Length limits have been implemented by fisheries management agencies to achieve population density, size structure, and angler satisfaction objectives. By redirecting harvest towards or away from particular length‐ or age‐groups, length limits rely on harvest by anglers to maintain a population at or near a desired state. The fish population changes that follow the implementation of harvest regulations may take several years to manifest, so long‐term monitoring may be needed to adequately evaluate length limits. We used an innovative application of cluster analysis to facilitate evaluation of the effects of three consecutive length limits on a population of Largemouth Bass Micropterus salmoides over a 28‐year period in Ross Barnett Reservoir, Mississippi. A 13–16‐in protected slot length limit (10 years), followed by a 15‐in minimum length limit (MLL; 11 years), followed by a 12‐in MLL (7 years) failed to restructure the Largemouth Bass population due to what we suggest was the expansion of a voluntary catch‐and‐release attitude that started in the first decade of the study period. Various population metrics shifted towards values expected in an unharvested population, and the observed shifts can be attributed to a harvest deficit created by the prevailing catch‐and‐release attitude. Largemouth Bass harvest regulations may no longer be relevant in many waters. The utility of regulations for restructuring Largemouth Bass populations is largely dependent on harvesting attitudes that vary geographically, depending on cultural characteristics and demographics.
Received September 15, 2016; accepted March 15, 2017 Published online May 4, 2017
Strategic, data driven conservation approaches are increasing in popularity as conservation communities gain access to better science, more computing power, and more data. High resolution geospatial data, indicating ecosystem functions and economic activity, can be very useful for any conservation expert or funding agency. A framework was developed for a data driven conservation prioritization tool and a data visualization tool. The developed tools were then implemented and tested for the U.S. Gulf of Mexico coastal region defined by the Gulf Coast Ecosystem Restoration Council. As a part of this tool development, priority attributes and data measures were developed for the region through 13 stakeholder charrettes with local, state, federal, and other non-profit organizations involved in land conservation. This paper presents the measures that were developed to reflect stakeholder priorities. These measures were derived from openly available geospatial and non-geospatial data sources. This database contained 19 measures, aggregated into a one km2 hexagonal grid and grouped by the overarching goals of habitat, water quality and quantity, living coastal and marine resources, community resilience, and economy. The developed measures provided useful data for a conservation planning framework in the U.S. Gulf of Mexico coastal region.
The composition of land use/land cover (LULC) in coastal watersheds has many implications for estuarine system ecological function. Land use/land cover can influence allochthonous inputs and can enhance or degrade the physical characteristics of estuaries, which in turn affects estuaries' ability to support local biota.However, these implications for estuaries are often poorly considered when assessing the value of lands for conservation. The focus of research regarding terrestrial and estuarine interfaces often evaluates how LULC may stress estuarine ecosystems, but in this study we sought to understand how LULC may both positively and negatively affect estuaries using measures of observed biotic richness as proxies for estuarine function. We investigated the influence of LULC on estuarine biotic richness with Bayesian hierarchical models using multiple geospatial data sets from 33 estuaries and their associated watersheds along the Gulf of Mexico coastal region of the United States. We designed the hierarchical models with observed species richness of three functional groups (FGs) (i.e., pelagic fishes, forage fishes, and shrimp) from fishery-independent trawl surveys as response variables. We then set salinity and water temperature as trawl-specific covariates and measures of influence from six LULC classes as estuary-specific covariates and allowed the models to vary by estuary, trawl program, salinity, and temperature. The model results indicated that the observed richness of each FG was both positively and negatively associated with different LULC classes, with estuarine wetlands and forested lands demonstrating the strongest positive influences on each FG. The results are generally consistent with past studies, and the modeling framework provides a promising way to systematically quantify LULC linkages with the biotic health of estuaries for the purposes of potentially valuing the estuarine implications of land conservation.
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