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

type Chinook salmon, it is the 3-month period the sub-yearling smolt spend in the estuary and
nearshore habitats (i.e., estuary survival). The weight distributions from the organismal model
are converted to length distributions by applying condition factors from data for each modeled
species (cf; 0.0095 for sockeye and 0.0115 for all others) as shown in Equation L.
Equation L: length(mm) = ((fish weight(g)/cf)^(1/3))*10
The relationship between length and early winter or estuary survival rate was adapted from Zabel
and Achord (2004) to match the survival rate for each control model population (Howell et al.
1985, Kostow 1995, Myers et al. 2006). The relationship is based on the length of a sub-yearling
salmon relative to the mean length of other competing sub-yearling salmon of the same species
in the system, Equation D, and relates that relative difference to size-dependent survival based
upon Equation S. The values for α and resulting size-dependent survival (survival φ) for control
runs for each species are listed in Table 2. The constant α is a species-specific parameter
defined such that it produces the correct control survival φ value when ∆length equals zero.
Equation D: ∆length = fish length(mm) – mean length(mm)
Equation S: Survival φ = (e ( α+(0.0329*∆length)) ) / (1 + e (α+(0.0329*∆length)) )
Randomly selecting length values from the normal distribution calculated from the organismal
model output size and applying equations 1 and 2 generates a size-dependent survival probability
for each fish. This process was replicated 1,000 times for each exposure scenario and
simultaneously 1,000 times for the paired control scenario and results in a mean size-dependent
survival rate for each population. The resulting size-dependent survival rates are inserted in the
calculation of first-year survival in the respective control and pesticide-exposed transition
matrices.
The investigation of population-level responses to pesticide exposures uses life history projection
matrix models. Individuals within a population exhibit various growth, reproduction, and
survivorship rates depending on their developmental or life history stage or age. These age
specific characteristics are depicted in the life history graph (Figure 1A-D) in which transitions
are depicted as arrows. The nonzero matrix elements represent transitions corresponding to
reproductive contribution or survival, located in the top row and the subdiagonal of the matrix,
respectively (Figure 1E). The survival transitions in the life history graph are incorporated into
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