While the prevalence of density-dependence is well-established in population ecology, few field studies have investigated its underlying mechanisms and their relative population-level importance. Here, we address these issues, and more specifically, how differences in body-size influence population regulation. For this purpose, two experiments were performed in a small coastal stream on the Swe...

A natural reach of montane stream (length 96 m and 7 m width) was grided into 150 cells (2 × 2 m). Density and biomass of fish (Salmo trutta L. and Cottus poecilopus Heckel) were estimated at each cell, as well as stream depth, current velocity, Froude number, bed granulation and its roughness were measured, and benthic samples from exposed bricks were collected from mid August to early October...

Brown trout (Salmo trutta) are extensively harvested and its habitat highly influenced by human encroachments. Using a 40-year time series of mark-recapture data we estimate vital rates for a piscivorous trout population. This population spawns upstream of a waterfall, which historically acted as a migration barrier for smaller trout. In 1966, the waterfall was dammed and a fish ladder construc...

Caspian brown trout (Salmo trutta caspius) is one of the economically valuable species in the Caspian Sea. Artificial propagation and production of larvae are the main problems in the early culture of this species. The purpose of this paper is to study the effect of reproductive performance of female broods on opposition reproduction efficiency in Caspian brown trout in the breeding season of 2...

On the basis of the experiments carried out over various years, it was concluded that (1) grayling Thymallus thymallus and brown trout Salmo trutta are resistant to temperature-induced sex reversal at ecologically relevant temperatures, (2) environmental sex reversal is unlikely to cause the persistent sex ratio distortion observed in at least one of the study populations and (3) sex-specific t...

Evidence is reported for balancing selection acting on variation at major histocompatibility complex (MHC) in wild populations of brown trout Salmo trutta. First, variation at an MHC class I (satr-uba)-linked microsatellite locus (mhc1) is retained in small S. trutta populations isolated above waterfalls although variation is lost at neutral microsatellite markers. Second, populations across se...

  Random amplified polymorphic DNA (RAPD) markers were used to estimate genetic relationships between two seasonal immigrant forms (namely fall-run and spring-run) of Caspian trout Salmo trutta caspius. In this regard, 62 fin tissue samples were collected from southern parts of the Caspian Sea basin and examined with 16 oligodecamer primers to asses their genetic diversity as well as probable s...

 The endocrine cells of Salmo trutta macrostigma stomach and pyloric caeca have been investigated using immunohistochemical techniques. 8 antisera were tested and 6 of them were detected in the endocrine cells serotonin, somatostatin, substance P, galanin, CCK and neuropeptide Y. These immunoreactive cells are described for the first time in the stomach and pyloric caeaca of Salmo trutta macros...