Summary Oceanic‐migratory behavior of adult Atlantic Sturgeon, Acipenser oxyrinchus oxyrinchus, was examined using pop‐up satellite archival tags (PSAT). Twenty‐three Atlantic Sturgeons were caught and tagged with PSATs in the Hudson River, New York during 2006 and 2007. Fifteen of those fish returned to the ocean (with PSATs attached) 6–132 days after tagging. These PSATs remained attached to fish for a period of 108–360 days archiving light, temperature, and depth, before releasing from fish, ascending to the surface, and transmitting data to satellites. The location of PSATs was measured to within ±150 m by satellites using Doppler shift of radio transmissions within hours after tags reached the surface. Positions prior to pop up were initially estimated using only archived‐light data and the tag manufacturers’ proprietary software. Positional error associated with light‐based estimates is high, especially with regard to latitude. This error was reduced by applying depth, distance, and temperature filters. Thirteen of the 15 Atlantic Sturgeons that left the Hudson River with PSATs attached remained within the Mid‐Atlantic Bight for up to 1 year after tagging. Their geographic distributions generally extended from Long Island, New York to Chesapeake Bay at depths between 5 and 40 m. Aggregation areas were identified off southwest Long Island, along the New Jersey coast, off Delaware Bay, and off Chesapeake Bay. Depth distribution was seasonal; fish inhabited deepest waters during winter and shallowest waters during summer and early fall. Two Atlantic Sturgeons traveled outside of the Mid‐Atlantic Bight. One migrated north to Cobequid Bay (terminal end of the Bay of Fundy, Nova Scotia), whereas the other traveled south to the coast of Georgia.

No abstract

Populations of Atlantic sturgeon Acipenser oxyrinchus are at historically low levels along the Atlantic coast of North America. Atlantic sturgeon is a long-lived species with a complex life history, making population assessment difficult. The purpose of this study was to determine seasonal habitat use by juvenile Atlantic sturgeon in the Hudson River estuary and provide recommendations for future population monitoring. Our study focused on Newburgh and Haverstraw bays in the Hudson River, as these are areas of known juvenile sturgeon concentrations. The habitat within each bay was coarsely stratified according to substrate (hard versus soft) and depth (deep versus shallow). Sampling occurred during fall 2003, spring and fall 2004, and spring and fall 2005. Fall sampling occurred from October through November and spring sampling occurred from March through April. We used anchored gill nets of 76-, 102-, and 127-mm stretch mesh fished together at a sampling site. A total of 562 individual juvenile Atlantic sturgeon were captured during the course of this study (14 were captured more than once), the majority (90%) coming from Haverstraw Bay. Soft and deep habitat comprised only 25% of the available habitat in Haverstraw Bay but yielded the greatest frequency of catches, the highest mean catch per unit effort (CPUE), and lowest variance of CPUE. Catch per unit effort was highest during spring seasons in soft-deep areas of Haverstraw Bay. These results suggest that future population monitoring should focus sampling effort in soft-deep areas of Haverstraw Bay to have the greatest statistical power in detecting population trends.

The Hudson River currently supports the largest population of Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus) in the United States despite currently supporting less than a percent of historic abundance. Listed as Endangered throughout much of their range, Atlantic Sturgeon are still impacted by multiple threats, resulting in habitat destruction or direct mortality that has inhibited a population rebuild despite 20+ years without directed fishing pressure. To assist in management and reduction in anthropogenic impacts to adult Atlantic Sturgeon in the Hudson River we have examined sex specific patterns related to spawning. Utilizing hundreds of adult Atlantic Sturgeon, telemetered along the Atlantic Coast, and an extensive passive acoustic array from 2010-2016 we were able to estimate arrival, departure, and duration of occupancy for four segments of the Hudson River for male, female, and unknown sex individuals. Male Atlantic Sturgeon arrived above river kilometer 100 at an average date of May 27, 12 days prior to females on June 8. While there were only few significant differences in the timing of departure, the average date from RKM 100 was July 11 for males, June 29 for females and July 23 for unknown sex individuals, as such occupancy was significantly longer for male Atlantic Sturgeon. This study shows female Atlantic Sturgeon often spawn in consecutive years and had much shorter mean intervals between spawning appearances (females 1.66 years, males 1.28 years) than the historical literature suggests. While the timing of spawning is consistent with the historic record, we provide a much greater detail and finer resolution timeline for adults in the Hudson Accepted Article This article is protected by copyright. All rights reserved River as well as update the historic estimate of spawning return rates. Conservation measures to reduce direct impacts to spawning habitat and mature Atlantic Sturgeon would likely provide the most benefit if conducted between mid-May through the end of July.

There is considerable interest in evaluating the status and trends of sturgeon populations, yet many traditional approaches to estimating the abundance of fishes are intractable due to their biology and rarity. Side-scan sonar has recently emerged as an effective tool for censusing sturgeon in rivers, yet challenges remain for censusing open populations that may visit specific habitats over periods of time (e.g., spawning runs). We use a hierarchical model to integrate side-scan sonar with acoustic telemetry, to estimate the proportion of a spawning run fitted with acoustic tags (12%; 95% CrI = 8%–16%) and extrapolate to the total run size in 2014. Our investigation represents a novel approach to generating run size estimates in a large river and provides the first estimate of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) spawning run size for the Hudson River ([Formula: see text] = 466; 95% CrI = 310–745) since the fishery moratorium in the 1990s. Our estimate suggests that the Hudson River holds one of the largest contemporary populations of Atlantic sturgeon, but also indicates that it remains sharply depleted relative to virgin conditions.