Fingerling production is very similar to hybrid striped bass phase I fingerling production. Newly hatched fry are stocked into organically fertilized ponds that have established zooplankton blooms. This occurs generally from late January into March. A real advantage that yellow perch fry have over hybrid striped bass fry is that they are larger, approximately 7mm long, and can eat a greater variety and size of zooplankton. After approximately 8 weeks in the pond, the fry are harvested as 1-1.5 inch fingerlings. These fingerlings then need to be trained to a manufactured feed. This cannot be effectively done in a pond. The removal of these fingerlings from the nursery pond appears to be somewhat stressful on them and they have a tendency to develop bacterial infections that must be dealt with. If not, mortalities approaching 90% can occur.
Feed training the fingerlings is relatively straight forward. Hybrid striped bass and trout starter diets have both proven to be accepted by the yellow perch fingerlings. The feed should be introduced at regular intervals throughout the daylight hours as the fish are very much sight feeders. Care should be taken not to "push" the fingerlings to larger feed too quickly as they have a tendency reject the larger feed size. Belt feeders work adequately, but timed feeders that drop larger volumes of feed into the holding tanks at each increment seem to do a better job of training the fish.
Intensive pond production has been attempted for 2 years, but has not yet been successful. In 1998 and 1999, too few 1-1.5 inch feed trained fingerlings were stocked into the pond. It is thought that 100,000, 1-1.5 inch fingerlings need to be stocked per acre so that the fish will remain on feed. When these fish attain a length of approximately 4 inches, they then need to be restocked at a rate of 25,000 per acre for the final phase of growout.
Extensive pond production was attempted in 1999 with mixed results. A 0.25 acre pond was stocked with 50 lbs. of fathead minnows weighing 0.64 lbs. per 100 in February, 1999. 1500 non-feed trained yellow perch weighing 1 lb. per 1000 were then stocked into the same pond on May 12, 1999. On June 28, 1999, 2 yellow perch (4 and 5.75 inches long) were captured by cast net. The pond was sampled again using a cast net on July 12, 1999. 9 of the fish averaged 3 inches in length and weighed an average of 13.12 grams. 5 of the fish averaged 4.75 inches long and weighed an average of 21.8 grams. These fish were on track and well on their way to the 120-130 gram market size when the very warm temperatures (90oF+) in August occurred. Water temperatures exceeded 91oF and when the pond was drained on November 11, 1999, there was no yellow perch survival. Yellow perch in other larger ponds at the same location survived the excessive heat of the 1999 summer. I will be exploring this production method again, as I believe this could be an economically viable production method.
Spring is also as late as you would want to try to solve an over-population problem. Research has shown that the number one cause of small, or stunted, crawfish is too many crawfish in the pond. The best way to cure a crawfish pond of this problem and to assure production of the desirable large crawfish (15 count and larger), is to reduce the population. Several methods have been tried to selectively kill crawfish in a pond. The best seems to be draining the pond early in the year, stranding many of the young crawfish, and then applying urea to kill many more before they have a chance to burrow. Reducing the population as early in the season as possible allows time for the surviving crawfish to grow to the desired size. How do you determine if your crawfish pond is over-populated? The producer needs to sample the pond starting at approximately 4 weeks after the initial flood of the pond. The ideal density of crawfish in the pond is 5 to 10 crawfish per square yard. Fewer crawfish means yields may not be optimal. More than this means there is a potential for over- population, with the greater the number, the greater the potential.
Spring is also the time crawfish producers begin to harvest the ponds. Crawfish are cold blooded animals so the warmer the water gets, the more active the crawfish get. By the time the water temperatures reach 65oF (18oC) the crawfish are nearly as active as they will get. Normally in North Carolina, crawfish harvests begin in earnest around the first of April. Harvesting ponds with 15 to 20 traps per acre which are run 3 times per week will optimize the yields while keeping costs down. Remember, the cost of harvesting can be as much as 70% of the cost of raising the crawfish.
Spring time is also a fairly stressful time for the
fish. They have just endured a prolonged
period of cold water and their immunity and
natural resistance to diseases tends to be low.
It is also in the spring that the naturally
occurring antimicrobial substances in the fish's
blood are low, making them more susceptible
to infections from disease causing organisms
naturally occurring in the water. Also, water
temperature will increase into that dangerous
18o-28oC range which is optimum for many
fish pathogens already present in the pond. It
is especially important to keep stress to a
minimum during this time of the year to limit
disease outbreaks. Water quality parameters
that the producer has control over should be
kept to as optimum of a level as is possible.
Just cross you fingers that water temperatures
do not change too much too fast and stress the
fish any further. Should your fish show signs
of a disease outbreak, get some sick fish (not
healthy ones caught on a hook and line or fish
that are already dead) to your closest
diagnostic facility. Be sure to get an accurate
diagnosis. Many bacterial, viral, and parasitic
infestations can look similar but treatments are
drastically different. If the problem is bacterial
and a treatment of medicated feed is
necessary, be sure to have sensitivity tests run
on the bacterial cultures to make sure the
bacteria is sensitive and not resistant to the
antibiotic chosen. In many cases, depending
on the circumstances, no treatment may be
the best treatment and economically the
correct treatment. Be sure of what you are
dealing with before making your informed
decision.
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