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Distribution and Abundance of Saprolegnia in the Water System of a Chinook Salmon Hatchery
Author(s) -
Waterstrat P. R.
Publication year - 1997
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(1997)009<0058:daaosi>2.3.co;2
Subject(s) - hatchery , saprolegnia , biology , fishery , chinook wind , raceway , fish hatchery , biomass (ecology) , fish farming , abundance (ecology) , aquaculture , ecology , oncorhynchus , fish <actinopterygii> , physics , finite element method , thermodynamics
A pour‐plate fungal assay was used to monitor the abundance of Saprolegnia fungi in the water supply of a hatchery for Columbia River chinook salmon Oncorhynchus tshawytscha that was supplied with both single‐pass creek water and 90% reuse well water. Hatchery production records were used to explore the relationship between the hatchery environment and fungal abundance. Saprolegnia was not detected in well water supplying the hatchery. Only minimal levels of Saprolegnia were detected in raceways receiving singlepass creek water. However, significant levels of Saprolegnia were observed in raceways receiving water from the 90% reuse system during the hatchery production cycle. During 1993, Saprolegnia in the reuse system increased from 33.5 colony‐forming units per liter (cfu/ L) upon the introduction of fish to the raceways to 592.5 cfu/L just prior to the final release of fish as smolts. Similar results were observed during the 1994 production cycle in which Saprolegnia increased from 141.6 cfu/L at the initiation of rearing to 550.0 cfu/L just prior to release. The major variables affecting the abundance of Saprolegnia in the reuse system were the duration of hatchery rearing, total fish biomass in the reuse system, and water temperature. Reuse system biomass was more significant than individual raceway biomass in determining the abundance of Saprolegnia . In reuse systems where water is mixed in common biofilters or aeration towers, reducing fish density within an individual raceway may have little effect on the exposure of fish to infectious agents unless the total biomass within the reuse system is reduced.