scholarly journals Distribution by origin and sea age of Atlantic salmon (Salmo salar) in the sea around the Faroe Islands based on analysis of historical tag recoveries

2012 ◽  
Vol 69 (9) ◽  
pp. 1598-1608 ◽  
Author(s):  
Jan Arge Jacobsen ◽  
Lars P. Hansen ◽  
Vegar Bakkestuen ◽  
Rune Halvorsen ◽  
David G. Reddin ◽  
...  

Abstract Jacobsen, J. A., Hansen, L. P., Bakkestuen, V., Halvorsen, R., Reddin, D. G., White, J., Ó Maoiléidigh, N., Russell, I.C., Potter, E. C. E., Fowler, M., Smith, G. W., Mork, K. A., Isaksson, A., Oskarsson, S., Karlsson, L., and Pedersen, S. 2012. Distribution by origin and sea age of Atlantic salmon (Salmo salar) in the sea around the Faroe Islands based on analysis of historical tag recoveries. – ICES Journal of Marine Science, 69: 1598–1608. A database of 2651 tags applied to Atlantic salmon (Salmo salar) smolts in 13 countries or jurisdictions and recovered in the Faroes longline salmon fishery from 1968 to 2000 was analysed for geographic distribution and origin of the salmon captured with respect to differences in sea age, season of the fishery, and hydrographic features in the Faroes area. The results indicated that salmon were not distributed randomly in the Faroes area by fishing season, sea age, or country of origin. The distribution of salmon in the Faroes zone partly depends on their geographic origin; salmon from countries in the northern European stock complex were distributed significantly farther northeast than those from countries in the southern European stock complex. Furthermore, the proportion of tag recoveries from southern European countries was higher in autumn, and the proportion recovered from northern European countries higher in winter. The apparent temporal and spatial segregation of stocks of different origin suggests that there may have been differential exploitation on these stocks, which provides information that could inform fishery management with regard to temporal and/or spatial fishery options for the Faroes commercial salmon fishery should it recommence in future.

1979 ◽  
Vol 36 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Philip E. K. Symons

Smolt production at different egg deposition densities is estimated from data on survival rates and space requirements of juvenile Atlantic salmon (Salmo salar) reported in the literature. Average maximum production of smolts is estimated to be approximately 5/100 m2 for 2+ smolts, 2/100 m2 for 3+ smolts, and 1/100 m2 for 4+ smolts. Minimum egg depositions recommended for production of these numbers of smolts are 220/100 m2, 165–220/100 m2, and 80/100 m2 for each age of smolts, respectively. The escapement of adults required to produce these depositions must be estimated from observed average weights of returning females and a reported fecundity of Atlantic salmon between 1650 and 1760 eggs/kg of female. With the exception of Ungava rivers, average smolt age in any particular river can be estimated from the number of days per year on which water temperature reaches or exceeds 7 °C. Key words: fishery resources, fishery management, production (biological), escapement, survival, game fish, freshwater fish, rivers


1989 ◽  
Vol 46 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Dennis L. Scarnecchia ◽  
Árni Ísaksson ◽  
S. E. White

Investigations were conducted on the effects of oceanic variations (as measured by sea temperatures) and catches by the West Greenland salmon fishery on the sea age composition of Atlantic salmon (Salmo salar) stocks from 21 Icelandic west coast rivers. Annual ratios of grilse to two-sea-winter (2SW) salmon were strongly correlated among the 21 rivers. All eight rivers with time series extending back before the expansion of the West Greenland fishery showed lower ratios during the earlier period. Only 2 of the 21 rivers, however, had significantly declining ratios over their time series. In addition, for only one river was West Greenland catch significantly related to the ratios (P < 0.05), and for only one river did ratios increase when the expanded West Greenland fishery was active. Overall, the effects of the fishery on stock composition are evidently minimal. The mean April–May temperature when the smolts were to migrate out of rivers was significantly and positively related to subsequent ratios for five of the rivers, which, along with correlations among the ratios, indicated that more rapid growth of smolts in their first summer may have increased the ratios of grilse to 2SW salmon on several rivers.


2011 ◽  
Vol 68 (6) ◽  
pp. 977-987 ◽  
Author(s):  
Charles Perrier ◽  
Françoise Daverat ◽  
Guillaume Evanno ◽  
Christophe Pécheyran ◽  
Jean-Luc Bagliniere ◽  
...  

This study combines otolith trace element and genetic analyses to explore the origin of individuals when hatchery-reared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon ( Salmo salar ) in four rivers in Normandy (France) and in the hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the hatchery strain (FST ≈ 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the hatchery, allowing the identification of their geographic origin (83%–100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that hatchery-born juveniles released into the wild can migrate to the sea and return as adults to breed on natural spawning grounds. Their progeny have pure hatchery pedigrees but have otoliths typical of river-born juveniles, meaning that they can be mistaken for hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with hatchery pedigrees can breed with wild conspecifics.


1985 ◽  
Vol 42 (10) ◽  
pp. 1658-1667 ◽  
Author(s):  
Kjell B. Døving ◽  
Håkan Westerberg ◽  
Peter B. Johnsen

The behavior of sham-operated and anosmic Atlantic salmon, Salmo salar, was studied in a fjord system with close reference to the fine-scale hydrographic features. Control fish made small-amplitude vertical movements, with sudden large-amplitude excursions. The anosmic fish made large continuous searches up and down in the water column, descended below the sill depth of the fjord, and followed the bottom contours. None of these three behaviors was seen in the control fish. The trauma caused by the surgical incision did not prevent the fish from active swimming, and a fish with unilateral sectioning of the olfactory nerve returned to the river of release. Activity of single olfactory bulb neurons was recorded during stimulation of salmon olfactory epithelium with water samples taken from different depths of the fjord. These water samples had been taken from regions that showed layering and to which migrating salmon demonstrated behavioral preferences in ultrasonic tracking experiments. Ninety percent of responding neurons showed differencial responses to the water samples, indicating the capacity of the olfactory system to discriminate among stratified water layers found in the ocean. We conclude that olfactory discrimination of fine-scale hydrographic features may provide a necessary reference system for successful orientation in nearshore regions by salmon.


1985 ◽  
Vol 63 (9) ◽  
pp. 2032-2037 ◽  
Author(s):  
Hugh R. MacCrimmon ◽  
Ross R. Claytor

Juvenile representatives of seven river stocks of Baltic salmon, Salmo salar, in northern, north-central, central, and southern Sweden are examined to determine if meristic and morphometric characters can be used to identify regional and home river origins. Morphometric features (> 80% accuracy) provide a better means of identification of salmon stocks than do meristic features. Both methods are congruent in identifying cohesive somatic salmon stocks based on river and regional geographic origin. Examination of within-stock differences between immature and mature (precocious) parr shows meristic homogeneity but significant morphological dichotomy. These significant morphological differences, involving different character sets, do not alter the capability to discern regional and river stocks containing disparate maturation stages of parr.


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

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