I think that it is a mis-nomer to call the species of Gambusia a
"Mosquito-fish".....this common name seems to infer that this species is
effective in controlling the malaria-carrying larvae of the Aedens family,
when in fact they are only marginal in effect and also are more adept at
displacing endemic species, wherever they are introduce mistakenly as a
means of epidemic prevention.
Otherwise, you have a good plan!
Regards,
BG
----- Original Message -----
From: Denkhaus, Robert <DenkhaR_at_Ci.Fort-Worth.TX.US>
To: 'North American Native Fish Association' <nanfa_at_aquaria.net>
Sent: Tuesday, December 26, 2000 4:33 PM
Subject: Re: NANFA-- Fish-Watching - LONG
> This topic seems to have cooled off the past few days and I hope that it
is
> only because of the holidays. I spent part of the weekend trying to
refine
> the idea after gathering list member input and re-reading a couple of
> population monitoring articles and related materials. So, being back at
> work I would like to see if we can get some discussion going again. I
know
> that there are lots of ideas and opinions out there so let's hear them!
>
> The Concept:
>
> A day or weekend in which people across the country, led by NANFA members,
> would "count" fish. Data collected would include species and some figure
of
> abundance. The count would be repeated annually on an agreed upon date
> (something like 3rd Saturday in June or similar).
>
> Existing Models:
>
> "Citizen Scientists" are responsible for data collection at a national
level
> for an array of taxonomic groups. Birders run two national counts
> (Christmas Count and May Count) where people of all birding abilities get
> out to count birds and report species and numbers seen to a national data
> center (Audubon Society and Cornell Lab of Ornithology). Butterfly
watchers
> do the same although I am not sure who is the clearinghouse for data
> (possibly the Lepidopterist Society). Anurans (frogs and toads) are
counted
> in a variety of ways with data compiled nationally (North American
Amphibian
> Monitoring Program). Of particular interest is the count of anuran
> vocalizations and the varying levels of sampling intensity that are a part
> of the program. Texas has a freshwater mussel inventory and a horned
lizard
> inventory with primarily citizen scientists doing the data collection.
>
> Goals:
>
> Goals can include, but not be limited to:
> 1) Developing an index of native fish populations throughout the
> country/continent whereby the positive effects of management or the
negative
> effects of development could be identified and monitored. Usefullness of
the
> data would increase greatly as the years of data and number of sites grows
> annually.
> 2) Monitoring the presence/expansion of non-native fish throughout the
> country/continent for management purposes.
> 3) Involving the public in the monitoring of native fish populations and
> their habitats.
>
> Problems and Hurdles:
>
> Since no one, to the best of my knowledge, has attemped anything like this
> for fish there is no cookbook recipe for putting this together. Some
> problems and hurdles that I see as needing to be overcome are:
> 1) Except for the mussel inventory, all of the models above have the
luxury
> of being able to see and/or hear the targeted fauna without any real
> problem. We have to overcome the water hurdle.
> 2) Data collection. All of the above models, except for the anuran
> program, rely on seeing/hearing the animals without having to capture
them.
> Hence, only the anuran monitoring program uses a variety of sampling
> techniques. We will need to devise a means of combining the various
methods
> that we all use and have available to us into a useable whole.
> 3) National Scope: Obviously, we don't have enough members to make year
one
> data all that useful. So, we would need to increase the number of data
> collectors by involving other groups with environmental interests (local
> Audubons, Sierra Clubs, Sportsmens Groups, etc.) and student groups
> (university level icthyology, ecology, etc. classes, high school
> environmental science classes, etc.) by teaming up a knowledgeable NANFA
> member with each group and/or leading training workshops for those that
want
> to get involved (that's what the anuran program does).
>
> Suggested Data Collection and Reporting Method:
>
> In looking at the models, I have a rough idea of how data can be collected
> and reported in a meaningful way. First, it is important to note that
this
> data, and that of all of the models, is only an index to populations and
not
> a census or even a count. An index is a starting point by which other,
> future, numbers can be compared and not an actual count or census of a
> species or population. An index can show trends in populations which can
> often be linked to external causes.
>
> Data on the abundance of a fish species at a site can be collected by
> seining, dip netting, actually counting by snorkeling, etc. but
regardless,
> the fish are not being censused because we can't be sure that we counted
> every one. We all probably have our own abundance descriptions that we
use
> informally based upon how many of a species that we catch/see per unit
> effort but we would need to standardize these informal descriptions.
>
> The anuran vocalization monitoring people have a very simple system to
> handle this. When listening to calls, they designate a species abundance
> factor of 1 if individuals can be counted. An abundance factor of 2
> indicates indivudal calls can be distinguished but there is some
overlapping
> of calls. An abundance factor of 3 means that there are so many
individuals
> calling that they can be distinguished. An abundance factor of 0 means
that
> the species was not calling. These abundance factors assume that the
counts
> are made in proper habitat and do NOT factor in prefered population
density
> for a species, territoriality, etc.
>
> Comparing this to fish abundance is relatively simple. An anuran species
> "0" doesn't mean that it wasn't there. It means that it wasn't heard. A
> fish species "0" would therefore indicate that is wasn't found and not
that
> it didn't exist. It would be assumed that it was not a common species. A
> fish species "1" would indicate that the species was captured/seen in
> numbers that could be counted. For example, if you caught 1 or 2 of a
> species per seining attempt or saw 6 of the species in 15 minutes of
> snorkeling, the species would be given an abundance factor of 1. A fish
> species "2" would indicate that the species was common and a researcher
with
> nothing better to do, could have counted each and every one without too
much
> trouble. This would apply when you get the occasional net full of a
species
> or if you were observing a group of fish that you could count if you tried
> hard enough. A fish species "3" would be for those species that you see
so
> many in the net or in the water that there is no way that you could count
> them except with great effort.
>
> Using this system, last week when I went out and sampled with a dip net
for
> about an hour in the West Fork of the Trinity River, I could have turned
in
> the following report:
>
> Orangespotted Sunfish - Lepomis humilis ..... 1
> Blackstripe Topminnow - Fundulus notatus.....1
> Mosquitofish - Gambusia affinis....3
> Longnose Gar - Lepisosteus osseus.....2
> Spotted Gar - Lepisosteus occulatus....2
> Common Carp - Cyprinus carpio....2
>
> Specifically, I caught 3 sunfish (all in 1 net), about a dozen topminnows
> (0-1/net), and a ton of Gambusia. The gar and carp were spotted from the
> surface and while I could identify the species, it would have been
difficult
> but not impossible to get an accurate count of individuals. Of course,
> weather and water data would be included as well.
>
> So, what do y'all think? Would it work? In talking with my staff here, I
> think that we may try it out on the Refuge and see what comes of it.
Let's
> hear it!
>
> Rob Denkhaus
> Fort Worth Nature Center & Refuge
>
>
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