Troy D. Tuckey

Influence of Survey Design on Fish Assemblages: Implications from a Study in Chesapeake Bay Tributaries

Abstract Aquatic resource surveys that span multiple decades provide valuable information about fish population responses to environmental and human-induced changes. Often, surveys are altered as scientific objectives change or in response to management needs. These modifications usually result in inconsistencies in the time series, which must be addressed for proper analysis of fish community data. Since 1997, juvenile fishes in Virginia tributaries of Chesapeake Bay have been captured monthly using a bottom trawl at both fixed and random sites. Previous surveys in these tributaries (1955–1996) were conducted at fixed sites only; thus, an understanding of the effect of this design change would allow us to infer fish community status through multiple decades. We compared samples from the fixed site design with those from the stratified random design in the James, York, and Rappahannock rivers and examined species composition, biodiversity, relative abundance estimates, and size distributions to understand...

Variability in Fish Tissue Proximate Composition is Consistent with Indirect Effects of Hypoxia in Chesapeake Bay Tributaries

Abstract The spatial and temporal extent of summer hypoxia (dissolved oxygen [DO] concentration ≤ 2 mg/L) in Chesapeake Bay and its tributaries has been increasing for decades, consequently affecting fish distribution and abundance by shifting biomass to non-hypoxic habitats. Hypoxia in coastal waters impacts food web dynamics, thereby limiting ecosystem productivity and affecting regional fisheries. Additionally, laboratory studies of Atlantic Croakers Micropogonias undulatus have shown that hypoxia serves as an endocrine disruptor, reducing the production of the yolk precursor vitellogenin as well as affecting other biochemical pathways. Reproductive potential is therefore lower in hypoxia-exposed Atlantic Croakers than in fish that are taken from normoxic conditions. We examined field-caught Atlantic Croakers from three Chesapeake Bay tributaries with different DO levels to evaluate patterns in the lipid content of somatic and gonadal tissues. We found that somatic lipid content was not affected by the presence of hypoxia, whereas ovarian lipid content was significantly affected by the severity of hypoxia. Furthermore, Atlantic Croakers that were exposed indirectly to mild hypoxia (lasting hours to days) exhibited greater ovarian lipid content than fish that were captured from normoxic sites. As expected, severe hypoxia reduced the ability of Atlantic Croakers to accumulate lipids in their ovaries, likely affecting reproductive output. Stock assessment models that ignore the effects of hypoxia may yield overly optimistic production estimates for hypoxia-exposed populations, particularly if environmentally invariant fecundity and growth are assumed.

Maturity Schedules of Female American Shad Vary at Small Spatial Scales in Chesapeake Bay

Abstract Recent assessments of American shad Alosa sapidissima have used stock-specific maturity schedules in biomass-per-recruit models to establish benchmark total mortality rates for management. Because stocks of American shad are managed separately, an appropriate maturity schedule for each stock is required. Additionally, projections of adult biomass require knowledge about year-class strength and the maturation process. Changes in age at maturity can occur when strong year-classes enter the spawning stock; such changes may affect stock assessment models and management decisions. Maturity schedules may also change due to fishing or other external factors. If stock-specific maturity patterns exist, then identical fishery regulations could have different impacts on neighboring stocks. Most American shad matured by age 5 in this study, with year-class-specific estimates of the percentage mature ranging from 46% to 80% in the James River, 58% to 79% in the Rappahannock River, and 49% to 82% in the York R...

Low Apparent Survival and Heterogeneous Movement Patterns of Invasive Blue Catfish in a Coastal River

AbstractBlue Catfish Ictalurus furcatus were purposefully introduced into freshwater tributaries to Chesapeake Bay in the past, and populations have subsequently spread to new areas, negatively impacting native communities and causing concern for resource managers. To aid development of management strategies, we implemented a multiyear (2012–2015) tagging study of invasive Blue Catfish in a 40-km stretch of the Potomac River to estimate survival and assess movement patterns. Blue Catfish (N = 1,237) were captured by electrofishing and double-tagged to allow us to estimate tag retention rates; we used reward tags to increase reporting rates. Recaptured fish (N = 104; 8.4% return rate) were at large for between 2 and 1,208 d. Tag retention rates were 0.88 (SE = 0.045) after 1 year and declined to 0.31 (SE = 0.107) after 2.7 years. The mean minimum distance moved by fish was 24.1 km (range = 0.0–112.6 km). Most (63%) fish displayed downriver movements, but distance moved was unrelated to fish size or days at...

Evaluating the Current Status of American Shad Stocks in Three Virginia Rivers

Abstract Directed commercial fisheries for American shad Alosa sapidissima in the primary Virginia tributaries of the Chesapeake Bay have been under moratorium since 1994. Monitoring of adult American shad within these rivers has been ongoing since 1998 through a cooperative program involving commercial fishers. The monitoring program is designed to mimic traditional commercial fishing practices so that stock status can be inferred by comparing contemporary catch-per-unit-effort levels with those derived from historic logbooks. In this paper, we present analyses of the available monitoring and historic catch rate data along with updated stock status information for American shad in the James, York, and Rappahannock rivers. Two analytical methods were used to derive annual indices of relative abundance; both methods yielded very similar patterns for each river system. Comparisons of contemporary and historic indices of relative abundance suggest that American shad in the James and York rivers continue to persist at low levels of abundance. Measures of stock abundance in the Rappahannock River have been higher than the logbook reference value for much of the monitoring period. However, current moratoria and restoration strategies, which include hatchery releases of fry, the removal of obstructions blocking spawning and nursery habitat, and reductions in bycatch from other fisheries, should continue into the foreseeable future.

Estimating Relative Abundance of Young-of-Year American Eel, Anguilla rostrata, in the Virginia Tributaries of Chesapeake Bay (Spring 2014)

Estimating Relative Abundance of Young-of-Year American Eel, Anguilla rostrata, in the Virginia Tributaries of Chesapeake Bay (Spring 2011) Final Report Submitted by Troy D. Tuckey and Mary C. Fabrizio Department of Fisheries Science Virginia Institute of Marine Science College of William and Mary Gloucester Point, Virginia 23062 Submitted to Virginia Marine Resources Commission Marine Recreational Fishing and Commercial Fishing Advisory Boards

Estimating Relative Abundance of Young-of-Year American Eel, Anguilla rostrata, in the Virginia Tributaries of Chesapeake Bay (Spring 2011)

Estimating Relative Abundance of Young-of-Year American Eel, Anguilla rostrata, in the Virginia Tributaries of Chesapeake Bay (Spring 2011) Final Report Submitted by Troy D. Tuckey and Mary C. Fabrizio Department of Fisheries Science Virginia Institute of Marine Science College of William and Mary Gloucester Point, Virginia 23062 Submitted to Virginia Marine Resources Commission Marine Recreational Fishing and Commercial Fishing Advisory Boards