fisheries resources of the Bohle River, Queensland.

The fisheries resources of the Bohle River and its small catchment area adjacent Townsville, north Queensland, were investigated through available literature, scientific research surveys and analysis of commercial and recreational catch and effort data. Research surveys produced a total of 4383 fish from the waters of the Bohle River during 1997-1998. These were classified into 104 fish species from 49 families. Gillnetting, cast netting, fish trapping and crab potting techniques were used in the estuarine waters of the Bohle River with freshwater reaches in the upper catchment surveyed by electrofishing. This range of survey techniques was used to estimate the relative abundance of ten commercially and recreationally important species: Barramundi (Lates calcarifer), king threadfin (Polydactylus macrochir), blue threadfin (Eleutheronema tetradactylum), mangrove jack (Lutjanus argentimaculatus), banded and spotted grunter (Pomadasys kaakan and Pomadasys argenteus), pikey and yellowfin bream (Acanthopagrus berda and Acanthopagrus australis), tilapia (Oreochromis spp.), jungle perch (Kuhlia rupestris) and mud crab (Scylla serrata). The results of each survey method are discussed with a focus on spatial and temporal patterns in diversity and catch rate