Upstream Migration of Yellow-Phase American Eels (Anguilla rostrata) At Norrell Lock and Dam, Arkansas River Navigation System

The American eel (Anguilla rostrata) has experienced a decline from historical population sizes in parts of its range.  Previous studies focus on Atlantic river systems, however limited data exist in the Mississippi River Basin.  It is hypothesized the American eel has experienced similar declines in the Arkansas River.  Limited recruitment into the Arkansas River could explain a declining population within the system.  Our objective was to describe the upstream migratory phenology of yellow-phase eels in the Arkansas River Navigation System.  A concrete sill below Norrell Lock and Dam, the first obstacle fishes migrating upstream from the Gulf of Mexico encounter, was sampled by backpack electrofishing from 22 March 2012 to present.  Nineteen yellow-phase eels (mean length = 487mm, + 97mm) were collected below Norrell Dam.  Seventeen were collected from 7 April 2012 to 21 May 2012, two others were collected on 13 January 2013 and 23 February 2013.  Maximum eel abundance corresponded to increasing river flow and temperatures ranging from 22-27°C.  Presence of eels below Norrell Dam for a limited period and within a certain temperature and flow regime suggests migratory yellow-phase eels are seeking entry into the Arkansas River.