TABLE OF CONTENTS Pages Symposium 1 - the National Sea ...

splittail were collected from the Delta during the summer l998 and held until
completion of the 1999 summer trials in the Tracy Aquaculture Facility. Mean
lengths (TL) of splittail during the pump study (December 1998 to July 1999)
increased from 83 to 107mm and those of juvenile Fall-run chinook salmon obtained
from the hatchery Mokelmumne River Hatchery, increased from 44 to 97mm in
February and May, respectively. Growth was relatively good considering that these
fish were held on a maintenance diet (< 1% body weight).
Descaling rates for splittail and chinook salmon (Table 1) were low, averaging 1.9
and 2.4% of the body, respectively. Comparisons among quality control (handling
effect), control (no pump passage) indicated no effect on descaling for either splittail
or chinook salmon. Scale loss was in both species, and generally increased at warmer
water temperatures.
Table 1. Descaling (% body) and injury analysis (% fish) for quality control
(recirculation system) groups of splittail and chinook salmon at Tracy Pumping Plant,
California.
Fish Descalin
g
Body Injury (% fish)
Month (N) (% body)
Group
Splittail:
Head Eyes Skin Fins
Quality
Control
Dec. 40 1.4 20 55 2.5 53
Quality
Control
Feb. 36 3.1 0 3 0 31
Quality
Control
March 32 1.4 0 6 0 9
Quality
Control
April 44 1.1 0 0 0 0
Quality
Control
May 40 1.6 0 0 0 0.2
Quality
Control
June 50 3.9 0 5 0 7
Quality
Control
July 40 2.4 0 0.3 0 0.1
Chinook Salmon:
Quality
Control
Feb. 28 0.1 14 0 4 4
Quality
Control
March 38 0.3 0 0 0 18
Quality
Control
April 44 0.7 0 0 0 0
Quality
Control
May 40 4 0 0 0 0
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