Fish community responses to the establishment of a Piscivore, Northern Pike (Esox lucius), in a Nebraska Sandhill Lake

摘要

Northern pike (Esox lucius) was first documented in West Long Lake, Nebraska, in 1998 when two pike <380 mm were collected. In 2002, a Peterson mark-recapture population estimate on northern pike revealed density and standing stock (i.e., biomass) estimates of 35.8 fish/ha (95% CI= +/- 8.8) and 22.0 kg/ha (95% CI= +/- 5.4), respectively. Consequently, West Long Lake was sampled in 2002 to compare relative abundance, size structure, and growth of bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), and yellow perch (Perca flavescens) prior to and after the establishment of a high-density northern pike population. Bluegill, largemouth bass, and yellow perch relative abundances were significantly lower in 2002 than 1998. Similarly, size structures of all three species were significantly different between years. Size structure declined for both bluegill and yellow perch, and increased for largemouth bass. Growth was significantly higher for bluegill, largemouth bass, and yellow perch in 2002 than 1998. While the fish community changes were expected with the establishment of northern pike, they occurred in a relatively short time period (i.e., four years).