نتایج جستجو برای: overfished biomass threshold
تعداد نتایج: 185078 فیلتر نتایج به سال:
Airborne laser scanning, collected in a sampling mode, has the potential to be a valuable tool for estimating the biomass resources available to support bioenergy production in rural communities of interior Alaska. In this study, we present a methodology for estimating forest biomass over a 201,226-ha area (of which 163,913 ha are forested) in the upper Tanana valley of interior Alaska using a ...
An assessment of the stock status and historical changes in abundance Coilia mystus C. nasus Yangtze River Estuary, China, was carried out based on field surveys conducted 2019–2020 published length-frequency (L/F) data from earlier periods. These two species’ current past relative biomasses (B/BMSY) were estimated using a length-based Bayesian biomass estimation method (LBB). The LLB also thei...
Based on length frequency data of miter squid ( Uroteuthis chinensis ) collected in the northeastern South China Sea 1975–1977, 1997–1999, and 2018–2019, asymptotic length, optimal at first capture, relative mortality, biomass stock were estimated using length-based Bayesian estimation (LBB). The LBB-estimated for 2018–2019 was smaller. Optimal lengths capture later far exceeded average catches...
Two SAR and biomass data sets of forests with different canopy architectures were examined for commonalties regarding backscatterhiomass saturation. The SAR data were collected using the NASNJPL AIRSAR at incidence angles between 40’ and 50’ for tropical broadleaf evergreen forests in Hawaii and coniferous forests in North America and Europe. Radar signal saturation L i t s with respect to biom...
Abstract Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown, however, whether these be altered by other key change drivers known affect the water-use efficiency productivity vegetation, elevated CO2 nitrogen (N) enrichment. Using &...
A model describing macroalgal early life stages and adult dynamics was used to quantify the effects of non-adult forms on the productivity of adult macroalgae in a eutrophic estuary. Predictions indicate that during years with mild winters and low rainfall, spring blooms will occur at the expense of the growth and reproduction of overwintering adults and without the contribution of the spore ba...
Abstrac t —Although bocaccio (Sebastes paucispinis) was an economically important rockfish species along the west coast of North America, overfishing has reduced the stock to about 7.4% of its former unfished population. In 2003, using a manned research submersible, we conducted fish surveys around eight oil and gas platforms off southern California as part of an assessment of the potential val...
Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the large-bodied characid, Colossoma macropomum. During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be ...
Since the collapse of the pelagic fisheries off southwest Africa in the late 1960s, jellyfish biomass has increased and the structure of the Benguelan fish community has shifted, making the bearded goby (Sufflogobius bibarbatus) the new predominant prey species. Despite increased predation pressure and a harsh environment, the gobies are thriving. Here we show that physiological adaptations and...
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