The prevalence of serum antibodies against Saprolegnia parasitica in wild and farmed brown trout Salmo trutta from the province of Le6n (NW Spain) was studied by enzyme-linked immunosorbent assay (ELISA). Blood samples from healthy and Saprolegnia-infected brown trout were collected over 2 yr with a seasonal periodicity (January, April, July and October) from a hatchery and river with frequent ...

—In regional survey studies of habitat and fish assemblages, potentially important biological interactions can be masked by strong gradients in habitat variables and associated collinearities among biological variables. We used structural equation modeling to compare the causal influences of local habitat and biotic factors on fish density in rivers and to determine the extent to which the set ...

Between species and across season variation in growth was examined by tagging and recapturing individual brook trout Salvelinus fontinalis and brown trout Salmo trutta across seasons in a small stream (West Brook, Massachusetts, U.S.A.). Detailed information on body size and growth are presented to (1) test whether the two species differed in growth within seasons and (2) characterize the seaso...

Predation during early life history is an important component of fitness in salmonids. Farmed Atlantic salmon display lower survival in the wild in comparison to wild salmon; however, the underlying mechanisms remain unknown. Salmon eggs from 69 families of farmed, hybrid and wild parentage were planted into a river. Following swim-up, 760 brown trout predators were non-lethally sampled. Of the...

Skin removal is a generally accepted method to reduce exposure to contaminants through fish consumption. However, inconsistent results from studies on the effectiveness of this method suggest influence of other factors such as characteristics of contaminants and fish species. This study investigated the effects of skin removal on the lipid contents and concentrations of total mercury, α-chlorda...

For semi-anadromous brown trout, the decision whether or not to smoltify and migrate to the sea is believed to be made at the end of the preceding summer in response to both local environmental conditions and individual physiological status. Stressors experienced during the fall may therefore influence their propensity to migrate as well as carry over into the winter resulting in mortality when...

In the first part of this paper, we review the evolutionary aspects of age and longevity in fish and then summarize the theory of maturity due to Ray Beverton. This theory allows one to predict age at maturity (and thus a putative point for the onset of senescence) from information on growth rate and mortality rate. We illustrate the application of this theory with data on tilapia species and t...

The detection of low levels of pharmaceuticals in aquatic environments has lately raised concerns regarding possible adverse effects of these highly active substances on aquatic organisms. The non-steroidal anti-inflammatory drug diclofenac (DCF) is one of the pharmaceutical substances regularly detected in surface waters and has lately been demonstrated to elicit adverse effects in salmonid sp...

The red coloration of rainbow trout muscle is an important quality criterion. Duplicate groups of rainbow trout (Oncorhynchus mykiss; initial weight of 200±10g) were fed diets either supplemented 0 (control), 0.5, 2, or 4%, of the Caspian Sea gammarus (Pontogammarus maeoticus) respectively as a prospective alternative carotenoid source. The feeding trial lasted for 39 days. No significan...