A technique for the hypophysectomy of the brown trout is described which might be applicable to other salmonids. Hypophysectomy produced a decrease in water turnover which was corrected by prolactin therapy. Hypophysectomy resulted in a decrease in the next flux of osmotic water. Both osmotic and diffusional water permeabilities were evenly decreased after hypophysectomy, such that the ratio of...

It has long been known that brown trout (Salmo trutta Linn.) grow to different sizes in different waters, and there has been much speculation concerning the factors determining these differences. Dahl (1918-19) suggested that the food supply and the degree of crowding were important; also that small, slowly growing trout were derived from smaller ova than those growing more rapidly. Southern (1...

Reaction norms are a valuable tool in evolutionary biology. Lately, the probabilistic maturation reaction norm approach, describing probabilities of maturing at combinations of age and body size, has been much applied for testing whether phenotypic changes in exploited populations of fish are mainly plastic or involving an evolutionary component. However, due to typical field data limitations, ...

Subsidies of energy and material from the riparian zone have large impacts on recipient stream habitats. Human-induced changes, such as deforestation, may profoundly affect these pathways. However, the strength of individual factors on stream ecosystems is poorly understood since the factors involved often interact in complex ways. We isolated two of these factors, manipulating the flux of terr...

Exotic species present a great threat to native fish conservation; however, eradicating exotics is expensive and often impractical. Mechanical removal can be ineffective for eradication, but nonetheless may increase management effectiveness by identifying portions of a watershed that are strong sources of exotics. We used mechanical removal to understand processes driving exotic brown trout (Sa...

Density-dependence is a major ecological mechanism that is known to limit individual growth. To examine if compensatory growth (unusually rapid growth following a period of imposed slow growth) in nature is density-dependent, one-year-old brown trout (Salmo trutta L.) were first starved in the laboratory, and then released back into their natural stream, either at natural or at experimentally i...

We applied the adaptive management approach to analyze the demand and feasibility of adaptive management of fish stocks in a large regulated lake, Oulujärvi, in northern Finland. The process consisted of four phases: (1) analysis of the current state of the fisheries system (fishers, related markets and industry, fisheries researches and authorities, related organizations, etc.); (2) analysis o...

Metabolic rates reflect the energetic cost of living but exhibit remarkable variation among conspecifics, partly as a result of the constraints imposed by environmental conditions. Metabolic rates are sensitive to changes in temperature and oxygen availability, but effects of food availability, particularly on maximum metabolic rates, are not well understood. Here, we show in brown trout (Salmo...

The reproductive characteristics of 2 brown trout (Salmo trutta) populations were examined in 2 tributaries, the Anuri and Cenker streams, of the Çoruh River, north-eastern Turkey. Sampling was carried out by electrofishing monthly from November 2000 to October 2002. Age varied from 0 to 6 in the Anuri Stream, and from 0 to 7 in the Cenker Stream. Fork length (L) ranges were 4.29-29.9 cm and 3....