Southern Flounder Symposium
March 20, 2024
9:00 a.m. - 5:00 p.m.
Riverfront Convention Center
New Bern, North Carolina
Purpose
A day-long event to provide an opportunity for stakeholders, researchers and North Carolina Division of Marine Fisheries (NCDMF) staff to discuss various topics related to Southern Flounder (Paralichthys lethostigma). Though Southern Flounder represent a coast-wide stock along the south Atlantic U.S. coast, this symposium will focus on North Carolina centric research and management.
The goals of the North Carolina Southern Flounder Symposium:
- Allow stakeholders to engage with each other, as well as researchers and NCDMF staff, on topics related to Southern Flounder.
- Provide stakeholders opportunity to both learn about and contribute to ongoing flounder research.
Presentations
Southern flounder have evolved a complex life history strategy that includes continental shelf spawning, long larval duration (45-60 d) and advection into estuarine nursery habitats, followed by spatially variable benthic settlement, an early shift to piscivory, and rapid growth to maturity. Several aspects of their life history remain poorly understood, with impacts on our ability to model stock dynamics and identify the most appropriate management strategies. This presentation will describe the major features of southern flounder life history, focusing specifically on features for which knowledge has advanced in recent year, as well as features about which understanding remains poor. These will include ocean spawning locations, larval delivery to estuaries, settlement dynamics, sources of mortality in the estuary, habitat use/migration timing, variation in maturity scheduling, and the extent of ocean residency by adults. Each of these has the potential to contribute to the spatial scale of stock mixing in both the Atlantic and Gulf of Mexico, and to inform our ability to accurately model southern flounder stock dynamics and promote effective management.
Dr. Fred Scharf
Professor of Fisheries Biology, Department of Biology and Marine Biology, University of North Carolina - Wilmington
Dr. Scharf earned his PhD in Wildlife and Fisheries Conservation from the University of Massachusetts, Amherst in 2001 and joined the faculty in the Department of Biology and Marine Biology at UNCW in January 2003, where he teaches undergraduate courses in animal biodiversity and fisheries biology, and graduate courses in biostatistics, population dynamics, and fisheries science. Dr. Scharf’s research program at UNCW has been focused on the population dynamics of marine and estuarine fishes, including the study of recruitment processes, the estimation of mortality rates, fish reproductive dynamics, and behavioral ecology, particularly movement and migration. Research findings have been published in several journals, including the Journal of Fish Biology, Marine and Coastal Fisheries, ICES Journal of Marine Science, Transactions of the American Fisheries Society, Marine Ecology Progress Series and the Canadian Journal of Fisheries and Aquatic Resources. As a faculty mentor, Dr. Scharf has supervised the thesis/dissertation research of more than 20 UNCW graduate students, including 5 doctoral students. He is an active member of the American Fisheries Society, hosting conferences in Wilmington in 2009 and 2011, serving as President of the Tidewater Chapter, and officer roles with Early Life History Section and the Southern Division. He has provided extensive service to both state and federal fisheries management, chairing advisory committees for the North Carolina Division of Marine Fisheries, and currently serving as the Vice Chair of the South Atlantic Fishery Management Council’s Science and Statistical Committee. In 2013, Dr. Scharf received the award for Excellence in Fisheries Education from the American Fisheries Society, and was named to the inaugural class of American Fisheries Society Fellows in 2015.
Habitat characteristics can have a strong impact on overall populations of coastal fish. This is especially true for juvenile survival, where habitat quality may impact refuge availability, food availability, and other aspects of growth and survival. Juvenile mortality is a significant determinant of many fish populations and is often dependent on availability of favorable environments. In this presentation we will examine flounder use of various habitats, characteristics of these habitats affecting survival and growth, how they vary along North Carolina’s coastal regions, and factors affecting habitat quality. We will also look at direct and indirect impacts of varying water quality. The emphasis will be on juvenile / subadult flounder habitat and changes in distribution with growth.
Dr. Martin Posey
Professor of Biology and Marine Biology, University of North Carolina Wilmington
The coastwide stock assessment for southern flounder (Paralichthys lethostigma) indicates a need to better understand offshore migration and movement patterns. Collaborative research between the North Carolina Division of Marine Fisheries and the University of North Carolina Wilmington uses two Pop-Up Satellite Archival Tag (PSAT) models to identify offshore spawning locations and timing of spawning movements for southern flounder. Tagging efforts occurred in 2020-2023 with tags released primarily throughout North Carolina and a subset of tags released in South Carolina. Female southern flounder were captured using commercial pound nets, hook-and-line, gill net, and dependent sampling gears. Results of PSAT releases indicate that while some fish migrate out of the estuaries to inner and outer shelf habitats, others remain inshore. Temperature and depth data suggest that fish migrating to outer shelf habitats fluctuate between depths across short periods, which may be indicative of spawning behavior found in other flatfish species. Deviances between the timing of individual migrations highlight the potential variability and complexity of movement patterns. A better understanding of southern flounder migration patterns and offshore spawning habitats and behaviors will provide valuable information for the spatial management of the South Atlantic population and offer avenues for future research on histology and reproduction of southern flounder.
Dr. Shelby B. White
Marine Business Specialist, Virginia Institute of Marine Science
William and Mary
Dr. Shelby White is the Marine Business Specialist at the Virginia Institute of Marine Science in Gloucester Point, VA where she serves as a liaison for various industries, including commercial and recreational fishing, seafood processing, aquaculture, and working waterfronts. She grew up both commercial and recreational fishing in northeastern NC and her interest in fisheries has continued throughout her academic and professional career. She recently graduated with her PhD in Fisheries Science from VIMS, which focused on participation and diversification in Virginia’s commercial fisheries. Shelby also has an extensive background in marine biology and has worked at the Division of Marine Fisheries as an intern, technician, biologist, and social research scientist over the years. During her time as a biologist, Shelby conducted satellite tagging research on southern flounder through a Commercial Fishing Resource Fund grant.
Southern flounder has been the most valuable finfish fishery in North Carolina but is currently overfished. A challenge for management is that the location of its offshore spawning grounds is unknown. To address this, we applied a multifaceted approach to investigate the species’ offshore migration and spawning habitat: 1) Acoustically tagged flounder were tracked with inshore and offshore receivers and a wave glider; 2) A hydrodynamic model back calculated larval fish dispersal pathways to potential spawning habitats; 3) DNA barcoding identified fish eggs collected during surveys of potential spawning habitat; 4) Fish ear-bone microchemistry was used to determine migration histories since certain chemicals serve as proxies for salinity; 5) Reproductive staging assessed where and when fish were preparing to spawn. Collectively, these techniques generated convergent answers to questions about behavior. We learned there is substantial behavioral variability between individuals. Fish tagged at the same location on the same date exited sounds through diverse pathways. Emigration timing may vary between southern and northern estuaries in North Carolina since our study detected later emigration than previous research from the southern part of the state. Examination of gonads revealed batch spawning occurs and a portion of the population are spawning capable prior to offshore emigration in late October/November. Both tagging and egg surveys suggest that some spawning may occur near the edge of the continental shelf, but other fish spent substantial time on the inner shelf where flounder eggs were also detected. The hydrodynamic model indicated that many larvae originated from a potential spawning “hotspot” in coastal, southern Onslow Bay. This model also suggested episodic connectivity with populations as far south as Florida. After overwintering, some fish moved shoreward and were detected again at North Carolina Inlets, while other fish traveled as far south as Georgia. Return of some fish to the sound after overwintering offshore was also confirmed via ear-bone microchemistry. A small segment of tagged fish appeared to overwinter near North Carolina inlets, likely without traveling offshore. Lastly, gonadal examination indicated that only fish collected from offshore waters in summer showed signs of previous spawning. Given the diversity of behaviors, more research is needed to understand which behavioral modes are most common and if certain habitats should be protected to conserve this species.
Dr. Rebecca Asch
Assistant Professor, East Carolina University
Established in 2014, the North Carolina Division of Marine Fisheries (NCDMF) Multi-Species Tagging Program is a comprehensive tag-return study designed to collect more accurate information on North Carolina’s marine finfish species. Tagging animals is one successful method researchers can use to monitor fish and wildlife populations. Scientists track animals on land, through the air, or in the water using a variety of tagging techniques. Tracking fish and other marine animals is very important when managing populations, but it also has its challenges. Aquatic organisms spend most of their time underwater, hidden from visual observation, which makes researching them quite difficult. Tagging—the process of marking and recapturing an animal—provides important information about the life history of fish that researchers would otherwise be missing. When a fish is tagged, released, and then recaptured later, the information collected provides managers with insights on migration patterns, habitat use, population structure, and mortality rates. The success of tagging programs comes from public participation by reporting a tagged fish or helping to tag fish. Through collaborative efforts by Division staff, state and federal agencies, university researchers, and public volunteers within the fishing community, the Multi-Species Tagging Program tags over 15,000 Striped Bass, Red Drum, Southern Flounder, Spotted Seatrout, and Cobia each year. Tagging programs play a vital role in tracking fish movements and populations, but it’s also an opportunity for the fishing community to get involved in scientific research and contribute to the management of North Carolina’s coastal resources.
Ami Staples
Conservation Biologist II, N.C. Division of Marine Fisheries
Ami Staples is the Marine Fisheries Biologist II for the Multi-Species Tagging Program at the North Carolina Division of Marine Fisheries. Ami oversees all aspects of the Tagging Program from administration and research to public engagement and outreach. Her favorite part of the job is tracking fish movements and working directly with the fishing community. Ami is always eager to speak to an angler about their tagged fish recapture, lead engaging presentations about the Tagging Program to fishing clubs, train volunteers on how to tag fish and collect scientific data, or conduct hands-on science activities for school groups.
Originally from Georgia, Ami received her B.S. in Fisheries and Wildlife Management and M.S. in Forest Resources from the University of Georgia. Ami has a passion for science communication and is a published author and illustrator. When not at work, Ami spends most of her time outdoors and her favorite spot is fishing on the dock with her husband, two daughters, and four cats.
John Carmichael
Executive Director, South Atlantic Fishery Management Council
John Carmichael is the Executive Director of the South Atlantic Fishery Management Council. He has worked at the Council since 2003, originally as Program Manager for the SEDAR assessment process and later as the Deputy Director for Science prior to becoming Executive Director in 2020. Previous positions include serving as a stock assessment scientist with the NC Division of Marine Fisheries working with striped bass, red drum and river herring; an FMP coordinator with the Atlantic States Marine Fisheries Commission; and a biologist with the Maryland Department of Natural Resources. He has a BS in Fisheries and Wildlife from Virginia Tech and an MS in Zoology from NC State.
Poster presentations
Despite being one of North Carolina’s most valuable fisheries, southern flounder (Paralichthys lethostigma) are managed without knowledge of their spawning location. Managing a species without an understanding of its spawning behavior can be challenging, but this is made more difficult as southern flounder are managed on a state level, even though evidence suggests there is genetically one stock from Virginia to Florida. In addition to these challenges, southern flounder experienced a marked decline in the mid-to-late 2000s. While there are little data on southern flounder spawning in situ, research suggests that southern flounder move out of sounds into the ocean in fall and winter to spawn. We used larval dispersal models to simulate larval dispersal and provide insight into possible spawning locations. This model was developed utilizing larval abundance data from Beaufort Inlet, along with larval ages from these samples. Ages allowed us to estimate how many days larvae had been drifting in the plankton prior to reaching Beaufort Inlet. The Connectivity Modeling System (CMS) is a larval dispersal model that moves particles, which represent fish larvae, based on oceanographic conditions. CMS was used together with oceanographic conditions from CNAPS2 (a regional ocean modeling system) to identify potential spawning grounds by backtracking larvae from their site of collection. We show that there is a broad range of possible spawning locations. Nonetheless, before and after population declines, the highest probability of spawning appeared off the coast in southern Onslow Bay, NC. There is also evidence that some larvae may episodically originate from greater distances further to the south, suggesting that genetic homogeneity may be due to infrequent, long-distance dispersal. While these findings show great variability as to where southern flounder may spawn, they provide insight into locations that may serve as primary spawning grounds, which can be valuable for stock delineation and protection of spawning habitat in the future.
Brian Bartlett
Doctoral Candidate, Coastal Resources Management, East Carolina University
A total of 210 age 2-3 southern flounder (Paralichthys lethostigma), selected for larger sizes (349-645mm, mean 503mm TL) and assumed to be mature or maturing, were surgically implanted with Vemco V-9 and V-13 acoustic tags after capture in the estuaries of NC (Albemarle, Pamlico, and Core Sounds) via pound or gill nets. Range and detection tests were conducted in Barden’s Inlet in shallow water and Cape Lookout Shoals offshore in deeper water with 50% detection rates out to 200m and 500m respectively. Capture and tagging were performed at the end of the commercial season and when fish are expected to be emigrating out of the inlets for spawning in October-December of 2020 and 2021. ECU deployed a network of receivers at inlets from Oregon Inlet to Bogue Inlet and an offshore array staggered from Cape Lookout Shoals in phase 1 to Frying Pan Shoals in phase 2 to monitor fish passage. Four missions were also launched with R/V Blackbeard- an autonomous Waveglider with on-board Vemco receiver to search along the continental shelf during the spawning season outside of stationary receiver coverage. This effort also relied on partner arrays deployed by Atlantic Cooperative Telemetry (ACT) Network and Mid-Atlantic Acoustic Telemetry Observation System (MATOS) member institutions and agencies to expand spatial and temporal coverage. These tagged individuals exhibited a generally S-SW movement towards an emigration inlet and once offshore. Selectivity was seen for Barden’s Inlet as the primary emigration inlet and Diamond Shoals as a preferred area once offshore for both total detections and number of individual fish detected in the area. This concentration of detections also coincided with higher array coverage in the same area. Southern flounder were detected offshore in January and February across the continental shelf during the expected spawning season, with most detections in northern Onslow Bay near Cape Lookout Shoals and to a lesser extent Frying Pan Shoals. There were limited detections at the edge of the continental shelf break. Tagged flounder exhibited a divergent pattern of migratory behavior, where some “retentive” individuals remained or returned to near their emigration inlet, while other “exploratory” individuals continued much farther south in subsequent years post-emigration as far as Georgetown and Charleston SC and Savannah GA.
Tyler Peacock
Graduate Student, East Carolina University
Southern flounder (Paralichthys lethostigma) are an economically important species to North Carolina’s commercial fisheries - representing around $5.6 million in landings in 2017 – but are considered overfished. Due to stock decline and harvest restrictions, the value of commercial landings in 2022 was less than $1 million. For stock recovery efforts to be successful, it is critical fisheries managers to protect key spawning grounds, juvenile habitats, and migration corridors important to reproductive success. However, little is known about the location of offshore southern flounder spawning grounds in NC waters. Our aim in this study is to identify the species’ spawning grounds by collecting fish eggs at potential spawning sites and identifying them using molecular techniques. Due to limitations to morphological identifications of fish eggs, we chose to use DNA barcoding to amplify the mitochondrial cytochrome oxidase subunit 1 (COI) gene to identify fish eggs to the species level. Eggs were collected at stations along offshore transects based on historical larval fish surveys during which Paralichthyid early-stage larvae were identified morphologically. Surveys were conducted in March of 2021, February, and March of 2022. Eggs over 850-microns in diameter for each sampling year were selected for station level subsampling, proportional to the number of eggs captured at each respective station and sequenced via Sanger sequencing. Out of the 930 eggs sequenced, we identified five southern flounder eggs: one egg in year 1 from March 15th from a station closer on the outer shelf, and four eggs in 2022 from stations closer to the shoreline. Of the year-2 southern flounder identified two were collected on February 2nd, one on February 16th, and one on March 2nd. These results differ from previous surveys that suggested that spawning occurred offshore yet agree with telemetry work by our team that indicate southern flounder presence in these same areas during their spawning season. Work by our team, as well as other researchers, using southern flounder birthdates calculated from larval fish otoliths from Beaufort Inlet, NC, allows for spawning to extend into March. Our results support: 1) the feasibility of molecular identification of fish eggs to assess breeding grounds and fish community composition in North Carolina’s coastal waters and 2) the likely presence of southern flounder breeding grounds in NC’s coastal waters. This study could provide the baseline for more comprehensive egg collection and sequencing efforts to understand spawning patterns of fish communities on North Carolina’s coast.
Paul Salib
Master’s Student, East Carolina University