Improving bycatch reduction strategies and escape vents in Queensland Mud Crab fisheries

Project number: 2021-119

Project Status:

Current

Budget expenditure: $129,915.00

Principal Investigator: Julie B. Robins

Organisation: Department of Primary Industries (QLD)

Project start/end date: 30 Apr 2022 - 29 Jul 2023

Contact:

FRDC

Need

The proposed work directly targets the opportunity
• to benchmark bycatch reduction devices (including escape vents) and strategies currently in use in the Queensland Crab Fishery,
• to trial refined escape vents for better (i) retention of legal crabs and exclusion of non-legal crabs and fish bycatch.

Recommended refinements to the regulation of escape vents in commercial mud crab pots will be provided to Fisheries Queensland by October/November 2022 for potential inclusion in the next round of regulatory amendments to the Crab Fishery.

More appropriately specified escape vents will produce better commercial outcomes (i.e., retention of legal crabs) and better ecological outcomes (e.g. exclusion of sub-legal crabs and finfish prone to entrapment in crab pots). Reports from crabbers indicate that some of the regulated escape vents allow legal crabs to escape, whilst the small escape vent (75 x 60 mm) reportedly allows very little bycatch to escape. A quantitative study that encompasses regional variation in mud crab morphometrics (i.e., carapace depth/height ~carapace width) would provide empirical data upon which management decisions can be objectively made.

Better documentation on marine turtle entrapment in crab pots (which is currently of limited public access) and gear modification to efficiently reduce or prevent marine turtle entrapment would be of benefit to threatened and endangered marine turtle populations of Queensland (in particular loggerhead turtles) and would contribute to the development of a risk mitigation strategy for the fishery.

Objectives

1. Benchmark bycatch reduction devices and strategies currently in use in the Queensland crab fishery.

2. Trial alternate configurations and advise on potential changes to escape vent regulations achieve better commercial and ecological outcomes.

3. Collate information on marine turtle interactions with crab pots (including ghost pots) and consider pot configuration(s) that could contribute to a risk mitigation strategy for marine turtles in the Qld crab fishery.

4. Develop options for adoption of bycatch reduction devices and strategies in the recreational sector of the Qld crab fishery.

Final report

ISBN: 978-0-6456352-7-0

Authors: J.B. Robins N.J. Stratford S. Seghers and S.M. Leahy

Final Report • 2024-11-11 • 6.03 MB

2021-119-DLD.pdf

Summary

The Queensland Crab Fishery is an iconic fishery, which encompasses the harvest of mud crabs (Scylla serrata, the Giant Mud Crab, and Scylla olivacea, the Orange Mud Crab) and Blue Swimmer Crabs (Portunus armatus and Portunus pelagicus), predominately using baited crab pots of various designs. The Fishery has a limited entry commercial sector that requires a C1 symbol to catch these species of crabs, plus possession of appropriate quota to catch mud crabs on the Queensland East Coast (EC1), Queensland Gulf of Carpentaria (GC1) or Blue Swimmer Crabs anywhere in Queensland (BC1). The Fishery also has a significant recreational sector, that uses similar apparatus and does not require a licence, but does have in possession limits.

The current research investigated the performance of escape vents in crab pots targeting Giant Mud Crabs to determine if current Queensland fisheries regulations should be revised to provide better commercial outcomes (i.e., retention of legal mud crabs – male and 150 mm carapace width or greater), whilst minimising the bycatch of non-legal crabs, finfish and other bycatch species, such as water rats. The research focussed on the Giant Mud Crab as it comprises greater than 99% of the commercial harvest of mud crabs in Queensland
The ongoing issue of marine turtle interactions with crabbing apparatus, including a recent increase of stranding reports, led to the research also collating available information about these interactions to support a risk mitigation strategy for the fishery’s interaction with protected marine turtle species.

Results are to be considered by management, Fisheries Queensland and the Crab Working Group as part of the Harvest Strategy arrangements for the Queensland Crab Fishery.