Home fish farming as a means of producing
a supply of inexpensive protein is an enticing
idea to urban and rural dwellers alike, especially now
that overfishing (coupled with the pollution of many
spawning and feeding areas) has led to higher seafood
prices.
Fish can , of course, be grown in basements (as
Dr. Fernwood Mitchell proved when he raised rainbow trout
in his Washington, D.C. cellar). Such closed systems,
however, require perpetual filtering and aeration of the
water, constant temperature control, and regular
supplemental feedings… and they’ll only be worthwhile
when transportation expenses become so high that basement
growing, with all of its costs, becomes
economically competitive with our present commercial
fisheries.
On the other hand, not all aquaculture is as
intensive and financially prohibitive as are basement
systems. Ocean ranching is a good example of the
other “fin farming” extreme. Salmon hatcheries on our
northeastern and northwestern coasts release millions of
juveniles each year, fish that are subsequently harvested
by both commercial boats and sports anglers. (The
Lummi Indians of Bellingham, Washington–who use their
trout and salmon hatcheries as a spur to encourage
community economic development–produce nearly five
million fingerlings a year.)
In addition, there’s an extension of ocean ranching–a
system that’s appropriate for a wider variety of
species–in which the juveniles are released into a
partially enclosed environment that can
receive some management. Known as parc
culture, this system was initially developed to grow
oysters in Brittany’s tidal flats, but is now being used in
many American shellfish beds. For more
mobile forms of marine life, gates can be
used to retain the finned groups in the “cropped” bay,
tidal flat, or whatever.
Raft culture provides still another fish farming
alternative. By growing mussel colonies on rafts anchored
in the middle of an unpolluted estuary, Ed Meyers of
Damariscotta, Maine is able to raise the shellfish for less
than 20¢ a pound!
Cage culture is an even more intensive method: The
cultured organisms are enclosed in either plastic mesh or
bamboo cages which are, in turn, secured in a large natural
body of water.
However, it’s pond systems that have
been–and still are–the basic aquacultural unit
throughout the world ranging from Africa’s tilapia/carp
polyculture to the rather intensive catfish farming of
North America. This type of aquaculture–which is
midway between extensive and intensive farming–is
likely to remain the most widely used system, because it
incorporates some of the advantages of each extreme.
On the one hand, the pond provides a controlled growing
environment from which fish can easily be harvested,
while–on the other hand–such “open air
aquariums” are also able to benefit from inlets
and outlets that flush fish wastes; from sunlight which
aids in the growing of food; and from the natural
aeration and circulation of water by wind.
It’s premature, of course, to evaluate aquaculture’s
potential as a community food or income source in either
rural or urban areas, since many of the possibly useful
systems are still in the developmental stages. However,
fish farmers in the U.S. are beginning to realize that they
can increase their yields dramatically by adopting the
Asian polycultural practice of growing
combinations of ecologically compatible species in the same
water rather than limiting production to one variety of
fish per pond, as has been the American tradition.
As for seafood farming in the city… neither closed,
intensive systems (such as basement aquaculture) nor
extensive techniques are appropriate for urban fish
production. Intensive systems have very high start-up
costs, require a great deal of energy for operation, and
produce expensive products. On the other hand, although
extensive aquaculture systems make sense from an
energy usage perspective, most cities use their natural
tidal and river resources to dilute a heavy output of
sewage, industrial waste, and runoff pollution, so such
bodies of water would require massive purification
facilities before they could be successfully (and safely!)
farmed.
Ponds are, therefore, the best hope for city fish farming.
Such small “lakes” can take advantage of the energy
available from solar radiation, the higher temperatures
of the urban environment, and perhaps even wind power
to provide water circulation.
While fallout from air pollution or runoff from streets and
pesticide-treated areas may present problems to the city
aquaculturist, his or her largest challenge will
be to develop this medium-intensity system to the point
where it can have a significant impact on neighborhood
protein production. Advertising will likely be needed to
build consumer acceptance of products like mussels and
catfish, and energy-efficient filtration and aeration
systems must be developed so that stocking densities can be
increased.
Once such “barriers” are crossed, however, the dream of the
backyard urban fishpond–next to the vegetable garden
and supplied by a neighborhood hatchery–can become
far more than just a fantasy.
For the past several years, the good folks at the Institute for Local Self-Reliance in Washington, D.C. have worked to help urban residents gain greater control over their lives through the use of low-technology, decentralist tools and concepts. We strongly believe that more people (city dwellers and country folk alike) should be exposed to the Institute’s admirable efforts … which is why we’ve made this “what’s happening where” report by ILSR staffers one of MOTHER EARTH NEWS’ regular features.
