Department of Fish and Wildlife Conservation
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Browsing Department of Fish and Wildlife Conservation by Subject "0704 Fisheries Sciences"
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- Estimates of Food Consumption Rates for Invasive Blue CatfishSchmitt, Joseph D.; Hilling, Corbin D.; Orth, Donald J. (Wiley, 2021-04-28)As a prolific invasive species, Blue Catfish Ictalurus furcatus threaten native organisms in numerous estuarine and tidal freshwaters along the Atlantic coast of the United States. However, no published estimates of consumption rates are available for Blue Catfish in the scientific literature. This information is critical for development of bioenergetics models or estimation of population-level impacts on native species. Using a combination of field and laboratory studies, we provide the first estimates of daily ration, maximum daily ration, and consumption to biomass ratios for Blue Catfish populations. Ad libitum feeding trials conducted in our laboratory reveal that maximum daily ration in Blue Catfish varies by prey type, temperature, and fish size, with maximal feeding occurring in medium-sized Blue Catfish (500-600 mm total length) and at temperatures >= 15 degrees C. Furthermore, estimates of daily ration were higher for fish prey (Gizzard Shad Dorosoma cepedianum) than for crustacean prey (blue crab Callinectes sapidus). Diel feeding chronologies based on field-collected diet samples from 1,226 Blue Catfish demonstrated river-specific variability in daily ration and maximum daily ration. Blue Catfish daily ration ranged between 2.27% and 5.22% bodyweight per 24 h, while maximum daily ration ranges between 8.56% and 9.37% bodyweight per 24 h. Estimates of consumption to biomass ratios varied by river and Blue Catfish size groupings but range between 2.42 and 3.39, which is similar to other benthic omnivores. This research will inform the assessment of predatory impacts of invasive Blue Catfish in the Chesapeake Bay and beyond as it will enable researchers to estimate predatory impacts through the coupling of population models, food habit information, and consumption rate information (current study).
- The farming and husbandry of Colossoma macropomum: From Amazonian waters to sustainable productionHilsdorf, Alexandre Wagner Silva; Hallerman, Eric M.; Valladao, Gustavo Moraes Ramos; Zaminhan-Hassemer, Micheli; Hashimoto, Diogo Teruo; Dairiki, Jony Koji; Takahashi, Leonardo Susumu; Albergaria, Francielly Correa; Gomes, Maria Emilia de Sousa D. S.; Venturieri, Rossana Luiza Leite; Moreira, Renata Guimaraes; Cyrino, Jose Eurico Possebon (Wiley, 2021-11-25)Within the rich diversity of South American freshwater fish, Colossoma macropomum (Characiformes: Serrasalmidae), known as tambaqui, cachama or blackfin pacu, can reach 30 kg, is a traditional product in regional fish markets and has drawn the attention of fish farmers since the 1930s. Considerable progress achieved in different fields of aquaculture science has contributed to the growth of tambaqui production. Tambaqui has proven suitable for both monoculture and polyculture systems, and for both extensive and intensive production systems aimed at achieving sustainable, higher productivity with minimal environmental impact. Studies of the reproductive anatomy and physiology of the species proved fundamental to development of techniques to boost commercial production, contributing to development of protocols for hormonally induced spawning and artificial propagation in the 1970s. Newly hatched larvae must be fed with live foods until they can be weaned to artificial feeds at about 100 mg weight. Despite its importance for aquaculture, only a few studies have reported components of quantitative genetic variance and parameters for weight at age, morphometric traits and disease resistance. Genomic tools currently available can be applied to detect variation relevant to performance and to accelerate the process of genetic improvement. While the species’ feeding habit allows the use of diets containing 75%–85% plant protein, much more work needs to be done to optimize aquafeeds. Refinement of tambaqui production methods has the potential to significantly boost South American aquaculture. We recommend research on diets, genetic improvement and system optimization to spur further productivity and achieve sustainable tambaqui culture.
- Growth Dynamics of Invasive Blue Catfish in Four Subestuaries of the Chesapeake Bay, USAHilling, Corbin D.; Jiao, Yan; Bunch, Aaron J.; Greenlee, Robert S.; Schmitt, Joseph D.; Orth, Donald J. (Wiley, 2021-01-25)Biological invasions occur as a multistage process, and life history traits can change during the invasion process. Blue Catfish Ictalurus furcatus were introduced in three Virginia tidal tributaries of the Chesapeake Bay during the 1970s and 1980s but have expanded their range to almost all large tributaries of the bay. An understanding of the species’ growth is important for evaluating impacts on other resident species and population dynamics. Virginia Blue Catfish exhibited wide variability in individual growth, prompting the testing of six alternative hypotheses (similar growth across space and time as well as variable growth by river system, sampling year, cohort, and both river system and time) on its growth dynamics within four Virginia tidal rivers (James, Mattaponi, Pamunkey, and Rappahannock rivers) over the period 2002–2016. Blue Catfish growth in Virginia was best explained by a model considering cohort and river as random effects. The Rappahannock River was the first in Virginia to receive Blue Catfish; growth was slower in this river than in the other systems during the observation period. Growth rates declined for all ages examined in the James, Mattaponi, and Pamunkey rivers but only for ages 7, 10, and 13 in the Rappahannock River. We did not generally observe synchronous growth responses among rivers, supporting that finer-scale factors may be influencing growth rates. This work suggests that the growth rates of nonnative species may decline over time and that comparisons of nonnative growth may be most useful when variability over space and time is considered.
- Population Genetics of Brook Trout in the Southern Appalachian MountainsKazyak, David C.; Lubinski, Barbara A.; Kulp, Matt A.; Pregler, Kasey C.; Whiteley, Andrew R.; Hallerman, Eric M.; Coombs, Jason A.; Kanno, Yoichiro; Rash, Jacob M.; Morgan, Raymond P. II; Habera, Jim; Henegar, Jason; Weathers, T. Casey; Sell, Matthew T.; Rabern, Anthony; Rankin, Dan; King, Tim L. (Wiley, 2022-01-07)Broad-scale patterns of genetic diversity for Brook Trout Salvelinus fontinalis remain poorly understood across their endemic range in the eastern United States. We characterized variation at 12 microsatellite loci in 22,020 Brook Trout among 836 populations from Georgia, USA, to Quebec, Canada, to the western Great Lakes region. Within-population diversity was typically lower in the southern Appalachian Mountains relative to the mid-Atlantic and northeastern regions. Effective population sizes in the southern Appalachians were often very small, with many estimates less than 30 individuals. The population genetics of Brook Trout in the southern Appalachians are far more complex than a conventionally held simple “northern” versus “southern” dichotomy would suggest. Contemporary population genetic variation was consistent with geographic expansion of Brook Trout from Mississippian, mid-Atlantic, and Acadian glacial refugia as well as differentiation among drainages within these broader clades. Genetic variation was pronounced among drainages (57.4% of overall variation occurred among 10-digit hydrologic unit code [HUC10] units or larger units) but was considerable even at fine spatial scales (13% of variation occurred among collections within HUC12 drainage units). Remarkably, 87.2% of individuals were correctly assigned to their collection of origin. While comparisons with fish from existing major hatcheries showed impacts of stocking in some populations, genetic introgression did not overwhelm the signal of broad-scale patterns of population genetic structure. Although our results reveal deep genetic structure in Brook Trout over broad spatial extents, fine-scale population structuring is prevalent across the southern Appalachians. Our findings highlight the distinctiveness and vulnerability of many Brook Trout populations in the southern Appalachians and have important implications for wild Brook Trout management. To facilitate application of our findings by conservation practitioners, we provide an interactive online visualization tool to allow our results to be explored at management-relevant scales.