- Identification of Key Nutrients in Baitfish Broodstock
Diets to Improve Egg and Larval Quality.
Rebecca Lochmann, Nathan Stone & Sathya Kumaran
Fathead minnows spawn repeatedly over a prolonged spawning
season. There was concern that the quality of eggs and fry
produced later in the spawning season would be lessened,
reducing growth and survival of the young. However, testing of
various fish diets found that feeds with the least expensive
feedstuffs (vegetable meals and poultry fat) were still
adequate for fathead minnows, as various indices of
reproductive success (egg number, egg diameter, hatching
percentage, larval length and larval stress tolerance) did not
differ significantly among tested diets. Fatty acid composition
of the eggs was significantly affected by diet, but there were
no differential effects of fatty acid composition on indices of
reproductive success.
- Stocking Densities for Golden Shiner Fry in Ponds
Nathan Stone and Alex Kachowski
Golden shiner fry can be stocked at very high densities into
prepared nursery ponds for transfer as juveniles to
multiple-batch production ponds. Hatchery fry were stocked May
11, 2005, into 12, 0.10-acre earthen ponds at four densities
ranging from 0.5 to 2.0 million/acre and cultured for nine
weeks. Yield ranged from 456 to 1,136 lb/acre and averaged 757
lb/acre across all densities. Survival was significantly lower
only at the highest density, with average survival rates of
79.5, 57.1, 70.6 and 40.0% respectively, for stocking rates of
0.5, 1.0, 1.5 and 2.0 million fry/acre. Stocking 1.5 million
fry/acre produced 1 million/acre of juvenile fish, with an
average yield of 838 lb/acre and an average weight per fish of
0.35 g.
- Stocking Densities for Large Shiners
Nathan Stone and Alex Kachowski
Stocking rates for golden shiner juveniles designed to produce
jumbos (> 12 g) in one season were tested in 12, 0.1-acre
ponds. Juvenile golden shiners (average weight of 0.5 g) were
stocked at rates of 10,000 to 40,000/acre on July 25, 2005, and
cultured for 105 days. At 10,000/acre, 98% of the fish weight
was in jumbos (average individual wt of 18 g), but yields
averaged only 321 lb/acre. At 30,000/acre, gross yield averaged
570 lb/acre, of which 333 lb/acre were of jumbo size. In a
previous study in which fry were stocked at low densities for
direct rearing to jumbo size, 500 to 650 lb/acre of jumbos were
produced in a single season (with total fish yields of 750 to
1,500 lb/acre).
- Corn Gluten Feed as a Fertilizer or Feed for Fathead
Minnow Fry
Nathan Stone
Fathead minnow producers were interested in substituting a
lower cost feedstuff, corn gluten feed, in place of commercial
fish feed during the initial rearing period for fry, and
several producers were using the product. However, a 12-pool
study revealed that growth of fathead minnow fry fed the corn
gluten feed was only half that of fish fed commercial fish
feed, and the condition of fish fed corn gluten meal was
significantly poorer as well. Results indicated that reducing
costs by using corn gluten feed dramatically reduces fish
production.
|
