5 resultados para Integrated Design
em Aquatic Commons
Resumo:
This document lists the undesirable effects of water hyacinth (Eichhornia crassipes) on fisheries in Lake Kainji (Nigeria) and the integrated Water Hyacinth Control Programme in its ongoing fisheries management and development activities on the lake. Special regard is given to the design, construction and installation of a water hyacinth barrier across the River Niger. (PDF contains 44 pages)
Design and implementation of fishery modules in integrated household surveys in developing countries
Resumo:
Fish and other aquatic animals contribute to the food security of citizens of developing countries, both as a source of income and as a component of healthy diets, yet fishing is not currently captured in most integrated household surveys. This sourcebook provides essential technical guidance on the design of statistical modules and questionnaires aimed at collecting fishery data at the household level. Background on the main policies important to the fishery sector, information on the data needed to analyze issues of policy relevance, and methodology on the construction of survey questions to collect necessary data are also provided. The document is organized to provide essential technical guidance on how to design statistical modules and questionnaires aimed at collecting fishery data at the household level. It includes an overview of the main technical and statistical challenges related to sampling fishery-dependent households. The document starts with an introductory section identifying the potential reasons why fisheries and in particular small-scale fisheries have not been adequately included in national statistical systems in a large number of countries. The report then proposes a succinct review of what is known (and what remains unknown) about small-scale fisheries and their contribution to the livelihoods of households in sub-Saharan Africa. It also provides readers with background on the main policies that are important to the fishery sector, information on the data needed to analyze issues of policy relevance, and methodology on the construction of survey questions to collect necessary data.
Resumo:
A study was conducted to assess the status of ecological condition and potential human-health risks in subtidal estuarine waters throughout the North Carolina National Estuarine Research Reserve System (NERRS) (Currituck Sound, Rachel Carson, Masonboro Island, and Zeke’s Island). Field work was conducted in September 2006 and incorporated multiple indicators of ecosystem condition including measures of water quality (dissolved oxygen, salinity, temperature, pH, nutrients and chlorophyll, suspended solids), sediment quality (granulometry, organic matter content, chemical contaminant concentrations), biological condition (diversity and abundances of benthic fauna, fish contaminant levels and pathologies), and human dimensions (fish-tissue contaminant levels relative to human-health consumption limits, various aesthetic properties). A probabilistic sampling design permitted statistical estimation of the spatial extent of degraded versus non-degraded condition across these estuaries relative to specified threshold levels of the various indicators (where possible). With some exceptions, the status of these reserves appeared to be in relatively good to fair ecological condition overall, with the majority of the area (about 54%) having various water quality, sediment quality, and biological (benthic) condition indicators rated in the healthy to intermediate range of corresponding guideline thresholds. Only three stations, representing 10.5% of the area, had one or more of these indicators rated as poor/degraded in all three categories. While such a conclusion is encouraging from a coastal management perspective, it should be viewed with some caution. For example, although co-occurrences of adverse biological and abiotic environmental conditions were limited, at least one indicator of ecological condition rated in the poor/degraded range was observed over a broader area (35.5%) represented by 11 of the 30 stations sampled. In addition, the fish-tissue contaminant data were not included in these overall spatial estimates; however, the majority of samples (77% of fish that were analyzed, from 79%, of stations where fish were caught) contained inorganic arsenic above the consumption limits for human cancer risks, though most likely derived from natural sources. Similarly, aesthetic indicators are not reflected in these spatial estimates of ecological condition, though there was evidence of noxious odors in sediments at many of the stations. Such symptoms reflect a growing realization that North Carolina estuaries are under multiple pressures from a variety of natural and human influences. These data also suggest that, while the current status of overall ecological condition appears to be good to fair, long-term monitoring is warranted to track potential changes in the future. This study establishes an important baseline of overall ecological condition within NC NERRS that can be used to evaluate any such future changes and to trigger appropriate management actions in this rapidly evolving coastal environment. (PDF contains 76 pages)
Resumo:
Tagging experiments are a useful tool in fisheries for estimating mortality rates and abundance of fish. Unfortunately, nonreporting of recovered tags is a common problem in commercial fisheries which, if unaccounted for, can render these estimates meaningless. Observers are often employed to monitor a portion of the catches as a means of estimating reporting rates. In our study, observer data were incorporated into an integrated model for multiyear tagging and catch data to provide joint estimates of mortality rates (natural and f ishing), abundance, and reporting rates. Simulations were used to explore model performance under a range of scenarios (e.g., different parameter values, parameter constraints, and numbers of release and recapture years). Overall, results indicated that all parameters can be estimated with reasonable accuracy, but that fishing mortality, reporting rates, and abundance can be estimated with much higher precision than natural mortality. An example of how the model can be applied to provide guidance on experimental design for a large-scale tagging study is presented. Such guidance can contribute to the successful and cost-effective management of tagging programs for commercial fisheries.
Resumo:
A study was conducted in June 2009 to assess the current status of ecological condition and potential human-health risks throughout subtidal estuarine waters of the Sapelo Island National Estuarine Research Reserve (SINERR) along the coast of Georgia. Samples were collected for multiple indicators of ecosystem condition, including water quality (dissolved oxygen, salinity, temperature, pH, nutrients and chlorophyll, suspended solids, fecal coliform bacteria and coliphages), sediment quality (granulometry, organic matter content, chemical contaminant concentrations), biological condition (diversity and abundance of benthic fauna, fish tissue contaminant levels and pathologies), and human dimensions (fish-tissue contaminant levels relative to human-health consumption limits, various aesthetic properties). Use of a probabilistic sampling design facilitated the calculation of statistics to estimate the spatial extent of the Reserve classified according to various categories (i.e., Good, Fair, Poor) of ecological condition relative to established thresholds of these indicators, where available. Overall, the majority of subtidal habitat in the SINERR appeared to be healthy, with over half (56.7 %) of the Reserve area having water quality, sediment quality, and benthic biological condition indicators rated in the healthy to intermediate range of corresponding guideline thresholds. None of the stations sampled had one or more indicators in all three categories rated as poor/degraded. While these results are encouraging, it should be noted that one or more indicators were rated as poor/degraded in at least one of the three categories over 40% of the Reserve study area, represented by 12 of the 30 stations sampled. Although measures of fish tissue chemical contamination were not included in any of the above estimates, a number of trace metals, pesticides, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) were found at low yet detectable levels in some fish at stations where fish were caught. Levels of mercury and total PCBs in some fish specimens fell within EPA guideline values considered safe, given a consumption rate of no more than four fish meals per month. Moreover, PCB congener profiles in sediments and fish in the SINERR exhibit a relative abundance of higher-chlorinated homologs which are uniquely characteristic of Aroclor 1268. It has been well-documented that sediments and fish in the creeks and marshes near the LCP Chemicals Superfund site, near Brunswick, Georgia, also display this congener pattern associated with Aroclor 1268, a highly chlorinated mixture of PCBs used extensively at a chlor-alkali plant that was in operation at the LCP site from 1955-1994. This report provides results suggesting that the protected habitats lying within the boundaries of the SINERR may be experiencing the effects of a legacy of chemical contamination at a site over 40km away. These effects, as well as other potential stressors associated with increased development of nearby coastal areas, underscore the importance of establishing baseline ecological conditions that can be used to track potential changes in the future and to guide management and stewardship of the otherwise relatively unspoiled ecosystems of the SINERR.