<<I think deliberate introductions are dangerous, often ineffective and do
often lead to loss of local genetic diversity.
Anyway what is the ANGFA?>>
I agree whole heartedly George - the significant word of course is
"deliberate". The major arguing point for the discussion here on the RML (
Rainbowfish Mailing List) was an importation ban on Rainbowfish (
especially those from PNG) . Aside from all the usual disease/quarantine
arguments the principal objection to this group was the argument that these
fish might be introduced to natural waterways and lead to "introgression"
of existing stocks.
The discussion waged back and forth for some time bur fizzled out
eventually. Some of the significant points to me were that as these fish
were desired as aquarium fish they would mostly be kept in the major
population centres and threrefore well away from streams where they could
survive or compete with existing stocks, or interbreed. Most fish of these
genera require higher temperatures and good water quality without
considering the moral issues about accidental Vs deliberate introductions.
Also some of the PNG species have been here in Australia for about 20 years
and there is not one example to my knowledge of translocation to our
streams.
Another thread concerned the co-existence of more than one species in many
locations ( up to 4 in some areas) and the fact that wild hybrids are
extremely rare , as opposed to the artificial production of hybrids in
captivity ( accidental or otherwise). I understand in the wild the usual
circumstance is that the male of the species displays and if a receptive
female is impressed enough she will allow spawning to take place. Obviously
this is a very simplistic view and that genetic programming as part of the
evolutionary process makes the females of a particular species more likely
( if she is in breeding condition) more likely to be receptive to the
display of her own species. Obviously there are other factors like
temperature , light etc. Males of other species are unlikely to be as
appealing. So even if there are 4 species co-existing there seems to be
little evidence of hybridisation in the wild.
Can you tell me why it would be any different if another species is
introduced, not that I want this to happen? I contend that even if a
?viable number did somehow get there that it is far more likely that they
would just create the situation of 5 species in that habitat instead of 4.
Les Kaufman's hybrids were just reminding us that like things tend to stick
together if given a choice. Obviously other factors come into the argument
when we consider the survival of the hybrid brood to the adult and next
generation stage. Rainbowfish are schoolers and will tend to stick
together, sometimes in mixed schools with Rainbowfish of other species as
well as other families such as Blue-eyes and Hardyheads. There is safety in
numbers but even there the odd ones (likely the hybrids) will be the first
targets for predators.I suspect that they will be unlikely to survive to
the breeding stage and even if they do they would be unappealing to future
mates and that is why natural hybrids are so few and why speciation works
so well. It is not logical to apply captive experimental evidence to the
wild situation.
Just to be contentious why should introductions lead to loss of local
genetic diversity and not increases ? I guess it depends on the original
genetic make-up of both stocks.
Les feels that we may have a genuine concern on our hands with this
situation. We certainly have - would he like to assign a realistic
statistical risk evaluation to the situation?
Even such subjective categories as slight, small, moderate , high would do
for a start so we could examine the components of the risk for reality
rather than theory.
ANGFA (Australia New Guinea Fishes Association) is a hobby-based group
interested in native fishes of Australia and PNG from both captive and
conservatiom viewpoints. We are interested in promoting the keeping of
native fish and furthering knowledge about their need and welfare and
publish regularly a Journal named "Fishes of Sahul". We have regional
groups in most Australian states as well as overseas in North America and
Russia.
I am concerned about the illegal importation of Rainbowfish species into
this country because of the lack of credible arguments about the real risks
to our native populations from PNG fish. They are seemingly inoffensive
desirable aquarium specimens and unless the debate gets away from the
current one of "father knows best" could lead to disease problems and
confrontation with officialdom and wholesale dumping of existing stocks of
PNG fish in our streams. The very opposite of what we want! Most
responsible hobbyists can see that a Papuan Black Bass population in our
streams would please our angling friends but would play havoc with the
existing fish stocks. They want to keep and breed them in aquaria in their
homes not breed them up at great effort and expense to then bundle them
into plastic bags with oxygen and styrofoam boxes and drive hundreds of
kilometers (again at great expense and effort) to find a suitable stream to
release them into so that they may or may not survive. Could any of the
fish stocking people tell us accurately how many thousands of fingerlings
are regularly poured into recreational catchments just to maintain a few
fish for the anglers to catch? Let's take the bias and intellectual "high
Ground" out of this discussion and start assigning some REAL RISK figures
to these decisions and allow the bureaucrats to get on with their jobs of
designing laws and policies that are appropriate and realistic and will
have the respect of the citizens that pay to be "protected".
I thank you all for the opportunity to once again air this topic and also
Peter Unmack for cross-posting. After our last discussion he was going to
try to get some "outside" viewpoints - perhaps this opportunity will do
this.
Bruce Hansen
ANGFA