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Diel and Seasonal Patterns of Spotted Gar Movement and Habitat Use in the Lower Atchafalaya River Basin, Louisiana
Author(s) -
Snedden Gregg A.,
Kelso William E.,
Rutherford D. Allen
Publication year - 1999
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1999)128<0144:daspos>2.0.co;2
Subject(s) - diel vertical migration , dusk , nocturnal , floodplain , fishery , ecology , biology , geography , environmental science
We used radiotelemetry to determine diel and seasonal movements, habitat use, and home range behavior of 37 adult spotted gars Lepisosteus oculatus in the Atchafalaya River basin, Louisiana. The Atchafalaya River exhibits a distinct spring flood pulse each year, inundating a 3,640‐km 2 floodplain that includes a complex network of canals, bayous, and lakes. During nonflood months, diel locations of 27 fish recorded at 2‐h intervals (median = 24 locations/fish) indicated that most spotted gars were shoreline oriented ( P < 0.0001), preferred submerged branches as cover, and avoided areas of exposed bank ( P < 0.0001). Median spotted gar movement rates were higher during summer (40.4 m/h) than fall–winter (15.1 m/h), and during both seasons, rate of movement and percentage of home range used were significantly greater at night than during dawn, day, or dusk periods ( P < 0.03). Increased nocturnal activity appeared to be related to feeding periodicity, as a substantially greater proportion (70%) of spotted gars collected at night ( N = 30) contained food compared with dawn, day, and dusk samples (29%; N = 90). Seasonal movement studies (twice‐weekly locations; N = 37 fish) indicated that spotted gar activity increased as water temperature and river stage rose in the spring, resulting in greater median movement rates (130.1 m/d) and home ranges (265.1 ha) than during fall–winter (35.8 m/d; 6.2 ha) and summer (34.6 m/d; 10.5 ha). Spotted gar home ranges established during the flood pulse typically included large areas of inundated floodplain, which provided extensive areas of suitable spawning and nursery habitat.