University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- ubP lished Research US Geological Survey 9-30-2016 Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon, Acipenser oxyrinchus desotoi Vladykov, 1955 K.J. Sulak Wetland and Aquatic Research Center, [email protected] F. Parauka US Fish and Wildlife Service W. T. Slack U.S. Army Engineer Research and Development Center R. T. Ruth Louisiana Department of Wildlife and Fisheries M. T. Randall Wetland and Aquatic Research Center FSeoe nelloxtw pa thige fors aaddndition addal aitutionhorsal works at: http://digitalcommons.unl.edu/usgsstaffpub Part of the Geology Commons, Oceanography and Atmospheric Sciences and Meteorology Commons, Other Earth Sciences Commons, and the Other Environmental Sciences Commons Sulak, K.J.; Parauka, F.; Slack, W. T.; Ruth, R. T.; Randall, M. T.; Luke, K.; and Price, M. E., "Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon, Acipenser oxyrinchus desotoi Vladykov, 1955" (2016). USGS Staff -- Published Research. 1055. http://digitalcommons.unl.edu/usgsstaffpub/1055 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- ubP lished Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors K.J. Sulak, F. Parauka, W. T. Slack, R. T. Ruth, M. T. Randall, K. Luke, and M. E. Price This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/usgsstaffpub/1055 Journal of Applied Ichthyology J. Appl. Ichthyol. 32 (Suppl. 1) (2016), 87–161 Received: September 30, 2016 © 2016 Blackwell Verlag GmbH Accepted: November 2, 2016 ISSN 0175–8659 doi: 10.1111/jai.13245 Supplement Article Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon, Acipenser oxyrinchus desotoi Vladykov, 1955 By K. J. Sulak1,*, F. Parauka2,*, W. T. Slack3, R. T. Ruth4, M. T. Randall1, K. Luke2, M. F. Mettee5,* and M. E. Price6 1Wetland and Aquatic Research Center, US Geological Survey, Gainesville, FL, USA; 2US Fish and Wildlife Service, Panama City, FL, USA; 3U.S. Army Engineer Research and Development Center, Vicksburg, MS, USA; 4Louisiana Department of Wildlife and Fisheries, Inland Fisheries, Lacombe, LA, USA; 5Geological Survey of Alabama, Tuscaloosa, AL, USA; 6University of Florida, Gainesville, FL, USA Summary mass mortality due to major stochastic events including hur- The Gulf Sturgeon, Acipenser oxyrinchus desotoi,isan ricanes, flooding, hypoxia, and toxic spills. The present anadromous species of Acipenseridae and native to North manuscript provides a comprehensive synthesis of knowledge America. It currently inhabits and spawns in the upper regarding the Gulf Sturgeon at the organismal and popula- reaches of seven natal rivers along the northern coast of the tion levels, identifying knowledge gaps as priorities for future Gulf of Mexico from the Suwannee River, Florida, to the research. Topics not treated in the present synthesis include Pearl River, Louisiana, during spring to autumn. Next to the morphology, internal biology, physiology, and endocrinol- Alligator Gar (Atractosteus spatula), the Gulf Sturgeon is ogy. Topics only briefly treated include parasites and dis- currently the largest fish species occurring in U.S. Gulf Coast eases, contaminants, and sturgeon aquaculture. 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 Introduction rivers from which the species has been wholly or nearly extir- The present manuscript has been prepared based on the accu- pated, such as the Mobile and Ochlockonee rivers, and possi- mulated scientific knowledge of the Gulf Sturgeon (GS) to the bly the Rio Grande River. Most Gulf Sturgeon populations present time. It builds upon a paper (Sulak et al., 2009b) with were decimated by unrestricted commercial fishing between that same goal originally presented in the symposium 1895–1910. Subsequently most populations remained unre- ‘Acipenseriformes in North America – where do we stand in covered or extirpated due to continued harvest until the 2009?’, convened at the American Fisheries Society (AFS) 1970s–1980s, and the construction of dams blocking access 139th Annual Meeting, Nashville, TN), 30 August-3 Septem- to ancestral upriver spawning grounds. Late 20th Century ber. The symposium was organized by the North American harvest bans and net bans enacted by the several Gulf Coast Chapter of the World Sturgeon Conservation Society states have stabilized several populations and enabled the (WSCS), now the North American Sturgeon and Paddlefish Suwannee River population to rebound substantially and Society (NASPS) (Haxton et al., 2016 – this volume). An out- naturally. Hatchery supplementation has not been necessary growth of the 2009 symposium, this resultant manuscript pro- in this regard to date. Sturgeon are resilient and adaptable vides a comprehensive synopsis of all that is known about the fishes with a geological history of 150 million years. Research GS and identifies knowledge gaps to guide future research. undertaken since the 1970s has addressed many aspects of Gulf Sturgeon life history, reproduction, migration, popula- tion biology, habitat requirements, and other aspects of spe- Materials and Methods cies biology. However, many knowledge gaps remain, This manuscript relies both on published research and prominently including the life history of early developmental important unpublished technical reports prepared by stages in the first year of life. Natural population recovery is resource agencies and academic institutions, as well as histor- evident for the Suwannee River population, but seems ical reports, photographs, and oral history recordings of 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 fac- *Retired Disclaimer: Any use of trade, product, or firm names is tors. These two populations, and perhaps the Escambia for descriptive purposes only and does not imply endorsement River population, are particularly vulnerable to periodic by the U.S. Government. U.S. Copyright Clearance Centre Code Statement: 0175-8659/2016/32S1–87$15.00/0 88 K. J. Sulak et al. sturgeon fishermen from the early 20th century. Key unpub- Free embryo = hatched embryo after emerging from the lished information sources comprise the extensive mark and egg at ca 6.8–8.8 mm TL (in the literature alternately termed recapture databases consolidated by the U.S. Geological Sur- yolksac larva, pre-larva, or eleutheroembryo [Balon, 1971]). vey – Wetland and Aquatic Research Center (USGS- This is a non-dispersal stage in the GS. WARC). A database has been assembled for each GS natal Larva = exogenously-feeding individual after consump- river population based on research undertaken since 1977 by tion of the yolksac and expulsion of the yolksac plug at age the U.S. Fish and Wildlife Service (USFWS), U.S. Geologi- 5–8 days, 14.7–17.5 mm TL. This is the GS stage that is ini- cal Survey (USGS), U.S. Army Corps of Engineers tially a free-swimming hemi-benthic, hemi-pelagic dispersal (USACE), Mississippi Museum of Natural Sciences stage, later transforming to a completely benthic existence. (MMNS), Louisiana Department of Wildlife and Fisheries Young-of-the-Year (YOY). YOY = all age-0 stages from (LDWF), other state natural resources agencies, several uni- larva through first migration to the estuary in January-Feb- versities, and several non-government organizations (NGOs). ruary (at age 9 months, 330–450 mm TL). These consolidated databases, maintained in Microsoft Black-stage YOY = YOY of age 2–4 months, 85– Excel©, are current up to and including 2008, except for the 150 mm TL, in which the body is pigmented dull black Suwannee River database which is current through 2015. dorso-laterally. This is apparently a non-dispersal stage that They have been used herein to prepare species distribution occupies riverbed deposits of black decaying leaf litter. maps, length frequency distribution plots, weight-length Bicolored-stage YOY = YOY of age 4–9 months, 150– plots, and to provide fundamental summary information that 450 mm TL, in which the body acquires the typical adult has not otherwise been published. bicolored pigmentation, tan to gray dorsolaterally, cream colored ventrally, scutes light gray to whitish. This is a forag- ing stage that disperses widely within the natal river. Life history stage terminology for the GS Juvenile = age-0 through age-6 individual, <900 mm Life history stage terminology employed for the GS in the TL, in which gonads remain undeveloped. This stage con- present manuscript are defined in terms of age (days or ducts an annual seasonal movement back and forth between months) and/or TL, recognizing however that these criteria riverine freshwater and estuarine brackish water. are approximate with wide individual variation. Certain Subadult = age-6 through age 9–12 (sex dependent) stages are illustrated in Fig. 1 and are defined as follows: individual, >900 mm TL, < 1350 mm TL. This stage, in Ova = unfertilized eggs retained in the ovaries prior to which early stages of gonad development are observed,