Fish survey

Step 2. Determine the lowest IC25 from a battery of sublethal toxicity tests. Step 2. Assign an LTF rating of 1 to 5 to the fish survey based on the percentage of potentially effluent-related effects relative to all the endpoints measured. 

Step 4 assess the strength of the relationship between a sublethal test and a field measurement (fish survey or ICS) based on similarity between ratings. 

Table 3. Calculation of number of effects for fish survey.

The final LTF rating for the fish survey is assigned according to Table 4 using the percentage PERE value. A rating from 1 ( no effects ) to 5 ( severe effects ) is the LTF rating for the fish survey. 

Table 7. Fish survey summary statistics analyses1 for white and longnose sucker, Kimberly-Clark...

Sublethal toxicity test Fish survey Benthic survey... 

A LTF rating of 1 ( very low level of effects or no effects observed ) to 5 ( severe level of effects ) was assigned to the fish survey based on the percentage of potentially effluent-related effects relative to all the endpoints measured. Statistically significant differences at a = 0.05 between reference and exposed white sucker (Catastomus commersoni) collected for the Provincial Papers study, including significant interactions from covariate analysis, in either sentinel species and in either sex, were considered to be possibly effluent-related effects (PERE). 

Using the LTF scheme, the study of effluent discharge situations at 16 Ontario pulp and paper mills has illustrated predominantly moderate to strong qualitative relationships between toxicity tests and ecosystem indicators (fish populations and benthic invertebrate communities). Ceriodaphnia- to-benthos, Selenastrum-to-benthos and fathead-to-fish survey relationships were qualitatively rated strong or moderate in 94%, 75% and 60% of the sixteen studies, respectively. Regression analysis of LTF scores has revealed that the relationship between the Ceriodaphnia reproduction test and benthic invertebrate field survey measurements was significant (p < 0.001, r = 0.79). However, there were not sufficient data to determine if this can be used as a predictive tool (Borgmann et al., 2004). 

Six-carbon volatile alcohols and aldehydes have been found in all freshwater fish surveyed (23-24). However, these compounds have not been found in either salmon residing in saltwater (unpublished data) or in oysters (26). Hexanal has been found in modestly fresh (5-6 days old) saltwater fish (24), but its formation may be the result of autoxldation rather than via enzyme-mediated reactions. Thus, data for the occurrence of hexanal in freshly harvested saltwater fish remains to be developed. Hexanal and (E)-2-hexenal contribute coarse, green-plant-like, aldehydic aroma notes to freshly harvested finfish where their aroma dominates the overall odors within seconds after the death of the fish. (Z)-3-Hexen-l-ol contributes a clean, green-grass-like aroma note. Hexanal always occurs in substantially greater abundance than 1-hexanol in fish. 

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