Benthic Habitats and the Effects of Fishing

Fish Habitat Studies: Combining High-Resolution Geological and Biological Data

W. Waldo Wakefield, Curt E. Whitmire, Julia E. R. Clemons, and Brian N. Tissot

doi: https://doi.org/10.47886/9781888569605.ch10

Abstract. Traditionally, estimates of the distribution and abundance of exploited groundfish species and their associated habitats are based on fishery-dependent sampling of catch and fishery-independent survey data using fishing gears such as trawls and a variety of fixed gears. Survey data are often collected as individual samples integrated over a scale of kilometers, compiled at a larger geographic scale (100 km), and extrapolated to an overall estimate of stock size. Considerations of the nonextractive effects of fishing on habitat are extremely limited. Within the past 15 years, a number of collaborations have developed among marine ecologists, fisheries scientists, and marine geologists hallmarked by an integration of sonar mapping of the seafloor with ground-truthing (verification of type of substratum) and direct observation and enumeration of fish and invertebrate populations in the context of their seafloor habitat. An example of such work, targeting a 725-km2, deepwater, rocky bank from the Oregon continental margin, Heceta Bank, is chronicled in this review. The approaches that have been applied to characterize groundfish–habitat relationships in this region have evolved from stand-alone, human-occupied submersible observations to fully interdisciplinary programs employing the most advanced technologies available to marine research. The combination of multibeam swath mapping sonars and accurate geographic positioning systems has enhanced mapping the seafloor and benthic habitats. The challenge now is to efficiently relate small-scale observations and assessments of animal–habitat associations to the large geographic scales on which fisheries operate. Large-scale benthic habitat characterization at appropriate scales is critical to the accurate assessment of fish stocks on a spatial scale pertinent to fisheries and those natural physical and biological processes and anthropogenic disturbances (e.g., fishing gear impacts) that influence them.