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Aaron and Dr Sneddon:
I'd like to see these references as well. Having worked with hybrid
striped bass, certainly I have seen cultured fish develope aggressive
tendencies, but I have directly observed this to be detrimental in the
natural environment. To be specific, hybrid bass of all sizes raised in a
tank where there are no predators don't do well and released (accidentally)
into an effluent pond are observed to be active, aggressive predators, often
beating the indigenous fish to food items. This only lasts a day or so,
though, as the ospreys and herons quickly pick off the hybrid stripers. The
hatchery fish are not lurking to pick off unsuspecting prey, but out moving
around actively seeking it: making them easy targets. Of course, this may
not be true with salmonids.
Larry
>From: Aaron Tinker <[log in to unmask]>
>Reply-To: Scientific forum on fish and fisheries <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: PhD Studentship
>Date: Mon, 31 Jan 2000 10:36:37 -0800
>
>Greetings Dr. Lynny Sneddon,
> I have a question about your posting and mention of 'recent evidence'
>of
>farmed fish having detrimental effects on wild stocks. I have seen some of
>this evidence, but had not come across any mentioning increased
>aggressiveness as a factor. It makes sense, but could you please send me
>any references you have on that topic?
>
> I have just recently begun investigating this topic for a graduate
>school project on salmon aquaculture impacts.
>
>Thanks, Aaron Tinker
>School of Marine Affairs
>University of Washington
>
>
>
>----------
> >From: Lynne Sneddon <[log in to unmask]>
> >To: [log in to unmask]
> >Subject: PhD Studentship
> >Date: Mon, 31 Jan 2000 02:17
> >
>
> > PhD Studentship at the University of Edinburgh
> >
> > Supervisors: Dr Victoria Braithwaite & Dr Lynne Sneddon
> >
> >
> >
> > Improving the welfare of farmed and wild fish
> >
> >
> > A common practice to enhance recreational and commercial fisheries is
>the
> > release of hatchery reared fish into streams, rivers and lakes.
>Typically
> > very large numbers of these released fish die. More surprisingly,
>however,
> > recent evidence is now suggesting that the increased size and
>aggressiveness
> > of the surviving hatchery reared fish is having detrimental effects on
>the
> > natural wild populations. Hatchery reared fish are forced, through
>their
> > rearing conditions, to become aggressive competitors and work has
>recently
> > found that natural wild fish can be out-competed and forced out of their
> > home territory by hatchery fish.
> >
> > The goals of this studentship will be to determine whether simple, cost
> > effective alterations to existing practises can improve the welfare of
>both
> > the hatchery and the natural wild populations of fish.:
> > · Improve the ability of the hatchery fish to survive when released.
> > · Produce hatchery fish with lower aggressiveness.
> > · Determine whether these hatchery reared fish would be less of a threat
>to
> > natural wild populations.
> >
> > The alterations to the hatchery rearing conditions will need to be
>simple
> > and cost effective if they are to be adopted by fisheries. To try to
> > increase survivorship, experiments will be designed where brown trout (a
> > fish commonly reared in hatcheries and used to enhance, preserve or
> > re-establish threatened populations) will be reared under a range of
> > environmental conditions to expose them to variable substrates and
>levels of
> > flow. It has been suggested that hatchery fish frequently select
> > unfavourable habitats and perish through an inability to find sufficient
> > food. If the fish are given the opportunity to learn basic facts about
> > variable environment this should increase their survivorship. Work will
>also
> > determine whether different feeding regimes, such as unpredictable
>feeding
> > times and multiple feeding locations will reduce the aggressiveness of
> > hatchery fish.
> > Fish reared under these different types of condition will be
>behaviourally
> > screened to compare their aggressiveness and competitive ability with
>wild
> > caught trout. Finally, such reared fish will be released into natural
> > systems and their survivorship and growth rate (weight gain) will be
> > compared with regularly hatchery reared and wild fish.
> >
> > For more information about the Institute of Cell Animal and Population
> > Biology see: http://helios.bto.ed.ac.uk/icapb/icapb.html. If you are
> > interested in the proposed research please send a covering letter
>outlining
> > why you are attracted to this area and a CV (with two named referees) to
>Dr
> > Victoria Braithwaite, ICAPB, King's Buildings, Edinburgh University,
>West
> > Mains Rd, Edinburgh EH9 3JT. E-mail: [log in to unmask] CLOSING
>DATE
> > FEBRUARY 11th 1999.
> >
> > A successful candidate will be expected to start in October 2000 and
>will
> > either be funded by a UFAW scholarship (~£12,600 rising to ~£14,900) or
>a
> > BBSRC Case studentship (~£6,600pa rising to ~£7,100).
> >
> > Lynne U. Sneddon,
> > Animal Welfare Research Group,
> > Roslin Institute,
> > Roslin,
> > Midlothian EH25 9PS
> > U.K.
> > Tel. No. +44 (0)131 527 4200
> > Fax +44 (0)131 440 0434
> > E-mail [log in to unmask]
> >
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