Sacramento River green sturgeon acoustic telemetry detections

Abstract for publication titled: Intraspecific variation in migration
timing of green sturgeon in the Sacramento River system Understanding
movement patterns of anadromous fishes is critical to conservation
management of declining wild populations and preservation of habitats.
Yet, the duration of observations for individual animals can constrain
accurate descriptions of movements. In this study, we synthesized over a
decade (2006-2018) of acoustic telemetry tracking observations of green
sturgeon (Acipenser medirostris) in the Sacramento River system to
describe major anadromous movement patterns. We observed that green
sturgeon exhibited a unimodal in-migration during the spring months but
had a bimodal distribution of out-migration timing, split between an
‘early’ out-migration (32%) group during May - June, or alternatively,
holding in the river until a ‘late’ out-migration (68%), November -
January. Focusing on these out-migration groups, we found that river
discharge, but not water temperature, may cue the timing of migration, and
that fish showed a tendency to maintain out-migration timing between
subsequent spawning migration events. We recommend that life history
descriptions of green sturgeon in this region reflect the distinct
out-migration periods described here. Furthermore, we encourage the
continued use of biotelemetry to describe migration timing and life
history variation, not only this population but other green sturgeon
populations and other species.