Population estimates of juvenile Atlantic salmon, Salmo salar, as indices of smolt production in the R. Scorff, Brittany

1986 ◽  
Vol 29 (4) ◽  
pp. 467-482 ◽  
Author(s):  
J.-L. Bagliniere ◽  
A. Champigneulle
1983 ◽  
Vol 40 (6) ◽  
pp. 671-680 ◽  
Author(s):  
D. M. Rimmer ◽  
U. Paim ◽  
R. L. Saunders

Autumnal changes in behavior and distribution of three age-classes of juvenile Atlantic salmon (Salmo salar) were determined during 3 yr in the Little Sevogle River of northeastern New Brunswick. In summer, salmon were always observed above the streambed, each holding a station over a single, unshaded stone. About 84% of the entire population occurred in the run habitat-type, 12% in riffles and 5% in pools. Underwater visual censuses showed the salmon to be continuously numerous in summer, but, as soon as water temperature fell to or below 10 °C in autumn, they disappeared from their stations and their visible population decreased by 92–98%. Thereafter, the salmon were found almost exclusively in sheltered substrate chambers beneath surface streambed stones. However, salmon distribution among runs, riffles, and pools (77, 18, and 5%, respectively) did not differ significantly from that in summer. Trapping, marking, and absolute population estimates indicated neither dwindling nor egress of the resident population. Thus, instead of suddenly leaving the river area or moving to another habitat-type at low temperatures, the salmon merely moved from their unsheltered summer stations to sheltered winter stations within the streambed. The results indicate the importance of winter habitat management in managing juvenile Atlantic salmon populations.


2015 ◽  
Vol 41 (4) ◽  
pp. 1029-1051 ◽  
Author(s):  
Kirsten O. Hannesson ◽  
Elisabeth Ytteborg ◽  
Harald Takle ◽  
Grethe Enersen ◽  
Grete Bæverfjord ◽  
...  

1999 ◽  
Vol 56 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
Sveinn K Valdimarsson ◽  
Neil B Metcalfe

Traditionally, behavioural studies on juvenile Atlantic salmon, Salmo salar, have been conducted during the day in summer. It is known that Atlantic salmon become nocturnal in winter, but very little is known about their behaviour at that time. Therefore, observations in a seminatural stream were carried out during the day and night, from February to June, comparing diel and seasonal differences in behaviour between fish adopting alternative life history strategies. The results showed a general trend for more activity in spring than in winter, and the fish were found to be foraging at surprisingly low light levels. There were differences in relative feeding rate between the life history strategies; the early migrant fish foraged mostly during the day whereas the delayed migrant fish did more foraging at night. There is some evidence that the early migrant fish made fewer feeding attempts over the winter, which is surprising, since they grow faster over that period. This suggests differences in foraging efficiency, which could contribute to the separation into these two life history strategies.


2001 ◽  
Vol 15 (6) ◽  
pp. 701-711 ◽  
Author(s):  
B. JONSSON ◽  
T. FORSETH ◽  
A. J. JENSEN ◽  
T. F. NAESJE

1969 ◽  
Vol 26 (9) ◽  
pp. 2535-2537 ◽  
Author(s):  
J. H. C. Pippy

Bacterial kidney disease was presumptively identified in each of 25 hatchery-reared juvenile salmon (Salmo salar) but in only 2 of 235 wild juveniles in the Margaree River system. Apparently spread of disease from the hatchery to wild salmon in the river is very gradual.


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