02620nas a2200241   4500008004100000245013300041210006900174300001200243490000700255520187800262653001402140653001102154653001502165653001902180653001902199653002302218653002202241653001502263653001802278653001602296100002002312856004602332       2001                        eng d00aUntested Assumptions: The Role of Canals in the Dispersal of Sea Lamprey, Alewife, and Other Fishes in the eastern United States0 aUntested Assumptions The Role of Canals in the Dispersal of Sea   a309-3290 v603 a<p>Canals provide aquatic organisms with an excellent thoroughfare to disperse, expand their range, and gain access to new drainages. The evidence used to support this contention is vast and dates to at least the early nineteenth century. In most cases however, the evidence used to defend the contention is not a direct observation of fish dispersing through a canal. Instead, the transfer is generally inferred after the new species is observed in a new watershed, one connected by a canal to the watershed in which the fish was already established. Often, these inferences are developed without considering aspects of the life history and behavior of the fishes involved, or the structure of the canal. I explore the historic transfer of sea lamprey, alewife and other fishes from one watershed to another in the inland waters of eastern North America, primarily New York. New York is an ideal area for examining this phenomenon as a canal has connected each of the five major drainages in the state during part of the previous 200 years. These twelve major canals, and the Welland Canal that connects lakes Ontario and Erie, bypassed major obstructions and created a continuous water route among drainages. Also, many of the 167 freshwater and diadromous fishes of New York exhibited distribution patterns historically limited to a watershed or set of neighboring watersheds. When several important cases are re-examined, dispersal through a canal is not the most parsimonious explanation for the presence of the species in a new drainage. To argue fish dispersal through navigation canals, researchers must consider the natural history and ecological requirements of the species, the characteristics and environmental conditions of the canal, and alternative explanations. The mere presence of a canal does not demonstrate that fish used the canal for dispersal.</p>
10aaqueducts10acanals10aErie Canal10aexotic species10afish dispersal10afish introductions10airrigation canals10anavigation10arainbow smelt10awhite perch1 aDaniels, R., A.  uhttp://dx.doi.org/10.1023/A:1011032907484