Science NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of the Atlantic sturgeon. This research informs management decisions and enhances recovery efforts for endangered and threatened Atlantic sturgeon populations. Tagging and Tracking Scientists are using tagging techniques to learn about the migration patterns of Atlantic sturgeon and identify important juvenile habitats. Dart, passive integrated transponder, radio, satellite, pop off, and acoustic tags are being used. Tags such as PIT tags and dart tags allow for an individual fish to be identified by other researchers when it is captured. Acoustic and satellite telemetry tags let researchers learn where Atlantic sturgeon migrate, at what depths, and at what speeds. NOAA Fisheries biologist, Jason Kahn, holds an Atlantic sturgeon as part of a collaborative research project. Photo: NOAA Fisheries Genetics Atlantic sturgeon researchers take small fin clips from every sturgeon they catch to better understand the genetic composition of all populations. Atlantic sturgeon that are accidentally captured or killed in non-research-related projects can be matched to the river where they were born using information in their DNA (“genotype”). In other cases, a tissue sample from sturgeon spawning (releasing or depositing eggs) in a particular river can be taken. After the sample is processed by a lab, the genetic information in that sample can be stored with other Atlantic sturgeon genotypes to create baselines of the unique genotypes found for each spawning population. Those baselinesallow sturgeon to be identified back to their natal river. Genetic variation (“heterogeneity”) within the population can also be used to estimate the minimum number of spawning adults that would have been required to generate that level of heterogeneity, which helps us learn more about the approximate number of successfully spawning adults, their natal river, and their family history. NOAA Fisheries is creating a searchable database to allow researchers to know which samples are available to be analyzed and which have already been analyzed. NOAA Fisheries, in partnership with numerous federal and academic researchers monitors effective population size of the spawning populations that have been adequately sampled to produce estimates. While effective population sizes are not easily translated to actual abundance estimates, they can provide a rough comparison between populations to better understand relative abundance and threats of inbreeding or extirpation. The most recent population estimates are, from north to south: St. Lawrence River - between 28 and 99 individuals. St. John River - between 85 and 577 individuals. Kennebec River - between 63 and 110 individuals. Connecticut River - between 2 and 3 individuals. Hudson River - between 172 and 230 individuals. Delaware River - between 75 and 186 individuals. James River - between 40 and 100 individuals. York River - between 6 and 12 individuals. Albemarle Sound (likely Roanoke River population) - between 16 and 22 individuals. Edisto River - between 30 and 51 individuals. Savannah River - between 50 and 99 individuals. Ogeechee River - between 33 and 78 individuals. Altamaha River - between 76 and 189 individuals. Side Scan Sonar Recently, side scan sonar has been used to approximate the number of sturgeon that appear on the image. However, this approach is still being perfected. Most rivers are wide enough that multiple 50m wide transects are needed and long enough that sampling the entire river isn’t possible. Therefore, an equation to account for unsampled areas and fish counted multiple times is needed to correct the estimate. Reducing Bycatch To reduce bycatch, we have funded research that is creating promising new fishing gear configurations that maintain catch rates of target species but protect Atlantic sturgeon. For gill nets, using a raised footrope has shown promise for some fisheries. For trawls, the turtle excluder devices are also effective at keeping Atlantic sturgeon out. The likelihood of mortality of incidentally gill-netted Atlantic sturgeon appears to be related to water quality, how the net is set, and the length of time it is left before being tended. Overall, anchored gill nets (i.e., set on the bottom, as opposed to floating at the surface) tend to cause the greatest risk for mortality of Atlantic sturgeon, compared to other gill nets or types of gear. Atlantic sturgeon incidentally captured in cooler waters have a greater likelihood of survival than those captured in warmer waters. However, the likelihood of survival also appears to increase when bycatch reduction devices are used. Stock Assessment In 2013, the Atlantic States Marine Fisheries Commission initiated a coastwide benchmark population assessment for Atlantic sturgeon to evaluate stock status, stock delineation, and bycatch. The assessment was completed in October 2017 and determined Atlantic sturgeon populations are depleted but stable.