Resolving Uncertainties in Gulf Sturgeon Mortality and Movement Rates PDF Download

Author: Merrill B. Rudd
Publisher:
ISBN:
Category :
Languages : en
Pages : 130

Get Book Here

Book Description
This study utilized the data collected from a standardized acoustic telemetry tagging program and historic mark-recapture database to resolve uncertainties in Gulf sturgeon mortality and movement rates at spatial scales relevant to management. Using multi-state models with river mouth acoustic receiver detections over a two year period, I estimated detection probabilities greater than 0.50 across all rivers and time periods. River and marine survival rates were similar in all regions except the western Gulf, where riverine survival was lower. Gulf sturgeon exhibited non-random fidelity to their natal rivers, and were more likely to enter their natal river or genetically related riverine population. High fidelity rates to rivers or genetically distinct units combined with differential mortality rates spatially provides support for considering Gulf sturgeon stocks as distinct population segments. This delineation could be important if population segments show divergent evidence of recovery. Using estimates of mortality from the telemetry study and a historic mark-recapture database, I updated the Gulf sturgeon stock assessment using an age-structured mark-recapture (ASMR) model. I fit initial marking and recapture data from the Suwannee, Apalachicola, and Choctawhatchee Rivers, incorporating uncertainty in initial age assignment, to estimate a time series of abundance, recruitment, and survival in each riverine population. Assuming a negative binomial probability distribution, model results were possibly divergent depending on pulsed or constant effort sampling designs. These results demonstrate important tradeoffs between monitoring time, size of the marked population, and capture probability, which are necessary to consider in managing a protected species.