Spatial variation in environmental characteristics of Atlantic salmon (Salmo salar) rivers

1998 ◽  
Vol 55 (S1) ◽  
pp. 267-280 ◽  
Author(s):  
Scott R Elliott ◽  
Treva A Coe ◽  
James M Helfield ◽  
Robert J Naiman
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Riparian Forest ◽  
Full Range ◽  
Anthropogenic Disturbances ◽  
Physical Factors ◽  
Physical Habitat ◽  
Atlantic Salmon Salmo Salar ◽  
Biological Variables ◽  
Rivers And Streams

Rivers and streams occupied by anadromous Atlantic salmon (Salmo salar) occur across a diverse array of landscapes. This article describes the general ecology of these rivers and streams, including many of the physical and biological variables that are important characteristics of all lotic systems. For analytical purposes, the geographic range of Atlantic salmon rivers is divided into five regions, based on geomorphology and climate. The physical habitat available to anadromous Atlantic salmon is diverse. The geology varies from granitic bedrock to volcanic and glacial substrates, which influence a broad array of other ecological variables, ranging from water chemistry to catchment morphology (e.g., river length). Flood regimes and system hydrology are dependent, as expected, on climate. Many of the catchments receive substantial precipitation in the form of snow; rivers in four of the five regions experience primarily spring freshets. Aquatic temperatures are also variable, representing close to the full range of thermal tolerance of S. salar, with lows just above 0°C in the northernmost latitudes to summer highs in western Europe approaching 25°C. Most rivers are best characterized as oligotrophic with relatively low annual primary productivity. However, physical factors such as availability of suitable spawning and rearing habitat, as well as aquatic temperature and flow regimes, may drive anadromous productivity. In general, most of the rivers have been modified by flow regulation and many suffer from impacts related to other anthropogenic disturbances, principally riparian forest clearing for agriculture, forestry, and urban development. We conclude that the rivers and streams occupied by anadromous Atlantic salmon are diverse across the species' range and have been heavily impacted by anthropogenic disturbances.

Age at Sexual Maturity in Icelandic Stocks of Atlantic Salmon (Salmo salar)

1983 ◽  
Vol 40 (9) ◽  
pp. 1456-1468 ◽  
Author(s):  
Dennis L. Scarnecchia
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Sexual Maturity ◽  
Physical Factors ◽  
Thermal Gradients ◽  
Ocean Temperature ◽  
Growth And Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Life History Pattern ◽  
Second Year

For Icelandic stocks of Atlantic salmon (Salmo salar) in 77 rivers, the combination of June ocean temperature, length of river ascended by the salmon, discharge of the river in July–September, and latitude explained much of the variation in percentages of grilse — 72% for females and 62% for males. For both sexes, percentage of grilse was directly related to ocean temperature but inversely related to length of river, discharge of river, and latitude. For stocks in 23 Southwest Coast rivers, length of river explained 72% of the variation in percentage of females that were grilse. Females in stocks south of the thermal gradients separating Atlantic from Arctic or Polar water tended to return as grilse; females north of the gradients tended to return after more than one winter at sea. The decline in percentages of grilse clockwise from southwestern to northeastern rivers corresponded closely with the decline in June ocean temperatures between these areas. I hypothesize that the salmon stocks have adapted their age at sexual maturity to the length and discharge of the rivers, natural mortality rates during their second year at sea, and average expected ocean temperatures, reflecting conditions for growth and survival, that the smolts encounter. Age at maturity appears not to be a direct causal response to any of these physical factors, and appears best understood only with reference to the entire life history pattern of each stock.

Atlantic salmon (Salmo salar) in winter: "the season of parr discontent"?

1998 ◽  
Vol 55 (S1) ◽  
pp. 161-180 ◽  
Author(s):  
R A Cunjak ◽  
T D Prowse ◽  
D L Parrish
Keyword(s):  
Atlantic Salmon ◽  
Interannual Variability ◽  
Salmo Salar ◽  
Specific Reference ◽  
Physical Habitat ◽  
Running Waters ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Abundance ◽  
Strong Relation ◽  
Break Up

Winter is a dynamic period. Effects of the winter regime on northern streams and rivers is extremely variable and characterized by dramatic alterations in physical habitat to which Atlantic salmon (Salmo salar) must acclimate and adapt to survive. In this paper, we synthesize recent advances in the biological and hydrologic/ geomorphic disciplines, with specific reference to Atlantic salmon overwintering in the freshwater portions of those running waters subject to freezing water temperatures. The specific requirements and adaptations for surviving winter at the three distinct life-stages in freshwater (egg, parr, kelt) are identified in relation to the characteristics of three biophysical phases: early winter (temperature decline and freeze-up), midwinter (ice growth and habitat reduction), and the break-up/warming phase. In a case study of Catamaran Brook (New Brunswick), a hydro-ecological analysis was used to explain interannual variability in juvenile abundance, especially for young-of-the-year salmon. A strong relation was found between winter discharge and interstage survival (egg to 0+, 0+ to 1+, 1+ to 2+) in 5 of 6<~>years. That is, juvenile salmon abundance in summer was highest following winters with high streamflow, presumably a function of habitat availability, especially beneath ice cover. However, the lowest measured egg-0+ survival (9.2%) was related to an atypical midwinter, dynamic ice break-up triggered by a rain-on-snow event that resulted in severe scouring of the stream-bed and redds. Thus, interannual variability in Atlantic salmon parr abundance from 1990 to 1996 was largely explained by density-independent (environmental) constraints to winter survival. The complexity of stream processes during winter underscores the need for interdisciplinary research to quantify biological change.

Microstructure and texture of fresh and smoked Atlantic salmon, Salmo salar L., fillets from fish reared and slaughtered under different conditions

2001 ◽  
Vol 32 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Sjofn Sigurgisladottir ◽  
Margret S. Sigurdardottir ◽  
Helga Ingvarsdottir ◽  
Ole J. Torrissen ◽  
Hannes Hafsteinsson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar

Persistence of Orally Administered Salmonella enterica Serovars Agona and Montevideo in Atlantic Salmon (Salmo salar L.)

2005 ◽  
Vol 68 (7) ◽  
pp. 1336-1339 ◽  
Author(s):  
L. L. NESSE ◽  
T. LØVOLD ◽  
B. BERGSJØ ◽  
K. NORDBY ◽  
C. WALLACE ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Salmonella Enterica ◽  
Most Probable Number ◽  
Fish Feed ◽  
Internal Organs ◽  
Probable Number ◽  
Atlantic Salmon Salmo Salar ◽  
Gastric Intubation

The objective of our experiments was to study the persistence and dissemination of orally administered Salmonella in smoltified Atlantic salmon. In experiment 1, salmon kept at 15°C were fed for 1 week with feed contaminated with 96 most-probable-number units of Salmonella Agona per 100 g of feed and then starved for 2 weeks. Samples were taken from the gastrointestinal tract and examined for Salmonella 1, 2, 8, 9, 15, and 16 days after the feeding ended. In experiment 2, Salmonella Agona and Montevideo were separately mixed with feed and administered by gastric intubation. Each fish received 1.0 × 108, 1.0 × 106, or 1.0 × 104 CFU. The different groups were kept in parallel at 5 and 15°C and observed for 4 weeks. Every week, three fish in each group were sacrificed, and samples were taken from the skin, the pooled internal organs, the muscle, and the gastrointestinal tract and examined for the presence of Salmonella. The results from the two experiments showed that the persistence of Salmonella in the fish was highly dependent on the dose administered. Salmonella was not recovered from any of the fish that were fed for 1 week with the lowest concentration of Salmonella. In the fish given the highest dose of Salmonella, bacteria persisted for at least 4 weeks in the gastrointestinal tract as well as, to some extent, the internal organs. The present study shows that under practical conditions in Norway, the risk of Salmonella in fish feed being passed on to the consumer of the fish is negligible.

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