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Effects of Regulated Flows on Standing Crops of Juvenile Salmon and other Fishes at Barrows Stream, Maine
Author(s) -
Havey Keith A.
Publication year - 1974
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1974)103<1:eorfos>2.0.co;2
Subject(s) - brood , standing crop , juvenile , biology , fishery , zoology , fish <actinopterygii> , age groups , crop , confidence interval , ecology , demography , mathematics , statistics , sociology , biomass (ecology)
Mean standing crop of 5 brood years of age 0+ salmon prior to regulation of stream flows was estimated for each kg of female spawners/ha. Estimate was 20.1 fish/ha weighing 0.035 kg. Mean standing crop of 5 brood years of age 0+ salmon for each kg of female spawners following flow regulation was 39.0 fish/ha weighing 0.088 kg. The estimates are not significantly different at the 95% confidence level but are at the 70% confidence level. Mean standing crop of 5 brood years of 10–15 cm age I+ salmon prior to regulation of stream flows was estimated for each age 0+ salmon/ha and for each kg of age 0+ salmon/ha of the same brood years. So measured each age 0+ salmon produced 0.0040 kg of age I+ salmon and each kg of age 0+ salmon produced 1.876 kg of age I+ salmon. For 4 brood years of 10–15 cm age I+ salmon following flow regulation each age 0+ salmon produced 0.0029 kg of age I+ salmon and each kg of age 0+ salmon produced 1.115 kg of age I+ salmon. Differences for before and after flow regulation are not significant at the 95% confidence level. Mean annual survival from age 0+ to 10–15 cm age I+ salmon prior to and following flow regulation was 18.69% and 19.61% respectively. The differences in survival are not significant at the 95% confidence level. Prior to water control, mean annual number of all fish except salmon was 3,775/ha while mean annual weight was 19.003 kg/ha. After water regulation mean annual number of all fish except salmon was 6,795/ha while mean annual weight was 21.504 kg/ha. Neither number nor weight differences are different at the 95% confidence level. Small fish tended to respond to the increased flows more than the larger fish. Some practical aspects of operation of small water control dams are discussed particularly the desirability of releasing additional water following large rains in dry seasons.