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NFC: Field observations 2 -2/12/99
A tributary canal, once thriving and abundant with small natives and
exotics such as C. salvini and bimaculatum was, about 3 months ago,
barrackaded, which completely blocked the flow of water, vital to this system.
This is the result of a DOT project, widening the road the canal intersects.
The culvert was/is blocked on both sides and the tributary canal isolated.
This little canal runs for about 2 miles south off the main canal it feeds. It
was heavily vegitated and a prime breeding ground for the afore mentioned
critters, especially the small natives and salvini. The water in the canal
behind the barrier is stagnant and the vegitation melted and rotting. A few
samplings with the dipnet produced little of what, prior to this event, would
have been relpeat with examples of most of the small natives available in
South Florida. Not to paint an overly dismal picture, the system is still
alive, but in decline. Oil slicks, probably the result of polutants and
rotting vegitation, have begun to appear on the surface of the stagnant water,
once carried of and dispersed with the flow. Hopefully, the project will be
complete soon and the flow restored before the summer temperatures kick in.
An isolated space approximately 20' by 30' between the newly extended
culvert and the metal wall/ barrakade is now heavily silted with a single
stand of Cabomba about 3' square. With little faith the excersise would
produce anything, I raked my dipnet through the Cabomba and to my surprise
came up with 5 exotics; 4 C. salvini and 1 Oscar. A second scoop brought
another group of salvini and a single small bass, which I summarily released
into the canal on the other side of the barrier. The third netting took a few
more salvini and a couple of bimaculatum and a single pleco. All of these fish
ranged in size from 3" to 5", close to the maximum size for salvini. They are
very healthy looking, inspite of the terrible water conditions and I can only
summize that they've been caught at the end of whatever feeder material was
available to them, as there was no signs of any other fish or food sources.
Each scoop brought out these fish covered in silt to the point of being
unrecognizable until rinsed. Subscequent runs through what was left of the
Cabomba had no more fish. There was no where else for them to hide except the
interior of the culvert, wasn't going there.
This is yet another example of the concentration of exotic populations and
thier ability to survive extremely adverse conditions and completely use up
the feeder populations. The lone bass, now free to grow to adulthood, was the
one saving grace in this day.
It will probably take only a year for this system to revive once the flow
is restored, which means 2 years before this site is viable for collecting
again, with the exception of exotics ofcourse. Viable too, and perhaps more
importantly, as a breeding ground for the food fishes the canal once produced
for the rest of the canal system it flows into. I will continue to observe and
sample this site throughout the next year in expectation of a healthy revival.
Daryl Roche
Exotic Removal Program, NFC