Final Technical Report: - Southwest Fisheries Science Center - NOAA

comparison is based on a separate set of models developed from remotely-sensed environmental
variables instead of in situ shipboard data. Predictive ability across seasons is estimated by
applying these models to aerial survey data collected during different seasons. This approach
provides the advantages of a large, robust data set for construction of models (the shipboard data)
and a more comprehensive seasonal data set (the aerial survey data) for examination of seasonal
predictions.
Although the foundations for habitat and spatial modeling had been laid at the time we
started our project, many questions were still unanswered. Our project focused on improving
the science of cetacean habitat modeling in several key areas. We studied and compared the
effectiveness of three different modeling approaches, GLMs, GAMs, and tree-based models. We
studied the importance of scale (both resolution and extent) in habitat modeling and used this
information to chose the most appropriate scales for our final models. We evaluated alternative
methods for interpolating habitat variables and cetacean density estimates. We evaluated
alternative statistical models (Poisson, quasi-likelihood, and negative binomial) for describing
the variance seen in cetacean encounter rates. We developed new methods to estimate the
uncertainty in cetacean density estimates based on habitat models. We evaluated the
improvements in the precision of habitat models that would result from adding additional
information about mid-tropic components of cetacean habitat. Finally, we applied what we
learned from these basic research topics to obtain habitat-based density models for 12
species/guilds in the California Current Ecosystem and 15 species/guilds in the Eastern Tropical
Pacific Ecosystem.
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