The Crystal River Mariculture Center is located at Progress Energy
Complex in Crystal River near the Gulf of Mexico.
A BRIEF HISTORY
Progress Energy Florida, a subsidiary of Progress Energy, provides
electricity and related services to more than 1.5 million customers
in Florida. The company is headquartered in St. Petersburg, Fla.,
and serves a territory encompassing over 20,000 square miles
including the cities of St. Petersburg, Clearwater, as well as the
central Florida area surrounding Orlando. It operates five electric
generating units at the Crystal River energy complex. Progress
Energy is required to have several environmental permits for the
operation of these electric generating units. In response to
Environmental Protection Agency (EPA) permit requirements,
environmental studies were conducted at the Crystal River Power
Station from June 1983 through January 1985. Data collected as part
of these studies projected annual impact levels on local fishery
populations. The annual impact levels for some species were
determined to be unacceptable by EPA.
The concept of a multi-species marine hatchery to mitigate
fisheries impacts at Crystal River was developed as an innovative,
cost-effective, alternative to conventional engineering solutions.
The Crystal River Mariculture Center became part of a negotiated
settlement, which included flow reduction at two of the power
plants and helper cooling towers to further decrease the discharge
The Crystal River Mariculture Center began operation October
1991. The facility will remain operative as long as water from the
Gulf of Mexico is utilized for condenser cooling at the power
plants. Besides offsetting the impacts of power plant operation,
the facility will provide educational opportunities for students,
teachers, and the general public. New and innovative aquaculture
techniques will be developed as different species are selected for
culture. Since the Mariculture Center represents an innovative,
cost-effective, solution for the mitigation of environmental
impacts, the success of this program is of interest to the utility
industry as well as federal and state agencies.
WHAT IS MARICULTURE?
Mariculture is defined as the farming and husbandry of marine
plants or animals. Mariculture can be used to replenish natural
populations which have been depleted by natural or man-made
effects. The Mariculture Center will integrate technology
associated with fisheries science, marine ecology, and the
aquaculture industry to develop effective production techniques for
the cultivation of several marine species.
The Mariculture Center complex includes a two-story,
8100-square-foot, hatchery building and eight one-acre ponds. The
hatchery building includes a water-chemistry laboratory, four spawn
rooms, an incubation tank room, aglae production room, and
administrative spaces. Each spawn room contains two
12-foot-diameter tanks connected to a recirculation system. This
system includes a biological filter for the removal of dissolved
waste products, a sand filter for removal of particulate matter,
and an ultraviolet filter for pathogenic bacteria control. The
grow-out ponds are located a short distance from the hatchery
building. Each one-acre pond has a synthetic rubber liner to
prevent water leakage, will hold approximately one million gallons
of seawater when filled to capacity, and is three to five feet
deep. At one end of the pond is a specially designed concrete drain
structure, complete with adjustable drain valve, two removable
screens, and a sump area where fish are collected during
WHAT SPECIES ARE CULTURED?
This is a multi-species marine hatchery with twelve species
targeted for culture. Species were selected based on abundance and
the estimated level of impact from the power plant. Since not all
species are cultured simultaneously, species are listed by priority
based on level of impact, ecological importance, and availability
of aquaculture information. The first species selected for culture
are redfish, spotted seatrout, and pink shrimp. It is important to
note that the selection of species is not restricted to
recreationally and commercially important fishes but also includes
forage fish such as pinfish and pigfish, unique non-game species
such as batfish, and certain crustaceans such as stone crab and
Each species requires a unique set of conditions under which it
will spawn and the newly hatched larvae will grow. For some of the
species, those conditions are well documented; for others, they
have yet to be discovered. One of the biggest challenges at the
Mariculture Center will be to meet the special conditions required
by the individual species.
WHICH FISH FIRST?
Since there is a great deal of information available regarding the
successful culture of redfish, it was a logical species to start
with at the Mariculture Center. The production of fingerling fish
for release basically involves a three step process: (1) egg
production by the adult fish; (2) collection and incubation of the
fertilized egges, and (3) the grow-out of the hatched larval
HOW IS IT DONE?
Adult redfish, called broodstock, are conditioned by careful
manipulation of photoperiod and water temperature to spawn in
12-foot diameter tanks. In the tanks, a one-year natural cycle can
be condensed into 120 days and the fish will begin to spawn at the
end of this shortened cycle. With four spawn rooms available at the
site, it is possible to have fish producing eggs at various times
throughout the year. A single redfish can release over 500,000 eggs
during a single spawning event. The released eggs float to the
surface of the water where they can then be skimmed off and placed
in incubation tanks until hatching.
Upon hatching, the fish larvae are ready to feed and must either
be stocked in ponds or provided with live food in the incubation
tanks. Organic and inorganic fertilizers are used prior to stocking
to prepare the ponds. The fertilizers create a thick "soup" of
microscopic organisms as food for the pond-stocked larvae. Larvae
kept in incubation tanks must also be provided with live food. For
redfish, a microscopic animal called a rotifer is an ideal live
food organism. Rotifers are relatively easy to grow in large
numbers using certain types of algae as their food; they then
provide good nutrition for the larval fish.
The larvae stocked in the ponds are grown to what is called
fingerling size, about one to three inches in length. That takes
approximately 60 days, depending upon water temperature and food
availability. At harvest, the ponds are drained and the fingerlings
are collected and placed in a fish trailer for transport. A single
pond may yield as many as 30,000 three-inch fingerlings at harvest
WHERE DO THEY GO?
The harvested fish are released into the Gulf of Mexico in areas
determined suitable for their survival. The determination is based
upon the numbers of fish released, the size of fish, the time of
the year, and the availability of acceptable water conditions.
Several release sites are identified so no one area is overloaded
and to better ensure the survivability of the released fingerlings.
To avoid mixing different fish stocks, broodstock are collected on
the west coast of Florida only.
HOW DO WE KNOW?
One of the most difficult tasks for a stock replacement program
such as this one is an accurate assessment of success. How do we
know that the released fingerlings survive? In order to determine
the success of releases, it is necessary to tag as many fish as
possible. Returns on these tags can be used to calculate
survivability and track movements after release.
Tagging large numbers of small fish is a very difficult task.
One of the recommended techniques for tagging one-to-three-inch
fingerlings involves the use of coded wire tags. The tag is a tiny
piece of wire marked with a binary code. The tag is inserted under
the skin of the fish near the head. This efficient tagging process
allows large numbers of small fingerlings to be tagged with a
minimum of handling and disturbance. The only drawback to this
system is that there are no external marks on the fish, making
identification after release difficult. The tags can only be
detected with the use of a special device, and this requires a
labor intensive effort for the capture and identification of marked
fish. The Mariculture Center will continue to investigate the
latest technologies available for the most effective and efficient
tagging of fish to be released.
WHAT IS NEXT?
The Crystal River Mariculture Center integrates marine ecology,
the aquaculture industry, and the technology associated with
fisheries science to develop effective production techniques for
the cultivation of several marine species. The great thing about
the Mariculture Center is the many opportunities that will be
available. The center will not only be able to offset the impacts
of the power plants at Crystal River, but it can go far beyond that
goal and enhance local fish populations. Procedures developed at
the center can be utilized by the aquaculture industry. There will
be many educational opportunities through cooperative programs and
The Mariculture Center has a small staff of dedicated
biologists, and there will be occasion to seek outside assistance
for specific aquaculture needs. The center is in the process of
developing cooperative programs with several agencies and
institutions throughout the state. These agreements will provide
the Mariculture Center access to a network of aquaculture experts,
and the center can, in turn, provide culture space for their use.
For additional information call (352) 563-4584.