Kenneth J. Semmens

The effect of a flaxseed oil-enhanced diet on the product quality of farmed brook trout (Salvelinus fontinalis) fillets.

The effects of dietary modification with flaxseed oil-enhanced (Flax) feed on the product quality of brook trout fillets were examined. Trout were fed a commercial feed supplemented with fish oil (CD) or flaxseed oil (Flax) for 165 d before harvesting. Proximate composition and fatty acid profile were determined on fillets. Quality parameters of the raw fillets were examined over the storage period by measuring color (L*, a*, b*), muscle pH, and thiobarbituric acid reactive substances test. Evaluations on the cooked fillets included sensory evaluation with triangle tests and a paired preference test. There were no differences in proximate composition between the groups; however, the total omega-3 fatty acids were greater in Flax fillets (P<0.05). Diet and day were shown to interact in their effect on whiteness, pH, and lipid oxidation (P<0.05); however, linear regression did not determine that malondialdehyde concentration was associated with time in either diet type implying that lipid oxidation in the vacuum-packed fish was controlled at storage temperatures (4°C). Sensory panelists were able to choose the odd sample in a replicated triangle test analyzed using the β-binomial model, and there was preference for Flax fillets (P<0.05). Results indicate that a Flax-enhanced diet would have favorable effects on product quality of farmed brook trout.

Effect of Diet and Strain on Growth and Performance in Hybrid Bluegills

Abstract Little is known about the diets and genetic strains that are optimal for the production of hybrids of bluegill Lepomis macrochirus. The objective of this study was to determine whether there are differences in feed, nitrogen and amino acid conversion, lipid deposition, liver lysine oxidation, and liver glycogen in two such hybrids—Georgia Giant (GG, a proprietary strain of hybrid bluegill) and a commercial hybrid bluegill (CHBG, green sunfish L. cyanellus × bluegill)—fed five commercially available diets. The diets were formulated to the following minimum crude protein (CP)–fat ratios: 32/3, 38/8, 40/10, 42/16, and 45/20. Fish were randomly allotted to 20 tanks, with two tanks per diet within each strain. After 12 weeks in experimental conditions, GGs had higher feed intake (P < 0.001), higher weight gain (P < 0.001), better feed conversion (P < 0.05), and lower liver glycogen (P < 0.05) than CHBG. Liver lysine oxidation and whole-body lipid deposition was not significantly different between stra...

Habitat Use, Survival, and Site Fidelity of Rainbow Trout Stocked into an Appalachian River

Rainbow trout from private culture facilities were stocked into Bluestone River, West Virginia, to evaluate biological feasibility of stocking to enhance local angling opportunities. Between fall 2007 and spring 2009, over 2,400 fish were stocked. A subset of fish was tagged using radio transmitters (ATS model 1580), each bearing a unique frequency (48.000 to 49.999 Mhz) to monitor survival and availability of fish to anglers along a 1.6 km river reach. Tagged fish were 366 mm TL (33 mm SD) and 617g (128g SD) on average. Summarized seasonally, 73%–96% of fish remained within the study reach. Survival varied between years. Between fall 2007 and spring 2008 seasonal survival was 62%–89%, but from fall 2008 through spring 2009 it was 32%–66%. Mean availability (product of survival and site fidelity) ranged from 48%–78% over the study except it declined to 23% in winter 2008 due to low survival. This case study shows that cultured rainbow trout from private producers can be stocked into seasonally suitable streams to enhance local angling.

Evaluation of Lettuce Between Spring Water, Hydroponic, and Flow-through Aquaponic Systems

ABSTRACT Lettuce (Lactuca sativa L.) is an important vegetable crop that can be grown in hydroponic and aquaponic systems. A comparative study to evaluate the efficacy of a cold water flow-through aquaponic system (FTS) to a hydroponic system is lacking. Twenty-seven lettuce cultivars with green or red leaves, in seven subtypes, belonging to four popular types in the Western diet, were grown in spring water or aquaponic or hydroponic treatments. Spring and aquaponic water flowed directly from a spring and a raceway growing rainbow trout, respectively. The hydroponic treatment had nutrients added to a recirculated system. Stand establishment, average yield, and productivity (yield/week) were determined for each subtype or cultivar and compared among water treatments. No comparison among lettuce types, subtypes, or cultivars was made due to inherent differences among genotypes. Total yield and productivity (402.5 g·m−2 and 4.9 kg/tray/week, respectively) in the FTS were lower than those in the hydroponic system (468.9 g·m−2 and 6.7 kg/tray/week, respectively). Average yields of butterhead and bibb subtypes in aquaponics were higher than in the hydroponic treatment. Bibb subtype lettuces performed better in the aquaponic treatment, and average yields of butterhead and romaine, one of the most popular and nutritious lettuce types, were similar to those in the hydroponic treatment. The cvs. Outredgeous in romaine, Winter Density in bibb, Red Sails in leaf, and Red Saladbowl in oakleaf subtypes were recommended for an FTS. Average yields of green lettuces were higher than red lettuces in the bibb subtype in all treatments. Lettuce yield, depending on cultivar, could be comparable to hydroponic or field production based upon yield per area.