Chapter 15: Potential Geographic Range
To gain a better understanding of the types of environments black carp Mylopharyngodon piceus might successfully invade, in this chapter, we identify and assess factors important to the survival and persistence of black carp populations in the wild. Special attention is given to environmental tolerances and to spawning and habitat requirements. We include details about the Kara-Kum Canal and Tone River, two aquatic systems where introduced black carp have successfully become established and have persisted for several decades. In addition, we discuss possible reasons why black carp are uncommon or have failed to become established in other areas. We also discuss the potential geographic range of introduced black carp in the United States. Finally, we review information on methods used to capture or sample black carp.
Temperature often is considered the most important determining factor in predicting the potential distribution of many introduced species. Because little information exists on the thermal tolerance ranges of many foreign fishes, potential range is sometimes inferred from distributions within native ranges. Temperature constraints provide only a broad predictor of the potential range and types of environments likely to be invaded. In most cases, the realized range would likely be less than that predicted by temperature tolerance alone. Additional factors considered important in the survival and establishment of black carp populations, and likely useful in making predictions about their potential range, include other environmental tolerances (e.g., salinity and water quality), availability of food resources, habitat and spawning requirements, and ecological factors (e.g., predation and competition). Moreover, when considering potential range of introduced black carp (and also other Chinese carps), it is essential to distinguish between the types of environments where black carp would likely survive versus environments where the species would more likely persist through establishment of reproducing populations. For instance, although black carp is a lowland species, it has been introduced into upland lakes and ponds in China that exceed 1,700 m above sea level (Chu et al. 1989; Yang 1996). In these habitats, stocked fish are known to survive many years without reproduction. Considering their potential lifespan, such nonreproducing populations may persist well over a decade even without additional stockings. In contrast, it appears that a combination of conditions (e.g., availability of particular habitats, select range or minimum water temperature and river flow) have to be present (and correctly timed) for black carp to successfully reproduce and complete their life cycle.