ECOLOGICAL NICHE MODELING AS A PREDICTIVE TOOL: ASIATIC FRESHWATER FISHES IN NORTH AMERICA

Abstract

A major problem with invasive aquatic species is that they are almost impossible to eradicate once established. Hence, the best method to prevent establishment of such species is to assess their invasive potential proactively and respond appropriately. After introduction, the most effective way is to predict their spread, to discover populations early, and to adopt measures to eradicate or at least contain them. This dissertation uses ecological niches modeling to estimate the ecological requirements of 33 Asiatic freshwater fishes from native-range occurrence points, and to use these data to forecast their invasive potential in North America. The silver carp, bighead carp, grass carp, black carp, northern snakehead, Asian swamp eel and the oriental weather-fish have been introduced into the United States. Native-range niche models for each species predict known occurrences in North American significantly better than null expectations. The silver and bighead carps are predicted to have the potential to spread throughout the eastern U.S. and selected areas of the West Coast. The black carp was predicted suitable throughout the eastern U.S., and the West Coast. The grass carp was to find suitable habitat in a broader area than black carp, and of being able to extend more in the west. The northern snakehead was predicted being able to spread throughout much of the eastern half of the U.S. The Asian swamp eel was predicted being able to establish populations in the southern U.S., all of the lower Mississippi River drainage, and the West Coast. The oriental weather-fish was predicted suitable in the entire conterminous USA except the Rocky Mountain and desert areas. Native-range models for the other 25 fishes suggest that Myxocyprinus asiaticus, Channa maculata, Sinilabeo decoru, Cirrhinus molitorella are not likely to establish populations and spread broadly in North America. Siniperca chuatsi, Elopichthys bambusa, Micropercops swinohonis, Squaliobarbus curriculus, Leuciscus waleckii, and Rhodeus ocellatus may be able to become locally established. Abbottina rivularis, Hemiculter leucisculus, Hemibarbus labeo, H. maculatus, Plagiognathops microlepis, and Pseudorasbora parva have the potential to occupy the entire conterminous USA as the common carp has done.