Download or read book Predation Impacts of Invasive Blue Catfish on Blue Crabs in Estuarine Environments written by Mary C. Fabrizio and published by . This book was released on 2021 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blue crab (Callinectes sapidus) is an important resource in Chesapeake Bay serving as predator and prey in the estuarine food web and supporting one of the most valuable fisheries in the region with landings in 2019 exceeding 55,501,000 lbs. and valued at more than $81,465,000 (NOAA Fisheries 2021). Fluctuations in the abundance of blue crabs in the Chesapeake Bay reflect annual changes in recruitment, fishing mortality, and natural mortality (Lipcius and Van Engel 1990). During the 1990s, blue crab abundance in Chesapeake Bay declined markedly (Lipcius and Stockhausen 2002) and management plans were subsequently enacted to rebuild blue crab stocks to former levels of abundance. Such rebuilding plans aim to protect the spawning stock to ensure recruitment and required significant reductions in fishing mortality rates. Recruitment in this stock is closely monitored, and fishing mortality is regulated through area closures, minimum size, and seasonal harvest limits, but natural mortality due to predation is not well known or estimated. Indeed, a comprehensive list of blue crab predators is lacking for Chesapeake Bay (Bromilow and Lipcius 2017). Nonetheless, predation mortality on blue crabs may contribute to notable annual fluctuations in the abundance of juvenile and harvestable blue crabs.
Download or read book A Preliminary Study of Predation on Blue Crabs by Three Fish Predators in a Seagrass Bed written by Robert Joseph Orth and published by . This book was released on 1999 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report serves as a preliminary assessment of potential feeding impacts on blue crab prey inhabiting a seagrass bed in the York River by three species of recreationally and commercially important fish (striped bass, croaker, and red drum). We also provide an historic perspective indicating possible changes in relative abundance of these predatory fish between the period 1978-1980 and 1998. In no way do we intend for this report to reflect an accurate, bay-wide assessment of these relationships; the extremely limited temporal and spatial scope of this effort precludes such conclusions. However, this report supports the contention that habitat-specific predation impacts on juvenile crabs inhabiting seagrass beds that serve as nurseries for blue crabs may be important to consider when examining sources of natural crab mortality. Definitive conclusions regarding such impacts await more comprehensive research efforts targeting these relationships at the appropriate bay-wide scale. Finally, it is important to recognize that mortality impacts on blue crab populations stem from a combination of causes. Natural mortality via predation (which is difficult to control) apparently impacts crabs less than 75 mm (3 inches) in carapace width (Moody, 1994; Smith, 1995), whereas those individuals larger than 75 mm likely experience heaviest mortality from commercial and recreational fisheries (which can be controlled through effective management policy).
Download or read book Juvenile Blue Crab Survival in Nursery Habitats written by Amanda Marie Bromilow and published by . This book was released on 2017 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. To reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.
Download or read book Predation on Juvenile Blue Crabs Callinectes Sapidus Rathbun in Lower Chesapeake Bay written by Kirt Edward Moody and published by . This book was released on 1994 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Blue Crab written by Victor S. Kennedy and published by Maryland Sea Grant College University of Maryland. This book was released on 2007 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Ecology of Blue Crab Callinectes Sapidus Megalopae in the Mission Aransas Estuary Texas written by Kimberly Marie Bittler and published by . This book was released on 2013 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blue crabs are a widely distributed estuarine species with broad economic and ecological importance. Several studies have linked blue crabs to freshwater inflows, but the precise nature of this link is still uncertain, as blue crabs have a complex life cycle that utilizes both marine and estuarine environments. One potential link between blue crabs and freshwater inflows is during recruitment, when megalopae developing offshore return to estuaries before molting into juvenile crabs. Megalopae swim during the flood tide to ensure delivery into and farther up estuaries. The behaviors regulating selective tidal stream transport (STST) on the flood tide were originally studied in North Carolina in an estuary with regular freshwater inflows and a strong salinity gradient. The model of STST was re-examined in the Mission-Aransas, an estuary with episodic freshwater inflows and salinity gradients ranging from normal estuarine conditions to hypersaline during droughts. The behavioral responses of megalopae to a range of rates of salinity increase were tested, and then modeled onto rates of salinity change observed in the field to determine the theoretical ecological consequences of STST for blue crab populations in the Mission-Aransas Estuary. To validate the ecological trends predicted by the behavioral model of STST, a simple, long-term data set reflecting changes in megalopae abundance is needed. Hog's hair collectors are a simple and widely used method of quantifying abundance of brachyuran megalopae, including blue crabs. However, the efficiency of hog's hair collectors in sampling for megalopae is unknown. Several studies have reported poor correlations between settlement on hog's hair collectors, transport, and abundance of megalopae in the plankton due to disparate temporal scales and potentially turbulence-driven decoupling. Each of these issues were addressed in field and flume experiments, which were used to develop a model for interpreting settlement on hog's hair collectors in terms of transport and planktonic abundance.
Download or read book The Effects of Predation by the Blue Crab Callinectes Sapidus on a Macrobenthic Infaunal Community in Galveston Bay Texas written by Eddie Augusto Fort and published by . This book was released on 1983 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stage structured Blue Crab Population Model with Fishing Predation and Cannibalism written by Fangming Xu and published by . This book was released on 2020 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blue crab is a species of crab commonly found in the waters of the western Atlantic Ocean. It is one of the most important shellfish in the Chesapeake Bay. The blue crab fishing industry has a notable impact on the local economy, and blue crabs form a key link in the Chesapeake Bay food web. Between the mid-1990s and 2004, the blue crab population dropped by two thirds. Factors such as habitat loss, harvest pressure and climate change may have contributed to the decline. However, there hasn’t been enough research on the long term dynamic equilibrium, making it difficult to explain the change of the population. In this study, a dynamic population model is built for blue crab using ordinary differential equations. Factors such as reproduction rate, cannibalism, predation rate and fishing mortality are considered, trying to predict the long term stable state under different conditions. Our conclusion is that bistable positive states are not likely to happen with biologically realistic parameter values. Also, crabs can sustain higher fishing pressure under the more realistic assumption of sigmoidal predation/cannibalism than under the constant predation/cannibalism assumption often used in stock assessment models. This model will be useful to evaluate the effects of disease, climate change and overharvesting, and thus help regulators to make appropriate policies and conserve the blue crabs in the Chesapeake Bay.
Download or read book Predation Techniques Used by Blue Crabs Callinectes Sapidus on Bivalves and Effect of Relative Bivalve Size on Handling Time written by and published by . This book was released on 1990 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ecological Impacts and Social Perceptions of the Invasive Flathead Catfish in Pennsylvania written by Sydney Stark and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: AIS not only negatively affect aquatic ecosystems, but also often have negative socioeconomic consequences, quantifying impacts and assessing the public's knowledge and level of concern is extremely important. Flathead Catfish are voracious piscivores that have decimated native and recreational fisheries in other systems making the recent invasion into the Susquehanna River Basin highly concerning. In addition, Flathead Catfish represent a fish species closely tied to the public given its recreational appeal. Yet, it is not well known how the public perceive the introduction of Flathead Catfish or if they even know that it has been introduced in the system. To date, there has been no study of the diet or of the angler population's perceptions of the Flathead Catfish in this system. The Susquehanna River is unique compared to other systems Flathead Catfish have invaded -- it is one of the most northern introduced populations and the aquatic community in the Susquehanna River differs substantially from other invaded river systems. For example, the Susquehanna River has species like Muskellunge, which are not present in other more coastal and southern rivers the Flathead Catfish is invasive in. These unique aspects of the Susquehanna River make it impossible to simply extrapolate information on the impacts of Flathead Catfish from other invaded systems. Importantly, current knowledge of what they are eating is anecdotal and this is important to understand because prey composition identifies species that could be most impacted and elucidates predator prey interactions occurring in the system. In Chapter 1, I combined molecular and morphometric analyses to identify vulnerable prey species to Flathead Catfish predation in the Susquehanna River Basin. As expected, I found that Flathead Catfish consumed a mix of fish and invertebrates, with certain species occurring more frequently in the diets. A total of 47 species were identified in Flathead Catfish diets. The most frequently detected species included Margined Madtoms (Noturus insignis), Mimic Shiners (Notropis volucellus), Tessellated Darters (Etheostoma olmstedi), Channel Catfish (Ictalurus punctatus), Lepomis sp., Rock bass (Ambloplites rupestris), and Rusty Crayfish (Faxonius rusticus). I used a Bayesian hierarchical multivariate probit model to identify variables that influenced prey species occurrence probabilities in diets. I found that prey items observed within diets sometimes varied as a function of Flathead Catfish size (total length). The probability of a prey species being consumed by Flathead Catfish was most often related to the length of the Flathead Catfish. My findings identified which species within the aquatic community are most at risk to predatory impacts by Flathead Catfish. This is important because I can inform resource managers which species need to have prioritization in assessing population changes. Further, this work elucidates the species who may be negatively impacted by this species in a major river system within the United States and informs future efforts to understand the long-term effects of Flathead Catfish predation on the aquatic community. In Chapter 2, I conducted a human dimensions survey of Pennsylvania anglers to understand the current level of knowledge, concern, and perception on AIS and the Flathead Catfish. I used Qualtrics (Qualtrics, Provo, UT) to send an online survey to 450,547 anglers in Pennsylvania with 18,666 anglers responding. The survey consisted of two sections asking about -- (1) general AIS knowledge and (2) Flathead Catfish angler behavior and perceptions. I found that most anglers knew some about AIS with only a few (3.2%) identifying themselves experts on the subject. I presented two scenarios that gauged level of concern for impacts of newly introduced species on target species as well as concern regarding distance moved when introduced. When presented with these scenarios, participants tended to be concerned about AIS introductions regardless of if the effects were known or not. However, anglers were slightly more concerned with known effects than unknown effects. Additionally, anglers were more concerned with species moving long distances (e.g., between continents) than short distances (e.g., 5 miles upstream). I found that most anglers (69.9%) in PA do not directly target Flathead Catfish, with differing reasons as to why. Those that did fish for Flathead Catfish mostly fished in the Susquehanna River Basin (41.0%) and did not travel more than 50 miles to fish for Flathead Catfish. While a lesser amount of Flathead Catfish anglers actively harvested them, anglers also indicated that they would support population control and would harvest populations if state management recommended it. Our survey shows that the public is concerned about AIS and helps highlight knowledge gaps in angler understanding of AIS ecology. Additionally, this survey helps to inform state management agencies of the behaviors of Flathead Catfish anglers in a recreational fishery for an invasive species. AIS is a growing problem both within the United States and globally. Once an AIS is established, it's costly and often impossible to eradicate making understanding their effects and how the public perceives their impacts and interacts with them imperative. This work helps to elucidate negative ecological consequences and societal interactions of AIS by investigating predatory impacts and surveying the angler population in the same region. I provide valuable knowledge that can be used to develop effective outreach material that addresses knowledge gaps within the public as well as insight into how willing the public is to support management efforts. This work provides information not only on which species Flathead Catfish actively prey upon, but also on how our angling community perceives this AIS, both of which can be used to inform management strategies and AIS prevention measures.
Download or read book Human Impacts on Salt Marshes written by Brian R. Silliman and published by Univ of California Press. This book was released on 2009-06-03 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Human Impacts on Salt Marshes provides an excellent global synthesis of an important, underappreciated environmental problem and suggests solutions to the diverse threats affecting salt marshes."—Peter B. Moyle, University of California, Davis
Download or read book Ecosystem Based Fisheries Management written by Jason S. Link and published by Oxford University Press. This book was released on 2021-11-15 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ecosystem-based fishery management (EBFM) is rapidly becoming the default approach in global fisheries management. The clarity of what EBFM means is sharpening each year and there is now a real need to evaluate progress and assess the effectiveness and impacts. By examining a suite of over 90 indicators (including socioeconomic, governance, environmental forcing, major pressures, systems ecology, and fisheries criteria) for 9 major US fishery ecosystem jurisdictions, the authors systematically track the progress the country has made towards advancing EBFM and making it an operational reality. The assessment covers a wide range of data in both time (multiple decades) and space (from the tropics to the poles, representing over 10% of the world's ocean surface area). The authors view progress towards the implementation of EBFM as synonymous with improved management of living marine resources in general, and highlight the findings from a national perspective. Although US-centric, the lessons learned are directly applicable for all parts of the global ocean. Much work remains, but significant progress has already been made to better address many of the challenges facing the sustainable management of our living marine resources. This is an essential and accessible reference for all fisheries professionals who are currently practicing, or progressing towards, ecosystem-based fisheries management. It will also be of relevance and use to researchers, teachers, managers, and graduate students in marine ecology, fisheries biology, biological oceanography, global change biology, conservation biology, and marine resource management.
Download or read book Coastal Ecosystems in Transition written by Thomas C. Malone and published by John Wiley & Sons. This book was released on 2020-12-17 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores how two coastal ecosystems are responding to the pressures of human expansion The Northern Adriatic Sea, a continental shelf ecosystem in the Northeast Mediterranean Sea, and the Chesapeake Bay, a major estuary of the mid-Atlantic coast of the United States, are semi-enclosed, river-dominated ecosystems with urbanized watersheds that support extensive industrial agriculture. Coastal Ecosystems in Transition: A Comparative Analysis of the Northern Adriatic and Chesapeake Bay presents an update of a study published two decades ago. Revisiting these two ecosystems provides an opportunity to assess changing anthropogenic pressures in the context of global climate change. The new insights can be used to inform ecosystem-based approaches to sustainable development of coastal environments. Volume highlights include: Effects of nutrient enrichment and climate-driven changes on critical coastal habitats Patterns of stratification and circulation Food web dynamics from phytoplankton to fish Nutrient cycling, water quality, and harmful algal events Causes and consequences of interannual variability The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Read a review of this book in Marine Ecology review of this book
Download or read book Evolutionary Ecology written by and published by Eric R. Pianka. This book was released on 2011 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finally, an eBook version of this now classic textbook has become available. Largely based on the 6th edition, published in 2000, this version is competitively priced. Written by well-known ecologist Eric R. Pianka, a student of the late Robert H. MacArthur, this timeless treatment of evolutionary ecology, first published in 1974, will endure for many decades to come. Basic principles of ecology are framed in an evolutionary perspective.
Download or read book Impacts of climate change on fisheries and aquaculture written by Food and Agriculture Organization of the United Nations and published by Food & Agriculture Org.. This book was released on 2019-01-06 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report indicates that climate change will significantly affect the availability and trade of fish products, especially for those countries most dependent on the sector, and calls for effective adaptation and mitigation actions encompassing food production.
Download or read book Freshwater Biodiversity written by David Dudgeon and published by Cambridge University Press. This book was released on 2020-05-21 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing human populations and higher demands for water impose increasing impacts and stresses upon freshwater biodiversity. Their combined effects have made these animals more endangered than their terrestrial and marine counterparts. Overuse and contamination of water, overexploitation and overfishing, introduction of alien species, and alteration of natural flow regimes have led to a 'great thinning' and declines in abundance of freshwater animals, a 'great shrinking' in body size with reductions in large species, and a 'great mixing' whereby the spread of introduced species has tended to homogenize previously dissimilar communities in different parts of the world. Climate change and warming temperatures will alter global water availability, and exacerbate the other threat factors. What conservation action is needed to halt or reverse these trends, and preserve freshwater biodiversity in a rapidly changing world? This book offers the tools and approaches that can be deployed to help conserve freshwater biodiversity.
