Issues seldom addressed in such legislation, but desperately needed, are the
availability of sound environmental data for the species under
consideration, and the taxonomic acuity of importers, wholesalers, breeders,
and retailers.
For example, water temperatures provide barriers to dispersal and
reproduction of many introduced species -- BUT the temperature ranges of
many snakeheads are unknown or equivocal (e.g., "tropical" species [e.g.,
Channa maculata, the blotched snakehead] that have become acclimitized and
established in areas far north of their native range). Complicating
matters, is the previous lack of comprehensive taxonomic references for this
species-rich (> 25 spp.) group. Again, if you have any interest in
snakeheads, I urge you to read the recent "Biological Synopsis" by Walter
Courtenay and James Williams. It is EXCELLENT!
Tetras are "similar but different." Many taxa (silver dollars, pacu,
piranha, etc.) are species rich with similar morphologies making conclusive
identification of safe and dangerous species iffy-in-best (especially with
juveniles that dominate the commercial trade). With fish like these, a
broader group-level ban, or some restrictions, may be justified.
Conversely, some tetra taxa (neons, serpae, lemons, cave) are so
distinctive, and presumed safe, that a very broad group-level ban to include
them is not necessary.
Here is an example that has not received much attention (but probably will
in the very near future). There are two groups of species rich suckermouth
catfishes: Plecostomus or armadillo del rio (Hypostomus spp.) and sailfins
(Pterygoplichthys spp.). Both have established populations in the southern
US. Both have similar form and biology. Both are marketed as ornamanetals.
One group (Plecostomus spp.)has proven, so far, to be environmentally
innocuous, the other (sailfins) a major ecological threat. Both are
frequently confused with each other. I have exhibited a taxidermic specimen
of a sailfin to several groups of biologists and aquarists who confidently
identified it as a Plecostomus. Of greater concern - large-scale retailers
of tropical fish are selling thousands of sailfins and calling them
Plecostomus.
Check it out for yourself - go into a tropical fish store or pet shop - ask
for a Plecostomus and watch for a sailfin.
-- Jan Hoover
Vicksburg, MS
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