科研之友
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摘要
Historically, Polyodon spathula (American Paddlefish) occurred within the Mississippi River Basin's large rivers, traversing hundreds of kilometers to complete their life cycle. However, populations declined in response to the installation of lock and dam (L/D) structures, declining water quality, and the loosely regulated harvest of the species. By the late 1800s, American Paddlefish were extirpated from many portions of their historic range. In response, federal and state agencies sought to restore inter-jurisdictional populations of this fish. Our objective was to assess reintroduction efforts in the northeastern-most portion of its range. Using a combination of gill nets, boat electrofishing, and larval drift nets, populations were sampled in Pennsylvania and New York over a 10-year-period, post-stocking. Although American Paddlefish were at large in navigable waters of the upper Ohio River Basin, free-flowing and tail-water areas below L/D structures appeared to hold more fish than impounded reaches. The presence of L/D structures and fixed-crest dams may inhibit upstream passage of fish and reduce the availability of forage, as reflected in reduced condition-index scores. Although gravid fishes were captured in Pennsylvania and New York, little evidence exists to suggest the presence of self-sustaining populations, as only one larval American Paddlefish was captured. The recovery of this species to its historic northeast range may hinge on continuing stocking efforts, development of fish-passage structures, conservation lockages, and improvement and protection of suitable spawning habitats.
- 出版日期2016-12
