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Special Symposium I - Recent Fish Health Issues in the Chesapeake Bay Watershed Shenandoah
River Fish Kill Investigations 2004-2005. The Shenandoah River has the reputation as one of the best smallmouth bass fisheries in the United States. An estimated 80% of the adult smallmouth bass and redbreast sunfish were lost from the Shenandoah River in 2004-2005 as result of chronic fish kills occurring in the Spring of the year. Other fish species appear to have been lightly affected. Roughly 75 miles of the North Fork Shenandoah River were impacted in 2004 and 100+ miles of the South Fork and Main stem Shenandoah River were affected in 2005. Adult smallmouth bass and redbreast sunfish exhibited bacterial lesions that resulted in mortality. These lesions appeared following the first major precipitation/runoff event in the Spring. The diagnosis of fish tested by two independent fish health labs indicated that the bacterial infections were a "secondary" effect, and that fish were being stressed by an unknown source(s). Affected fish were also tested for a suite of known fish viruses and all were negative. In addition, water quality data collected from the periods surrounding these fish kills did not indicate abnormal conditions. Currently, the cause of these fish kills remains a mystery. The Shenandoah River Fish Kill Task Force was formed in July 2005 to include all interested stakeholders in the investigation process. The Task Force is comprised of representatives from state and federal agencies, universities, angler groups, riparian landowners, agriculture, and citizen environmental organizations. Research and monitoring projects focused on determining the cause of the fish kills will be discussed.
During 2003 smallmouth bass (SMB) were surveyed in the South Branch of the Potomac River in response to concerns regarding frequent skin lesions and occasional fish kills. Interest in this fish population has continued due to the observation of intersex in male SMB. Since 2003 we have monitored the population on a seasonal basis and continue to find intersex males. The frequency of intersex is notably higher during the spring, but is present during all sampling seasons (spring, summer and fall). Intersex has also been found in largemouth bass at these sample sites, but at a lower frequency. Intersex is often associated with exposure to endocrine disrupting chemicals (EDCs). Consequently, efforts have been made to determine if such compounds exist in the South Branch. A number of EDCs were detected during a preliminary screening of water-bourne chemicals. Sediment and water samples have also been collected, and extracts from the samples are currently being tested for estrogenic activity using in vitro screening methods. Plasma from these fish has tested positive for EDCs as well as vitellogenin in male fish. Current experiments are in progress to determine if some of the detected compounds can induce intersex and Vtg in these species of interest.
Numbers of young of year (Y-O-Y) smallmouth bass, Micropterus dolomieui, collected per 50m of river or stream shoreline (CPM) in early summer using back pack electrofishing has been annually measured since the late 1980's across Pennsylvania. Catch of smallmouth bass per 50m of river or stream shoreline has fluctuated, depending upon river basin, from 7 to 40 fold. We used a linear model to explore the relationship between mean catch per 50m of shoreline to mean discharge, water temperature, and standard error of each mean for 15 river or stream reaches for which discharge and/or temperature measures were available. We produced significant (P < 0.05) regressions for 7 of 15 reaches using discharge and/or standard error of discharge as predictors. We explained between 36 and 74 percent of the variation in Y-O-Y CPM in these instances. In the lower Susquehanna River basin discharge parameters had significant influence on Y-O-Y CPM. From 2000 through 2004 Y-O-Y CPM measurements were below the long-term mean, in 2005 measurements reached and slightly exceeded the long term mean. Fall densities of smallmouth >300mm (~12 in) collected by john-boat electrofisher in 2005 in the lower Susquehanna Basin exhibited decreases in density compared to historic mean values. Low densities were, in part, associated with low densities of young measured in prior years. In 2005, smallmouth bass Y-O-Y were collected that exhibited skin lesions with dead and dying Y-O-Y observed during collections. Examination of a sample of smallmouth bass Y-O-Y collected from the Juniata River (lower Susquehanna Basin) during the outbreak showed that approximately 50% contained systemic columnaris (Flavobacterium columnare) infection. Examination of water quality parameters through time indicated no unusual values in 2005 with the exception of dissolved oxygen, where daytime measurements exhibited depressions in the summer of 2005, but not in other years. Limited pre-dawn dissolved oxygen (D.O.) measurements made in 2005 were observed to be sufficiently low to cause stress in warmwater fishes. Discharge in the Susquehanna Basin exhibited few flushing events and protracted warm air temperatures may have contributed to low D.O. measurements in 2005. Low density of smallmouth bass >300mm (~12 in) observed in the lower Susquehanna Basin in 2005 were unrelated to diseased and dead smallmouth bass Y-O-Y observed in 2005 but were related to below average Y-O-Y CPM measured from 2000 to 2004.
A mycobacteriosis epizootic was reported in Chesapeake Bay striped bass (Morone saxatilis) in 1998 by investigators at the Virginia Institute of Marine Science. Since that time researchers from academic, state, and federal facilities have been involved in numerous projects designed to generate a better understanding of the disease. Projects include the characterization of pathogens, pathogenesis, distribution, pathogen host interactions and disease ecology. A new project on striped bass population effects began in 2005. The disease is widespread in the Bay but varies both in prevalence and severity based on season, locality and striped bass year class. Mycobacterium shottsii appears to be the predominate mycobacteria associated with the disease and polymicrobial infections have been reported. Internal and external disease presentations are known to occur. Disease prevalence exceeding 50% has been reported in some samples. Heavily infected fish exhibit significantly reduced condition factor. Studies using striped bass held under laboratory conditions and the common mycobacteria isolated from Chesapeake Bay striped bass indicate that the disease can be progressive and fatal. Histological data indicate that the disease may have been present in the Bay for decades. The cause for this recent and on-going epizootic is not known.
There are three species of snakehead fishes established as reproducing populations in waters of the United States. The blotched snakehead, Channa maculata, has been established in Oahu, Hawaii, since before the year 1900. In 2000, the bullseye snakehead, C. marulius, was found to be established in Broward County, southeastern Florida. The northern snakehead, C. argus, was discovered to be established in a pond in Crofton, Maryland, in 2002 and later eradicated later that year. Channa argus is now known to be established in waters of several states. Aspects of the biology of this species from within its native and introduced ranges in Asia and Eurasia are reviewed.
Abstract - A northern snakehead Channa argus population was documented within a 23-km reach of the tidal freshwater Potomac River and associated tributaries in 2004 when 20 snakeheads were collected with several gears including hook-and-line and electrofishing. An additional 271 snakeheads were collected in 2005 primarily with various electrofishing gears. Boat electrofishing mean catch rate increased from 0.2 fish/hr in 2004 to 2.8 fish/hr in 2005. Mean total length was 282 mm (SD=124), and mean weight was 521 g (SD=619). Minimum and Maximum total lengths were 88 and 655 mm, while weight extremes were 7 and 3145 g. Dominant habitat uses were shallow waters with floating and/or emergent vegetation. Natural reproduction was the likely explanation for the collection of age-0 fish both years and identification of nine year-classes in 2005. Trends in female GSI and otolith daily ring counts of age 0 fish suggested protracted and/or repeat spawning beginning in early May and extending through July. The collection pattern suggested snakeheads originated from Dogue Creek, as over 93% came from this watershed. Snakeheads appeared to display a fall migration from tidal waters to headwater tributaries following a major rain event. Eight forage species were identified, but banded killifish comprised 66% of identifiable food items. Bluegill, pumpkinseed and white perch were also commonly consumed
Mitochondrial sequence variation was examined in the northern snakehead, Channa argus (Cantor, 1842), a species of fish native to Asia and recently collected in the eastern United States. There are seven unique haplotypes in 29 specimens studied, with no haplotype shared between areas of introduction. One haplotype was shared by 15 individuals from the Potomac River system (both males and females <480 mm total length), indicating possible breeding within the system. A single large adult male from the Potomac River system has a unique haplotype. All Crofton, Maryland, specimens had one haplotype. Two haplotypes were found in Meadow Lake, FDR Park, Philadelphia, Pennsylvania. Unique haplotypes were found in Wheaton, Maryland, and Shrewsbury, Massachusetts. These results support the conclusion that there were several independent introductions of the northern snakehead into these waters, and that no two introductions came from the same maternal source.
The occurrence of non native northern snakeheads in the United States has received a great deal of media, public and political attention. Unfortunately, this awareness has not served to prevent further introductions. Snakeheads have been introduced in several areas of the Northeast including tributaries of the Potomac River below Washington D.C. Twenty were captured there in 2004 and over 300 individuals were captured in 2005. These fish are successfully foraging, utilizing available habitat, reproducing and appear to becoming firmly established in the Potomac River. Very little is known about the potential impacts of snakehead introductions. Information concerning the biology, behavior, movement and stock dynamics of this fish are needed to determine their impacts. The Maryland Fishery Resources Office has initiated research on salinity tolerance and parasite loads. It appears that snakeheads are somewhat tolerant to salinity and may be able to spread out of the Potomac River during high flow events. Congress requested that the U. S. Fish and Wildlife Service address concerns about the introduction of Northern Snakeheads (Energy & Water Appropriations Bill 2006). The USFWS has assembled a working group that includes representatives from state and federal agencies, industry, law enforcement and other interested stakeholders to prepare a National Snakehead Control and Management Plan (SCMP). The focus of the plan is to identify specific control actions for existing introductions in the Northeast and to identify prevention, enforcement, early detection and rapid response, control, research and outreach measures for the entire United States.
This vicious street gang started in El Salvador and now has members throughout the U.S. with over 5000 members in the northern Virginia area alone. MS13 often chooses remote areas to conduct meetings, hold gang court, and practice their firearms skills; these areas have included boat ramps, wildlife management areas, and parks. This presentation will explain MS13 gang structure, graffiti, tattoos, and modes of operation. Surveillance video of meetings in remote areas will also be shown. Upon completion fisheries personnel will know how to identify MS13 gang activity within their work areas and respond appropriately.
Spawning behavior and hybridization of Etheostoma nigrum and E. olmstedi was studied for populations in central Virginia. Hybridization is common in the genus Etheostoma, but there have been conflicting results in studies involving E. nigrum and E. olmstedi. The question is pertinent to central Virginia because "problematic" populations (i.e., those with characteristics intermediate of the two species) occur there, and it may be that these are hybrids. We collected both darter species in the wild and placed various inter- and intraspecific mating pairs in small aquaria. Through behavioral observations, we found that males spent more time than females in nuptial behavior (24.1% v. 7.5%), that the percentages were not different between the species, but that E. nigrum males spent more time courting E. olmstedi females than they did their own species (32% v. 12.4%). Viable eggs were produced in six of 26 tanks, including two inter-specific crosses. In both inter-specific crosses the female was E. olmstedi and the male E. nigrum. Fry were produced from all six successful matings, but 100% mortality had occurred by week four, probably because we did not provide a suitable diet.
Drift-feeding trout appear to distribute themselves to maximize energy intake. Less well understood are the mechanisms fish use to find the "best" locations. I monitored locations selected by fish in two pools under natural conditions, and then manipulated drift density with artificial feeders and velocity with plywood baffles. Under natural conditions, fish foraged in the deepest, fastest sections of the pool near cover. Artificial feeders where then placed in either the main velocity "thread" in the pool (Location A), or outside it (Location B). Under natural conditions, fish readily found feeders in Location A but not B. However, when velocity was manipulated to be high at Location B, fish found the feeders. Moreover, once fish located the feeders, they were willing to move into very shallow water (20 cm) away from cover (4 m) in order to feed. Finally, one fish "remembered" the Location B feeder at least 24 h after natural velocity conditions were restored. These results indicate that trout used velocity as the main proximate cue to locate food, that this search strategy was insufficient to give fish perfect knowledge of all food sources in a pool, and that trout used previous experience to modify their search strategy.
We evaluated movement and re-colonization rates of Potomac sculpin sampled from eight habitat reaches (90-meters each) on Smith Creek, a stream heavily impacted from agriculture and dominated in species abundance by Potomac sculpin (mean 129/100m2). Four of the sampling units had all fish removed from the middle 30 meters (Treatment: T1). A total of 3,335 Potomac sculpin were marked in the original samples (June 2005) and 665 (19.8%) sculpin were recaptured (July 2005) approximately 30 days later. Most of the recaptured Potomac sculpin were "stayers" (81%). Upstream movers (17%) were greater than downstream movers (3%). However, individual tagged fish moved upstream up to 1,300 meters. The presence or absence of fish in adjacent 30 m habitat sections influenced upstream movement of Potomac sculpin. T1 sections (fish removed from middle sections) averaged 8.5% upstream movement while T2 sections (no fish removed from middle section) averaged 2.6% upstream movement. There were no statistical differences in the downstream movement of Potomac sculpin the between the two treatments. T1 sections averaged 0.8% while T2 sections averaged 1.0%. There were no differences in length between "movers" or "stayers". Treatment sections where all fish were removed were re-colonized in 30 days to baseline numbers with similar length frequencies.
Essential Fish Habitat (EFH) refers to habitats, typically nursery, spawning and/or feeding grounds which are necessary for the survival of a species, for example seagrass beds in Chesapeake Bay. EFH has important implications for commercially fished species and their management even more so as the seagrass beds in Chesapeake Bay appear to be diminishing. Determining which seagrass beds function as EFH is a daunting task. The identification of EFH has been simplified by recently developed techniques such as otolith chemistry. This technique has extensive usage as a natural tag to track dispersal, measure population connectivity, and determine provenance. As a natural tag, it records the environmental history for a given specimen and therefore can be used to identify habitat usage. We examined the variability of otolith chemistry in juvenile spotted seatrout (Cynoscion nebulosus from seagrass habitats in 1998, 2001, and 2002 to determine if the isotopic and elemental signature can be used to identify the EFH for these fish. We found significant variability in otolith chemistry (Ca, Mn, Sr, Ba, La, δ13C, and δ18O) both between and within years for five major seagrass habitats. Although there is a high level of variability, we were able to correctly classify juvenile spotted seatrout to their seagrass habitat with an accuracy of 80-100% and identify seagrass habitat at spatial scales of 15 km. This technique will allow discrimination of fish to individual seagrass beds and shows great promise as a tool for identifying the most Essential Fish Habitat.
Tracking dispersal of age-0 smallmouth bass (Micropterus dolomieu) away from their spawning locations has previously only been accomplished by genetic 'fingerprinting' of broods. An efficient method for tracking age-0 dispersal would be useful for studying spatial dynamics and recruitment processes within and between river populations of smallmouth bass. Understanding the biotic and abiotic factors affecting recruit, juvenile, and adult exchange between connected river fisheries would be particularly helpful when those fisheries are managed under different strategies. We analyzed trace element chemistry of water samples and otoliths from 3-5 week old fry collected from 5 representative reaches of the Maury River and 4 reaches of the Upper James River bracketing its confluence with the Maury. Results indicate that trace element signatures can distinguish natal origins of individual smallmouth bass between these two rivers with greater than 90% accuracy. Distinction between reaches within rivers was less precise on average, though the water and otolith chemistry data reveal spatial pattern in variation of trace elemental composition. Two conclusions are apparent from these results: 1) 'signature' chemistry of otoliths holds strong potential for tracking dispersal of smallmouth bass away from their natal range; and, 2) accounting for within-river spatial variation in trace element chemistry is important for achieving maximum accuracy in distinguishing natal origins between rivers. Ongoing research is focused on assessing potential of these methods for tracking movements of juveniles and adults at finer temporal resolution (i.e. sub-annual movements or migration).
We evaluated population densities and age and growth of Potomac sculpin sampled from eight habitat reaches (90-meters each) on Smith Creek, a stream heavily impacted from agriculture. Potomac sculpin had an average population density of 129/100m2 (range 30/100m2 to 297/100m2 and were the dominant fish in the ecosystem both by numbers and biomass. Potomac sculpin averaged 71 mm in total length (range 49 mm to 127 mm). The majority of Potomac sculpin were less than 3 years old.
Atlantic croaker larvae were collected on a cruise during September 2000 beginning just south of Beaufort Inlet and ending near the mouth of Delaware Bay. At each sampling location salinity and temperature was measured for each tow. This allowed us to define the water-mass boundaries for potential groups of spawning Atlantic croakers. Otoliths from larval Atlantic croakers (1 - 7 mm) were extracted in a class-100 clean room and prepared for solution-based inductively-coupled plasma mass spectroscopy. We used multivariate analysis of variance (MANOVA) to determine whether the multivariate otolith-elemental signature differed among the potential groups of larval Atlantic croaker. Cluster analysis revealed three well defined water masses which were also validated with a temperature-salinity plot. These water masses were Chesapeake Bay plume water, North of Chesapeake Bay, and near Cape Hatteras. Results from MANOVA indicated differences in the multivariate elemental signature existed among the three groups of larval Atlantic croaker. A quadratic discriminant function was applied to the data to determine our classification accuracy of larval Atlantic croaker to their water mass of origin. We were able to correctly classify fish from North of Chesapeake Bay 77% of the time, Cape Hatteras 71% of the time, and from the Chesapeake Bay plume water 37% of the time. Results from this study indicate that it is possible to obtain measurable elemental concentrations from otoliths much smaller than previously analyzed (range 6-39 µm and averaged 16.9 µm) and contrary to previous studies; there may be some spatial structuring of spawning Atlantic croaker in the mid-Atlantic Bight.
This presentation is a brief overview of the Virginia Department of Game and Inland Fisheries's Landowner Incentive Program (LIP). The purpose of this program is to protect certain endangered, aquatic species. Important aspects of the program include: species targeted, watersheds eligible, cost-share specifics, practices employed, and sample projects description.
The Nature Conservancy sets conservation priorities through ecoregion-based planning. Freshwater ecoregions are drainage basins delineated based on similar physiographic, ecological and zoogeographic patterns and processes. The goal of freshwater ecoregional planning is to design a network of biologically significant aquatic areas that if conserved will ensure the long-term survival of all viable native species and community types of the ecoregion. Four freshwater ecoregions as defined by WWF intersect in Virginia: the Chesapeake, Ohio, Upper Tennessee and South Atlantic Basin. The Conservancy has developed a classification method for freshwater ecological systems to represent both common and rare native freshwater biodiversity at multiple scales and capture key ecological processes. Freshwater ecological systems are classified through a GIS-analysis of two variables: environmental setting (defined by geology, elevation and landform) and size of stream system. Through interviews with expert aquatic biologists and a condition analysis, we select the most viable examples of each system type, ensuring optimal representation and connectivity among systems. Additionally, we integrate data and expert knowledge regarding the occurrences of rare, endemic and migratory aquatic species. The result is a set of priority conservation areas for freshwater in Virginia and the ecoregions at large, which we hope to effectively conserve through working closely with partners.
Black crappie Pomoxis nigromaculatus population dynamics were evaluated in spring 2002 in four northern Virginia public fishing lakes to determine candidates for size structure enhancement. Based on FAST models, Lake Orange (50-ha) was deemed to have acceptable population parameters that may benefit from restrictive harvest (Growth was fast to age-3, but total annual mortality was estimated at 56%). In March of 2003, 735 crappies were floy tagged at Lake Orange as part of an exploitation study. Between March and October of 2003, 182 tagged crappies were reported for an unadjusted 25% fishing mortality rate. An access point creel survey has been conducted since 2003. Black crappie harvest in 2003 was 2,681 fish with a mean TL of 214-mm, mean WT of 0.13 kg, and an overall yield of 333 kg. In order to reduce angler exploitation and to allow crappie to maximize growth potential, a 229-mm minimum size limit was implemented January 1, 2004. Since implementation of the minimum size restriction, mean TL of harvested fish increased from 214-mm in 2003 to 239-mm in 2004 and then to 244-mm in 2005. Similarly, yield increased from 333 kg in 2003 to 417 kg by 2005. Mean WT also increased from 2003 to 2005 (0.13-0.18 kg). In spring 2005, 541 black crappie were tagged to re-evaluate angler exploitation during 2005. By fall, 124 tagged crappie had been creeled for an un-adjusted exploitation rate of 22%. During 2005, anglers harvested 2,388 fish. It appears the minimum size restriction has reduced angler exploitation and allowed the size distribution of black crappie to improve at Lake Orange. Number of fish harvested decreased from the pre-regulation period, but mean TL, mean WT, and overall yield increased. Future analysis will evaluate year class effects and monitor changes to population dynamics following the regulation change.
Knowledge of patterns of genetic variation would inform management of smallmouth bass (Micropterus dolomieu dolomieu) populations. 316 individuals representing 13 populations were screened at 10 microsatellite loci. Numbers of alleles per locus ranged from 2 to 10. Native populations were more variable (4.5 alleles/locus) than introduced populations (3.9 alleles/locus), although ranges for the respective groups overlapped. 82.7% of genetic variation was found within, and 17.3% between populations. Matrices of FST, GST, RST, and ρmetrics were subjected to cluster analyses to construct population trees. Results were broadly convergent, tending to show clusters of: (1) Caddo Lake, Arkansas, the M.d. velox out-group, (2) the native, Tennessee drainage populations, and (3) all other, introduced populations, including that in the upper New River. The Maury and Jackson river populations clustered with Tennessee drainage populations for some metrics, likely reflecting historic stocking events. We recommend that the native, Tennessee River populations be regarded as one management unit and all other, introduced populations as another. Native Tennessee system stocks are likely to be locally adapted and should not be subject to stocking from outside sources. Introduced stocks likely would not have become locally adapted, and a more permissive stocking regime would be justifiable.
The Potomac River smallmouth bass fishery is Maryland's most popular non-tidal fishery. Yet, prevailing angler opinion has been that the Potomac River produces relatively few quality size bass (>280 mm TL) in comparison to other major rivers in the region. Over the past 26 years six different regulations were implemented in order to increase the abundance of larger bass. In 1990 a Trophy Bass Management Area was established with a 5 fish per day creel limit with only one >381 mm and a protected slot between 279 mm and 380 mm. In 1995 a separate Catch and Release Bass area was established which allowed no harvest. Electrofishing data from 1977 to present were pooled by area and pre- and post- regulation periods and analyzed for evidence of changes in population indices. CPUE of quality smallmouth bass showed no significant improvement after regulation changes (P< 0.05). Mean length at age remained unchanged as well. Proportional stock density improved in the 'Trophy Bass' reach however it also improved at adjacent sites managed under general state-wide regulations. Overall annual mortality estimated from catch curves was 50.5%. Annual mortality decreased from pre- to post-regulation periods at all areas including those not under special management and therefore did not appear to be related to regulation. Special regulations had no discernable effect on smallmouth bass populations.
We synthesize the results of six years of research on brook trout population dynamics in the upper Shavers Fork watershed of eastern West Virginia. The over-riding objective of this research has been to quantify the fine-scale spatial structure of brook trout populations and develop watershed scale management approaches for the Allegheny Plateau ecoregion. Our research can be divided into four lines of inquiry: 1) describing watershed scale variability in brook trout foraging and reproductive habitat; 2) quantifying the extent and rate of brook trout dispersal in the watershed; 3) quantifying seasonal and spatial variabilility in brook trout demographic rates (e.g., survival and immigration); and 4) quantifying fine-scale genetic structure using microsatellites. Our results indicate that small tributaries function as non-substituteable, complementary, source habitats that are linked via relatively low rates of dispersal. In contrast, larger tributaries and the mainstem function as supplementary, high quality sink habitats. These areas tend to posses foraging habitats that supplement small tributaries but local populations in these areas are dependent on immigration. Genetic evidence on population structure is consistent with ecological studies and underscores the importance of considering watershed scale processes when managing brook trout populations in Appalachian watersheds.
An old proverb says: "The more things change, the more they stay the same." The same could be said about warmwater streams management. Each generation of scientists builds on the body of knowledge given to them by the previous generation of scientists. Each generation answers questions using the technology they have at hand. A previous generation of warmwater stream managers convened a national symposium on warmwater streams in Knoxville, Tennessee in March 1980. That symposium emphasized the importance of warmwater streams, summarized current ecological knowledge about warmwater streams, discussed warmwater streams resources, problems, and management needs, examined methods for protecting their integrity, and stimulated fresh ideas and new approaches in warmwater streams management. While the past 26 years have brought new innovations and approaches, some management techniques remain the same. The 2004 warmwater streams symposium, held in Oklahoma City, Oklahoma (www.sdafs.org/wwstreams/wwsc1.htm), provided a report on current issues, principles, and practices in warmwater streams management. My talk will provide guidance for a new generation of warmwater stream managers, drawing on the visionaries of the last generation for guidance.
Virginia is a signatory of the Chesapeake Bay Agreement and Chesapeake 2000. After the Bay states accomplished the original 10-year goal of reopening over 1500 miles of historic spawning and rearing habitat for migratory fishes such as American shad (Alosa sapidissima), a new 10-year fish passage goal through 2014 was recently set. Virginia contributed over 600 miles to the original goal and will play a large role in reaching the new goal of 1000 miles from 100 projects Baywide. Seventeen fish passage projects have been completed in Virginia's Bay drainage since the 1980s with four of them being removals. Natural breaching of several dams contributed to the total mileage reopened. Several projects are currently active (e.g. Woolen Mills Dam removal) and several are planned for completion over the next ten years (e.g. Ashland Mill Denil fishway). Fish passage projects are monitored to determine successful use by target species. For example, Boshers Dam vertical slot fishway on the James River is monitored by collecting digital video during the spring run. The Embrey Dam removal project is monitored by collecting target species at upstream locations. Funding for coordination, monitoring, and implementation comes from a variety of sources (e.g. EPA Chesapeake Bay Program).
Many state agencies have adopted the practice of stocking fingerlings instead of fry without any rigorous evaluation. Fingerlings are generally have higher survival rates, but are much more expensive to produce than fry. We evaluated the effectiveness of stocking fry instead of fingerling hybrid striped bass based on their first-year survival estimates. First-year survival rates of hybrid striped bass stocked as fry ranged from 0.4% - 18.2% and averaged 6.7%. First-year survival rates of hybrid striped bass stocked as fingerlings ranged from 3.4% - 57.0% and averaged 26.4%. Estimates of age-1+ survival ranged from 16 - 61% based on comparing gill net catches at age. Direct cost analysis indicated that currently it is 12.2 times more expensive to stock fingerlings than fry and that fry survival would have to be 0.042% or less for fingerling stockings to be an economically viable alternative. First-year survival of hybrid striped bass was best explained (R2 = 0.9549) by a linear model incorporating the estimated number of age-1 hybrid striped bass, the number of fingerlings stocked, the number of threadfin shad gill netted in fall, and the mean spring air temperature. Additional research should evaluate fry and fingerling stocking during the same year and stocking site characteristics on immediate post-stocking survival.
Trace-element signatures in otoliths provide Fisheries Biologists with a wealth of information. Growth bands in otoliths chronologically record environmental information that can be used to discriminate fish populations, distinguish habitats, and monitor water quality. We show how new techniques using ICPMS laser ablation can sample discrete periods in fish growth. The structure of the otolith provides a three dimensional record of the environmental trends during specific stages of fish development. We investigated the effects of differing trench depth on the concentration of Ba, Sr, Mn, and Mg in Atlantic Croaker (Micropogonias undulates) otoliths. Results from this analysis showed that there are significant differences in elemental composition across the otolith at different depths. This indicates that elemental analysis of different sections of the otoliths can provide environmental information for a specific period in the growth of the fish.
Mountain Run is located in the George Washington National Forest, part of the Massanutten Mountain Range of Virginia. Brook trout (Salvelinus fontinalis) and other species suffered severe losses in the 1980s due to atmospheric acid injection (acid rain) reducing pH and raising aluminum concentrations in the base poor stream. The stream was initially treated (1993, 1997) with limestone to restore water quality at a location in a lower reach that flows perennially and later on (1999, 2002, 2005) in an upper reach that sinks into the channel substrate then resurfaces downstream several times. Mountain Run drains from fine sandy loam soil of the Laidig classification. The watershed soils are extremely acid with soil pH 4.21, 3% organic content and cation exchange capacity of 147 ± 11 meq per 100 gram dry soil. Water quality parameters (WQPs) were analyzed monthly from 1992 until present time (January 2006) throughout the watershed. Key WQP values were as follows for four locations that bracketed liming sites: upstream (control) and 1.25 km downstream (treated) for the perennial stream reach, upstream (control) and 1.25 km downstream (treated) for the sinking stream reach. Average values found for 77 months post liming were pH (s.u.) = 4.64, 5.73, 4.59, 5.05; ANC (µeq/L) = -22.2, +18.3, -28.2, -6.3; Ca:H (ratio) = 1.3, 251.5, 0.9, 9.6; Al (ppb) = 417, 137, 276, 189 for these four sampling sites, respectively. This study compares the effectiveness of liming Mountain Run in the two locations, and how the response in the upper reach is less dramatic due to the sinks in the stream and the acidic nature of the soil through which it percolates.
We summarized existing knowledge regarding the distribution and status of self-sustaining populations of brook trout Salvelinus fontinalis across their native range in the eastern United States (east of Ohio), a region that represents approximately 25% of the species native range and 70% of the native range in the United States. Based on known and predicative models our results show that brook trout are Intact > 50% in 1,612 subwatersheds (30%), Reduced > 50% in 1,938 subwatersheds (37%) and are Extirpated from 1,451 subwatersheds (28%) from their potential (historic) range within the study area. Brook trout are known to be absent in another 277 subwatersheds (5%), but it was not known if they were extirpated or never occurred in these subwatersheds. Six core subwatershed and subwatershed water corridor metrics (% total forest, sulfate and nitrate deposition, % mixed forest in the water corridor, % agriculture, road density and latitude) were useful as predictors of brook trout distribution and status. Intact populations of brook trout are more likely to in subwatersheds where the percentage of total forest was greater than 68%. Continued habitat loss associated with land use practices, existing and new populations of naturalized exotic coldwater and warmwater fishes threaten remaining brook trout populations.
In multi-jurisdictional settings such as Virginia's tidally-influenced rivers, data transformations allow fisheries managers to more accurately compare the findings from differing sampling programs. Sampling protocols can differ due to gear type, gear methodology, measurement and recording methods. To effectively compare fish sampling programs with different protocols, an assessment of the differences should occur to create standardized conversions. In this study the author determines length-length conversions for anadromous forage species, Alosa aestivalis, A. psuedoharengus, A. sapidissima, Dorosoma cepadianum and Morone americana. These species are found annually in the tidal freshwater Potomac River and its tributaries. Species were collected in 2005 through George Mason University's (GMU) long-term sampling program, and the Interstate Commission on the Potomac River Basin's (ICPRB) American shad restoration project. The author also compares, and converts, the GMU seine methodology to those employed by the VIMS and Maryland DNR Juvenile Striped Bass Seine Surveys. This study illustrates the power of using conversions which allow fisheries managers to quickly standardize information and compare historical data sets based upon differing measurement and reporting methodologies.
Acid-sensitive St. Marys River lies within the St. Mary Wilderness in Virginia's George Washington-Jefferson National Forest. In 1986 the Virginia Department of Game and Inland Fisheries (VDGIF) established six electrofishing reaches and began long-term monitoring of fish populations within the watershed. The monitoring program has revealed a downward trend in fish populations, related to an increase in stream acidification. In 1989, The U. S. Forest Service (USFS) began additional fish population monitoring using basinwide visual estimation technique (BVET) fish inventories in support of a proposed stream liming project. The two monitoring programs provide pre- and post-liming fish data for comparison; both showed increases in blacknose dace (Rhinichthys atratulus) numbers immediately following liming and documented a return of several other extirpated species to the watershed. Our results demonstrate the strengths and limitations of both monitoring approaches and show the benefits of coordination among resource agencies. Potential
roles of intraovarian growth factors during follicle maturation in rainbow
trout, For years the regulation of follicle maturation in fishes has focused on the roles of pituitary derived peptides (i.e., luteinizing hormone and follicle stimulating hormone) and sex steroids, while the roles of intraovarian growth factors have been largely ignored. Critical roles for intraovarian growth factors have been identified in mammals, but little is known about these regulators in fishes. We investigated the ovarian mRNA expression of members of the transforming growth factor beta (TGF-β) superfamily and some of their known inhibitors [i.e., bone morphogenetic protein 4 and 7 (BMP4 & 7), growth and differentiation factor 9 (GDF9), inhibin, follistatin, and BAMBI (BMP and activin membrane-bound inhibitor)], as well as insulin-like growth factor I & II (IGF-I & II), during follicle maturation in rainbow trout. The responses to incubation with maturation inducing hormone (MIH; 17α,20β-dihydroxy-4-pregnen-3-one), IGF-I, estradiol (E2), testosterone, and human chorionic gonadotropin were investigated. Incubation with MIH caused a ~21-fold increase in BAMBI mRNA, while all other transcripts remained unchanged. The stimulatory effect of MIH on BAMBI mRNA was also examined for dose dependence and steroid specificity. Both of these characteristics were confirmed, supporting a role for BAMBI in the regulation of follicle maturation in fishes. |