> Peter , I thank you for spreading the discussion to one of my concerns - =
> the effect of habitat alteration on behaviour , even something as basic =
I don't know if this quite applies to disturbed wild habitats as much as
it does to aquariums, but it is an interesting and valid point that
nobody I'm aware of has looked at to any great degree. I know there has
been some stuff done on alterations to behaviour caused by introduced
fish, both within and between species, ie hatchery trout negatively effect
wild trout.
> Presumably the continuous aquarium breeding, =
> usually no longer under optimal conditions, causes some kind of change =
> in the ?instinctive code for breeding in that strain.
"optimal conditions"? Wild conditions don't always equal optimal ones.
I'm being picky and technical here, but that's just the way I tend to be
sometimes.... :-) Behaviour also gets tricky. How much of a given
behaviour is genetic vs environmental? Can captive fish be "retrained" as
wild fish? Difficult questions to answer.
> Surely there is a large number of potential study projects for =
> aquarists, students, researchers etc in this particular field.
Too many!!
> Back to the question of translocations - is there any published =
> literature on the numbers of individuals needed to successfully =
> translocate a species? I recall that the geneticists calculated 500 0r =
> so individuals were needed to maintain genetic viability in a population =
> so why wouldn't these same figures pertain to a population being =
> translocated for it to survive. If so then it is most unlikely that this =
> will ever accidentally happen.
You are defining success differently to a geneticist. Success to a
geneticist is to maintain as much genetic variation as possible to allow
it to adapt to future changes in the environment, ie long time scale.
You don't need genetic variation in the short term in a stable
environment (short term may be as much as several thousand years or
so). Redfin or European perch (Perca fluviatilis) are a good example.
Originally seven fish were released into Wendoree Lake (spelling??) at
Ballarat Vic in the 1800's. I'm unsure as to if further were brought
from Europe. They have absolutely thrived and grow far bigger here than
anywhere else in the world (17lbs vs 6lbs in Europe!). There are
probably some better known examples than this one (since there may have
been further importations). Rather than drag on though, I'll leave it at
that as I think I have made the point I wanted. If you have further
queries though, just hit me with them.
Hooroo
Peter Unmack