A small group of lakes near Rotorua has been the sub ject of research by the Marine Department for a number of years to determine the rate of growth of the resident rainbow trout (Salmo gairdnerii) (Smith 1959) and the effect of increasing these trout populations by artificial stocking with hatchery-reared fingerlings. As a result, fish size in some lakes has been noticeably reduced in recent y...

Proliferative kidney disease in brown trout – infection level, pathology and mortality under field 1 conditions 2 3 Heike Schmidt-Posthaus, Regula Hirschi, Ernst Schneider 4 5 Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University 6 of Berne, Laenggassstrasse 122, P.O. Box 8466, 3001 Berne, Switzerland 7 Alte Landstrasse 156, 8800 Thalwil, Switzerlan...

Sexual maturation of rainbow trout during production has a negative effect on the slaughter yields and flesh quality. Induction of triploidy is a method to prevent the development of fertile trout. In many investigations sexually mature triploid and diploid rainbow trout had been compared. In the present study the slaughter characteristics and flesh quality of female immature diploid and triplo...

—Management of the effects of water quality and flow on fisheries requires an understanding of the factors that control fish movements. We used radiotelemetry to monitor the movements of adult brown trout Salmo trutta in a New Zealand river over 11 months (September 2004 to August 2006) and linked those movements to the changes in flow and water temperature. Individual fish moved up to 41 km du...

Proliferative kidney disease in brown trout – infection level, pathology and mortality under field 1 conditions 2 3 Heike Schmidt-Posthaus, Regula Hirschi, Ernst Schneider 4 5 Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University 6 of Berne, Laenggassstrasse 122, P.O. Box 8466, 3001 Berne, Switzerland 7 Alte Landstrasse 156, 8800 Thalwil, Switzerlan...

Long-term preservation of fish fertility is essential for the conservation of endangered fishes. However, cryopreservation techniques for fish oocytes and embryos have not yet been developed. In the present study, functional eggs and sperm were derived from whole rainbow trout that had been frozen in a freezer and stored without the aid of exogenous cryoprotectants. Type A spermatogonia retriev...

The desaturation and elongation of [1-(14)C]18:3n-3 was investigated in hepatocytes from different populations and three different species of salmonids indigenous to Scotland, brown trout, Atlantic salmon and Arctic charr. Two groups of fish were sampled, before and after they were fed two experimental diets, a control diet containing fish oil and a diet containing vegetable oil (a 1:1 blend of...

Traditionally, fish meal and fish oil have been used as main sources of proteins and energy in the commercial fish feeds. Nowadays these ingredients have been partially substituted with materials of plant-origin (e.g. maize, wheat and soy) due to their more inexpensive price and easier availability. If contaminated plant material is used in the making of fish feed, the finished product can cont...

Reliable fish condition estimates help managers better understand ecosystem population dynamics. Therefore, our study objectives were to measure seasonal changes in percent dry weight and energy density (physiological-based measures of condition) of stream-dwelling Appalachian Brook Trout Salvelinus fontinalis, field-validate bioelectrical impedance analysis (BIA) models, and compare reliabilit...

The purpose of this investigation was to explore the ontogeny of certain respiratory responses of rainbow trout. Adult trout respond to hypoxia with an increase in the flow of water over the respiratory surfaces, and with a reflex bradycardia (Holeton & Randall, 1967). When adult rainbow trout are exposed to 5% carbon monoxide (CO) and thus rendered anoxaemic while at the same time their arteri...