Collecting finfish broodstock

Introduction

Broodstock, or brood  fish, are the parent fish from which fry and fingerlings are produced. The  success of stocking programs, fish farms and aquaculture industries depend upon  a reliable supply of healthy fry/fingerlings that have a sound genetic base.  Fish reared in hatcheries may be used for grow-out on fish farms, farm dam  stocking, stock enhancement, conservation stocking or the aquarium trade.  Hatchery operators require access to new brood fish periodically to undertake  their breeding programs. Brood fish are usually sourced externally (dams, lakes  and rivers) and held in facilities (ponds, cages, tanks) at the hatchery.  Replacement brood fish are required due to declining reproductive performance in  captivity, brood fish mortality or to maintain genetic diversity. NSW DPI regulates  the collection of brood fish, and hatchery operators must obtain a permit and  authorisation before collecting commences.

Applying  for a Broodstock Collection Permit

Permits are issued  under Section 37 of the Fisheries Management Act 1994 to regulate  brood fish collection.
Several factors are  taken into consideration before NSW DPI grant a brood fish collection permit.  These include:

• The species and number of brood fish required.
• The source of brood fish.
• The hatchery facilities for brood fish  holding, artificial spawning and larval rearing.
• The proposed brood fish collection methods.
• The potential to obtain brood fish from  locations other than the wild eg. captive stock.
• Consideration of any impacts on threatened  fish species.
• Any potential conflict with the public, commercial  or recreational anglers.

To ensure the activity  is acceptable, aquaculture and conservation managers and local Fisheries  Officers assess the permit application. If there are threatened species,  populations or ecological communities present in the collection area, an "7  Part Threatened Species Test" report may be required.

Brood Fish  Collection Methods

The physical injury and  physiological stress resulting from capture, handling, transporting, and  holding brood fish can have a detrimental effect on survival and spawning  success. Poor water quality, rough handling, and capture may cause females of  some species to undergo rapid physiological changes resulting in breakdown  (resorption) of the eggs in the ovary.
The brood fish  collection permit will outline the collection method to be used. These include:

• Haul or seine net
• Gill net
• Trap
• Angling

Species -  Specific Considerations

Silver  Perch (Bidyanus bidyanus)

• Significant decline of wild populations in  most parts of the Murray-Darling River System.
• Low level of genetic variation in wild stocks.
• Threatened species, officially classified as  "vulnerable".
• The fecundity of brood fish is high (100,000 –  150,000 eggs/kg), but decreases within 4 – 5     years in captivity.
• NSW DPI maintains discrete, wild genetic lines  in captivity.
• The collection of fish from impoundments and  farm dams is not recommended.
• Collection of wild brood fish from rivers is  prohibited.

Murray Cod (Maccullochella  peelii peelii)

• Brood fish should not be handled a minimum of  6 months prior to the hatchery breeding season.
• Brood fish have relatively low fecundity  (approx. 5,000 eggs/kg).
• Natural pond spawnings usually result in  higher hatch rates than hormone-induced spawnings.
• The viability of eggs and larvae from brood  fish held in ponds decreases after 6-7 years.
• Progeny should only be stocked back into  waters from which the brood fish were captured.

Golden  Perch (Macquaria ambigua)

Since publication of the Hatchery Quality Assurance Program in 2004 there have been advances in the field of genetics but also a considerable volume of genetic work done that relates to Australian native fish in general, in particular the species considered in HQAP.

A review of the genetic work undertaken since 2004, indicates that there is strong evidence to support no requirement for genetic separation of Golden Perch in NSW.

The HQAS now has no specific genetic zones for Golden Perch in NSW.

Australian  Bass (Macquaria novemaculeata)

• Genetic variations occur between populations  ranging from Queensland to Victoria.
• Fingerlings spawned from the collected brood  fish must only be stocked into waters as specified by NSW DPI.

Angling or capture of  the following 3 species is prohibited:

• Trout Cod (Maccullochella macquariensis)
• Eastern Freshwater Cod (Maccullochella  ikei)
• Macquarie Perch (Macquaria  australasica)

Handling  Brood Fish

• Handling of brood fish should be kept to an  absolute minimum.
• Brood fish should always be kept in water.
• Use an anaesthetic to reduce physical injury  and stress.
• Good water quality should always be maintained  especially dissolved oxygen.
• When transferring brood fish, support with  hands, fine knotless netting or a sling.
• Transport brood fish in well oxygenated,  sealed tanks with plenty of room for movement.
• To minimise osmotic stress and infection, transport  and quarantine brood fish in a salt solution.

NSW Hatchery Quality Assurance Scheme

Techniques for the large-scale hatchery production of the Australian native fishes Murray Cod (Maccullochella peelii peelii), Golden Perch (Macquaria ambigua) and Silver Perch (Bidyanus bidyanus) were developed at the Narrandera Fisheries Centre in the early 1980’s, and commercial hatcheries began to produce and sell fingerlings in 1982/83.

Over the last 25 years, the regular stocking of native fish into impoundments and rivers has established large, popular recreational fisheries and contributed significantly to the conservation of these species.

In recent years, there have been concerns about some aspects of native fish hatcheries, in particular genetics, diseases and trash fish. Research has found discrete populations of Murray Cod, Golden Perch and Silver Perch in other drainages and within the Murray-Darling River System; mixing of populations through inappropriate stockings may reduce their reproductive fitness.  Pathogens and diseases that are transferred on hatchery fish may reduce survival and introduce new diseases to regions and farms.

To address these concerns, NSW Department of Primary Industries has developed The NSW Hatchery Quality Assurance Scheme (HQAS) which accredits fish hatcheries for the production of Murray Cod, Golden Perch, Silver Perch and Australian Bass fingerlings for enhancement stocking programs for recreational fishing. The scheme was developed by NSW DPI Aquaculture and Recreational Fishing Staff with significant industry consultation and input.

A major objective of stocking programs is to maintain genetic integrity and genetic diversity in wild populations, ensuring “fitness” and evolutionary potential. The HQAS is designed to meet these genetic goals, and to ensure good health of stocked fish and the absence of non-target species.

For more information and detail about the HQAS please see the HQAS Manual.

The HQAS divides the state into various regions by drainage; these regions are based on current knowledge of the population genetics of each species. The regions set out the areas from which brood fish must be collected; in order for a hatchery to stock a particular region, brood fish must be collected from that region. The key genetic regions for Murray Cod, Golden Perch and Australian Bass in NSW are shown on the following maps.

Murray Cod

Northern (MC1) (Map zone 4): Castlereagh, Namoi, Gwydir, Macquarie and Macintyre Rivers. Barwon River above Brewarrina.

Southern (MC2) (Map zone 5): Lachlan, Murray and Murrumbidgee Rivers. Bogan, Barwon and lower Darling rivers below Brewarrina.

Golden Perch

The latest research indicates that there are no specific genetic zones in NSW.

Australian Bass

North Coast (AB1): All rivers north of the Macleay River

Central Coast (AB2): All rivers between the Macleay and the Hawkesbury River (both rivers included)

South Coast (AB3): All rivers south of the Hawkesbury River