Fisheries long term monitoring program : summary of sea mullet (Mugil cephalus) survey results: 1999–2006

Abstract

Sea mullet (Mugil cephalus) is a schooling species that is distributed in fresh, estuarine and coastal waters throughout the world (Kailola et al. 1993). Its main distribution in Queensland is between Townsville and the New South Wales border (Williams 2002).
Queensland commercial fishers target schools of mullet on ocean beaches and in estuaries. The main component of the Queensland commercial mullet fishery has historically been the ocean beach sector, which targets sea mullet during their annual spawning migration between March and July (Virgona et al. 1998). The estimated 2005 harvest of mullet for the Queensland commercial fishery was approximately 1637 tonnes (DPI&F 2006). The recreational mullet catch is relatively insignificant compared with the commercial harvest (Bell et al. 2005).
The Queensland mullet fishery is managed by the Department of Primary Industries and Fisheries under the Fisheries Regulation 1995. The current management arrangements include spatial and seasonal closures, a minimum legal size limit and limited commercial entry.
The Long Term Monitoring Program (LTMP) monitors the length, weight, sex, and age of the commercial mullet catch. Catches from the ocean beach sector have been monitored since 1999 and from the estuarine sector since 2006. This report presents a summary of the data collected from the ocean beach sector from 1999 to 2006.
The LTMP measured 18,131 mullet from the commercial ocean beach fishery between Fraser Island and the Queensland – New South Wales border. The modal fork length (FL) of mullet was between 320 and 350 mm for all years. When separated by gender, region and year the modal length of females was larger than males, with ranges between 340 and 430 mm, and 310 and 350 mm FL respectively. There was a significant relationship between length and weight of mullet, with females appearing on average slightly heavier at a given length than males. Female mullet appeared to grow larger and quicker than males, although there was a poor relationship between length and age, and a lack of growth rate information for small young mullet. The majority of mullet collected were aged as three year olds, but very few were five years old or older. The length and age frequency data are considered representative of the commercial ocean beach fishery in southern Queensland.