scholarly journals Temporal synchrony and variation in abundance of Atlantic salmon (Salmo salar) in two subarctic Barents Sea rivers: influence of oceanic conditions

2004 ◽  
Vol 61 (12) ◽  
pp. 2384-2391 ◽  
Author(s):  
Eero Niemelä ◽  
Jaakko Erkinaro ◽  
J Brian Dempson ◽  
Markku Julkunen ◽  
Alexander Zubchenko ◽  
...  

Long-term variation in Atlantic salmon (Salmo salar) stocks was analyzed in two Barents Sea rivers, the Teno and Näätämöjoki, that represent the northernmost distribution area of the species. In contrast to most of the North Atlantic area, these rivers are among a group of northern salmon rivers that, despite wide annual variation in catches, demonstrate no consistent trend for declining abundance. Variations in abundance were generally synchronous for the total catch and numbers of 1-sea-winter (1SW) and 2SW salmon during period of 1972–2003. Part of the variation observed in catches could be related to ocean climate conditions as the mean seawater temperature in July during the year of smoltification for the Kola section of the Barents Sea was significantly related to numbers of 1SW, 2SW, and 3SW salmon in the large River Teno. In contrast, NAO (North Atlantic Oscillation) indices were not related to salmon catches. The latest increase (1999–2001) in salmon catches in these rivers reflects both temporarily improved oceanic conditions and past management measures affecting offshore, coastal, and river fisheries.

2007 ◽  
Vol 64 (2) ◽  
pp. 394-404 ◽  
Author(s):  
Aaron D. Spares ◽  
Jeffery M. Reader ◽  
Michael J. W. Stokesbury ◽  
Tom McDermott ◽  
Lubomir Zikovsky ◽  
...  

AbstractSpares, A.D., Reader, J.M., Stokesbury, M.J.W., McDermott, T., Zikovsky, L., Avery, T.S., and Dadswell, M.J. 2007. Inferring marine distribution of Canadian and Irish Atlantic salmon (Salmo salar L.) in the North Atlantic from tissue concentrations of bio-accumulated caesium 137. – ICES Journal of Marine Science, 64: 394–404. Atlantic salmon returning from marine migrations to eastern Canada and western Ireland during 2002 and 2003 were analysed for tissue concentrations of bio-accumulated caesium 137 (137Cs). Salmon from Canadian and Irish waters demonstrated concentrations (0.20 ± 0.14 Bq kg−1 and 0.19 ± 0.09 Bq kg−1, mean ± s.d., respectively) suggesting similar oceanic feeding distributions during migration. Canadian aquaculture escapees had a similar mean tissue concentration (0.28 ± 0.22 Bq kg−1), suggesting migration with wild salmon. However, significantly higher concentrations in 1-sea-winter (1SW) escapees (0.43 ± 0.25 Bq kg−1) may alternatively suggest feeding within local estuaries. High concentrations in some Canadian 1SW salmon indicated trans-Atlantic migration. Low concentrations of Canadian multi-sea-winter (MSW) salmon suggested a feeding distribution in the Labrador and Irminger Seas before homeward migration, because those regions have the lowest surface water 137Cs levels. Estimates of wild Canadian and Irish salmon feeding east of the Faroes (∼8°W) were 14.2% and 10.0% (1SW, 24.7% and 11.5%; MSW, 2.9% and 0.0%), respectively. We propose that most anadromous North Atlantic salmon utilize the North Atlantic Gyre for marine migration and should be classified as a single trans-Atlantic straddling stock.


1991 ◽  
Vol 220 (4) ◽  
pp. 829-830
Author(s):  
Rolf L. Larsen ◽  
Asbjørn Hordvik ◽  
Edward Hough ◽  
Knut Jynge ◽  
Lars Kr. Hansen

1990 ◽  
Vol 214 (2) ◽  
pp. 355-358 ◽  
Author(s):  
Arne O. Smal Ås ◽  
Asbjørn Hordvik ◽  
Lars Kr. Hansen ◽  
Edward Hough ◽  
Knut Jynge

2012 ◽  
Vol 69 (9) ◽  
pp. 1538-1548 ◽  
Author(s):  
Gérald Chaput

Abstract Chaput, G. 2012. Overview of the status of Atlantic salmon (Salmo salar) in the North Atlantic and trends in marine mortality. – ICES Journal of Marine Science, 69: 1538–1548. Since the early 1980s, the ICES Working Group on North Atlantic Salmon has collated and interpreted catch data, exchanged information on research initiatives, and provided advice to managers in support of conservation efforts for Atlantic salmon. During the past three decades, the annual production of anadromous Atlantic salmon from more than 2000 rivers draining into the North Atlantic has been less than 10 million adult-sized salmon. This represents a minor component, by number and biomass, of the pelagic ecosystem in the North Atlantic Ocean. Ideally, Atlantic salmon would be assessed and managed based on river-specific stock units, the scale that best corresponds to the spawner to recruitment dynamic. In reality, comparatively few river-specific assessments are available for either the Northwest or the Northeast Atlantic. The marine survival of Atlantic salmon is low and, based on return rates of smolts to adults from monitored rivers, has declined since the mid- to late 1980s. Abundance has declined more severely for the multi-sea-winter components, and especially in the southern areas of the species' range. Common patterns in abundance, inferred at the level of stock complex in the North Atlantic, suggest that broad-scale factors are affecting productivity and abundance and that they are acting throughout the salmon's time at sea.


2003 ◽  
Vol 60 (5) ◽  
pp. 563-583 ◽  
Author(s):  
K D Friedland ◽  
D G Reddin ◽  
J R McMenemy ◽  
K F Drinkwater

Landings of North American Atlantic salmon (Salmo salar) over the past century show multidecadal patterns, which most recently characterize unprecedented declines in abundance. Stock size is compared with sea surface temperature (SST) data in the marine nurseries of post-smolt Atlantic salmon. A previously described correlation between stock abundance and winter SST conditions was again documented; however, of more relevance to the survival of salmon post-smolts, a correlation was also observed between abundance and spring SST in the Gulf of St. Lawrence. The relevance of the winter SST correlation was further investigated by considering winter conditions in the freshwater nurseries as a factor causing elevated overwintering mortality of pre-migrant parr. The salmon abundance time series was compared with air temperature and rainfall trends averaged over time and space. Air temperature and rainfall do not appear to be significant environmental variables in shaping salmon recruitment. The timing of smolt runs appears to be out of synchronization with ocean conditions in the post-smolt nursery areas. The relationship between marine and freshwater impacts may change with changing climate conditions. Persistent positive phase forcing in the North Atlantic Oscillation raises the concern that recent declines in Atlantic salmon are, in part, due to global climate change.


2011 ◽  
Vol 68 (3) ◽  
pp. 444-457 ◽  
Author(s):  
Arne Johan Jensen ◽  
Peder Fiske ◽  
Lars Petter Hansen ◽  
Bjørn Ove Johnsen ◽  
Kjell Arne Mork ◽  
...  

More synchronous growth was observed between close, than more distantly separated populations of Atlantic salmon ( Salmo salar ), during both the first and the second year at sea. The marine growth of seven Norwegian populations, located between 60°N and 70°N, were correlated with sea surface temperatures (SSTs) in the Barents Sea, the Norwegian Sea, and the North Sea, and it was found that growth correlated best with the water temperatures in the area located closest to their home river. Growth was also compared with three broad-scale climate indices (North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation, and subpolar gyre), with the strongest relationship occurring with the NAO index. However, SSTs explained more of the variability than the climatic indices did. Growth increment for the first year, but not the second year, was higher for southern than northern populations, mainly because of later smolt migration to sea in the north, and hence, a shorter growth season. For multi-sea-winter fish, all populations except one had a negative trend in growth with years for both the first and the second year at sea. For the second year at sea, this was most pronounced after the beginning of the 1980s. This is in accordance with the negative trend in pre-fishery abundance of adult salmon during the same period.


2004 ◽  
Vol 61 (12) ◽  
pp. 2392-2400 ◽  
Author(s):  
Francis Juanes ◽  
Stephen Gephard ◽  
Kenneth F Beland

The Connecticut River historically represented the southernmost extent of the North American range of Atlantic salmon (Salmo salar), but the native population was extirpated 200 years ago by dam construction. An extensive restoration effort has relied upon stock transfers from more northerly rivers, especially the Penobscot River (Maine). Recent work has shown differences in age structure between donor and derivative populations. Here we focus on a related life-history trait, the timing of the adult migration. We examined 23 years of migration timing data collected at two capture locations in the Connecticut River drainage. We found that both dates of first capture and median capture dates have shifted significantly earlier by about 0.5 days·year–1. To conclude whether this is a consequence of local adaptation or a coast-wide effect, we also quantified changes in migration timing of more northerly stocks (in Maine and Canada). We found that the changes in migration timing were not unique to the Connecticut River stock and instead observed coherent patterns in the shift towards earlier peak migration dates across systems. These consistent shifts are correlated with long-term changes in temperature and flow and may represent a response to global climate change.


Viruses ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 465 ◽  
Author(s):  
Kannimuthu Dhamotharan ◽  
Torstein Tengs ◽  
Øystein Wessel ◽  
Stine Braaen ◽  
Ingvild B. Nyman ◽  
...  

Heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar) was first diagnosed in Norway in 1999. The disease is caused by Piscine orthoreovirus-1 (PRV-1). The virus is prevalent in farmed Atlantic salmon, but not always associated with disease. Phylogeny and sequence analyses of 31 PRV-1 genomes collected over a 30-year period from fish with or without HSMI, grouped the viral sequences into two main monophylogenetic clusters, one associated with HSMI and the other with low virulent PRV-1 isolates. A PRV-1 strain from Norway sampled in 1988, a decade before the emergence of HSMI, grouped with the low virulent HSMI cluster. The two distinct monophylogenetic clusters were particularly evident for segments S1 and M2. Only a limited number of amino acids were unique to the association with HSMI, and they all located to S1 and M2 encoded proteins. The observed co-evolution of the S1-M2 pair coincided in time with the emergence of HSMI in Norway, and may have evolved through accumulation of mutations and/or segment reassortment. Sequences of S1-M2 suggest selection of the HSMI associated pair, and that this segment pair has remained almost unchanged in Norwegian salmon aquaculture since 1997. PRV-1 strains from the North American Pacific Coast and Faroe Islands have not undergone this evolution, and are more closely related to the PRV-1 precursor strains not associated with clinical HSMI.


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