The Relation of Temperature to the Seaward Migration of Young Sockeye Salmon (Oncorhynchus nerka)

1937 ◽  
Vol 3 (5) ◽  
pp. 421-438 ◽  
Author(s):  
R. E. Foerster
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Weather Conditions ◽  
First Year ◽  
Temperature Conditions ◽  
Temperature Trends ◽  
Air Temperatures ◽  
Seaward Migration ◽  
Small Growth ◽  
Slight Rise

The period of seaward migration of young sockeye from Cultus lake each spring is inversely correlated with temperature conditions prevailing during the months immediately preceding. Correlating temperature readings of the outflow stream with date when twenty per cent migration occurred, a statistically significant correlation of −0.85 was obtained for February and March and −0.77 for January to March. Using air temperatures, coefficients of −0.91 for January to March and −0.74 for February and March were found. Commencement of migration coincides with vernal rise in lake temperatures. Under normal conditions, with low winter minimum, there appears to be a threshold migration temperature approximating 4.4 °C. (40°F.) but in seasons when lake temperatures are not depressed to this level a slight rise stimulates migration. Progress of migration is largely influenced by prevailing weather conditions and their effect upon temperature trends. Cessation of migration appears to be related to the setting-up of a "temperature blanket" which inhibits migration from the lake of sockeye still resident therein. These latter, showing small growth during their first year, remain in the lake until the following spring and then are among the first to migrate.

Recent sedimentary legacy of sockeye salmon (Oncorhynchus nerka) and climate change in an ultraoligotrophic, glacially turbid British Columbia nursery lake

2009 ◽  
Vol 66 (7) ◽  
pp. 1141-1152 ◽  
Author(s):  
Aaron C. Hill ◽  
Jack A. Stanford ◽  
Peter R. Leavitt
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Trophic Status ◽  
Oncorhynchus Nerka ◽  
Production Potential ◽  
Lake Trophic Status ◽  
Air Temperatures ◽  
High Sedimentation ◽  
Order Of Magnitude ◽  
Coastal British Columbia

Paleolimnological studies of sockeye salmon ( Oncorhynchus nerka ) nursery lakes have shown that lake trophic status is often regulated by climate and harvest via marine-derived nutrients (MDN) from adult spawners. However, these controls are not well understood for sockeye nursery lakes in coastal British Columbia, many of which are ultraoligotrophic and glacially turbid. We examined climate, sockeye population dynamics, and sedimentary indicators of lake algal production from 1958 to 2005 using a radioisotope-dated sediment core from Kitlope Lake, British Columbia. Despite high sedimentation rates (~4.7 mm·year–1), significant influence of terrestrial and aquatic organic matter from the main tributary, and the lowest mean (± standard deviation) δ15N (–0.28‰ ± 0.79‰; a proxy for MDN flux) yet reported from a sockeye nursery lake, sedimentary δ15N, C–N ratio, and fossil pigments were coherent with order-of-magnitude changes in sockeye escapements. Moreover, air temperatures were positively correlated with δ15N, indicating a climate influence counteracting declines of MDN import related to declining spawner returns. Despite elevated production potential, Kitlope Lake remains nutrient-limited with a declining sockeye population, and the productivity of this system would benefit from increased sockeye returns.

scholarly journals Influence of weather conditions, irrigation and plant age on yield and alpha-acids content of Czech hop (Humulus lupulus L.) cultivars

2020 ◽  
Vol 66 (No. 1) ◽  
pp. 41-46 ◽  
Author(s):  
Pavel Donner ◽  
Jaroslav Pokorný ◽  
Josef Ježek ◽  
Karel Krofta ◽  
Josef Patzak ◽  
...  
Keyword(s):  
Daily Rainfall ◽  
Weather Conditions ◽  
Plant Age ◽  
Optimal Time ◽  
First Year ◽  
Irrigation Level ◽  
Yield Increase ◽  
Air Temperatures ◽  
Humulus Lupulus L ◽  
Positive Effect

This study quantifies the effects of weather conditions, irrigation, and plant age on yield and alpha-acids content of Czech hop cultivars Saaz, Sládek, Premiant and Agnus in a 25-year long period, i.e., from 1993 to 2018. The yields of Czech hop cultivars were increasing for the first three years of plant age until they stabilized and then started to decline slightly for 15 to 20 years until they reached the optimal time for replanting. The highest alpha-acids content in hop cones was achieved in the first year of cultivation, followed by a logarithmic decline in the upcoming years. Rainfall was the most significant factor that positively influenced the yield of Saaz hops with correlations of r = 0.59 and 0.61 (P < 0.01) for total seasonal rainfall (April–August), 0.65 (P < 0.001) and 0.60 (P < 0.01) for daily rainfall above 3 mm, 0.37 (P < 0.05) and 0.58 (P < 0.01) for rainfall in May and 0.50 (P < 0.01) and 0.32 (P < 0.05) in July in the Saaz region and the Stekník farm, respectively. The yield of cultivars Sládek, Premiant and Agnus was not statistically influenced by the amount of precipitation, but there was a positive effect of irrigation level on yield increase with correlations 0.58 (P < 0.01), 0.55 and 0.49 (P < 0.05), respectively. High air temperatures during summer were the most significant factor that negatively influenced the alpha-acids content with the correlations ranging from –0.56 to –0.83. However, cv. Agnus showed a stable weather-independent alpha-acids content.  

Fish age, nematode (Philonema oncorhynchi) infection, and development of sexual dimorphism by the adult male sockeye salmon, Oncorhynchus nerka, in western Alaska

1995 ◽  
Vol 73 (11) ◽  
pp. 1999-2004 ◽  
Author(s):  
Ole Kristian Berg ◽  
Chris J. Foote ◽  
Thomas P. Quinn
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Parasite Infection ◽  
Mature Male ◽  
Sexually Dimorphic ◽  
Age Composition ◽  
Body Depth ◽  
Duration Of Residence ◽  
Significant Difference ◽  
Seaward Migration

Of 255 mature male sockeye salmon (Oncorhynchus nerka) from two Alaskan lakes (Aleknagik and Iliamna), 254 (99.6%) were infected with the nematode Philonema oncorhynchi with a mean wet mass of 3.1 g (SD = 3.4 g) of nematodes. Fish that had spent 1 year in the lake prior to seaward migration had significantly lower parasite masses than those that had spent 2 years in the lake (2.7 vs. 4.1 g). However, there was no significant difference in parasite masses between lakes or among spawning populations within the lakes for fish of a given age or of all ages combined, even though the populations differed in age composition. The variation in relative parasite mass (mass of parasite (g)/mass of fish (kg)) was mainly explained by the significant variation in total mass of the parasites and the sea age of the fish. Thus, total parasite mass was correlated with the duration of residence in fresh water, while the relative parasite mass was correlated with fish size, and hence with the duration of residence in the sea. In spite of heavy infections (up to 28 g of nematodes) in many salmon, there were no corresponding reductions in mass/length or in the development of two sexually dimorphic features, body depth and snout length. Thus, parasite infection did not appear to affect traits under sexual selection, as hypothesized by Hamilton and Zuk.

The Effect of reduction of Predaceous Fish on survival of young Sockeye Salmon at Cultus Lake

1941 ◽  
Vol 5b (4) ◽  
pp. 315-336 ◽  
Author(s):  
R. E. Foerster ◽  
W. E. Ricker
Keyword(s):  
British Columbia ◽  
Survival Rate ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Nerka ◽  
First Year ◽  
The Mean ◽  
Control Work ◽  
The Cost ◽  
Gill Netting

By persistent gill-netting in Cultus lake, British Columbia, the predaceous fish which feed on young sockeye (Oncorhynchus nerka) have been considerably, though unevenly, reduced in numbers. The populations of squawfish and char, of lengths greater than 200 millimetres, were reduced in three years to about 1/10 of their original numbers. The abundance of trout and coho salmon have been much less affected by netting, if at all, though a considerable number have been killed. From the first year of control operations the survival rate of young sockeye salmon was considerably increased. In the three years which have been tested, the mean survival rate has been increased three and a third times over average conditions prior to control. In absolute figures, this represents 3,800,000 migrants saved, which are expected to yield 380,000 adult sockeye. Even disregarding the important cumulative future increase, the immediate return from the work is a quantity of sockeye whose value is many times greater than the cost of control work.

Early marine growth of juvenile Fraser River sockeye salmon (Oncorhynchus nerka) in relation to juvenile pink (Oncorhynchus gorbuscha) and sockeye salmon abundance

2012 ◽  
Vol 69 (9) ◽  
pp. 1499-1512 ◽  
Author(s):  
Skip McKinnell ◽  
Maxine Reichardt
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
First Year ◽  
Fraser River ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Strait Of Georgia ◽  
Average Survival

Mortality of salmon in the ocean is considered to be greatest during the first few months and that its magnitude is an inverse of growth. First year marine growth (M1) in two Fraser River sockeye salmon ( Oncorhynchus nerka ) populations was positively correlated, reflecting a shared oceanic experience as postsmolts. M1 declined abruptly in both populations after 1977, corresponding to a well-documented change in climate. The reduction in average M1 was not accompanied by a detectable reduction in average survival. In both populations, M1 was significantly greater in even years when juvenile pink salmon ( Oncorhynchus gorbuscha ) are abundant in the Strait of Georgia, suggesting that interspecific competition there has little effect on M1. All correlations of M1 with regional pink salmon or sockeye salmon abundances, lagged to align ocean entry years, were negative, but few (pink) or none (sockeye) were statistically significant. The negative correlations were due to the long-term changes (pink salmon abundance increasing, sockeye M1 smaller). Odd year dominance of juvenile pink salmon in northern British Columbia, Canada, is persistent and corresponds with the biennial pattern of M1 variation in Fraser River sockeye salmon and may be the source of the significant odd–even year line effect on M1.

Perception of Polarized Light by Yearling Sockeye Salmon (Oncorhynchus nerka)

1971 ◽  
Vol 28 (9) ◽  
pp. 1319-1322 ◽  
Author(s):  
P. A. Dill
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Polarized Light ◽  
Seaward Migration ◽  
Linearly Polarized ◽  
Food Conditioning ◽  
Conditioning Experiments

Food-conditioning experiments conducted in the laboratory demonstrated that groups of yearling sockeye salmon (Oncorhynchus nerka) can discriminate between vertical and horizontal planes of linearly polarized light. Removal of the adipose eyelid, a possible analyser of polarized light, did not abolish the response. The findings support the hypothesis that these fish can use polarization patterns for orientation during their seaward migration.

Vulnerability of sweet cherry cultivars to continuous periods of spring frosts in Plovdiv, Bulgaria

2020 ◽  
Vol 12 (4) ◽  
pp. 348-352
Author(s):  
S. Malchev ◽  
S. Savchovska
Keyword(s):  
Sweet Cherry ◽  
Weather Conditions ◽  
Frost Damage ◽  
Cold Weather ◽  
Bud Burst ◽  
Intermediate Group ◽  
Air Temperatures ◽  
Wide Range ◽  
Group Form ◽  
Sweet Cherry Cultivars

Abstract. The periods with continuous freezing air temperatures reported during the spring of 2020 (13 incidents) affected a wide range of local and introduced sweet cherry cultivars in the region of Plovdiv. They vary from -0.6°C on March 02 to -4.9°C on March 16-17. The duration of influence of the lowest temperatures is 6 and 12 hours between March 16 and 17. The inspection of fruit buds and flowers was conducted twice (on March 26 and April 08) at different phenological stages after continuous waves of cold weather conditions alternated with high temperatures. During the phenological phase ‘bud burst’ (tight cluster or BBCH 55) some of the flowers in the buds did not develop further making the damage hardly detectable. The most damaged are hybrid El.28-21 (95.00%), ‘Van’ (91.89%) and ‘Bing’ (89.41%) and from the next group ‘Lapins’ (85.98%) and ‘Rosita’ (83.33%). A larger intermediate group form ‘Kossara’ (81.67%), ‘Rozalina’ (76.00%), ‘Sunburst’ (75.00%), ‘Bigarreau Burlat’ (69.11%) and ‘Kuklenska belitza’ (66.67%). Candidate-cultivar El.17-90 ‘Asparuh’ has the lowest frost damage values of 55.00% and El.17-37 ‘Tzvetina’ with damage of 50.60%.

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