A species-specific fish passage model based on hydraulic conditions and water temperature

Stream corridors contain many features that act as barriers to fish during migration. We built a model to determine the likelihood that each of 776 dams, culverts and waterfalls in New Jersey act as barriers to each of thirteen fish species during migration. We assessed each fish species at each potential barrier to determine if the fish could jump high enough to clear the barrier, swim fast enough to overcome the velocity of water to reach the barrier, dive deep enough in the plunge pool to reach maximum jump height, and persist with migration given predicted water temperatures. If all four were possible, the potential barrier was deemed passable. Blockages were mostly the result of predicted weak jumping abilities and water temperatures outside the acceptable range during migration. The model successfully predicted presence and absence above potential barriers for all species except the ubiquitous white sucker (C. commersonii). All locations with possible barriers were predicted to block at least two migratory fish species; 89% were predicted to block all species. Alewife (A. pseudoharengus) and blueback herring (A. aestivalis) were predicted to be blocked the most. Results allow prediction of which potential barriers block passage for each species, the length of waterways blocked by each barrier, and the reasons each barrier is predicted to block each species. We present our fish passage model as a tool for identifying possible barriers which if restored or removed, given appropriate field assessment, might reconnect migratory fish species with additional spawning habitat.