- Impact of Threadfin Shad Stocking Rate on Channel
Catfish Production
Bart Green
The present study was conducted to determine the impact of
three stocking rates of threadfin shad (Dorosoma petenense)
on pond chlorophyll a concentration and catfish production.
Twelve 0.25-acre earthen ponds were assigned at random to one
of three threadfin shad stocking rates (0, 50, or 200 lb/acre).
Pre-spawn, adult threadfin shad were stocked into ponds in
mid-April and allowed three weeks to spawn. Catfish were
stocked into ponds in late May to early June in mixed-batch
culture. Stocker catfish (0.49 lb average weight) were stocked
at 4,300 lb/acre and fingerling catfish (180 lb/1,000
fingerlings) were stocked at 6,000/acre. Fish were fed daily to
apparent satiation with a 32% protein floating extruded feed.
Ponds were equipped with a ½-hp electric paddlewheel aerator
that was operated when pond dissolved oxygen concentration was
less than 3.5 ppm. Ponds were harvested after 151 days of
culture. Gross yield of market-size catfish (> 1.25 lb each)
did not differ among shad stocking rate and averaged 7,627
lb/acre. Gross yield of catfish in the 0.75-1.25-lb and <
0.75-lb size classes did not differ among treatments and
averaged 4,883 and 2,137 lb/acre, respectively. Catfish average
individual weight at harvest was 1.6 lb (market size), 1.03 lb
(0.75-1.25-lb size class) and 0.59 lb (<0.75-lb size class).
Feed conversion ratio averaged 2.2 and did not differ among
treatments. Mean chlorophyll a concentrations did not differ
and were 385.6, 351.5, and 289.5 mg/m3 for the 0, 50, and 200
lb/acre shad treatments, respectively. There was no
relationship between shad biomass at harvest and mean
chlorophyll a concentration. Flavor score at harvest averaged
2.4 (moderate earthy-musty flavor) for fish in all three
treatments. Threadfin shad biomass at harvest did not appear to
affect catfish flavor score.
- Effect of Stocking Rate on Inland Production of Marine
Shrimp
Bart Green
The effect of stocking rate of post-larval Pacific white shrimp
(Litopenaeus vannamei) on growth and production was
evaluated in this study. Six 0.25-acre earthen ponds were
filled with water from an on-site well (total alkalinity = 154
mg/L as CaCO3, total hardness = 188 mg/L as CaCO3). K-Mag
fertilizer (0-0-22, 11% Mg, 22% S) was added to ponds at 2,400
lb/acre. Stock salt (NaCl) was added at 4,000 lb/acre. Final
salinity was 0.8 ppt. Ponds were in early May with 28,343,
56,686, or 125,519 PL15 shrimp/acre; shrimp were acclimated in
tanks to the pond salinity the day before. Shrimp were fed a
35% protein extruded sinking shrimp feed daily. Ponds were
harvested by draining 136 days after stocking. Aerator failure
during the latter part of grow out resulted in substantial
shrimp mortality in one pond each of the medium and high
stocking rate treatments. At harvest, shrimp average weight
(g/shrimp) was 20.5 (36 tails/lb), 15.7 (47 tails/lb), and 16.0
(47 tails/lb) for the low, medium, and high stocking rates,
respectively. Shrimp yield increased linearly with stocking
rate and ranged from 1,095 lb/acre in the low stocking rate
treatment to 4,433 lb/acre in the high stocking rate treatment.
Feed conversion ratio ranged from 1.56 to 2.06.
- Comparison of a Sock Saver and Paddlewheel for Aerating
the Grading Sock During Catfish Harvest
Phil Pearson, Sara Duke, Bart Green, Doug Minchew,
Rachael Beecham, and Jin Kim
A study was conducted to compare the aeration performance of a
sock saver to that of a paddlewheel in loaded grading nets
under on-farm harvest conditions. Eight field trials were
conducted during commercial catfish harvests at Top Cat II
Fishery, Chicot County, Arkansas. At harvest, 15,000-20,000 lb
of captured catfish (1.9-lb average weight) were loaded into
each of two 8 ft x 50 ft grading nets. During each trial one
grading net was aerated by a tractor-powered paddlewheel and
the second grading net received O2 from the sock saver. Fish
remained in the grading net from 1200 h on day 1 through 0500 h
on day 2. Dissolved oxygen concentration was monitored
continuously at three locations and two depths within each
sock, and one location and two depths outside each sock.
Dissolved oxygen concentrations did not differ significantly
between sample depths, or among locations or sample dates. The
water column was supersaturated with oxygen from 1430 to 2200
hours, and undersaturated from 2200 to 0500 hours. The sock
saver aeration system was comparable in aeration performance to
a tractor-powered paddlewheel under conditions existing in
Chicot County, Arkansas in August 2004.
- Effect of Mince Size and Cooking Method on Physical and
Textural Properties of a Catfish Patty
Jin Kim and Bart Green
Fresh catfish belly flap meat was minced through one of four
dies (3 18 x 35 mm kidney-shaped openings, 6 18-mm diameter
openings, 24 9-mm diameter openings, or 102 4.5-mm openings),
formed into patties, and either boiled or baked to an internal
temperature of 80 C. Fluid loss for each cooking method
increased as mince particle size increased, and fluid loss with
baking was greater than with boiling. Patty springiness,
cohesiveness and resilience did not differ among mince particle
sizes or between cooking methods. However, patty hardness,
gumminess, chewyness index and Kramer break force did vary with
mince particle size and cooking method. Hardness, gumminess and
chewyness index increased as mince particle size decreased.
Baked patties had higher values of hardness, gumminess and
chewyness index compared to boiled patties for all mince
particle sizes because of different rates of thermal
transition. Kramer break force increased as mince particle size
increased, but was unaffected by cooking method for any given
mince size.
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