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Subject: Re: Stock enhancement - wild vs. reared fish
From: Don McAllister <[log in to unmask]>
Reply-To:[log in to unmask]
Date:Tue, 6 May 1997 11:36:56 -0400
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> >And now to my request:
> >
> >- Does any of you have information on the causes of reared fish having a
> lower survival
> >than wild fish?

There are two ways (at least) of looking at this.

1) Dump hatchery fish close to catchable size and angler's catch them.
That produces some sort of benefits, though not the kind I would prefer
if I was an angler.  Put a lure on that resembles the hatchery food?

2) Planting fish in a stream or a lake with the intent of augmenting the
populations there over the long term. Here arise the problems.

a) Indigenous stocks are finely tuned to their environment, hatching
times, arriving at nursery grounds when the food is ready, moving to
herditary spawning grounds at the appropriate time and place.  For
example in Loon Lake, BC. 1) Inlet spawners move upstream to spawn and
the young must move downstream, 2) Outlet spawners move downstream to
spawn and the young must move upstream, 3) Tributary to the outlet
spawners must drop downstream, then move upstream in the tributary, and
young must reverse this pathway.  If young in the outlet or the outlet
tributary drop downstream while in the outlet, they will be swept over
the falls and lost to the population.

Planting outside hatchery stocks in such a case, and probably many
others may result in inappropriate responses of the hatchery stock. If
they cross with the native stock then the progeny may behave
inappropriately.

don


 >
> >--
> >Tina Grønborg  - thesis student
> >Univ. of Aarhus, Inst. of Biology, Dept. of Marine Ecology
> >Finlandsgade 14, DK-8000 Aarhus C, Denmark
> >E-mail: [log in to unmask]
> >
> >
> ***********************************************************
> Mario Lepage, biologiste
> ASSOCIATION GIRONDINE POUR
> L'EXPERIMENTATION ET DE DEVELOPPEMENT
> DES RESSOURCES AQUATIQUES (AGEDRA)
>
> 50 av. de Verdun, B.P. 53
> 33612 CESTAS cedex
> FRANCE
>
> Tel: (33)  05 57.89.08.10
> Fax: (33) 05 57.89.08.01
> e-mail: [log in to unmask]
>
> ************************************************************

--
Don E. McAllister             /& Canadian Centre for Biodiversity
Ocean Voice International          /Canadian Museum of Nature
Box 37026, 3332 McCarthy Rd. /Box 3443, Station D
Ottawa, ON K1V 0W0, Canada    /Ottawa, ON K1P 6P4
URL: http://www.ovi.ca  E-mail: [log in to unmask]
 (or: [log in to unmask]) Tel: (613) 264-8986, Fax: (613)
264-9204

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