Changes in Specific Gravity of Atlantic Salmon (Salmo salar) Alevins

1977 ◽  
Vol 34 (12) ◽  
pp. 2388-2395 ◽  
Author(s):  
R. H. Peterson ◽  
J. L. Metcalfe
Keyword(s):  
Specific Gravity ◽  
Atlantic Salmon ◽  
Key Words ◽  
Water Content ◽  
Salmo Salar ◽  
Artificial Turf ◽  
Atlantic Salmon Salmo Salar ◽  
Lower Specific Gravity ◽  
Length Measurements

The specific gravity of Atlantic salmon (Salmo salar) alevins decreases during posthatching development from 1.067 at hatching to 1.044 at terminal yolk resorption. The water content of the embryo is ca. 84% throughout posthatching development while that of the yolk is ca. 56%. Therefore, as the embryo grows at the expense of yolk material, the water content of the alevin increases during development. This increase in water content can entirely account for the observed change in specific gravity. Alevins reared at lower temperatures have a higher specific gravity for any given embryonic length, implying the presence of more yolk reserves. Splake alevins reared in a hatchery tray had a lower specific gravity at a given length than did alevins reared in gravel or artificial turf substrates. Measurements of specific gravity in conjunction with length measurements during development may be useful in comparing different incubation conditions. Key words: specific gravity, Atlantic salmon, alevin, yolk, embryo, water content, temperature, splake

Feeding by Hatchery-Reared and Wild Atlantic Salmon (Salmo salar) Parr in Streams

1979 ◽  
Vol 36 (11) ◽  
pp. 1408-1412 ◽  
Author(s):  
A. J. Sosiak ◽  
R. G. Randall ◽  
J. A. McKenzie
Keyword(s):  
Atlantic Salmon ◽  
Key Words ◽  
Salmo Salar ◽  
Food Selection ◽  
Stomach Contents ◽  
Stomach Fullness ◽  
Size Dependent ◽  
Atlantic Salmon Salmo Salar ◽  
Feeding Experience ◽  
Salmon Parr

Hatchery-reared Atlantic salmon (Salmo salar) parr were captured 1–3 mo after release in streams, along with wild parr from the same streams. Identification of their stomach contents showed total number of organisms and number of taxa per stomach were greater and there was a higher index of stomach fullness in wild than in hatchery parr resident ≤ 2 mo in a stream. Wild parr consumed more Brachycentridae, Hydroptilidae, Diptera, and Plecoptera than did hatchery parr, but sometimes less Odontoceridae and Heptageniidae. These differences may have arisen from size-dependent food selection, the effects of feeding experience, or possible microhabitat differences between wild and hatchery parr. Key words: salmon parr, hatchery-reared, wild, feeding

Variation in Age at First Spawning in Atlantic Salmon (Salmo salar)

1978 ◽  
Vol 35 (1) ◽  
pp. 145-147 ◽  
Author(s):  
Gunnar Nævdal ◽  
Marianne Holm ◽  
Oscar Ingebrigtsen ◽  
Dag Møller
Keyword(s):  
Atlantic Salmon ◽  
Key Words ◽  
Salmo Salar ◽  
Life Histories ◽  
Salmon River ◽  
Atlantic Salmon Salmo Salar ◽  
Mature Fish ◽  
Maturation Age

Significant differences in the proportion of mature fish in groups of Atlantic salmon (Salmo salar) of different river origins maintained under the same conditions were observed during the 1st and 2nd yr of sea rearing. Nearly all fish in sib groups originating from grilse rivers matured during the 2nd sea year, while few or no mature fish were found in the groups originating from rivers producing mainly multi-sea-winter salmon. The observations were in accordance with the life histories of the different river populations, indicating that salmon inherit rather than acquire a tendency to mature at a certain age. Key words: Atlantic salmon, maturation age, cultured salmon, river populations

Leaping Behavior of Juvenile Coho (Oncorhynchus kisutch) and Atlantic Salmon (Salmo salar)

1978 ◽  
Vol 35 (6) ◽  
pp. 907-909 ◽  
Author(s):  
Philip E. K. Symons
Keyword(s):  
Atlantic Salmon ◽  
Key Words ◽  
Freshwater Fish ◽  
Salmo Salar ◽  
Environmental Conditions ◽  
Temperature Effects ◽  
Species Differences ◽  
Oncorhynchus Kisutch ◽  
Atlantic Salmon Salmo Salar ◽  
Key Words Fish

Juveniles of coho (Oncorhynchus kisutch) and Atlantic salmon (Salmo salar) proved capable of leaping falls at least 5 body lengths in height. No species differences were apparent: both species leapt lower falls (12 cm) more readily than higher ones (27 and 57 cm) and proportionately more leaps occurred on days with temperatures between 14.0 and 17.0 °C than on days with lower temperatures. Key words: fish, freshwater fish, behavior, migrations, environmental conditions, temperature effects

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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