No abstract

The biological half-life [Formula: see text] of 31 dichloro- to decachloro-biphenyl congeners were monitored for 105 d in adult rainbow trout (Salmo gairdneri) that were exposed to a single oral dose. In whole fish [Formula: see text] increased from 5 d to no apparent elimination as the number of chlorines on the biphenyl increased. This structure–activity relationship was not as evident in muscle where [Formula: see text] ranged from < 5 to 127 d. We suggest the decline in muscle resulted from decreasing lipid levels and the redistribution of congeners within the fish. From structure–activity analysis of [Formula: see text] in whole fish we conclude that elimination is enhanced for those congeners with lower chlorine content, with no chlorine substitutions in the ortho positions, and those with two unsubstituted carbons that are adjacent (vicinal) on the biphenyl. A significant decline in total PCB content in whole fish, equivalent to a [Formula: see text] of 219 d, was partly due to the composition of the PCB mixture administered, and the selective elimination of the lower chlorinated biphenyls.

Rainbow trout (Salmo gairdneri), white sucker (Catostomus commersoni), white bass (Morone chrysops), smallmouth bass (Micropterus dolomieui), and yellow perch (Perca flavescens) were collected from Lakes Ontario and Erie to examine the relationship between contaminant levels in females and their eggs. Factors such as the percent lipid in the fish and percent of total lipid deposited in the eggs significantly influenced (P < 0.01) contaminant transfer. The percentages of the 9–11 organic contaminants transferred generally showed less variation within a species than the percentages for a substance transferred among the five species examined. This relationship was consistent even though there was over a 10-fold range in contaminant concentrations within a given species. Mercury did not demonstrate this response because the percentage in eggs was low for all species. The levels of PCB monitored in eggs of rainbow trout collected from Lake Ontario suggest that egg and fry survival rates could be affected based on the toxicological evidence from other studies. An examination of the possible effects of spawning on the kinetics of contaminants among these species suggests that relative body concentrations of organic contaminants may be decreased by 5% or be increased by 10%, and mercury levels may be increased by 6–22% following the deposition of eggs. The amount of change varies with species and is influenced by the percent egg weight of body weight, and the rate of contaminant transfer from females to eggs.Key words: toxicology, contaminants, reproduction, Lake Ontario, Lake Erie

No abstract

Changes in growth and proximate body composition of largemouth bass (Micropterus salmoides) were examined for fish of 8–150 g, between 18 and 30C. For most weights, growth of fish (grams/day) was highest at 25C, and lowest in fish at 18C. This was attributable in part to a higher satiation (maximum) feeding level at 25C. For a fixed level of feeding, growth rate (percentage wet weight/day) was highest for fish held at 18C.Lipid content (percentage wet weight) increased with feeding level and was highest at 18C, Moisture content varied inversely with lipid. Protein and ash content did not vary appreciably with temperature, body weight, or feeding level.Maintenance requirement of bass, expressed as grams/day, was about twice that lost during food deprivation, but only slightly different when expressed as kilocalories/day.Energy requirements for nonfecal losses were estimated as 10% of intake energy at all feeding levels. Standard metabolism accounted for 50% of intake energy near maintenance, but only 10% at the satiation feeding level. Growth requirements increased From zero at maintenance to 40% of intake energy at satiation feeding.