Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
6. The acute toxic range for larvae to chlorinated phenols was typically between 10 ppb and 100 ppb.
Larvae were more sensitive to DDAC.
7. The acute toxic range for feeding fry to chlorinated phenols was typically between 1 ppm and 10 ppm.
Feeding fry were more sensitive to DDAC.
8. There are no comparative data for the toxicity of the chlorinated phenolic test chemicals for other fish
larvae.
9. Sturgeon fry have a similar acute toxicity to 3,4,5,6-tetrachloroguaiacol and 4-chlorocatechol as found in
previous studies with juvenile bleak and pink salmon, and are at least five times more sensitive to
pentachlorophenol compared with a variety of other fish.
10. Sturgeon fry and larvae are considerably more sensitive (100 - 1,000 times) to DDAC compared with the
other juvenile fish we have tested.
11. Studies of growth rates following sublethal exposures were unsuccessful. The post-exposure death rate
was progressive for controls and for exposed fish (Figure 1). However, there was a marked pulse of
mortality after each handling to measure body mass. Interestingly, some of the survivors of test chemical
exposure shower excessive mortality following handling. These observations point to, but provide no
conclusive evidence, multiple stresses being a particular threat to juvenile sturgeon.
Recommendations
1. A source of white sturgeon eggs in B.C. needs to be established.
2. A standardized rearing and testing protocol needs to be established. We have only begun to understand
all the possible variables. Focus should be placed on acute toxicity testing of larvae and feeding fry,
since these life stages appear to be viable options. However, we do not feel that testing with sturgeon
eggs will produce consistent or reliable data. A different protocol to the one we used, possibly involving
less handling of the fish, will be needed before successful studies of juvenile growth are practical.
3. Relevant environmental chemical concentrations and the rate of chemical degradation must be obtained
in order to evaluate the consequences of exposure. A chemical transportation/fate model might be useful
here.
4. Information on the biology of white sturgeon is needed in order to determine where juveniles reside and,
therefore, what the actual chemical exposure might be.
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