scholarly journals Redefining the oceanic distribution of Atlantic salmon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Audun H. Rikardsen ◽  
David Righton ◽  
John Fredrik Strøm ◽  
Eva B. Thorstad ◽  
Patrick Gargan ◽  
...  

AbstractDetermining the mechanisms driving range-wide reductions in Atlantic salmon marine survival is hindered by an insufficient understanding of their oceanic ecology and distribution. We attached 204 pop-up satellite archival tags to post-spawned salmon when they migrated to the ocean from seven European areas and maiden North American salmon captured at sea at West Greenland. Individuals migrated further north and east than previously reported and displayed increased diving activity near oceanographic fronts, emphasizing the importance of these regions as feeding areas. The oceanic distribution differed among individuals and populations, but overlapped more between geographically proximate than distant populations. Dissimilarities in distribution likely contribute to variation in growth and survival within and among populations due to spatio-temporal differences in environmental conditions. Climate-induced changes in oceanographic conditions will alter the location of frontal areas and may have stock-specific effects on Atlantic salmon population dynamics, likely having the largest impacts on southern populations.

2017 ◽  
Vol 74 (5) ◽  
pp. 1356-1370 ◽  
Author(s):  
John Fredrik Strøm ◽  
Eva B. Thorstad ◽  
Graham Chafe ◽  
Sigrunn H. Sørbye ◽  
David Righton ◽  
...  

The ocean migration of 16 post-spawned adult Atlantic salmon [Salmo salar L.] from the Miramichi River, Canada, tagged concurrently with pop-up satellite archival tags and acoustic transmitters was reconstructed using a Hidden Markov Model. Individuals exclusively utilized areas within the Gulf of St Lawrence and the Labrador Sea, and showed little overlap with known distributions of European stocks. During the migration, individuals were generally associated with surface waters and spent >67% of the time in the upper 10 m of the water column. The Atlantic salmon occupied greater depths and showed more diving activity during the day than during the night, with a few exceptions. Although residing in the Gulf of St Lawrence, individuals used different geographical areas and displayed frequent dives to shallow depths (10–30 m). All fish that entered the Labrador Sea (n = 8) migrated through the Strait of Belle Isle (767 km from the river mouth), after spending 41–60 d in the Gulf of St Lawrence. After exiting the Gulf of St Lawrence, individuals utilized different areas in the Labrador Sea, and overlaps in spatial distributions among the individuals were largely limited to the Labrador Coast. This variation in area use was accompanied by individual differences in diving behaviour, with maximum depths recorded for individuals ranging from 32 to 909 m. Dives to depths exceeding 150 m were only performed by four individuals and mainly restricted to the central Labrador Sea (areas with water depths >1000 m). Vertical movements were shallower and resembled those in the Gulf of St Lawrence when fish migrated through shallower coastal areas along the Labrador Shelf. In conclusion, the large overall variation in migration routes suggests that post-spawners from the Miramichi River encounter different habitats during their ocean migration and that the growth and survival of adults may depend on ecological conditions in multiple regions, both in the Gulf of St Lawrence and in the Labrador Sea.


PLoS ONE ◽  
2012 ◽  
Vol 7 (8) ◽  
pp. e43129 ◽  
Author(s):  
Kevin A. Glover ◽  
María Quintela ◽  
Vidar Wennevik ◽  
François Besnier ◽  
Anne G. E. Sørvik ◽  
...  

Coral Reefs ◽  
2021 ◽  
Vol 40 (2) ◽  
pp. 283-288
Author(s):  
Kai L. Kopecky ◽  
Dana T. Cook ◽  
Russell J. Schmitt ◽  
Adrian C. Stier

AbstractA suite of processes drive variation in coral populations in space and time, yet our understanding of how variation in coral density affects coral performance is limited. Theory predicts that reductions in density can send coral populations into a predator pit, where concentrated corallivory maintains corals at low densities. In reality, how variation in coral density alters corallivory rates is poorly resolved. Here, we experimentally quantified the effects of corallivory and coral density on growth and survival of small colonies of the staghorn coral Acropora pulchra. Our findings suggest that coral density and corallivory have strong but independent effects on coral performance. In the presence of corallivores, corals suffered high but density-independent mortality. When corallivores were excluded, however, vertical extension rates of colonies increased with increasing densities. While we found no evidence for a predator pit, our results suggest that spatio-temporal variation in corallivore and coral densities can fundamentally alter population dynamics via strong effects on juvenile corals.


2015 ◽  
Vol 282 (1806) ◽  
pp. 20150173 ◽  
Author(s):  
Ayco J. M. Tack ◽  
Tommi Mononen ◽  
Ilkka Hanski

Climate change is known to shift species' geographical ranges, phenologies and abundances, but less is known about other population dynamic consequences. Here, we analyse spatio-temporal dynamics of the Glanville fritillary butterfly ( Melitaea cinxia ) in a network of 4000 dry meadows during 21 years. The results demonstrate two strong, related patterns: the amplitude of year-to-year fluctuations in the size of the metapopulation as a whole has increased, though there is no long-term trend in average abundance; and there is a highly significant increase in the level of spatial synchrony in population dynamics. The increased synchrony cannot be explained by increasing within-year spatial correlation in precipitation, the key environmental driver of population change, or in per capita growth rate. On the other hand, the frequency of drought during a critical life-history stage (early larval instars) has increased over the years, which is sufficient to explain the increasing amplitude and the expanding spatial synchrony in metapopulation dynamics. Increased spatial synchrony has the general effect of reducing long-term metapopulation viability even if there is no change in average metapopulation size. This study demonstrates how temporal changes in weather conditions can lead to striking changes in spatio-temporal population dynamics.


1976 ◽  
Vol 54 (4) ◽  
pp. 531-535 ◽  
Author(s):  
M. P. Komourdjian ◽  
R. L. Saunders ◽  
J. C. Fenwick

The effects of porcine growth hormone on growth and salinity tolerance were studied in Atlantic salmon (Salmo salar) parr. Fish were held in freshwater at 11.5 °C during June and July under a photoperiod with light to dark periods opposite to the prevailing natural conditions. Fish treated with 1.0 μg/g body weight of growth hormone preparation on alternate days were significantly longer (P <.05), after 4 weeks, than placebo-injected controls. All hormone-injected fish survived transfer to seawater, 30‰ salinity. But under the same conditions, placebo-injected control fish showed a high mortality rate. Growth-hormone treatment caused a darkening of fin margins and a yellowing of the operculae and fin surfaces. The silvering which normally accompanies smoltification was not observed. The role of growth hormone in eliciting these actions and its possible role in the parr–smolt transformation are discussed.


Author(s):  
C.J. Barrett ◽  
M.L. Johnson ◽  
S.L. Hull

The shanny/common blenny (Lipophrys pholis) and long-spined scorpionfish/bullhead (Taurulus bubalis) are commonly encountered, sympatric species within much of Great Britain's rocky intertidal zones. Despite being prey items of the cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) respectively, and both contributors to the diet of the near-threatened European otter (Lutra lutra), little is known on the population dynamics of the temperate specimens of Great Britain. It is further less known of the degrees of sympatricity between the two fish species and to what extent they are able to coexist. The current study examines spatio-temporal distributions and abundances at various resolutions: monthly population dynamics of both species along England's Yorkshire coast and seasonal population dynamics along the Yorkshire coast and around the Isle of Anglesey, Wales. Studies of their abundances, sizes, degrees of rock pool co-occurrence and diel activities are further examined, which indicate coexistence is maintained when interspecific co-occurrence takes place only between specimens of similar sizes, thus demoting size-related dominance hierarchies.


2017 ◽  
Vol 33 (7) ◽  
pp. 1004-1015 ◽  
Author(s):  
G. A. Maynard ◽  
M. T. Kinnison ◽  
J. D. Zydlewski

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