Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Summary of Toxicity Information from Open Literature
To organize the available toxicity information on listed salmonids and habitat, we developed risk
hypotheses with associated assessment endpoints as described in the Approach to the Assessment
section. Recall that assessment endpoints are biological attributes of salmonids and their habitat
potentially susceptible to the stressors of the action. In addition to toxicity data presented in the
BEs, we also considered information from other sources to evaluate both individual and
population-level endpoints. The results of those studies are summarized below under
corresponding assessment endpoints. We qualitatively assigned the most significance to study
results that were: 1) derived from experiments using salmonids (preferably listed Pacific
salmonids or hatchery surrogates); 2) measured an assessment endpoint of concern e.g.,
survival, growth, behavior, reproduction, abundance etc., identified in a risk hypothesis; 3)
resulted from exposure to stressors of the action or relevant chemical surrogates (i.e., other
AChE inhibitors); and 4) had no substantial flaws in the experimental design. When a study did
not meet these criteria, we highlighted the issue(s) and discussed how the information was used
or why the information could not be used.
Assessment endpoint: Swimming
Assessment measures: Burst swimming speed, distance swam, rate of turning, baseline speed,
tortuosity of path, acceleration, swimming stamina, and spontaneous swimming activity
Swimming is a critical function for anadromous salmonids that is necessary to complete their life
cycle. Impairment of swimming may affect feeding, migrating, predator avoidance, and
spawning (Little and Finger 1990). It is the most frequently assessed behavioral response of
toxicity investigations with fish (Little and Finger 1990). Swimming activity and swimming
capacity of salmonids have been measured following exposures to a variety of AChE-inhibiting
insecticides including the carbamates carbaryl and carbofuran and a variety of OP insecticides.
Swimming capacity is a measure of orientation to flow as well as the physical capacity to swim
against it (Howard 1975; Dodson and Mayfield 1979). Swimming activity includes
measurements of frequency and duration of movements, speed and distance traveled, frequency
and angle of turns, position in the water column, and form and pattern of swimming. A review
paper summarized many of the experimental swimming behavioral studies and concluded that
effects to swimming activity generally occur at lower concentrations than effects to swimming
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