Carp in NSW: Assessment of distribution, fishery and fishing methods
Graham, K.J., Lowry, M.B. and Walford, T.R., 2005. Carp in NSW: Assessment of distribution, fishery and fishing methods. NSW Department of Primary Industries - Fisheries Final Report Series No. 72. 88pp. ISSN 1449-9967.
The introduced common carp (Cyprinus carpio) is now widespread through much of inland New South Wales. Carp are considered a major pest and contributor to the environmental degradation of many inland waterways and reduction of native fish populations. Consequently, there has been considerable ongoing research, both nationally and within NSW, into ways of controlling carp numbers.
Key components of this study were to map the present distribution of carp in NSW, review the carp fishery including catch and market data, and assess harvesting methods with respect to their effectiveness in catching carp and their possible impact on native fish species or air-breathing vertebrates such as turtles and platypus. A fish trap designed for carp and incorporating a bycatch reduction device was tested and assessed.
Updated distributional data indicate that carp now inhabit over 75% of NSW waterways. Carp have continued to disperse throughout the inland waterways including much of the southern tablelands and the ACT. Of the inland drainages, only the arid northwest corner of the state and relatively small alpine areas along the Great Dividing Range between New England and the Snowy Mountains are now free of carp. Along coastal NSW, carp are now widespread in and between the Hunter and Shoalhaven River catchments, including the Hawkesbury-Nepean River system.
Commercial fishing for native fish from NSW inland waters was phased out in 2001. Despite incentives to encourage the commercial harvesting of carp, few fishers now catch carp and production has fallen to historically low levels. From a peak of 550 tonnes in 1977/78, the annual catch is now about 70 tonnes, reflecting the lack of demand and consequent low price offered for carp. In contrast, the recent National Recreational and Indigenous Fishing Survey estimated that annual catch by recreational fishers in NSW to be approximately 1.2 million carp weighing 877 tonnes.
Effective commercial fishing methods for carp include electro-fishing, hauling (seining), mesh-netting and trapping. The efficiency, suitability and viability of each of these methods varies and are dependent on the physical and environmental conditions at the fishing locations. Hauling is limited to locations such as shallow lakes or dams where the fished area is clear of obstructions, electro-fishing has high capital cost and is labour-intensive, and static fishing gear such as mesh-nets and traps (including drum nets and hoop nets) can adversely impact on protected air-breathing vertebrates such as turtles and platypus. These problems can be minimised by setting nets only for short periods, or by fitting traps with effective escape avenues for protected species.
Trials were run on a trap designed for commercial carp fishing. The trap was constructed with an in-built escape aperture for air-breathing vertebrates and its effectiveness at capturing carp while releasing turtles and platypus was tested. Under experimental conditions, about 80% of freshwater turtles escaped through the aperture; however, during fishing trials, less than half of captured turtles escaped indicating that further design improvements were needed to minimise potential turtle mortality. Experiments with platypus found that with a small modification to the trap, all animals were able to exited the trap in less than two minutes after entry. During fishing trials in a carp-infested irrigation creek, individual traps caught up to 18 carp per day.
Table of Contents I
List of Tables II
List of Figures II
Non-technical summary IV
1. Introduction 8
2. Objectives 9
3. Mapping of Carp Distribution in NSW 10-18
- Results and discussion
4. Commercial Fishing Methods 19-26
- Carp harvesting methods
- Discussion and summary
- Case Study: Mesh-netting in northern NSW storage dams by C & P Hyde
5. NSW Carp Production and Markets 27-32
- Annual production
- Sydney Fish Market Sales
- Other markets
6. Enviro-trap trials 33-45
- Description of Enviro-Trap
- Carp retention trials
- Turtle escape experiment
- Platypus escape experiment
- General discussion
Section 7, Conclusions and References
7. Fishing Gear Trials 46-57
- Small-scale gear
- Trials with large fish traps
- General discussion
8. Conclusion 58
9. References 59-60
10. Appendices 61-90
- Appendix 1. Mapping of carp distribution: data sources and metadata
- Appendix 2. Inland production areas
- Appendix 3. Morphmetric data for short-necked turtles from Botany Pond
- Appendix 4. Titles and abstracts of published papers detailing envirotrap experiments
- Appendix 5. Report on carp trapping in Eagle Creek
- Appendix 6. Capture details and size data fro bass and turtles caught in the Lane Cove River