scholarly journals Time and size at seaward migration influence the sea survival of Salmo salar

2014 ◽  
Vol 84 (5) ◽  
pp. 1457-1473 ◽  
Author(s):  
N. Jonsson ◽  
B. Jonsson
1945 ◽  
Vol 6d (4) ◽  
pp. 311-325 ◽  
Author(s):  
A. G. Huntsman

Salmon (Salmo salar) kelts from hatchery operations, when liberated in rivers and in or near river estuaries, show by the distribution of the recaptured fish an extent of seaward migration that varies from river to river, apparently in relation to the character of the estuary and river influence in the sea. For the very large St. John river (N.B.) they are mainly in the long, deepish estuary and rarely leave the zone of river influence, while for the smallish Margaree river (N.S.), with a short, shallow estuary well emptied by the tide, they are mainly near the coast outside the estuary and commonly wander to distant places in various directions. This distribution may (Margaree) or may not (St. John) correspond with that of virgin fish. The Miramichi (N.B.) with strong river influence and long estuary resembles the St. John, while the Annapolis and Philip rivers (N.S.) with slight river influence are more like the Margaree.For each river and location of liberation, the extent of seaward distribution is found to vary with differences in river discharge during a presumed settling-down period after liberation. Sharp freshets are correlated with more riverward distribution at least for a time. Heavy floods are correlated with a more seaward distribution. Continued low water is correlated with a wide distribution.


1989 ◽  
Vol 46 (4) ◽  
pp. 714-719 ◽  
Author(s):  
J. R. Foster ◽  
C. B. Schom

Experiments were conducted to determine if a process similar to imprinting occurs during each seaward migration of Atlantic Salmon (Salmo salar). Displaced Atlantic salmon kelts homed to the site from which they had previously emigrated to sea as smolts (Big Salmon River, New Brunswick, Canada) and did not home to their release sites, or their overwintering sites 150 km away. Delaying release of kelts past the time of normal seaward migration did not cause the behavioral changes associated with interference of the imprinting process described for smolts. Delayed release kelts did not remain near their seawater or estuarine release sites, home to their release sites, or non-selectively home to suitable spawning streams near their release sites. Delayed released kelts travelled away from the release site faster than kelts released during their normal time of seaward migration, but they did not return either to Passamaquoddy Bay or their natal stream in the calendar year of their release (the normal time for this stock) or in subsequent years.


1992 ◽  
Vol 49 (6) ◽  
pp. 1097-1106 ◽  
Author(s):  
Ingemar Berglund ◽  
Monika Schmitz ◽  
Hans Lundqvist

In three years, maximum seawater adaptability in 2-yr-old Baltic salmon (Salmo salar) was found during a period of about 2 wk in late May – early June. At this time the previously mature males developed in one of two directions. One group (8–44%) developed a seawater adaptability comparable with that of immature fish whereas the other did not. Previously mature males that did not adapt to seawater had larger gonadosomatic indices than males with good performance in seawater. Individually tagged previously mature males and immature fish released into the river in spring had a total adult recapture rate of 1.6 and 11.6%, respectively. In both groups the recapture rate was highest for fish released about 2 wk before the time of optimal seawater adaptability. The effect of size on recapture rate was more pronounced among previously mature males than among immature fish, with a particularly low recapture rate of small previously mature males. It is suggested that previously mature male parr can either mature sexually again or complete smoltification in spring and that the probability for smoltification and seaward migration is affected by body size and the conditions for growth during the previous autumn–winter.


2013 ◽  
Vol 20 (1) ◽  
pp. 61-75 ◽  
Author(s):  
Jaime Otero ◽  
Jan Henning L'Abée-Lund ◽  
Ted Castro-Santos ◽  
Kjell Leonardsson ◽  
Geir O. Storvik ◽  
...  

1986 ◽  
Vol 43 (12) ◽  
pp. 2531-2534 ◽  
Author(s):  
Patrick M. Ryan

The number of young Atlantic salmon, Salmo salar, in the spring in two lakes at the headwaters of the Gander River, Newfoundland, was positively correlated (r = 0.99) with the number of smolts in the subsequent seaward migration over a 5-yr period. Angler success (catch per unit effort) in the grilse fishery on the Gander River over a 7-yr period was positively correlated (r = 0.81) with the number of young in the lakes prior to the opening of the angling season of the previous year. Measures of the abundance of young salmon in freshwaters prior to the smolt run can be used to predict the size of the smolt run and allow for compensatory modifications to the adult fishery a year in advance of acticipated low adult returns.


2004 ◽  
Vol 61 (3) ◽  
pp. 328-331 ◽  
Author(s):  
K Håkan Olsén ◽  
Erik Petersson ◽  
Bjarne Ragnarsson ◽  
Hans Lundqvist ◽  
Torbjörn Järvi

Previous studies have shown kin recognition abilities in salmonid fish. Some authors have suggested that the attraction of juvenile fish to siblings may indicate preference for shoaling with kin. The aim of the present study is to test the prerequisite for the hypothesis that siblings swim spatially closer than unrelated fish during their seaward migration as smolts. Atlantic salmon (Salmo salar) eggs from three families were each reared in two tanks to create familiar and unfamiliar sibling smolts. Before the experiment started they were tagged individually withpassive integrated transponders (PITs). Twelve individuals from each of six groups were mixed and released together at several occasions in the upper end of the 400-m-long experimental stream. An automatic PIT-monitoring system placed in the outlet recorded the time for passage of each individual leaving the stream. Eighty-five percent of the juveniles monitored by the PIT antenna showed downstream migration at night hours and they migrated significantly more often closer in time to both known and unknown siblings than to unrelated fish. The results suggest that there is a genetic component in the migratory behaviour of Atlantic salmon smolts and support the hypothesis that smolts migrate in kin-structured groups.


1989 ◽  
Vol 46 (3) ◽  
pp. 410-415 ◽  
Author(s):  
L P. Hansen ◽  
B. Jonsson ◽  
R. I. G. Morgan ◽  
J. E. Thorpe

Sexual maturity of parr reduces the probability of a future seaward migration. In release experiments in two separate years with Atlantic salmon in the Imsa River, Norway, immatures migrated sooner and in significantly higher proportions (P < 0.001) than did previously mature males. Furthermore, higher proportions of 2-yr olds than of 1-yr olds migrated, and 86–92% of the descent occurred at night. Large 2-yr olds migrated before smaller ones. Among those which did not migrate, some (3.2% of those released in 1986) were recaptured in the autumn, of which 91.9% were mature males. At Lussa, Scotland, 5.6 and 5.9% of smolting fish released in two separate years remained resident at the release site throughout the summer, and 91.8 and 93.4% of these matured in the autumn of the release year.


1978 ◽  
Vol 35 (1) ◽  
pp. 60-68 ◽  
Author(s):  
E. M. P. Chadwick ◽  
T. R. Porter ◽  
P. Downton

Growth and sea survival rates decreased with increasing smolt age, with survival being 12, 6, and 3% for 3+, 4+, and 5+ smolt, respectively. All spawning fish were grilse, which suggests that older smolt became large salmon and were thus more vulnerable to the commercial fishery. A density-dependent relationship was observed for 3+ smolt in their 1st yr of growth, but not for older smolt; younger smolt probably spend their juvenile life in a more productive but space-limiting part of the river. Variation between river-system environments may be responsible for the opposing results of studies on Atlantic salmon (Salmo salar) life history. Key words: Salmo salar, growth, sea survival, density dependence, first-year growth, age at smoltification


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