Assessment of the impacts of hydro-electric dams on eel stocks in Tasmania and an evaluation and assessment of mitigation strategies

Project number: 2000-186
Project Status:
Completed
Budget expenditure: $282,684.00
Principal Investigator: Phillip Boxall
Organisation: University of Tasmania (UTAS)
Project start/end date: 23 May 2001 - 9 Aug 2004
Contact:
FRDC
TAGS
Stock Assessment
Reproduction
Mortality
Migration
SPECIES
Longfin Eel
Southern Shortfin Eel

Need

Stock enhancement strategies can be a cost-effective means of restoring or maintaining fisheries, and have proven essential in catchments with barriers to migration (Knights and White 1998). Regulation of natural river systems has obstructed eel migration in many catchments, and with the implementation of appropriate management tools such as fish passes / ladders and translocation through trapping / netting programs, restoration of stocks can be achieved. Such strategies have not only proven successful in increasing commercial fishery yields, but also contribute to enhanced spawning stocks and increased silver eel escapements.

Hydro electric operations (dams and power generating turbines) reduce the chance of successful emigration of silver eel, especially for larger female eel (Dekker 1999), and, depending on flow and turbine type and number, may represent a major source of mortality to pre-spawning adults (Ritter et al 1997).The design of downstream passage ways and the use of non-generating periods to reduce mortality have been trialled and implemented in New Zealand, the USA and Europe, but have yet to be adopted or investigated in Australia.

The sustainability of the eel resource in Tasmania and of existing (and potentially new) commercial eel fisheries in hydro-impounded catchments will ultimately depend on the implementation of appropriate and effective mitigation strategies (passage and/or translocations) specific to both upstream and downstream migrations.

This proposed program addresses the issue of sustainability by assessing both cause and effect of impacts and various mitigation options. It is envisaged that the results and recommendations arising from this proposed study will underpin the development of an integrated management strategy for managing eel fisheries in hydro-impacted catchments with direct benefits to managers and industry alike. Results from this study could be readily transferred to other States, with coordination and dissemination through the existing Australian and New Zealand Eel Reference Group (ANZERG).

REFERENCES

Dekker, W. 1999. Effects of Transfers and Restocking of Eel. Report of the EIFAC Working Group on Eels - Denmark, September 1999. Pp13-17.

Knights, B. and E. White, 1998. An appraisal of stocking strategies for the European eel, Anguilla anguilla - In Cowx, I.G. (ed): Stocking and Introduction of Fish. Fishing News Books. Pp 121-140.

Ritter, J.A., Stanfield, M. and Peterson, R.H. 1997. The American Eel in Eastern Canada - Stock Status and Management Strategies. Proceedings of Eel Workshop January 13-14 1997, Quebec City, QC. Can. Tech. Report 2196. 174p.

Objectives

1. To assess the impacts of hydro-electric dams on eel migrations and eel population structure in Tasmania’s lakes and rivers and to assess the impact of past elver restocking practices in hydro-impounded catchments on eel populations within those catchments.
2. To assess the direct impacts of hydro-electric dams and associated operations (turbine intakes and water management practices) on adult ‘silver’ eel survival rates during their downstream spawning migrations
3. To evaluate various management tools (ladders / bypasses and passage
netting / trapping and translocation) to mitigate impacts and provide recommendations for implementation.
4. To review the management of barriers to eel migration, including overseas experience.

Final report

ISBN: 0-7246-6965-5
Author: Phil Boxall
Final Report • 2004-02-17 • 3.15 MB
2000-186-DLD.pdf

Related research

All research
research
Environment
Environment
Environment
PROJECT NUMBER • 1998-128
PROJECT STATUS:
COMPLETED

Biological data and model development for management of longfin eel fisheries

1. Estimate population parameters required for a management model. These include survival, density, age structure, growth, age and size at maturity and at recruitment to the adult eel fishery. Estimate their variability among individuals in a range of habitats.
ORGANISATION:
Department of Primary Industries (QLD)

Effects of Trawling Subprogram: implementation and assessment of bycatch reduction devices in the Shark Bay and Exmouth Gulf trawl fisheries

Project number: 2000-189
Project Status:
Completed
Budget expenditure: $300,380.00
Principal Investigator: Mervi Kangas
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 5 Sep 2000 - 29 Apr 2005
Contact:
FRDC
TAGS
Wild Catch
Sustainability
Fisheries Management
Efficiency
Ecosystem

Need

There is an urgent need to assess the impact of the planned introduction of BRDs on the databases used to manage these major trawl fisheries during the transition to full BRD usage. The proper evaluation of BRD implementation is often lacking in trawl fisheries. There is an urgent need for the project because the whole fleet, in Shark Bay for one season will tow one net with a BRD and one without. In the Exmouth prawn fishery and Shark Bay Scallop fishery several vessels will tow nets(s) on one side with a BRD and one side without. Without the project the implementation of BRD’s into both nets could be delayed.

Specifically, the changes in gear efficiency and fleet fishing behaviour (ie distribution of fishing effort) need to be quantified and incorporated into the extensive fisheries databases for these three closely managed fisheries. Secondly, the success of these devices in reducing the quantity of bycatch throughout the season, needs to be accurately assessed to provide advice to fishery and marine conservation agencies for ecosystem management purposes. The industry and marine conservation groups require a quantitative assessment of the effect of BRDs on catches of prawns and bycatch to ensure they are showing the desired impact.

For companies to maintain an exemption to export fish species under the Commonwealth Wildlife Protection (Regulation of Exports and Imports) Act 1982, they will need to prove that associated fishing practices are undertaking in a manner that is demonstrably ecologically sustainable. The Draft National Policy on Fisheries By-Catch, developed by the National standing Committee on Fisheries and Aquaculture, was recently adopted by the WA State Minister for Fisheries. Under the Minister's plan, the WA trawl fisheries, has been given a 'Priority A' rating, meaning that a specific By-catch Action Plan is to be completed by the end of 2001. The trawl industry is actively participating in trialing of BRDs to meet the required deadline. An observer program is needed to complement commercial operator records as high nightly catch rates make it difficult for vessel skippers and crew to record detailed information from individual nets.

Objectives

1. To improve the efficiencies of BRDs (grids and fish escape devices) being introduced into the Shark Bay and Exmouth Gulf Trawl fisheries and ensure full implementation of the most appropriate BRD by the whole fleet in each fishery.
2. To assess the effect of implementation of BRDs (grids and fish escape devices) on trawl bycatch and on the relative fishing power of the Shark Bay Prawn and Scallop fleet and the Exmouth Gulf Prawn fleet.

Final report

ISBN: 1-877098-47-7
Author: Mervi Kangas
Final Report • 2004-12-04 • 2.88 MB
2000-189-DLD.pdf

Maximising survival of released undersize west coast reef fish

Project number: 2000-194
Project Status:
Completed
Budget expenditure: $420,543.00
Principal Investigator: Jill St John
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 16 Oct 2000 - 30 Jul 2008
Contact:
FRDC
TAGS
Stock Assessment
Fishing Gear
Fisheries Management
Education
SPECIES
Snapper
West Australian Dhufish
Tuskfishes
Coral Trouts

Need

The effectiveness of the main current conservation measure, the minimum legal length, on reef fish populations off the west coas, is unknown, largely due to an undetermined level of mortality in released undersized fish. There is an urgent need to measure the discard mortality for this key suite of reef fish species and to educate fishers in techniques which minimise this mortality.

Objectives

1. Estimate mortality of hook and line caught west coast reef fish released back to the sea, taking account of hook type, depth of capture and on-board handling techniques.
2. Collect information on the size of west coast reef fish in relation to depth, to assess the proportion of undersize fish at different depths.
3. Educate fishers in optimal catching and handling techniques to minimise the mortality of released fish.

Final report

ISBN: 1-921258-55-1
Author: Jill St John
Final Report • 2009-08-18 • 6.79 MB
2000-194-DLD.pdf