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

these labels satisfies EPA’s obligations to listed salmonids pursuant to section 7(a)(2) of
the ESA.
The NMFS evaluates whether endangered species, threatened species, and designated
critical habitat are likely to be exposed to the direct and indirect effects of the proposed
action. If those listed resources are not likely to be exposed to these activities, we would
conclude that EPA’s action is not likely to jeopardize the continued existence of
threatened species, endangered species, or result in the destruction or adverse
modification of designated critical habitat under NMFS’ jurisdiction. If, however, listed
individuals are likely to be exposed to these actions and individual fitness is reduced,
then we evaluate the potential for population-level consequences.
A Viable Salmonid Population (VSP) is an independent population of any Pacific
salmonid that has a negligible risk of extinction due to threats from demographic
variation, local environmental variation, and genetic diversity changes over a 100-year
time frame (McElhaney, Ruckleshaus et al. 2000). The independent population is the
fundamental unit of evaluation in determining the risk of extinction of salmon in an ESU.
Attributes or metrics associated with a VSP include the abundance, productivity, spatial
structure, and genetic diversity of the population. Abundance is defined as the size of the
population and can be expressed in a number of ways, e.g., the number of spawning
adults, the number of adults surviving to recruit to fisheries, or the number of emigrating
smolts. Abundance is a vital measure, as smaller populations run a greater risk of
extinction. The second VSP measure is productivity, generally defined as the growth rate
of a population. This Opinion discusses productivity in terms of lambda (λ). Appendix 1
contains a more detailed explanation of λ in the context of our population models. The
spatial structure of a population is inherently dependant on the quantity and quality of
available habitat. A limited spatial structure can hamper the ability of the ESU to
respond to evolutionary pressures. Genetic variability within the ESU gives the species
the ability to respond to short-term stochastic events, as well as to evolve to a changing
environment in the long-term. These VSP parameters provide an indication of the
population’s capacity to adapt to various environmental conditions and ability to be self-
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