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)

• There are genetically discrete populations in the wild.
• Fecundity is high (> 100,000 eggs/kg).
• Progeny should only be stocked back into waters from which the brood fish were captured.

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): Barwon River above Brewarrina, Castlereagh, Namoi, Gwydir and Macintyre Rivers and tributaries

Macquarie (MC2): Macquarie River and tributaries

Lachlan (MC3): Lachlan River and tributaries

Murray and Darling (MC4): Murray River, Murrumbidgee River, Darling River, Bogan River and Barwon River below Brewarrina and tributaries

Golden perch

Darling, Macquarie and Northern (GP1): Barwon, Castlereagh, Namoi, Gwydir, Macintyre, Macquarie, Darling and Bogan Rivers and tributaries

Lachlan (GP2): Lachlan River and tributaries

Murray (GP3): Murray and Murrumbidgee Rivers and tributaries

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