Evidence of Acidification of Some Nova Scotian Rivers and Its Impact on Atlantic Salmon, Salmo solar

1983 ◽  
Vol 40 (4) ◽  
pp. 462-473 ◽  
Author(s):  
W. D. Watt ◽  
C. D. Scott ◽  
W. J. White
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
River Discharge ◽  
Average Rate ◽  
Metamorphic Rocks ◽  
Ph Variation ◽  
The Past ◽  
Discharge Rates ◽  
Ph Range ◽  
Nova Scotian

River pH's in Nova Scotia are closely related to geology, and seasonal pH variation is well correlated with river discharge rates. In the geologically sensitive areas (granite and metamorphic rocks), river pH's have fallen significantly over the past 27 yr at an apparent average rate of 0.017 pH units/year. Concomitant with this decrease are a decline in [Formula: see text] concentrations and increases in Al+++ and [Formula: see text]. On average, 73% of the increase in acid is attributable to increased [Formula: see text]. Changes in Na+, K+, Ca++, and Mg++ concentrations were not significant. In rivers presently at mean annual pH's < 4.7, the Atlantic salmon (Salmo salar) runs have disappeared and are presumed extinct. Rivers in the pH range 4.7–5.0 show a decline in salmon angling returns of 2.8%/yr, beginning about 1954, and low densities of juvenile salmon. Rivers presently of pH > 5.0 generally have normal juvenile densities and show no significant trend in angling returns.

Behaviour and Microhabitat of Young Atlantic Salmon (Salmo salar) during Winter

1988 ◽  
Vol 45 (12) ◽  
pp. 2156-2160 ◽  
Author(s):  
Richard A. Cunjak
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Activity Pattern ◽  
Fork Length ◽  
Nocturnal Activity ◽  
Atlantic Salmon Salmo Salar ◽  
Sediment Compaction ◽  
Mean Diameter ◽  
Nova Scotian ◽  
Water Depths

Underwater observations at two sites along a small Nova Scotian river were carried out between December and April (water temperature range = 0.5–7.0 °C) to describe the winter microhabitat of young Atlantic salmon (Salmo salar). Salmon (5–15 cm fork length) were consistently found hiding beneath rocks (mean diameter = 16.8–23.0 cm) in riffle-run habitats where mean water depths were 40.9–48.9 cm and mean water velocities were 38.7–45.7 cm∙s−1. Many of the salmon were found overwintering within redd excavations. "Home stones" were distributed closer to midstream than to river banks and where sediment compaction was minimal. Monthly collections of fish (ages 1 and 2) indicated that feeding continued over winter. The data suggest a nocturnal activity pattern and photonegative response by young salmon during winter.

Isolation and Identification of an Atypical Aeromonas salmonicida Strain Causing Epizootic Losses Among Atlantic Salmon (Salmo salar) Reared in a Nova Scotian Hatchery

1980 ◽  
Vol 37 (12) ◽  
pp. 2236-2241 ◽  
Author(s):  
W. D. Paterson ◽  
D. Douey ◽  
D. Desautels
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Aeromonas Salmonicida ◽  
Biochemical Reactions ◽  
Isolation And Identification ◽  
Cumulative Mortality ◽  
Atlantic Salmon Salmo Salar ◽  
A Value ◽  
Nova Scotian

The bacterium causing 50% cumulative mortality among postyearling parr (pyp) Atlantic salmon (Salmo salar) reared at a Nova Scotian hatchery was identified to be an atypical, achromogenic Aeromonas salmonicida strain. This organism, although differing in several biochemical reactions from typical A. salmonicida, was sensitive to A. salmonicida bacteriophages. Antigenically, the Kejimkujik A. salmonicida was indistinguishable from typical A. salmonicida strains when the serological relatedness was examined using cross-adsorbed rabbit antisera. Analysis of DNA from the atypical A. salmonicida yielded a % GC value of 57.85, a value within the range expected for A. salmonicida.Key words: atypical, Aeromonas salmonicida, Atlantic salmon

The relationship between stream or river discharge and thyroid hormone levels in wild adult Atlantic salmon (Salmo salar L.)

1992 ◽  
Vol 70 (1) ◽  
pp. 140-144 ◽  
Author(s):  
Alan F. Youngson ◽  
John H. Webb
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Discharge Rate ◽  
Water Velocity ◽  
Hormone Levels ◽  
Stream Discharge ◽  
Atlantic Salmon Salmo Salar ◽  
Discharge Rates ◽  
Probable Consequence ◽  
The Relationship

Thyroxine and tri-iodothyronine levels were determined in groups of adult Atlantic salmon (Salmo salar L.) of both sexes at river entry in summer or as they entered a spawning tributary in late autumn. Hormone levels were considered in relation to river or stream discharge rate at capture. For tri-iodothyronine, there was a quadratic or linear relationship with discharge rate for each sex at both sites. For thyroxine, there was a quadratic relationship with discharge rate at tributary entry but no relationship with discharge rate at river entry. It is argued that raised hormone levels at higher discharge rates are a probable consequence of increased motor activity associated with greater water velocity. The quadratic nature of most of the models is attributed to physiological or behavioural limitation of the response.

scholarly journals Genetic variation in restored Atlantic salmon (Salmo salar L.) populations in the Ulla and Lérez rivers, Galicia, Spain

2006 ◽  
Vol 63 (7) ◽  
pp. 1290-1296 ◽  
Author(s):  
María Saura ◽  
Pablo Caballero ◽  
Armando Caballero ◽  
Paloma Morán
Keyword(s):  
Genetic Variation ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Allelic Richness ◽  
Tissue Samples ◽  
Supportive Breeding ◽  
The Past ◽  
Live Fish ◽  
Northwestern Spain ◽  
Stock Mixture

Abstract The populations of Atlantic salmon in the Ulla and Lérez rivers, located in Galicia in northwestern Spain, were close to extinction early in the 1990s. A restoration programme involving supportive breeding has been conducted since 1995, using a mixture of salmon populations from several Galician rivers. The programme utilizes progeny of adults returning to the rivers and wild parr reared in fresh water until maturity. Five microsatellite loci were used to compare genetic variability in the restored populations with that in populations before their collapse in the 1950s. DNA samples were obtained from scale collections (old samples) and from tissue samples of live fish caught in the rivers (modern samples). Average heterozygosities and allelic richness are very similar in modern and old samples. Populations inhabiting the Ulla and Lérez rivers today are more similar than they were in the past, possibly because they originated in the same stock mixture.

Advances in Fisheries Bioengineering

2008 ◽  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
River Discharge ◽  
Fish Passage ◽  
Migratory Fish ◽  
Small Hydropower ◽  
Passive Integrated Transponder ◽  
Fish Size ◽  
Diversion Structure ◽  
Hydroelectric Plants

<em>Abstract</em>.—A 2-year experiment was conducted on the Ariège River (southwest France) to assess effectiveness of downstream fish passage facilities for Atlantic salmon <em>Salmo salar </em>smolts at four consecutive small hydroelectric plants located on a diversion structure. The efficiency of these bypasses, evaluated using passive integrated transponder (PIT) telemetry, varied significantly between sites. The highest efficiency (greater than 65%) was obtained with two entirely new downstream passage facilities, whereas less than 40% of PIT-tagged smolts migrated through two other bypasses that were simple retrofits of existing trash sluices. Performances of two bypasses were significantly improved using either a submerged horizontal screen designed to limit upwelling or mercury lights at the bypass entrance. At two sites, a difference in fish size was also observed between smolts using the bypasses and those passing through the conventional intake trash racks, with larger fish using the bypass and smaller fish being entrained through the turbine intake. It was also demonstrated that the probability for spillway passage by tagged fish increased with increases in the proportion of total river discharge spilling and with decreases in fish size. The results of this study demonstrate how different parameters can influence downstream bypass efficiencies and provide information on how downstream passage for migratory fish can be improved at small hydropower projects.

Water quality requirements of smolting Atlantic salmon (Salmo salar) in limed acid rivers

1999 ◽  
Vol 56 (11) ◽  
pp. 2078-2086 ◽  
Author(s):  
Frode Kroglund ◽  
Magne Staurnes
Keyword(s):  
Atlantic Salmon ◽  
River Water ◽  
Salmo Salar ◽  
Acidic Water ◽  
Lower Plasma ◽  
Quality Requirements ◽  
Atlantic Salmon Salmo Salar ◽  
Seawater Tolerance ◽  
Ph Range ◽  
Acidic River

Groups of Atlantic salmon (Salmo salar) smolts were held 1-13 days in soft water with a pH range of 5.0-6.6, concentrations of labile inorganic monomeric Al (Ali) of 10-90 µg·L-1, and 0.7-2.3 mg Ca·L-1. Fish were exposed to either naturally acidic water from a river in southwestern Norway, limed water from the same river, mixtures of acidic and limed river water, acidic river water with sulfuric acid and Al added, or limed river water with additional lime. Mortality was observed in all groups exposed to water with pH < 5.8 and containing 30-90 µg Ali·L-1. No fish died in water with pH > 5.8 and 15-20 µg Ali·L-1, but fish in water with pH 5.8-6.2 had lower plasma Cl- concentration and gill Na+,K+-ATPase activity than fish in water with pH > 6.5. Smolts exposed to pH < 5.8 were unable to survive in seawater, and smolts exposed to water with pH 5.8-6.2 had lower hypoosmoregulatory capacity than smolts exposed to water with pH > 6.5. These results show that even moderately acidified water with low Al concentrations impairs smoltification and reduces the seawater tolerance of Atlantic salmon smolts.

Responses of Plasma Electrolytes, Thyroid Hormones, and Gill Histology in Atlantic Salmon (Salmo salar) to Acid and Limed River Waters

1990 ◽  
Vol 47 (12) ◽  
pp. 2431-2440 ◽  
Author(s):  
S. B. Brown ◽  
R. E. Evans ◽  
H. S. Majewski ◽  
G. B. Sangalang ◽  
J. F. Klaverkamp
Keyword(s):  
Atlantic Salmon ◽  
River Water ◽  
Salmo Salar ◽  
Plasma Osmolality ◽  
Gill Tissue ◽  
Acidic Ph ◽  
Handling Stress ◽  
Atlantic Salmon Salmo Salar ◽  
Ph Range ◽  
Altered Thyroid

Sexually maturing Atlantic salmon, Salmo salar, were held, in the acidic (pH range 4.7–5.2) Westfield River, Nova Scotia and in the nearby, less acidic (pH range 5.2–5.6) Medway River. Exposure to Westfield River water in 1985 (149 d) and 1986 (126 d) reduced plasma osmolality, Na+, Cl−, and Ca++ (in females only) concentrations of post-spawning fish compared to those in fish held in the Medway River. There were coincidental increases in plasma K+, glucose, and unidentified osmotic fraction (UOF). Gill tissue showed hyperplasia of primary lamellae epithelium. Together, these findings indicate compromised ionoregulatory ability. Decreased plasma T3 (3,5,3′-triiodo-L-thyronine) suggests altered thyroid function. Westfield River water did not affect plasma T4(L-thyroxine) or protein concentrations. An unintentional handling stress caused even more severely depressed plasma ions and more elevated plasma glucose in Westfield fish in 1985 relative to 1986; Medway fish largely recovered from this stress. These observations indicate that acid-exposed fish may be more sensitive to additional stressors. Limestone treatment of Westfield River water (elevating its pH to Medway values) ameliorated ionoregulatory ability but did not affect plasma T3 and Ca++ (female). A high salt diet (3% NaCl) failed to protect salmon from the effects of acidic water.

scholarly journals The influence of the freshwater environment and the biological characteristics of Atlantic salmon smolts on their subsequent marine survival

2012 ◽  
Vol 69 (9) ◽  
pp. 1563-1573 ◽  
Author(s):  
Ian C. Russell ◽  
Miran W. Aprahamian ◽  
Jon Barry ◽  
Ian C. Davidson ◽  
Peder Fiske ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Average Rate ◽  
Biological Characteristics ◽  
Freshwater Environment ◽  
The Past ◽  
Environmental Migration ◽  
Younger Age ◽  
Freshwater Habitats ◽  
Marine Survival ◽  
The Impact

Abstract Russell, I. C., Aprahamian, M. W., Barry, J., Davidson, I. C., Fiske, P., Ibbotson, A. T., Kennedy, R. J., Maclean, J. C., Moore, A., Otero, J., Potter, E. C. E., and Todd, C. D. 2012. The influence of the freshwater environment and the biological characteristics of Atlantic salmon smolts on their subsequent marine survival. – ICES Journal of Marine Science, 69: 1563–1573. Atlantic salmon have declined markedly in the past 20–30 years throughout their range. Much of the focus for this decline has been on increased mortality during the marine phase of the life cycle. However, marine mortality does not operate independently of factors acting in freshwater and the biological characteristics of smolts migrating to sea. Over recent decades, juvenile salmon in many rivers have grown faster and migrated to sea at a younger age, so have been typically smaller than earlier. This has shortened the generation time for many individuals and may dampen the impact of increased marine mortality, assuming that expected higher in-river survival prior to smolting is not outweighed by increased mortality of smaller smolts at sea. Over the same period, smolt run-timing across the geographic range has been earlier, at an average rate of almost 3 d per decade. This has given rise to growing concerns about smolts potentially missing the optimum environmental migration “window”, the timing of which may also be changing. Contaminants and other factors operating in freshwater also impact smolt quality with adverse consequences for their physiological readiness for life at sea. Given that managers have very limited ability to influence the broad scale factors limiting salmon survival at sea, it is vital that freshwater habitats are managed to both maximize the smolt output and to minimize the impact of factors acting in freshwater that may compromise salmon once they migrate to sea.

Influence of Seasonal River Discharge on Survival of Juvenile Atlantic Salmon Salmo Salar

1988 ◽  
Vol 45 (2) ◽  
pp. 344-348 ◽  
Author(s):  
R. J. Gibson ◽  
R. A. Myers
Keyword(s):  
Atlantic Salmon ◽  
New Brunswick ◽  
Salmo Salar ◽  
River Discharge ◽  
Positive Relationships ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Stock Recruitment

The effects of winter and summer river discharge on the survival of eggs and underyearlings of Atlantic salmon (Salmo salar) were examined in six rivers of Newfoundland and New Burnswick where stock–recruitment relationships were available. There were positive relationships between either winter discharge or temperature and survival of underyearling salmon for five rivers. For all rivers combined, survival and winter discharge were related (P < 0.05). The hypothesis that summer discharge was unrelated to survival could not be rejected. However, there was evidence that summer discharge enhances survival in the Miramichi and Northwest Miramichi rivers of New Brunswick.

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