Appendix 5: Description of Habitat Suitability Index (hsi) Modeling Conducted by Nos

Habitat suitability modeling (HSM) is a tool for predicting the quality or suitability of habitat for a given species based on known affinities with habitat characteristics, such as depth and substrate type. This information is combined with maps of those same habitat characteristics to produce maps of expected distributions of species and life stages. One such technique is termed habitat suitability index (HSI) modeling. A suitability index provides a probability that the habitat is suitable for the species, and hence a probability that the species will occur where that habitat occurs. If the value of the index is high in a particular location, then the chances that the species occurs there are higher than if the value of the index is low. HSI models use regression techniques to analyze data on several environmental parameters and calculate an index of species occurrence. Since this methodology has potential for use in designating EFH and HAPC, we review it briefly here. It is described in more detail in various scientific publications (see for example Christensen et al. 1997, Clark et al. 1999, Coyne and Christensen 1997, Rubec et al. 1998, Rubec et al. 1999, Monaco and Christensen 1997 and Brown et al. 2000).