Re: NANFA-- Fish-Watching - LONG

Denkhaus, Robert (DenkhaR_at_Ci.Fort-Worth.TX.US)
Tue, 26 Dec 2000 16:33:09 -0600

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 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
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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