|
PUMP HARVESTING SYSTEMS MAY HAVE FUTURE IN CATFISH INDUSTRY
AUBURN, Ala.__--By tapping into the latest information and technology,
commercial catfish producers have made great strides in the production
and processing of their crop. Now they can siphon a little know-how
from Auburn University scientists to "pump up" their harvesting
methods.
According to Len Lovshin, an Auburn fisheries researcher working with
the Alabama Agricultural Experiment Station, the advances made in growing
and processing fish have out-paced harvesting techniques.
"Most people still use the boom-and-basket system," he said,
adding this system has been effective, but producers want and need a
faster, more efficient method.
To help identify new harvesting options, Lovshin and other Auburn scientists
participated in a multi-state research effort to evaluate various pump
systems that have been used successfully to harvest trout and salmon.
The study, coordinated through the Southern Regional Aquaculture Center,
compared the traditional boom-and-basket system to a vacuum pump, which
uses positive and negative air pressure to move fish from the water
to the transport truck, and a turbine pump, which uses a propeller-type
system to load fish. Auburn researchers evaluated speed and efficiency
of harvest, trauma and physical stress caused by the devices and survivability
and growth of fish subjected to the harvesting procedures.
According to Lovshin, the study showed that the turbine method was the
fastest system of the three tested, loading an average of 650 pounds
of live catfish per minute. In comparison, the boom-and-basket system
loaded approximately 340 pounds per minute and the vacuum pump loaded
only 120 pounds per minute.
Lovshin noted that all three systems resulted in some stress and injury
to the fish, though the turbine system seemed to cause the greatest
amount of stress and more skin abrasions than the other two systems.
Still, stress indicators returned to normal within a short time after
harvest, regardless of the harvesting system used, and the skin abrasions
caused by the turbine pump were not severe enough to affect the marketability
of the fish.
Few puncture wounds, which Lovshin explained would "physically
damage the muscle and could reduce the value of the fillet of that fish,"
were found on fish subjected to any of the harvesting systems. Evaluation
of survivability and growth of the fish after harvest showed little
difference among the three systems. The results did suggest that harvesting
fish of a uniform size or adapting the harvester to handle larger fish
may increase survivability.
Results of these studies suggest that the boom-and-basket system remains
the most practical harvesting choice at this time, but the turbine pump
holds promise for the industry.
"If they are loading fish to go to the processing plant where they
will be slaughtered in a manner of hours, we think that the turbine
pump has very good potential," Lovshin said.
The greatest limitation for this system may be acceptability of the
measurement system used in the pump models. Lovshin explained that the
pump systems use volume displacement of the water, not traditional scales,
to determine pounds harvested.
"If you put anything in water, the water level will rise at a consistent
rate," he said. "If you know the area of your hauling tank,
every one-inch increase in height equates to a given weight of fish.
A sight gauge allows harvesters to watch the water level and measure
the weight. "The industry has not used anything like that. They
have always used the scale, and there may be a problem with acceptability
of this new system," he predicted.
-30-
By:
Katie Smith
9/10/91
|
