Evaluation of Habitat Suitability Index Models for Riverine Life Stages ofAmerican Shad, with Proposed Models for Premigratory Juveniles

摘要

Field evaluations of existing habitat suitability index (HSI) models for spawningadults, eggs, and larvae of American shad (Alosa sapidissima) were conducted in 1990-92; initial models for juveniles in nursery habitats were developed. Fish abundance in various habitats of the upper Delaware River was quantified by (1) observation of adult spawning activity, (2) collection of eggs and larvae with metered plankton and drift nets, and (3) enumeration of juveniles by underwater observation and seining techniques. Regression analysis, principal component analysis, and range analysis were used to relate abundance to an array of physical habitat variables potentially influencing fish distributions. No HSI model was previously developed for juvenile American shad in riverine habitats. The authors found four physical habitat variables that were correlated with juvenile abundance: Water temperature, dissolved oxygen (covariates), river depth, and turbidity.