Re: NANFA-- threatened fish

Dave Neely (rheopresbe_at_hotmail.com)
Wed, 03 Nov 1999 09:23:40 CST

Ray,

>Fundulus dispar: listed Endangered by wisconsin.
>Range maps published show a thin line bordering the southern edge of >the
>state and barely up the Mississipi river. yet if you went out >to areas
>away from the south border, you'd find plenty, and up the >Mississippi
>valley to the bend in the state. Inland from the >Mississippi in
>tributaries with the correct habitat, and this >includes somes sites on the
>great marsh area of central Wisconsin, >an interconnected bunch of swamp
>and canals , ditches and flowages.

A lot of states list peripherally occuring taxa. It's one of the perils of
a provincial viewpoint when determining conservation priorities. From
another viewpoint, however, peripheral populations are often the most
differentiated from populations in the rest of the range, and thus from an
evolutionary standpoint, peripheral populations might be just as important
as the main body of the population. If F. dispar are as common up there as
you mention, then maybe you need to talk to different folks in the F&G, or
alternatively in Natural Heritage.

As for the carp problem, from a fisheries management perspective, that's
bogus. From a toxicology standpoint, however, it has some merit. If the fish
die from natural causes, they are going to be releasing any metals or toxins
back into the system slowly, where they can be remetabolized by other
critters. In thic case, rotenone might actually have a beneficial effect- if
there's enough carp, and they die, when they partially decompose they'll
sink to the bottom. If there's enough of them, or if you guys have a hard
winter, the bottom layer of water will go anerobic, and the carcasses might
get covered up with sediment before the metals can be reincorporated back
into the system. While it's not an optimal solution, there's really no good
way to get metals OUT of a system once they're in- tying them up in deep
sediments might be the best alternative. This may be one of the few
beneficial side effects of zebra mussels in the Great Lakes.

One other thought- if the carp there are so loaded with contaminants, why
does F&G think that the gamefish they stock are going to fare any better?
Large piscivores (ie pike, walleye, bass) are probably going to
bioaccumulate contaminants as fast or faster than carp...

Cheers,
Dave

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