Macrophyte Structure and Growth of Bluegill (Lepomis macrochirus): Design of a Multilake Experiment

Book chapter from The Structuring Role of Submerged Macrophytes in Lakes , eds. Erik Jepsen, Martin Søndergaard, Morten Søndergaard, and Kirsten Christoffersen. About this chapter: Experimental manipulations of whole ecosystems can be a powerful test of ecological understanding. In particular, ecosystem-scale manipulations can evaluate basic ecological ideas in ways that complement comparative studies, models, and smaller-scale experiments (Carpenter et al., 1995a). From an applied perspective, ecosystem experiments can also give unique insights into what works at a scale directly relevant to managers (Kitchell, 1992). When management actions are coupled with scientific studies of the response of the ecosystem, learning may lead to improved management practices (Gunderson et al., 1995). Here we present early results of an experiment to test the idea that nuisance macrophytes can be managed to enhance fish growth.https://digitalcommons.usm.maine.edu/facbooks/1475/thumbnail.jp

Fisheries Bycatch: Implications for Management

A broad-based public consensus has emerged that bycatch should be minimized to levels approaching insignificance. This view, as reflected in U.S. and worldwide legislation and agreements, demonstrates the widely held belief that discarded portions of fishery catches (including economic resources, protected species, and unobserved mortalities of animals not caught) represent an unacceptable waste of natural resources. Bycatches in their various forms can have significant consequences for populations, food webs, and ecosystems. The economic effects of bycatches can influence not only the levels of yields to individual fisheries, but also may have major effects on allocations among competing fisheries. The lack of comprehensive monitoring programs in most areas to assess bycatches and integrate them into population and multispecies models seriously impedes a full understanding of bycatch consequences and the efficacy of measures for their amelioration. Nevertheless, where evidence for significant bycatches exists, a risk-averse and perhaps adaptive management philosophy is clearly warranted. Establishing the benefits and costs associated with bycatch management is a priority as managers attempt to define the practicality of bycatches approaching zero given the institutional, scientific, and industry resources necessary to accomplish the job

Early detection monitoring for aquatic non-indigenous species: Optimizing surveillance, incorporating advanced technologies, and identifying research needs

Following decades of ecologic and economic impacts from a growing list of nonindigenous and invasive species, government and management entities are committing to systematic early- detection monitoring (EDM). This has reinvigorated investment in the science underpinning such monitoring, as well as the need to convey that science in practical terms to those tasked with EDM implementation. Using the context of nonindigenous species in the North American Great Lakes, this article summarizes the current scientific tools and knowledge – including limitations, research needs, and likely future developments – relevant to various aspects of planning and conducting comprehensive EDM. We begin with the scope of the effort, contrasting target-species with broad-spectrum monitoring, reviewing information to support prioritization based on species and locations, and exploring the challenge of moving beyond individual surveys towards a coordinated monitoring network. Next, we discuss survey design, including effort to expend and its allocation over space and time. A section on sample collection and analysis overviews the merits of collecting actual organisms versus shed DNA, reviews the capabilities and limitations of identification by morphology, DNA target markers, or DNA barcoding, and examines best practices for sample handling and data verification. We end with a section addressing the analysis of monitoring data, including methods to evaluate survey performance and characterize and communicate uncertainty. Although the body of science supporting EDM implementation is already substantial, research and information needs (many already actively being addressed) include: better data to support risk assessments that guide choice of taxa and locations to monitor; improved understanding of spatiotemporal scales for sample collection; further development of DNA target markers, reference barcodes, genomic workflows, and synergies between DNA-based and morphology-based taxonomy; and tools and information management systems for better evaluating and communicating survey outcomes and uncertainty