Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon,Acipenser oxyrinchus desotoiVladykov, 1955

Abstract

Summary The Gulf Sturgeon, Acipenser oxyrinchus desotoi, is an anadromous species of Acipenseridae and native to North America. It currently inhabits and spawns in the upper reaches of seven natal rivers along the northern coast of the Gulf of Mexico from the Suwannee River, Florida, to the Pearl River, Louisiana, during spring to autumn. Next to the Alligator Gar (Atractosteus spatula), the Gulf Sturgeon is currently the largest fish species occurring in U.S. Gulf Coast rivers, attaining a length of 2.35 m and weights exceeding 135 kg, but historically attained a substantially larger size. Historically, the spawning populations existed in additional rivers from which the species has been wholly or nearly extirpated, such as the Mobile and Ochlockonee rivers, and possibly the Rio Grande River. Most Gulf Sturgeon populations were decimated by unrestricted commercial fishing between 1895–1910. Subsequently most populations remained unrecovered or extirpated due to continued harvest until the 1970s–1980s, and the construction of dams blocking access to ancestral upriver spawning grounds. Late 20th Century harvest bans and net bans enacted by the several Gulf Coast states have stabilized several populations and enabled the Suwannee River population to rebound substantially and naturally. Hatchery supplementation has not been necessary in this regard to date. Sturgeon are resilient and adaptable fishes with a geological history of 150 million years. Research undertaken since the 1970s has addressed many aspects of Gulf Sturgeon life history, reproduction, migration, population biology, habitat requirements, and other aspects of species biology. However, many knowledge gaps remain, prominently including the life history of early developmental stages in the first year of life. Natural population recovery is evident for the Suwannee River population, but seems promising as well for at least four other populations. The Pascagoula and Pearl River populations face a challenging future due a combination of natural and anthropogenic factors. These two populations, and perhaps the Escambia River population, are particularly vulnerable to periodic mass mortality due to major stochastic events including hurricanes, flooding, hypoxia, and toxic spills. The present manuscript provides a comprehensive synthesis of knowledge regarding the Gulf Sturgeon at the organismal and population levels, identifying knowledge gaps as priorities for future research. Topics not treated in the present synthesis include morphology, internal biology, physiology, and endocrinology. Topics only briefly treated include parasites and diseases, contaminants, and sturgeon aquaculture.

Sturgeon and paddlefish life history and management: Experts' knowledge and beliefs

“…The issue of senescence is rarely raised or approached in studies and reviews dealing with sturgeon and paddlefish ecology. Nevertheless, authors have reported or claimed either a lack of senescence or at least a lack of evidence of senescence in various sturgeon species such as white sturgeon ( Acipenser transmontanus ; Hildebrand et al., ), Gulf sturgeon ( A. oxyrinchus desotoi ; Sulak et al., ), and pallid sturgeon ( Scaphirhynchus albus ; Jordan et al., ).…”

“…According to Sulak et al. (), there are no indications of female gonadal senescence in any sturgeon species in the wild. Moreover, in lake ( A. fulvescens ) and white sturgeon, the interspawning interval does not change with age (Forsythe, Crossman, Bello, Baker, & Scribner, ; Webb, ).…”

“…Subpopulation differentiation in spawning site selection and repeatability can develop even within smaller systems (Forsythe et al., ). However, while pronounced spawning site fidelity in sturgeons is likely, they also tend to switch between different sites within and among rivers between years, and in some cases even within the same year (Bruch et al., ; Sulak et al., ). As hypothesized by Hilton et al.…”

“…Of those with an opinion on this issue, a majority believed that homing behavior is either equally strong in females and males, or stronger in females (37% and 19% of the total sample, respectively). In Gulf sturgeon, females have a pronounced fidelity towards a specific spawning site and can be very selective regarding the spawning ground location (Sulak et al., ).…”

Growth Estimation of Western Population Segment Gulf Sturgeon Using Length‐at‐Age and Mark–Recapture Data

“…Based on gill‐net surveys, Sulak et al. () stated that populations natal to the Pascagoula and Pearl rivers have the lowest abundances across the extant range of Gulf Sturgeon. Additionally, Ahrens and Pine () and Rudd et al.…”