The Hatchery

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A Brief History of the Salmon Hatchery Project

SALMON HATCHERY PROJECT

We are fortunate that Cornwall is still an area where wild salmon can be found, but stocks are under pressure from illegal and high seas netting. Anglers realise the problem and 70% of fish caught on the Lynher are returned alive, in addition to which fish are donated to our hatchery programme.

These hatchery brood fish are held until ready to spawn, their eggs stripped and fertilised, giving a far higher egg viability than from natural spawning – up to 95%. Of the fertilized eggs up to 85% will hatch successfully, giving high numbers of fry for stocking to the river, substantially boosting those from natural spawning.

BACKGROUND TO THE PROJECT

Over a number of years, with the assistance of the Environment Agency the Lynher Association had operated a small salmon breeding programme, in which the Agency held brood fish and stripped their eggs, which were then hatched by the Association.

In 2006 a trial in which hatched salmon fry from egg boxes were reared on for some three months was carried out by the Association.

In 2006 the Agency ceased to operate their hatchery, donating equipment to the Association so that we could hold brood fish and strip their eggs, hatch them and rear on the fry. This we did through the Winter and Spring of 2006/7, releasing fry into the river in June of the year.

Following the generous provision of a site by a member of the Association, a small hatchery operation has been established, largely by the voluntary efforts of several of our members, and guidance from the Agency.

BREEDING PROGRAMME

• October/November - Capture of brood stock – The hard part!

Special Environment Agency permission is given to catch fish outside of the normal fishing season. To preserve genetic integrity we are required to take equal numbers of male and female fish.

• October to December - Daily treatment of brood stock to prevent fungal infection. Cold work! Water temperature 3 degrees centigrade.  Air - minus 2 degrees
• December – Stripping of eggs, fertilization and transfer to rearing trays (brood fish returned alive to river).

• December to March – Daily removal of dead eggs.

• March  – Stocking of fry to river.

• March onward – Rearing on of retained fry for later stocking. These larger fry have a better chance of survival to adulthood.

THE EGG CYCLE

Normally water temperature must be below 9 degrees centigrade for fish to shed their eggs, usually it is nearer to 4 degrees!

Stripped eggs are fertilized with milt from male fish (the eggs must be kept dry until fertilization occurs). After fertilization the eggs are washed to remove surplus milt.

The eggs are counted and transferred to floating egg trays in tanks of flowing river water. Dead eggs removed daily.

Eggs hatch after 450 degree/days, the hatched fry feeding on an egg sac for one month – the aelvin stage.

Once the egg sac is exhausted the fry will feed naturally, and can be reared on, or stocked to the river.

THE DEVELOPING PLAN

Water supply – The first year’s operation identified a problem with silt, arising from taking water from the river at times of flood. A full re-design of the supply system has been made to eliminate this problem

Capacity – To be successful we needed  to increase the number of eggs hatched, and fry reared. This has required investment in further tanks and equipment.

Workforce – All hatchery work is undertaken by our members on a voluntary, unpaid basis, with a nucleus of some 8 members.

The hatchery can now handle some 16 brood fish, with a capacity of up to 60,000 eggs. Assuming a 2% return rate of adult fish this could boost stocks by over 1000 fish annually.

2007/2008 PROGRESS

Approaching 27,000 eggs were obtained from brood fish in the winter of 2007

From these eggs some 23,000 fry were hatched, and retained in the hatchery over the short term.

Approaching 14,000 fry were stocked into the river in March.

The balance were reared on and stocked in the summer. These larger fry stand a better chance of survival.

Hopefully a small percentage of these fry will return as adults in 3 or 4 years time, to add to the natural spawning stock of the river and ensure the future of Lynher salmon.

REARING ON

A good proportion of the fry are reared on from March until the Autumn using automatic feeders which require daily stocking with food.  The fry soon learn that their food supply comes from above, and queue for their share!  The larger they grow, the better their chance of survival in the river.

OTHER ACTIVITIES

The association carries out weed removal and gravel bed cleaning to maintain and expand suitable spawning areas for salmon and seatrout.

A section of the river where salmon normally spawn is rented by the association as a sanctuary area for salmon, no angling being permitted.

The association is a member of the South West Rivers Association which looks after the wider interests of rivers in the region, acting as a liaison body with the Environment Agency.

FINANCE OF THE PROJECT

We pay approximately £370 annually in Environment Agency charges to remove and return the hatchery water to the river!   In addition we spend some £100 monthly on electricity for pumping. Fungal treatment for fish and feeding costs are a further £300.

All work is done on voluntary basis thus we have no labour costs.  We receive no funding other than membership fees and small donations.

SPOTLIGHT VISIT MARCH 2008

BBC spotlight visited the hatchery in March and a small feature was broadcast prior to Easter

2009 PROGRESS

During 2008 new systems were installed to initiate aeration of the tanks in the event of electrical or pump failure, or interruption of water flow.

Twelve brood fish were obtained in October and November 2008. These were stripped during December and January.

Some 32,000 eggs were obtained, and 28,000 fry hatched.  This is an increase of some 30% on 2008 stocking.

Our target for the 2009/10 is 16 brood fish giving a capacity of 60,000 eggs.

BENEFITS OF HATCHERY PROJECT

• Improved egg fertilization rates
• Improved egg to fry rates
• Elimination of loss of eggs and aelvins due to washing out of spawning redds during major flood conditions
• Fry release into non-spawning areas

However we can only hope to augment the natural spawning on the river, and maintaining a healthy river environment remains a priority for the salmon’s future

THE FUTURE

Our efforts will hopefully be sufficient to boost the natural stocks to a sustainable level to preserve the salmon for the future of our sport, and more importantly for future generations. Indications are that the last two years have produced larger runs of salmon into the Lynher than for many years. We can never replace what nature  does, only help.

However there is one major cloud on the horizon. A parasite, Gyrodactilus, has appeared in some Norwegian rivers which is fatal to salmon. Currently the only treatment is to wipe out all aquatic life in affected rivers. Many Scottish salmon farms are stocked with Norwegian smolts!  We must watch, wait and pray!!

A fresh –run Lynher salmon.

Hopefully our efforts will enable future generations to enjoy not only the pleasure of catching such fish, but also to see them survive in their natural habitat.