Angling Success for Atlantic Salmon (Salmo salar) in the River Wye in Relation to Effort and River Flows

Salmon catch and effort data for 1977 from ten private fisheries on the River Wye are analysed and discussed. The 555 salmon caught represent 10.7% of the total Wye rod catch and the mean angling success rate of 0.045 ± 0.022 salmon per angler-hour, equivalent to about 22 h per salmon, compares favourably with that for other rivers in Britain and Canada. Over 75% of all salmon caught were 2 sea-winter fish, the age distribution of salmon caught in the sample being similar to those for the whole river. Angling success in the upper reaches during July and August may have been reduced by limited availability affected by water temperatures too high for migration, Flows most suitable for successful angling in each fishery are compared in relation to distance from the estuary and long-term average daily flows. Salmon appeared to be caught nearer the crest of a spate in the upper compared with the lower reaches of the river and this difference is discussed.     

Role of catalase in the virulence of Brucella melitensis in pregnant goats

An isogenic katE mutant derived from virulent Brucella melitensis 16M displays hypersensitivity to hydrogen peroxide in disk sensitivity assays but retains the capacity to colonize pregnant goats and induce abortion. These experimental findings indicate that although the sole periplasmic catalase of Brucella melitensis functions as an antioxidant, this enzyme does not play a critical role in virulence in the natural host.     

Determination of pyrethroid residues in agricultural products by an enzyme-linked immunosorbent assay

To determine cypermethrin and permethrin in agricultural products, a competitive enzyme-linked immunosorbent assay (ELISA) method was employed. The matrix interferences were minimized by direct dilution of the extracts. No further cleanup was needed. A minimum matrix effect with a 1:10 dilution of white wine for cypermethrin and a 1:200 dilution of red and white wines, fruits, and vegetables for permethrin was found when phosphate-buffered saline containing 40% methanol was employed as the diluent. Good recoveries of spiked levels were observed. The mean percentage recoveries of cypermethrin spiked in white wine and permethrin spiked in red and white wines were 99.7, 74, and 78%, respectively. The mean percentage recoveries of permethrin spiked in apple, banana, cucumber, lettuce, onion, and peach were 99.2, 105, 70.2, 97.5, 94.4, and 89.4%, respectively. Validation of the ELISA method with permethrin-spiked lettuce and peach was carried out using gas chromatography with mass spectrometry, resulting in a good recovery and correlation.