Decabromodiphenyl ether (BDE 209), the major congener in the high volume industrial flame retardant mixture "DecaBDE", has recently been shown to be metabolized by carp. To further explore this phenomenon, juvenile rainbow trout were exposed to BDE 209 via the diet for a five month period. Analysis of the whole body homogenate, liver, serum, and intestinal tissues revealed that BDE 209 accumulated in rainbow trout tissues and was most concentrated in the liver. In addition to BDE 209, several hepta-, octa-, and nonaBDE congeners also accumulated in rainbow trout tissues over the same period as a result of BDE 209 debromination. Based on the total body burden of the hepta- through decaBDE congeners, uptake of BDE 209 was estimated at 3.2%. Congener profiles were different among whole body homogenate, liver, and serum, with the whole body homogenates having a greater contribution of the debrominated biotransformation products. Extracts of the rainbow trout whole body homogenates were compared with extracts from a previous experiment with common carp. This comparison revealed that BDE 202 (2,2',3,3',5,5',6,6'-octabromodiphenyl ether) was a dominant debromination product in both studies. To determine whether the observed debromination was metabolically driven, liver microsomal fractions were prepared from both common carp and rainbow trout. Analysis of the microsomal fractions following incubation with BDE 209 revealed that rainbow trout biotransformed as much as 22% of the BDE 209 mass, primarily to octa- and nonaBDE congeners. In contrast, carp liver microsomes biotransformed up to 65% of the BDE 209 mass, primarily down to hexaBDE congeners. These microsomal incubations confirm a metabolic pathway for BDE 209 debromination.

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Accurate prediction of meat yield in live animals may allow more efficient genetic improvement of meat yield in farm-raised catfish. An initial trial with 30 channel catfish demonstrated significant correlations among weight-adjusted residuals for muscle area measured from transverse ultrasound images and transverse sections at five locations along the trunk musculature (r = 0.30 to 0.70). Relationships of weight-adjusted residuals for three meat yield traits (carcass, whole fillet, and shank fillet) with weight-adjusted residuals for 15 external body shape measurements and five transverse ultrasound measurements of muscle area were determined for 51 female and 91 male channel x blue catfish backcross hybrids. Compared to males, females had smaller heads; deeper, wider, shorter bodies; larger ultrasound muscle area; and higher meat yield. Correlations between carcass traits and body shape and carcass traits and ultrasound measurements were generally higher for females than for males. Correlations among carcass traits and ultrasound muscle area were typically higher than correlations among carcass traits and external body shape in both sexes. A single ultrasound measurement explained 40 to 50% and 16 to 23% of the variation in meat yield traits of females and males, respectively. The best three-variable model using ultrasound and body shape traits explained 48 to 56% and 31 to 38% of the variation in meat yield traits in females and males, respectively. Differences between males and females for the variability in meat yield traits explained by the models may be related to sexual dimorphism for body shape and fillet yield observed in catfish. Ultrasound has potential for predicting meat yield in live fish, but improved prediction accuracy is needed. Differences in meat yield traits between males and females and among individuals within sexes suggest that selecting for fish with smaller heads and deeper, shorter body shape posterior to the visceral cavity will increase meat yield in catfish.

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