Oral PresentationsStriped Bass Management Symposium
Exploitation and natural mortality of striped bass in the Santee-Cooper system, South Carolina. White, M.G., III, and Bulak, J. SC Department of Natural Resources. In 1997 and 1998, 1,302 striped bass were marked with anchor tags with return rewards of $10 and $100 to assess non-reporting. A portion of these fish were double tagged to assess tag loss. Short-term mortality due to tagging was assessed and was negligible. For both years combined, the recapture rate was estimated as 38%, providing an estimate of fishing mortality. In a separate evaluation, a catch curve was generated from experimental gill netting conducted in December-February over the past decade. Total mortality was estimated at 0.65 per year, indicating a natural mortality of 0.27/year, which is considerably higher than the 0.15/year assumed in previous evaluation efforts. If this value is accurate, it would have important management implications. Assessment of the 2004 Striped Bass Die-off at Lake Norman, North Carolina Waters*, C.T. North Carolina Wildlife Resources Commission, Smithfield, NC. Summer mortality is a concern for managers of reservoir striped bass fisheries across the southeastern United States. The mortality is typically attributed to the lack of cool, oxygenated water available to striped bass during summer months, commonly referred to as the “habitat squeeze”. However, in the late summer of 2004, the largest reservoir striped bass die-off ever observed in North Carolina occurred at Lake Norman despite the availability of suitable habitat. A total of 2,497 dead striped bass were collected over a 22-day period. This die-off resulted when a group of fish became trapped in the hypolimnion by an anoxic metalimnetic layer. The trapped striped bass were initially in water that had cool temperatures, forage, and sufficient oxygen. Over the following weeks, mortality occurred as hypolimnetic dissolved oxygen levels decreased through normal biological processes. A review of dissolved oxygen data from previous years indicated that similar pockets form annually in Lake Norman, but have not resulted in striped bass mortality. However, circumstantial evidence suggests this may be the mechanism for fish kills in other deep-water reservoirs and begs the question: How often might similar kills occur? A Summary of Striped Bass Sampling Strategies Used on Southeastern Reservoirs Waters*, C.T. North Carolina Wildlife Resources Commission, Smithfield, NC. For several decades, striped bass have been successfully cultured and stocked into reservoirs across the southeastern United States, and numerous fisheries have been established. More recently these fisheries have gained increasing popularity. Angling effort, catch, and harvest have increased, and anglers have expressed concern, whether real or perceived, about declines of these fisheries. Therefore, the need to conduct annual, systematic assessments of striped bass populations has developed. Numerous studies designed to address reservoir-specific questions are documented in the fisheries literature. However, information on the basic population assessment data collected annually by state agencies is generally less accessible. The collection methods employed range from angler creels and diaries to gill netting and electrofishing. The types of data and subsequent analyses vary as well. The objective of this effort is to summarize the techniques used by state agencies from across the southeast to collect and analyze data used to make basic management decisions. This initial evaluation should provide a basis for biologists to design standard sampling strategies for reservoir striped bass. Hooking Mortality and Physiological Responses of Striped Bass Angled in Freshwater and Held in Live-Release Tubes Bettinger*, J.M. South Carolina Department of Natural Resources (SCDNR), Eastover, SC. Tomasso, J.R. Clemson University, Clemson, SC. Isely, J.J. USGS, South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University, Clemson, SC. Mortality and physiological responses of adult striped bass Morone saxatilis angled from Lake Murray, South Carolina, and held in live-release tubes were evaluated during spring and summer 2003. To estimate mortality, external ultrasonic transmitters were attached to 59 striped bass (mean total length [TL] = 585 mm). Striped bass were caught with angling gear, tagged and immediately released or tagged and held in live-release tubes for 2, 4, or 6 hours and then released. No mortality of striped bass was observed during spring. Overall mortality during summer was 83%. Mortality of summer caught striped bass was not related to tube residence time, fish total length, depth of capture, or surface water temperature. To characterize physiological stress we measured plasma cortisol, glucose, lactate and osmolality of 62 striped bass (mean TL = 563 mm) angled and immediately released or angled and held in live-release tubes. Plasma cortisol, glucose, lactate and osmolality were positively related to tube residence time. When the hematological characteristics were considered only in relation to tube residence time, responses characteristic of physiological stress continued for about 150 minutes after which they began to return to normal. Live-release tubes appear to be useful for keeping striped bass alive when they are angled from cool water, but they are not effective when striped bass are angled from warm water. The high summer mortality of striped bass suggests a need for restrictive fishing regulations during the summer for the Lake Murray striped bass fishery. Special Striped Bass Regulations in Tennessee Negus*, J.A., and Churchill, T. Tennessee Wildlife Resources Agency (TWRA), Nashville, TN. Diverse striped bass fisheries and their associated user groups continue to challenge the Tennessee Wildlife Resources Agency (TWRA) to develop effective, and often unique, management strategies. Three unusual harvest restrictions may interest resource managers faced with similarly difficult situations. An elaborate oxygen diffusion system recently installed in Cherokee Reservoir to improve tailwater conditions created an expansive summer refuge for striped bass within the forebay. Tremendous exploitation and post-release mortality ensued, prompting the TWRA to establish a sizeable no-fishing zone from July 15 to September 15. The closed area conserves the striped bass stock from overexploitation and ensures adequate stock survival. Norris Reservoir has a relatively low density of striped bass and a history of producing quality fish. A recent die-off of large fish and reduction in stocking rates has led to a more conservative regulation of the fishery. Anglers are allowed two fish per day with a minimum length limit (MLL) of 15-inches from April through October, and one fish per day with an MLL of 36-inches from November through March. Releasing large fish in colder months should allow for increased survival and recruitment into the trophy size group. Melton Hill and Cordell Hull Reservoirs have limited striped bass fisheries, but excellent habitat and abundant forage. Both lakes have given up recent state record fish including the current 65 lb. 6 oz. state record from Cordell Hull. A 32 to 42-inch slot with only one over 42-inches was implemented. The regulation allows continued harvest below the slot, but maintains the trophy quality of these fisheries. Striped bass in Texas: a genetics overview Lutz-Carrillo*, D.J., and Fries, L.T. Texas Parks and Wildlife Department (TPWD), San Marcos, TX. Since 1965, the Texas Parks and Wildlife Department (TPWD) has stocked 54 water bodies with more than 145 million striped bass. Today, striped bass is among the most popular sport fish of licensed anglers in Texas. Although successful striped bass fisheries have been established in many Texas reservoirs, few experience natural reproduction and thus rely heavily on hatchery-produced fish. Beginning in 1985, TPWD biologists became concerned about several aspects of these fisheries. These concerns included genetic purity of the brood stock and the potential for inbreeding and subsequent depression of striped bass populations. This presentation will describe the brood fish genetic certification process used at TPWD fish hatcheries to assure the genetic integrity of propagated striped bass. Results from two investigations indicating that striped bass in Texas are not inbred also will be presented. Resolving Angler Conflicts in Striped Bass Management Churchill*, T. Tennessee Wildlife Resources Agency, Nashville, TN. Wilson, D. Virginia Department of Game and Inland Fisheries, Forest, VA. Waters, C. North Carolina Wildlife Resources Commission, Smithfield, NC. Striped bass managers have had several recent challenges on the human dimensions front. Three southeastern reservoirs: Norris Lake, Tennessee; Lake Norman, North Carolina; and Smith Mountain Lake, Virginia have been the backdrops for controversies regarding state management of striped bass resources and conflicts between angler groups wanting different things from their respective sport fisheries. The Norris Lake controversy has simmered for decades and was driven by a perception that the state’s striped bass stocking program was limiting native sport fisheries through predation and competition. A strong local contingent against striped bass stocking at Norris Lake forced the state to change its policies toward striped bass management in the lake. More recently, controversies at Lake Norman and Smith Mountain Lake arose when striped bass anglers perceived declines in their fisheries. Striper clubs levied substantial pressure on the states of North Carolina and Virginia to increase stocking rates and/or harvest restrictions despite warnings from biologists about potential for depletion of each lake’s forage base. Both states increased their stocking rates in response to these demands and the long-term effects on the striped bass populations are being monitored. Lessons learned from these conflicts should provide angler groups and striped bass managers a template on how to find common ground for providing the best outcomes in multi-species, multi-use fisheries. Message Boards, Websites, and Email: The Future of Reservoir Striped Bass Management Dorsey*, L.G., and Waters, C.T. North Carolina Wildlife Resources Commission, Raleigh, NC The organization of fishing clubs began in the late 1960’s with the formation of the Bass Anglers Sportsman Society (B.A.S.S.). Since that time, other national organizations have emerged that focused on additonal species. These organizations and their affiliated local chapters have used magazines, newsletters, and meetings to disseminate information and to discuss conservation issues. Recently, the preferred medium of communication has shifted towards the use of websites, message boards, and email to communicate at a much faster rate than previous methods. This is particularly true of reservoir striped bass fishing clubs in the Southeast who have become adept at using this modern communication technique to spread information and to comment on fishery management programs and actions by state agencies. State fisheries agencies have also begun to use this medium increasingly to promote programs, issue news releases, and provide data (both qualitative and quantitative) to these groups. The use of the internet and the dissemination of information via this medium will only increase. Fisheries biologists should consider how this trend can be used to garner information from their constituents and how they can use it to more effectively communicate with not only angling groups but also with the angling population as a whole. Oklahomas Lake Texoma Striped Bass Sampling Program Boxrucker, Jeff C. Oklahoma Department of Wildlife Conservation Lake Texoma has arguably the nations most prolific striped bass Morone saxatilis fishery with an estimated annual economic value of $30 million. The economic and social value of this fishery warrants an intensified sampling program to monitor population structure on an annual basis. Striped bass recruitment has been verified in both major tributaries of the reservoir. Drift nets were used from 2001-2004 to establish spawning locations on both tributaries and evaluate relative egg production between tributaries. Annual egg catches in the Washita River were consistently higher than the respective catches in the Red River although differences as great as 300% could not be detected statistically. Seine collections of juvenile striped bass have been ongoing since the late 1970s. However, the seine sampling program was intensified beginning in 2000. Given the catch rates and standard errors generally encountered in our seine sampling, a 50% change in mean catch can be detected with 80 hauls with a 12.3-m seine. Annual fall gill-net samples were collected beginning in 1978. Gill-net sampling was modified in 1993 to partner with Texas Parks and Wildlife. Mesh complement was changed to 6-7.6 m panels ranging from 25-75 mm mesh with sampling being conducted in February. Thirty net-nights of effort is sufficient to detect a 50% change in mean catch. Volunteer Assistance in Striped Bass Management Wilson*, D.M., Virginia Department of Game & Inland Fisheries Management of striped bass (Morone saxatilis) can be a difficult proposition for many biologists. The lack of manpower and resources for management agencies often limits a biologist’s ability to gather needed information. Volunteers can provide valuable resources for biologists to better manage striped bass populations. Volunteers (primarily from the Smith Mountain Striper Club) at Smith Mountain Lake, Virginia have provided valuable assistance to the Virginia Department of Game and Inland Fisheries in a variety of ways. Volunteers have contributed by maintaining an angler diary program, assisting with gill netting, tagging fish and maintaining the reward program for tagged fish, collecting fish for various projects, assisting with stocking programs, providing creel survey clerks, distribution of information, and by providing needed angler perspectives. Volunteer assistance has been a vital tool in the management of the Smith Mountain Lake striped bass fishery. Striped Bass Parasites, Are They Killing Striped Bass Or Just Biologists? Wilson*, D.M., Virginia Department of Game & Inland Fisheries In the fall of 2002 a parasitic copepod identified in the genus Achtheres, started showing up in the oral cavities of striped bass (Morone saxatilis) at Smith Mountain Lake, Virginia. During the following spring, a substantial striped bass kill at Smith Mountain Lake occurred. Achtheres species have been reported to parasitize a wide assortment of warmwater fish in a variety of habitats. Achtheres infection of striped bass was first documented in 2000 in several Tennessee reservoirs. Literature reviews have not provided any reports of major Achtheres fish kills in wild populations. Current information indicates that fish mortality is not a direct result of the parasite, but secondary infections (bacterial or viral) may be the cause of fish mortality. Fall gill net data collected in 2003-2004 indicates the numbers of young fish (up to three years of age) have not been significantly affected. It is the larger fish, especially fish over 15 pounds, which appear to have been the most seriously affected. Data from the Virginia Department of Game & Inland Fisheries citation program, angler diaries, and fish tag returns show drastic declines of larger striped bass. In contrast, numerous other reservoirs that have the same parasitic infestation have not noticed any fish kills with the exception of Norris Reservoir. Since these parasites have not exhibited characteristics reported in the scientific literature, it is difficult to predict with any certainty what the future holds. Other species at Smith Mountain Lake do not appear to have been detrimentally affected from the parasites. A Century in 15 minutes: History of striped bass fisheries and management in Maryland tidewaters. Zlokovitz*, E.R., and Tarnowski, M.L. Maryland Department of Natural Resources (MD DNR)-Fisheries Service, Tawes State Office Building, B-2, 580 Taylor Ave., Annapolis, MD 21401. D.H. Secor, University of Maryland, Chesapeake Biological Laboratory, P.O. Box 38/ One Williams St. Solomons, MD 20688. In Maryland tidewaters, important commercial striped bass fisheries did not emerge until the 1930s, when they overtook shad and herring fisheries in economic importance. Rudimentary conservation measures at this time included minimum and maximum size restrictions. After WWII, a fundamental shift from pound nets and haul seines to less expensive and more easily handled nylon gillnets contributed to expansion of the fishery. During the post-war economic boom, recreational fisheries exploded in popularity. Commercial harvests also showed an increasing trend, peaking at 2,453,000 kg in 1961. Management was based upon supporting yields of immature striped bass, the so-called “pan-rock” fishery. During the 1970s, intense commercial and recreational fishing pressure on immature striped bass, along with a series of mediocre strength year-classes led to stock collapse and a fishing moratorium in MD in 1985. In part due to this moratorium, stocks rebounded dramatically in the 1990s. Since 1990, landings have been tightly regulated. Increased reliance on demographic monitoring and stock assessments now safeguards against future collapse of the Chesapeake Bay stock. Current and future issues in managing striped bass include multi-species interactions, forage availability, disease, water quality, and the status of fisheries in federal offshore waters. Strategies for Managing Striped Bass and Palmetto Bass Fingerling Rearing Ponds in Golden Algae Impacted Waters. Kurten, Gerald L., Texas Parks and Wildlife Department (TPWD), Athens, TX. Texas Parks and Wildlife Department’s two striped bass (Morone saxatilis) and palmetto bass (M. saxatilis X M. chrysops) production fish hatcheries have battled golden algae in rearing ponds since a complete loss of fingerling production in 2001. Hatchery staff have developed and refined strategies for managing nearly every critical stage of fingerling production including pond filling, egg incubation, fry stocking, pond management, pond harvest, and fingerling delivery. The most effective strategy to date has been the application of ammonium sulfate to reduce algae densities; however, ammonium sulfate is not effective for all stages of production and can also have negative impacts on fish production if not used judiciously. Current strategies, refinements, future research needs, and past experiences will be outlined. Assessing the interacting effects of population size, forage availability and summer habitat conditions on growth of reservoir striped bass Thompson*, J.S., Davias, L.A., and Rice, J.A. North Carolina State University, Raleigh, NC. The relative role of environmental conditions and forage availability in determining the growth and condition of striped bass in southern reservoirs remains an issue of importance in the understanding and successful management of these populations. In previous bioenergetics modeling analyses of individual striped bass growth in two NC reservoirs, we evaluated the relative effects of food consumption and warm summer temperatures on growth and concluded that high forage availability may allow for relatively high growth even in systems with severe summer stratification events. However, this conclusion is clearly dependent on the relationship between forage availability and food consumption by the entire population. To address this issue we extend our analysis of individual striped bass consumption to the population level in Badin Lake, NC, a productive system with relatively high striped bass growth, high forage availability, and poor summer conditions. We then compare population-level consumption to lake-wide hydroacoustic estimates of forage biomass in several seasons during 2000 through 2002. This approach considers the combined effects of forage fish dynamics, habitat conditions and predator density on striped bass growth and may offer managers a way to tailor stocking rates and management strategies according to individual reservoir forage and habitat characteristics. Evaluating the relative effects of temperature, dissolved oxygen, and forage on growth of striped bass: and application of bioenergetics modeling in four North Carolina reservoirs. Davias*, L.D., Rice, J.A., and Thompson, J.S. North Carolina State University, Raleigh, NC. The relatively poor growth of stocked striped bass (Morone saxatilis ) in some southern reservoirs has often been attributed to the habitat ‘squeeze’ of high summer temperatures and low dissolved oxygen (DO). However, a recent study found that a North Carolina reservoir with poor summer water quality but good forage actually supported faster growth of striped bass than a reservoir with better temperature and DO conditions but less forage. We are using bioenergetic modeling to investigate this hypothesis for four reservoirs across NC. We profiled temperature and DO weekly at fixed locations down the main channel of each reservoir from May to October, 2004. Habitat differed greatly between reservoirs in the growing season of 2004; not all reservoirs exhibited a strong temperature/DO squeeze. We made assumptions about fish temperature selection using results from a previous telemetry study. Additionally, we collected age, growth, and energy density information with a fall gillnet sample. We used bioenergetics modeling to estimate relative importance on striped bass growth of food in light of the severity of the temperature/DO squeeze. By making these comparisons among reservoirs we can better assess the capabilities of NC reservoirs for striped bass growth, and guide future stocking and management decisions. Modeling The Spread of a Parasitic Copepod (Achtheres) in a Striped Bass PopulationDouglas Thomasey, Kevin Peterson and Thomas Shahady Lynchburg College, Lynchburg Virginia. In recent years, Smith Mountain Lake and other large reservoirs in Virginia, Tennessee and North Carolina have experienced outbreaks of the copepod parasite (Achtheres). While not directly deleterious to these fish high infestation rates are believed to tax fish populations indirectly leading to fish kills during periods of environmental stress. To study the impact of this parasite throughout a bass population and to understand the potential spread and threat we created a partial differential equation model to manipulate conditions to understand the problem. The model manipulates stocking rates, interaction rates among bass and mortality rates of bass to generate our conclusions. We found one fish introduced into a reservoir typically led to complete infection of the bass population within 18 months regardless of the size of the population of striped bass. How closely the fish interacted was very important to the spread. Since Morone saxatilis are a considered a “schooling” fish, the interaction between these fish is much greater and the parasite spreads much faster. On the other hand, with fish having a low interaction rate such as the black bass, the parasite does not spread as fast. Changes in mortality rates did not change output of our model. Continuing work is necessary to understand the impact this parasite will have on stocked striped bass populations throughout the southeast. Striped Bass Tournaments, Can they be effectively used for Data Collection?Turner*, Warren E. National Striped Bass Association (NSBA), Greer, SC The National Striped Bass Association, Inc. (NSBA) conducts a freshwater striped bass (Morone saxatilis) tournament trail of over 70-tournaments spread out across the Eastern and Southern United States. Currently, some areas use Fisheries Citation Programs, Angler Diaries, and Fish Tagging Programs to collect data, as well as the telemetry, shocking, and gill net programs all of which are managed by the local fishery biologist. However, just like the desires and tools used by fishermen can vary from area to area, the methods and actual data collected by various biologists can also vary greatly from area to area. Things change! With the NSBA tournament program crossing state and regional boundaries, comes fishermen and their tricks of the trade crossing those same boundaries. Also new to the striped bass environment was the NSBA tournament live weigh in and release Championship tournaments and the growth of others wanting to use the Striper Tube to bring live fish to the weigh in. This change in attitude of bringing in live striped bass along with the traditional catch for table fare of striped bass provides a great opportunity to collect and compare data from across the entire striped bass freshwater fishery. Live striped bass weighed in on certified scales and released with tags can provide tremendous growth data.
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