NANFA-- Fw: Hawaiian imports

B.G. Granier (
Mon, 23 Jul 2001 14:43:15 -0500

This is forwarded to NANFA by me, for the other members to
read.....concerning control/eradication of non-indiginous<sp? species of the
Hawiian Islands.


----- Original Message -----
From: Mark G Mcrae <>
To: B.G. Granier <>
Sent: Monday, July 23, 2001 12:13 PM
Subject: RE: Hawaiian imports

Hey B.G.

Sorry this reply is so late in coming. I've been busy preparing for our
upcoming conference in Hawaii. Should be fun. Anyway, I think that the
issue of exotic species eradication is a touchy one for the state of Hawaii
Division of Aquatic Resources (DAR). For one thing, there has hardly been
any research done on the effects of introduced fishes on Hawaii's stream
ecosystems. The DAR is reluctant to start an eradication effort unless
they are confident it is necessary. There are two main reasons they are so
cautious: One is that in order to get rid of the exotics, you would have
to poison the entire stream system, top to bottom, which would wipe out the
natives as well. This is usually a very unpopular move with the public.
Your average Joe hates to see their tax dollars spent on the killing of
hundreds of animals, unless you can convince them that it is absolutely
necessary. Another reason is that most of the papers written on fish
eradication end up with the conclusion that their efforts are often
complete failures. Many of the exotic fishes in Hawaiian streams are very
fecund and are capable of high reproductive output. So, for example, with
Gambusia affinis, if you fail to kill just a couple of pregnant females,
you will soon be overrun with Gambusia again.

Regarding your second question about collecting exotics for the aquarium
trade: Because the economy in Hawaii is so bad, the big concern is that if
commercial collecting is legalized, people will try to establish
populations of exotics in streams where they are not yet present so that
they can have more potential collecting sites.

The fact of the matter is that exotics are most abundant in streams that
have been altered by humans. Habitat conditions in these diverted,
channelized streams often favor exotic fishes moreso than the native
gobies. Streams in Hawaii that are relatively pristine (not diverted)
usually have many severe flash floods per year, which the native gobies are
adapted to survive (in fact they depend on these floods for reproductive
and migratory cues). The majority of exotic fishes in Hawaii are not able
to thrive under these extreme conditions. The goal of the Hawaii DAR is to
try and return altered streams to relatively natural flow conditions which
will benefit the natives and help to naturally control exotics.

Anyway, I hope that wasn't too long-winded an answer to your questions.
We'll be back in town on the 12th of August, so maybe we can get out after
that. Take it easy.

From:"B.G. Granier" <> on 07/18/2001 04:34 PM EST

Sent by: "B.G. Granier" <>

To: "Mark G Mcrae" <>

Subject: RE: Hawaiian imports

Very interesting site! Why doesn't the state eradicate the exotics or let
someone remove them for the aquarium trade?

Just asking.........



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