An assessment of gears for sampling shovelnose sturgeon in tributaries

Abstract

Despite potential importance of tributaries to Shovelnose sturgeon populations and historical declines range wide, limited population demographic and sampling efficiency information exists on shovelnose sturgeon populations in tributaries of the Upper Mississippi River. As such, we sought to evaluate the catch statistics of boat electrofishing, drifted trammel netting, and otter trawling for assessing shovelnose sturgeon populations on the Cedar River in Iowa. Trammel nets did not provide the highest estimate of CPUE or number of fish captured, however did provide the lowest CV of CPUE and thus required the least amount of effort needed to detect changes in relative abundance. Trammel netting also captured the widest size range of fish and most proportionate male:female ratio. If goals were to evaluate trends in relative abundance, male:female ratio, and spawning periodicity of females with the least amount of effort, trammel nets appear to be best suited. However, when sampling objectives require a large number of fish to be collected, the use of multiple gears may be appropriate. Our study highlights the need for an adaptive multi-gear sampling approach to properly evaluate shovelnose sturgeon in tributaries across the Upper Mississippi River.