The life history of longnose gar, Lepisosteus osseus, an apex predator in the tidal waters of Virginia

Longnose gar (Lepisosteus osseus) inhabit all of the major tributaries of Chesapeake Bay in Virginia, extending from fresh to estuarine waters. Literature concerning longnose gar from tidal environments is limited and this is study concerns important aspects of the life history (e.g., growth, reproduction, dimorphism, movements, and diet). Age, growth, and reproduction are important life history aspects for understanding the biology of fishes and may be affected by the environment in which an individual lives. This study found no differences in the age, growth, and fecundity parameters between longnose gar from tidal portions of Chesapeake Bay tributaries and previous studies in non-tidal environments. Fecundity averaged 30,000 eggs and a von Bertalanffy growth model described growth of longnose gar to be sexually dimorphic, rapid in the first year of life, and leveling off after maturity. Sexual dimorphism has been documented previously in two species of the family Lepisosteidae, L. osseus and L. oculatus. The present study expands upon previous work on this species by examining a broader array of morphometric characters, while removing the bias associated with overall body length. A stepwise discriminant function analyses found that five characters best distinguish the sexes: head width, mid-snout width, anal-fin height, anal-fin width, and prepectoral-fin length. Discriminant function analyses with the five characters and standard length yielded misclassification rates of 8.8% and 6.2% for females and males, respectively. Another goal of this project was to characterize the movements of longnose gar by using both acoustic and conventional tagging methods and by examining historical catch records from a trawl survey. Two individuals moved 69 and 74 km, which is greater than the distance observed in the only other report on long-distance movement by longnose gar individuals. Spawning data were collected from two acoustically tagged longnose gar and spawning residency time was approximately one month. Winter distributions of longnose gar, previously unknown, occurred both inshore and mid-channel and were similar to the summer and fall. Finally, this study characterized the diet of longnose gar inhabiting tidal rivers in Virginia. The top five prey types recovered from stomachs were white perch, menhaden, killifishes (Fundulus spp.), Atlantic croaker, and spot. Marine and anadromous fishes (%W = 59.4%) and resident fishes (%W = 40.6%) were equally important in the diet of longnose gar. The diet varied with the seasonal prey fish assemblages, longnose gar length, and salinity, reinforcing the categorization of the species as an opportunistic predator. The relative abundance, rapid growth, and high fecundity of this apex predator warrant further study and inclusion into ecosystem models

Site Fidelity, Home Range, and Daily Movements of White Perch, Morone americana, and Striped Bass, Morone saxatilis, in Two Small Tributaries of the York River, Virginia

Striped bass (Morone saxatilis) and white perch (M. americana) are two common species residing within Chesapeake Bay and its tributaries. These congeners are both commercially and recreationally important species. White perch are permanent residents in the Bay, while striped bass are only residents during the first few years of their life. During these initial years, striped bass co-occur with white perch. There is very little known about white perch and resident striped bass site fidelity and home range. This acoustic tagging study aims to examine site fidelity and home range of both species and determine if there is any spatial competition between these congeners. Sixteen white perch and sixteen striped bass residing in two small tributaries of the York River were utilized for this experiment. White perch exhibited a high degree of site fidelity along with a small home range. The minimum convex polygon (MCP) and minimum stream polygon (MSP) methods were utilized to measure home range size. The average MCP/MSP was 0.114 km2. Kernel densities were also examined to understand their utilization distribution within their home range. The output contours considered were the 95% contour (total home range) and the 50% contour (core area of activity). The kernel method areas were 0.0128 km2 and 0.0021 km2, respectively. White perch, in the Poropotank River, typically had two core areas of activity which often correlated to the tidal stage. They were often found during high tide upon the flooded marsh or up in shallow creeks and in the relatively deep main channels during low tide. However, white perch in the Queen Creek only had one core area of activity and they were always associated with submerged structure. White perch did not show any movement with sudden changes in salinity and/or temperature resulting from tropical depressions or Hurricane Isabel. They also did not display any change in behavior associated with episodic hypoxia within the creeks. Striped bass did not exhibit a high degree of site fidelity. In the Poropotank River, 58% of the striped bass displayed site fidelity, while zero striped bass exhibited it in Queen Creek. Local hypoxia events could explain the lack of site fidelity within Queen Creek. The home range data might be under-estimated due to the inability to track in the York River. The average MCP/MSP was 0.36 km.2 and the average 95% and 50% kernel densities were 0.02 km2 and 0.002 km2, respectively. Only two striped bass displayed a tidal interaction, utilizing the slack high water to flood up upon marsh corners or sandy beaches. Two other striped bass also displayed a lunar periodicity. Both fish would enter and leave the Poropotank River during the days surrounding new and full moons. Striped bass also did not display any change in behavior associated with sudden changes in temperature and/or salinity due to tropical depressions or Hurricane Isabel. There was very little space competition between these two congeners. White perch occupied 8.5% of the striped bass overall home range. The spatial overlap did increase when only core areas were examined. The two species shared a common core area in a small rivulet of the Poropotank River. This common core area was one third of the striped bass cumulative core area. Nevertheless, there very little evidence of spatial competition or resource partitioning between white perch and striped bass

It’s raining sturgeons: a likely occurrence of avian predation or scavenging of Atlantic Sturgeon (Acipenser oxyrinchus Mitchell, 1815)

Predation on the federally-endangered Atlantic Sturgeon (Acipenser oxyrinchus), and sturgeons generally is understudied. Most predation is presumed to occur on eggs and larvae, and bethe result of interactions with other aquatic organisms, primarily other fishes. Predation on larger juvenile sturgeon by terrestrial and avian predators remains largely unknown. Here we document the recovery of a juvenile Atlantic Sturgeon carcass (512 mm total length) approximately 120 m inland from the shore of the York River in Gloucester County, Virginia. This individual showed signs of predation by a bird of prey, most likely an Osprey (Pandion haliaetus), although a Bald Eagle (Haliaeetus leucocephalus) cannot be ruled out, as they are also residents in this area. The purpose of this note is to document this occurrence and suggest further study of predation on Atlantic Sturgeon in the Chesapeake Bay

Temperature selectivity and movement patterns of speckled trout

Speckled trout (Cynoscion nebulosus) is the focus of an important recreational fishery in the southeastern United States. Speckled trout in Virginia has been cited as both a transitional population and as a mostly non-migratory population. The degree of residency is important to understand for the effective management of the species. Management of speckled trout has also been marred by cold-stun events which can kill a significant portion of the stock and have detrimental localized effects. Virginia is the northern extent of speckled trout populations and is the most likely portion of its range to experience cold-stun events. Virginia water temperatures can reach 0 °C during some winters, well below lethal temperatures for speckled trout. The primary objective of this project was to provide managers and recreational fishermen with information regarding speckled trout movements. more..

Seasonal Distributions and Movements of Longnose Gar (Lepisosteus osseus) within the York River System, Virginia

The seasonal movements of Lepisosteus osseus (Longnose Gar) are largely unknown. The goal of this project was to characterize spawning movements and seasonal distributions by using acoustic tagging methods and examining historical catch records from a trawl survey. This is the first time that movements have been studied for an estuarine population of Longnose Gar. Two individuals moved greater minimum distances (69 and 74 km) than found in the only other report on movement in this species. Spawning-ground residency time, collected from two tagged Longnose Gar, was approximately one month, and tidal periodicity was observed for one of the two fish. Data from a fisheries independent trawl survey were used to examine seasonal catch distributions in Longnose Gar and represents the first report of winter distributions for this species. Winter locations occurred both alongshore and mid-channel, and the distributions were similar to those in the summer and fal

Patterns of Hatchery-Produced Returns of American Shad in the James River, Virginia

American Shad Alosa sapidissima is an anadromous clupeid that once supported a robust fishery but has declined drastically throughout its native range due to overfishing, dam proliferation, and poor water quality. A hatchery program on the James River in Virginia was introduced in 1992 to support the recovery of stocks. Following a moratorium of the fishery enacted in 1994, a fisheries-independent survey was initiated in 1998 to monitor the population recovery efforts and status of American Shad stocks in Virginia. This paper examined 22 years of monitoring data for the James River and determined the effect of hatchery inputs on the James River stock of American Shad. The spawning stock index increased from 2.57 in 1998 to a peak of 9.33 in 2003 but has generally been declining since and has been at very low levels in most recent years. The hatchery prevalence for female American Shad (i.e., the percentage of fish derived from the hatchery) ranged between 3.6% and 60.5%. Years with higher spawning stock index values were significantly correlated to higher percentages of hatchery fish returning to spawn. The stock–recruitment relationship was best explained by the Ricker model, which had the lowest residual standard error and Akaike information criterion value. A threshold level of hatchery-released individuals (approximately 4 million larvae) was necessary to achieve the highest numbers of returning spawners, but stocking above 7 million larvae correlated with declining returns. Long-term monitoring of the James River American Shad spawning population allowed for the critical examination of the contribution of hatchery individuals to the yearly spawning run and the relative success rate of each hatchery year-class. From these data, we consider that the James River spawning stock of American Shad was dependent upon hatchery inputs, with ideal hatchery returns occurring during years of moderate levels of hatchery stocking

Monitoring the Abundance of American Shad and River Herring in Virginia’s Rivers 2020 Annual Report

This report describes the results of the twenty-third year of a continuing study to estimate the relative abundance and assess the status of American shad (Alosa sapidissima) stocks in Virginia by monitoring the spawning runs in the James, York and Rappahannock rivers in spring 2020, evaluating hatchery programs, and contributing to coast-wide assessments (ASMFC 2007, ASMFC 2020). We also report on two fisheryindependent monitoring programs using anchor gillnets in the Rappahannock River (year 3) and the Chickahominy River (year 6; a major tributary of the James River), to determine relative abundance and stock structure for the adult spawning run of river herring (A. pseudoharengus, and A. aestivalis). Further, we report on the year 5 of a monitoring program for juvenile alosines by using nighttime surface trawls in the Chickahominy River and present an index of juvenile abundance from this survey. Additional objectives were to monitor bycatch of American shad in a permitted gill-net fishery and American shad and river herring in pound-net fisheries

Monitoring the Abundance of American Shad and River Herring in Virginia’s Rivers 2021 Annual Report

This report describes the results of the twenty-fourth year of a continuing study to estimate the relative abundance and assess the status of American shad (Alosa sapidissima) stocks in Virginia by monitoring the spawning runs in the James, York and Rappahannock rivers in spring 2021, evaluating hatchery programs, and contributing to coast-wide assessments (ASMFC 2007, ASMFC 2020). We also report on two fishery independent monitoring programs using anchor gillnets in the Rappahannock River (year 4) and the Chickahominy River (year 7; a major tributary of the James River), to determine relative abundance and stock structure for the adult spawning run of river herring (A. pseudoharengus, and A. aestivalis). Further, we report on the year 6 of a monitoring program for juvenile alosines by using nighttime surface trawls in the Chickahominy River and present an index of juvenile abundance from this survey. Additional objectives were to monitor bycatch of American shad in a permitted gill-net fishery and American shad and river herring in pound-net fisheries

Monitoring the Abundance of American Shad and River Herring in Virginia’s Rivers 2022 Annual Report

This report describes the results of a continuing study to estimate the relative abundance and assess the status of American shad (Alosa sapidissima) stocks in Virginia by monitoring the spawning runs in the James, York and Rappahannock rivers in spring 2022, evaluating hatchery programs and contributing to coast-wide assessments (ASMFC 2007a; ASMFC 2020). We also report on a fishery-independent monitoring program to determine abundance and stock structure of river herring (A. pseudoharengus, and A. aestivalis) in Virginia by evaluating the adult spawning runs in the Chickahominy River, a major tributary of the James River, and the Rappahannock River. Further, a recently added objective of this study was to complement the monitoring of the adult spawning population of American shad and river herring in the James River system by monitoring juvenile alosines by using nighttime surface trawls in the Chickahominy River and calculate an index of juvenile abundance. Additional objectives were to monitor bycatch of American shad in a permitted gillnet fishery and American shad and river herring in pound net fisheries

Monitoring the Abundance of American Shad and River Herring in Virginia\u27s Rivers: 2023 Annual Report

This report describes the results of the twenty-sixth year of a continuing study to estimate the relative abundance and assess the status of American shad (Alosa sapidissima) stocks in Virginia by monitoring the spawning runs in the James, York and Rappahannock rivers in spring 2023, evaluating hatchery programs, and contributing to coast-wide assessments (ASMFC 2007, ASMFC 2020). We also report on two fisheryindependent monitoring programs using anchor gillnets in the Rappahannock River (year 6) and a major tributary of the James River, the Chickahominy River (year 9), to determine relative abundance and stock structure for the adult spawning run of river herring (A. pseudoharengus, and A. aestivalis). Further, we report on the year 8 of a monitoring program for juvenile alosines by using nighttime surface trawls in the Chickahominy River and present an index of juvenile abundance from this survey. An additional result of this study was analysis of bycatch of American shad in a permitted gill-net fishery and American shad and river herring in pound-net fisheries