Chapter 7: Seabirds

Abstract

This chapter describes an assessment of the at-sea distribution of seabirds around the Main Hawaiian Islands (MHI). We analyzed at-sea visual sighting data collected by the National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) on shipboard surveys conducted during May and August-December between 1989 and 2012. We present the locations of sightings of 24 species, and for 14 of these species we develop spatial predictive models of relative density throughout the study area. Model predictions are presented with associated measures of precision and statistical fit in terms of a suite of performance metrics. Spatial distributions varied across species, with the majority of sightings occurring relatively close to land, occurring in particular parts of the study area, or occurring more evenly throughout the study area. Predicted spatial distributions for species that were modeled broadly aligned with the distributions of sightings. Some of the most important model predictor variables across species were day of the year, distance to shore or nearest terrestrial site, depth, sea surface height and projected longitude/latitude. Our assessment provides broad-scale spatial information that can aid marine spatial planning around the MHI. Importantly, our assessment also highlights gaps and limitations in the available data, which can guide future data collection efforts. In addition to our assessment, we discuss other studies and available datasets on the at-sea distribution of seabirds around the MHI