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02/14/2002
Ungreen Green Mussels
NOTE - New nominal posting day for this column to be Thursday (see
below). Probable actual posting day will be Tuesday or Wednesday.
I''m happy to report no more incidents of syncope down here on
Marco Island (see last week''s column in the archives). My car''s
air conditioning is now fixed, no longer flooding the interior with
its exhaust water. To round out the trilogy, my inability to get
online to file my column was found to be due to a faulty modem
connection, requiring a reconfiguration by Chris, my newfound
computer guru. Chris and his partner, Chris, both from Germany
and in business here for only 4 months, managed to accomplish
this in just a couple hours at a cost of $75. This computer
problem caused me to miss my nominal filing day, Tuesday, for
the first time since I started this column. The good thing is that it
provided an excuse for me to switch my filing day to Thursday
for this and future columns.
Last week, I noted that I saw no evidence of red tide down here.
However, the local news featured a piece on the definite presence
of red tide just across the water in nearby Naples. The Mote
Marine Laboratory has a web site that gives a daily report on the
red tide situation in the Gulf Coast waters. As usual when I''m
on Marco, the environment puts me into a "marine" frame of
mind. For example, I just finished watching the CBS Wink
News originating in Fort Myers and there was considerable
concern about the Asian green mussel.
It seems that restaurants sometimes serve this delicacy to mussel
lovers. Generally, the creature is harvested in New Zealand
waters and airlifted to the U.S. Speculation is that some
enterprising individual decided to see if New Zealand could be
bypassed and dumped some specimens of Asian green in the
waters of Tampa Bay. Unfortunately, if true, the experiment was
a rousing success for the Asian green mussel. It seems to love
Florida and is reproducing like crazy. One might suppose that
mussel lovers would enjoy the local abundance of the delectable
food item. However, the reporter noted that the eating of
mussels taken from unapproved waters in the area could be
dangerous to one''s health.
But that''s not the real problem. It turns out that Asian greens are
very sociable critters and they like to get together in big clusters
or sheets. These Asian green communities can become so heavy
that they can sink navigational aids such as buoys or even sink
small boats! We discussed some time ago the plugging of water
pipes by similar unwanted marine life in the Great Lakes region.
A power company in the Tampa area is reporting the same
problem in its water pipes thanks to the Asian green mussel.
When it comes to the environment, Asian greens are definitely
ungreen!
China has its problems with marine life as well. A letter to the
editor in the November 2001 issue of Science illustrates one of
those problems. Ping Xie and Yiyu Chen commented in their
letter on a previous letter in Science titled "Invasive carp in the
Mississippi River Basin". The villains in this story are the
bighead carp and the silver carp. The victim in China is the
barbless carp. Let''s call the victim Barby and B&S will be the
bighead and silver carps. Barby was getting along just fine in
Lake Xingyun in China and half of the fish caught in the lake
were Barbys. Barby is a filter feeder. That is, it feeds by
filtering the plankton and other small critters out of the water
flowing through its filtering apparatus. The amount of food it
gets depends on the "power" of its filter, that is, the amount of
water forced through the filter. The more water it filters, the
more food it gets.
Barby got along fine over the millennia, even though its filtering
apparatus never evolved to become very powerful. However,
there was plenty of plankton in the lake and Barby thrived.
Then, some 50 years ago, it was decided to "farm" B&S in Lake
Xingyun. In contrast to Barby, B&S are powerful filter feeders,
sucking up that water and filtering out the goodies much faster
than Barby. As a result, once B&S were firmly established in the
lake, they gobbled up more than their share of the plankton and
other good stuff. The concentration of plankton in the lake
diminished. Now Barby was pumping the same amount of water
as before but there wasn''t as much plankton in the water. Over
the past 50 years the number of Barbys declined steadily until,
instead of half the catch from the lake being Barbys, today less
than one percent are Barbys. Barby is on the verge of extinction
if the trend continues.
This destroying of the native environment by B&S is not limited
to Lake Xingyun. Other lakes in China have also been seeded
with B&S. Because all types of fish dine on plankton in their
early stages of life and because some, like Barby, are filter
feeders as adults, B&S are competitors for virtually every fish
species. And B&S aren''t small, especially the bighead, which
can grow to 75-90 pounds and each female has a couple million
eggs to help propagate the species. I haven''t read the letter about
the Mississippi that prompted the Chinese letter but from its title
it''s clear that the B&S effect is one to worry about here in the
U.S., as well as in the 33 other countries where either B and/or S
species have been introduced.
As if B&S aren''t enough to worry about, what about the decline
in caviar production? When we were in the USSR in 1973, one
of the joys of our visit was the caviar spread on that dark brown
bread - delicious! The most sought after caviar is the roe from
certain species of sturgeon. I''ve seen a number of articles over
the past couple of years lamenting the overfishing of sturgeon in
Russia or the former Soviet republics. Here in Florida, another
item on the local news program last week was about the caviar
crisis. Mote Marine Laboratory was mentioned in connection
with its research on sturgeon aquaculture. As in Russia, the
sturgeon population in the Gulf and in the rivers of this area has
been in serious decline.
The Mote Marine Laboratory has a joint program with the
University of Florida to bring back the populations of sturgeon,
in particular, the Gulf sturgeon and the shortnose sturgeon. The
Gulf sturgeon is an impressive animal. After its first year it
weighs about 6 pounds. As an adult it''s typically about 6 feet
long but can grow to 15 feet and a weight of up to about 800
pounds! Speculation is that the Gulf sturgeon can also live to
perhaps a hundred years. Not only does it yield good caviar but
it is reputedly an excellent tasting fish. However, with the
overfishing of the Gulf, one isn''t likely to encounter one that''s
survived long enough to achieve the impressive figures cited
above. Let''s hope that the program to reestablish the sturgeon is
successful so "we Floridians" can once again enjoy our caviar.
OK, to tell the truth I haven''t had real caviar since our trip to the
USSR and, actually, I''m not sure we were eating the good stuff
there.
Finally, I have only been fishing once in my life, in a small
stream near Mechanicsburg, Pennsylvania. Accordingly, I was
quite interested when yesterday, we watched a fellow from our
condo unit cleaning his catch of yellowish snappers. He neatly
cut the fish near the head, sliced off the skin with a stroke to the
tail and then slit out the "filet" for his dinner. The head and
attached skeleton were saved, to be recycled as bait, and the skin
was recycled by throwing it to the group of appreciative pelicans
that apparently show up every day around the time the fishermen
come to the cleaning station. This morning, on my walk, I came
across another approach to treating a captured fish. A gull was
on the shore, beginning to dig into a foot-long silvery fish that
the gull seemed to have caught and dragged onshore. The gull
was much less fastidious than our fisherman in his approach to
his catch. On my return a half hour later, I was surprised to see
that the same gull had maintained his catch in spite of other gulls
in the area and was still working hard for his meal. I was
tempted to get a sharp knife and teach the gull my newly learned
tricks of how to skin a fish but figured the gull would probably
not appreciate my efforts.
Well, so much for my marine mode. Next week, I''ll get back to
something not related to the environment, fish or anything
aqueous. I don''t know what the subject will be but now I''m
committed!
CORRECTION - I''ve just finished my early morning walk the
day after finishing this column. I decided I was definitely wrong
in concluding that the above mentioned seagull had pulled that
silvery fish onto the beach. Today, the beach was littered with
the same type of dead fish, to me a sign that the red tide has
reached Marco Island. Yesterday''s fish was probably a
harbinger of the carnage to come.
Allen F. Bortrum
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