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Bullfish being studied for baitfish production
By Charmain Tan Courcelle
MISSISSIPPI STATE -- A new project at the Coastal Aquaculture Unit of the Mississippi State University's Coastal Research and Extension Center may keep Mississippi saltwater anglers in fish year-round.
Mississippi Agricultural and Forestry Experiment Station researchers Ben Posadas and Mark LaSalle have initiated a study to develop an economically viable baitfish production system that will provide a year-round supply of live bait to the state's saltwater recreational fishing industry.
Mississippi's sportfishing industry makes a large economic contribution to the state every year. In 1996, the most recent year for which figures are available, the industry had an economic impact of more than $293 million and generated close to 4,000 jobs. Posadas said driving this economic output was retail sales of more than $155 million.
In spite of its popularity, the sport has not grown to be a year-round activity due to the lack of a dependable source of live bait. Most of the live bait purchased by recreational fishermen is caught in the wild.
"From Louisiana to Florida, the supply of live bait is nonexistent in winter," Posadas said. "So even though there is a demand, there are not enough baitfish to go around."
Posadas said he and his colleagues hope to change that. They are designing a tank-pond production system for bull minnows, or Gulf killifish, which are popular as live bait. They are determining the factors that influence the survival, growth and yield of these fish and assessing the costs of production.
This year, the group has evaluated one-pond and two-pond production systems. In a one-pond system, the fish population is expanded from brood fish that are stocked at a 2-1 ratio of females to males. Hatching and grow-out phases of production all occur in the same pond.
In a two-pond system, brood fish are stocked as for the one-pond system, but spawning mats are installed along four sides of the pond. The mats attract females to lay their eggs on them. After a week, the mats are removed and placed in a second pond which serves as a hatchery and grow-out facility.
The team used brood stocking densities of 10,000, 20,000 and 40,000 fish per acre.
"After a 12-week period this year, we managed to harvest bull minnows that were 2 1/2 inches long and weighed 3 grams each. We aim to get our baitfish up to 5 or 6 grams per fish, which is what retail bait dealers sell," Posadas said.
To get their numbers up and to optimize growth conditions, the team will try a three-pond system next. They will also determine optimal brood stocking density.
"We're hoping to figure out the optimal brood stocking density for optimal fry production," Posadas said. "Right now, we don't know how many fry we obtained from the spawning mats. Not all the eggs laid by a female are deposited on the mats.
"By including a third pond, or tank hatchery, for fry development, we will be able to more accurately determine how many fish to stock," he said.
The group has found water temperature to be a critical factor affecting spawning and hatching.
"There is an upper limit of temperature that strains spawning and hatching success," Posadas said. "We found temperatures from 24 to 28 degrees (Celsius) give optimal spawning and hatching."
When the bull minnow production system is optimized, it should be capable of providing a year-round supply of live bait, which could give farmers a new aquaculture product to grow as well, Posadas said.
Contact: Dr. Ben Posadas and Mark LaSalle, (228) 338-4710