Seasonal and diel patterns of movement of shortnose sturgeon in an un-encumbered section of the Connecticut River using acoustic telemetry

We present movement patterns of the US Federally Endangered shortnose sturgeon in Connecticut waters from acoustic telemetry. Thirty nine depth sensing ultrasonic transmitters (2002 - 20, 2003 - 19) were surgically implanted into adult shortnose sturgeon collected in the lower Connecticut River.  Twenty self contained acoustic receivers were deployed at throughout the river (river kilometer 4.0 - 119.0).  Receivers were downloaded monthly and seasonally moved within the river as necessary.  Over 1.4 million observations were recorded from 05/23/02 through 10/17/04.  Observations per fish ranged from 2,154 to 120,896 (mean 38,559).   Fish utilized deeper water (mean=15.0 m) during winter than during summer months (mean=5.5 m). Analyses of activity among five water temperature stanzas (0-5, 6-10, 11-15, 16-20, 20+) indicated that sturgeon were active year round.  Periodicity of vertical movement in the water column varied markedly among individuals and over the course of the year.  No obvious patterns were evident with individual fish displaying unique movement patterns, but all tagged sturgeon utilized deeper water during daylight hours.  Variation in movement patterns among individuals has important implications in providing adequate protection to this Endangered species in that not all sturgeon behaved similarly or utilize similar depth strata.