| Storm
surge damaged fish ponds have once again become an issue
only three short years after recovery from Hurricane Rita.
Depending
on the location of the pond, damages range from being completely
filled with debris carried by Ike’s massive storm
surge to tree and leaf litter causing dissolved oxygen problems.
For ponds with debris, the obvious recommendation is to
remove it.
Another
Ike-related pond issue is saltwater inundation. Most ponds
flooded by storm surge experienced an entire population
loss of freshwater fish. Ponds with salinities over 10 parts
per thousand certainly experienced total losses. For reference
purposes, full strength Gulf water is 35 parts per thousand.
Many
freshwater fish commonly stocked in ponds can survive in
brackish water; however reproduction is limited when salinities
go above 5 parts per thousand. What killed most ponds was
the quick change from freshwater to very salty, silt and
debris laden surge water.
If at
all possible, pump out all pond water. This is the most
efficient way of removing dissolved salt. If the pond is
gravity drained or evaporation is allowed, the salt will
concentrate and may become bound in the soil. It also may
be necessary to excavate some of the clay layer deposited
by the surge water. This may also be an opportunity to make
changes to the pond shape, bottom contours, add artificial
structure, aeration features like fountains, diffused air,
etc.
Many
of the ponds inundated by surge were also stocked by the
storm with a large population of estuarine dependent species,
such as crabs, shrimp and many saltwater finfish species.
If the pond cannot be pumped completely, these remaining
organisms will need to be removed or killed so they don’t
begin feeding on fingerling fish upon restocking.
Once
the pond is dewatered, this may also be an opportune time
to add agricultural or dolomitic lime to the pond bottom.
To determine the exact amount of lime needed, a soil sample
can be taken to your parish agent’s office and sent
off for a small fee. Most soils in Southwest Louisiana require
lime. It is easier to make lime applications to a bare pond
bottom than when filled. It also helps suppress small clay
particles from suspending when water begins refilling the
pond. Refill and stock fish once water reaches fill level
and water clears up.
For
more information on ponds, visit the LSU aquaculture Web
site www.lsuagcenter.com/en/crops_livestock/aquaculture/,
or the Louisiana Sea Grant aquaculture site www.seagrantfish.lsu.edu/aquaculture/,
or you can request publication #2573: “Management
of Recreational and Farm Ponds in Louisiana” from
your parish AgCenter office.
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