David A. Stuiber

Raising marketable yellow perch on a polychlorinated biphenyl contaminated diet: a feasibility study for the perch aquaculture industry.

The objective was to determine the feasibility of feeding yellow perch a PCB-contaminated diet without adversely affecting their rate of growth and without exceeding 5 ppm in the fillet. To determine the extent to which the fillet (skeletal muscle and skin) accumulates PCB, assessment was made of the whole body elimination and tissue distribution of a single PCB isomer [14C] 2,5,2′,5′-tetrachlorobiphenyl (4-CB) in fingerling and adult perch exposed to a single oral dose of 0.8 μg of [14C] 4-CB. Elimination and distribution of 4-CB was determined at regular intervals for five weeks after dosing. Fingerlings were found to eliminate 4-CB more rapidly than adults but the tissue distribution pattern of 4-CB residues not eliminated was similar in the two age groups. The carcass and viscera contained about 85% of 4-CB residues in the whole fish and 15% in the fillet. For chronic exposure to PCB-contaminated diets, perch fingerlings were reared under standardized aquaculture conditions that provided an optimal rate of growth. They were fed for 32 weeks either a control diet containing 0.2 ppm PCB or an experimental diet formulated from alewife meal that contained 1.8 ppm PCB. The data showed that growth of perch on the two diets was similar and that PCB concentrations in harvested fillets was less than 0.7 ppm. The significance of these findings is that the perch aquaculture industry may be able to feed lower cost PCB-contaminated diets and still harvest yellow perch fillets that meet U.S. Food and Drug Administration guidelines of 5 ppm for human food.

Inhibition of trout gill and soybean lipoxygenases by organotin compounds

Activity of trout gill and soybean lipoxygenase was inhibited by various low concentrations of tri-n-butyltin, di-n-butyltin and n-butyltin chlorides at pH 7.8. Tri-n-butyltin (0.044-0.19 mM; 8-100% inhibition) was significantly more inhibitory against trout gill lipoxygenase than di-n-butyltin (0.1-0.27 mM; 17-39% inhibition) or n-butyltin (1.2-3.6 mM; 26-43% inhibition). Soybean lipoxygenase displayed a similar sensitivity to the inhibitory effects of organotin compounds at pH 7.8. Although tri-n-butyltin (0.067-0.2 mM; 13-68% inhibition) was less inhibitory to soybean lipoxygenase, di-n-butyltin (0.134-0.537 mM; 51-75% inhibition) and n-butyltin (0.41-1.23 mM; 33-75% inhibition) were more inhibitory towards soybean lipoxygenase compared with trout gill lipoxygenase. Concentrations of butyltins required to provide substantial inhibition of trout gill lipoxygenase were of the order of magnitude of those reported for lethal water exposure concentrations of these compounds for trout and other fishes when bioaccumulation factors are considered. Thus, it is proposed that inhibition of lipoxygenase likely contributes to the biocidal activity of organotin compounds.

Evaluation of Burbot (Lota lota) Acceptability for Processing

Abstract Burbot ( Lota lota ) collected from Lakes Michigan and Superior yielded about 35% total fillets, but high quality anterior fillet sections were limited to yields of 15-20%. Development of severe surface-browning and excessive drip and cooking losses as a result of freezing or refrigerated storage were inhibited by dipping fillets in sodium tripolyphosphate solutions. Descriptive and preference sensory analysis showed that anterior burbot fillet sections prepared into fish sticks and portions, minced fish sticks, and chunks for poaching were similar in quality to commercially obtained cod, haddock, and pollack products. Burbot fillets were quite stable to oxidative deterioration during frozen storage, and Lake Michigan burbot fillets contained less than 1 ppm chlorinated hydrocarbon microcontaminants on a wet weight basis.