Final Technical Report: - Southwest Fisheries Science Center - NOAA

The number of striped dolphin sightings was 553 in the ETP and 43 in the CCE.
The large number of striped dolphin sightings in the ETP exerted a tremendous influence
on the combined model. In particular, the variables selected in the combined model and
their function forms were identical to the ETP model, with the exception that the
combined model showed an increase in the number of sightings in temperatures greater
than 16 degrees (Fig. 17). Habitat variables selected for the CCE model were different,
showing a strong avoidance of areas with temperature fronts (Fig. 17). Ratios of
observed to predicted encounter rates were biased (i.e., had a value of 0.907, rather than
the expected value of 1.0) when the combined model was used to predict striped dolphin
distributions in the CCE.
Figure 17. Encounter rate models built at a 60-km resolution for striped dolphin to explore the effect of
extent. Using the combined model to predict encounter rates in the California Current ecosystem resulted
in a bias, suggesting that the best predictive power was achieved by the ecosystem-specific models.
The number of short-beaked common dolphin sightings was 334 in the ETP and
301 in the CCE. The variables selected in all models were the same, with the exception
of the inclusion of a salinity variable with a weak effect on the number of sightings in the
CCE model (Fig. 18). However, the functional form of some variables was ecosystem
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