Study of ghost fishing in the NSW rock lobster fishery

Project number: 2007-038

Project Status:

Completed

Budget expenditure: $222,583.95

Principal Investigator: Geoff Liggins

Organisation: NSW Department of Primary Industries

Project start/end date: 8 Jul 2009 - 29 Nov 2011

Contact:

FRDC

Need

There is little information about the affect of ghost fishing in Australia’s fisheries and more importantly in one of Australia’s most economically important seafood resources, the rock lobsters- yet, preliminary research would suggest that ghost fishing is significant in the NSW rock lobster fishery. The environmental assessment process of the FMS for the NSW rock lobster fishery identified the need to quantify ghost fishing and find methods to alleviate this impact if necessary (Objective 1.1b of the FMS for the NSW rock lobster fishery). Information about the impact of ghost fishing is important in the FRDC Research and Development Plan (2005-2010) under strategy challenge #1 Natural Resource Sustainability

Results of the small scale pilot study in mid-shelf waters off the NSW south coast (Attachment 1) have shown that ghost fishing does occur in at least one part of the fishery. Considering the variability in water chemistry, bottom topography, oceanographic conditions and fishing operations across the fishery, there may be differences in rates of survival of lobsters and in times taken for traps to degrade among areas. Further investigations of ghost fishing and time taken for traps to break down and allow escape of contained lobsters are required across a broader spatial scale. In particular, investigations are required on the north coast of NSW, where the presence of larger lobsters and higher water temperatures likely result in greater metabolic rates, nutritional requirements and different behaviour of lobsters.

Investigation of ways to reduce losses of head-gear, traps and subsequent unaccounted fishing mortalities associated with ghost fishing and theft of lobsters is also indicated. Experiments concerning the effectiveness of scarificial panels in traps and the cost-effectiveness of acoustic releases for "at call" access to sunken head-gear will address these issues.

Objectives

1. Assess the mortality of lobsters due to ghost fishing of traps in the deep-water component of the fishery

2. Develop and test alternative methods for the setting of traps and deployment of head-gear to reduce mortalities of lobsters resulting from ghost fishing and theft

3. Design and test modifications to traps that facilitate the escape of lobsters from lost traps prior to mortality

Final report

Authors: Dr Geoffrey W. Liggins Marcus E. Miller & Giles Ballinger

Final Report • 2021-06-01 • 2.00 MB

2007-038-DLD.pdf

Summary

This project concerns an assessment of the significance ghost fishing in the NSW Rock Lobster Fishery and potential modifications to fishing gears and practices that could minimise trap loss and consequent ghost fishing of the target species, Eastern Rock Lobster, Sagmariasus verreauxi. The significance of ghost fishing in the deep-water component of this fishery was established by experiments that simulated ghost fishing over the life of traps set at 2 locations. Two approaches to minimise the potential for ghost fishing were examined in this project. The potential for trap doors to function as sacrificial panels that would facilitate the escape of lobsters from lost traps was examined experimentally. Longevity of wire mesh in the doors of traps was manipulated by excluding or varying the size of the sacrificial anode that provides cathodic protection to the wire mesh in the door. In contrast, the second approach to minimising ghost fishing considered here involved the use of technology that would minimise loss of traps in the first place, thereby minimising ghost fishing. We assessed the practical application of an acoustic release system that could provide at-call access to the submerged head-gear (floats and rope) of traps. Submerged head-gear is not exposed to the risk of being cut-off by shipping, theft or vandalism and consequent loss of access to the trap is thereby minimised. The ambition was to provide proof of concept and proof of effective application of this technology in the deep-water fishery for lobsters off NSW and this was achieved. The subsequent purchase and implementation of this system by several commercial lobster fishers in NSW represented the first routine use, anywhere in the world, of acoustic release technology to control access to commercial fishing gear.