Hatchery fish training course?

[Drakeblake]

I found this article at school the other day and even though it is a few years old I though it was still pretty interesting. Does anybody know if they have implemented this training at any hatcheries in Oregon? I sounds very interesting and like a low cost low effort way of improving hatchery returns. Check it out.

-blake

Hatchery fish get survival training
Fish raised in hatcheries need to go on training courses to help them cope with life in the wild. This tactic could make a big difference to the survival rates for the fish, which often succumb to predators they do not recognise.

Many countries - in particular the US, Norway and Japan - breed fish and release them into the rivers and oceans to boost stocks for anglers and trawlers, or help re-establish endangered species. But there is a problem: many of the fish don't make it.

Studies suggest that around five billion hatchery-reared salmon are released worldwide each year, but less than five per cent survive to adulthood. Hatchery fish do worse than wild fish because they have not learned the tricks of the trade, such as recognising the predators that will eat them. "Hatchery-reared fish are much more vulnerable than wild fish," says Culum Brown of the University of Edinburgh.

To explore possible solutions, Brown and Kevin Laland of Cambridge University have gathered reports on fish behaviour. They say the key to improving survival is for fish to copy their shoal mates. "Training gives them at least some hope when they get out there," says Brown.


Escape reaction


Fish are great candidates for group training because many species learn from watching the reactions of shoal mates, Brown says. He points out that rainbow trout, for example, can learn the identity of a predator simply by watching another fish's escape reaction.

One tactic for training, he suggests, would be to put clued-up demonstrator fish into a naive shoal and place a predator behind a transparent and porous screen. The inexperienced fish would see the escape responses of their tutors and should learn to associate the sight and smell of the predator with danger. A more drastic way would be to show a "video nasty" of the predator devouring sacrificial fish.

Brown also highlights a more benign alternative suggested by Sampsa Vilhunen of the University of Helsinki, Finland. He fed predator fish on Arctic charr before moving them to a new tank. Simply bathing naive Arctic charr in this water was enough for them to learn to avoid the predator.


Smell of fear
The results suggest that the naive fish associate the smell of faeces derived from eaten Arctic charr with danger, Vilhunen says: "They seem to have an innate ability to avoid these odours."

Markko Pursinen of Saimaa Fisheries Research and Aquaculture, Finland, which sponsors research in this area, says that until now, the main tactic for improving survival has been to feed up hatchery fish. This at least stops the smaller predators trying to eat them, he says.

Pursinen believes that sending the fish on training courses instead could save money because they could leave the hatchery leaner and earlier. "Maybe we don't want to give them the easy living for too long," he says.

Journal reference: Journal of Fish Biology (vol 59, p 471)


James Randerson

[foxer]

Makes sense to me

[Ty]

They have been doing this studies for over ten years. However, this training is difficult to implement in a "mass production" even on a relatively small scale.

Basically raceways would have to be redesigned and more raceways added, densities reduced, and many other modifications.

Unfortunately, new technology is dlwo to filter down in to the hatchery system.

I know Oregon had created a "hatchery resources and improvemnt team" to help increase hatchery practices and revamp old technology.
From workin at huge ocean ranching hatcheries in Alaska, Oregon is way, way, way behind with hatchery technology in most aspects. The money is just no there right now.

[Wood N' Fish]

Here is another logic slip------- Why would hatchery necessarily need training? Think about it------

[Salmonator]

"trained" brats would have a higher survival/return rate, reducing the number of fish planted reducing the competition with native fish in the rearing areas (river, estuary). I believe this is already happening with current broodstock rivers. Less smolts planted and more fish returning.

[Quasimodo the fish killer]

I hope peta hasnt seen that article or they will be pushing to tain them to avoid my hook. :grin:


I would think if they would just make the hatchery ponds a little closer to a real stream enviroment ( gravel bottom, increase water speed, big rocks to hide behind ) that would greatly increase the odds for the little suckers.

they need to do something but I aint sure popcorn and a movie is it. [img]graemlins/dork.gif[/img]


Quasi