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79,648 نتائج ل "Commercial fishing"
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Compass rose : a novel
Game warden Elsie Buttrick has just given birth to Dick's illegitimate daughter, Rose, and over the next 16 years the fiercely independent Elsie grapples with motherhood, aging, and love, and throws herself into a crusade to stop her land-grabbing brother-in-law from expanding his seaside resort. Meanwhile, Dick's wife, May, reconciles a public humiliation with an intense love for Rose. As Elsie's lust flares, May sinks deeper into her devotion to her children and Rose.
Mitigating seafloor disturbance of bottom trawl fisheries for North Sea sole Solea solea by replacing mechanical with electrical stimulation
Ecosystem effects of bottom trawl fisheries are of major concern. Although it is prohibited to catch fish using electricity in European Union waters, a number of beam trawlers obtained a derogation and switched to pulse trawling to explore the potential to reduce impacts. Here we analyse whether using electrical rather than mechanical stimulation results in an overall reduction in physical disturbance of the seafloor in the beam-trawl fishery for sole Solea solea. We extend and apply a recently developed assessment framework to the Dutch beam-trawl fleet and show that the switch to pulse trawling substantially reduced benthic impacts when exploiting the total allowable catch of sole in the North Sea. Using Vessel Monitoring by Satellite and logbook data from 2009 to 2017, we estimate that the trawling footprint decreased by 23%, the precautionary impact indicator of the benthic community decreased by 39%, the impact on median longevity of the benthic community decreased by 20%, the impact on benthic biomass decreased by 61%, and the amount of sediment mobilised decreased by 39%. The decrease in impact is due to the replacement of tickler chains by electrode arrays, a lower towing speed and higher catch efficiency for sole. The effort and benthic physical disturbance of the beam-trawl fishery targeting plaice Pleuronectes platessa in the central North Sea increased with the recovery of the plaice stock. Our study illustrates the utility of a standardized methodological framework to assess the differences in time trends and physical disturbance between gears.
Freshwater Commercial Bycatch: An Understated Conservation Problem
Bycatch from marine commercial fisheries has been regarded as a global conservation concern for decades. Fortunately, some headway has been made in mitigating bycatch problems in marine fisheries. Freshwater commercial fisheries, however, have been relatively understudied. Although freshwater yields comprise 11% of the global commercial catch, bycatch research focusing on freshwater commercial fisheries represents only about 3% of the total bycatch literature. This paucity of research is particularly alarming given that so many of the world's threatened species live in freshwater. The limited literature that does exist includes examples of population declines attributed to commercial bycatch (e.g., the Yangtze River dolphin) and illustrates that bycatch is substantial in some systems (e.g., lake trout in Laurentian Great Lakes fisheries). Encouraging results from the marine realm can serve as models for bycatch research and development in freshwater and can lead to measurable gains in the conservation of freshwater ecosystems. We summarize existing work on inland bycatch in an effort to draw attention to this understated and understudied conservation problem.
Effective fisheries management instrumental in improving fish stock status
Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.
Half a century of global decline in oceanic sharks and rays
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas . Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals : the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure. This depletion has increased the global extinction risk to the point at which three-quarters of the species comprising this functionally important assemblage are threatened with extinction. Strict prohibitions and precautionary science-based catch limits are urgently needed to avert population collapse , avoid the disruption of ecological functions and promote species recovery .
The future of food from the sea
Global food demand is rising, and serious questions remain about whether supply can increase sustainably . Land-based expansion is possible but may exacerbate climate change and biodiversity loss, and compromise the delivery of other ecosystem services . As food from the sea represents only 17% of the current production of edible meat, we ask how much food we can expect the ocean to sustainably produce by 2050. Here we examine the main food-producing sectors in the ocean-wild fisheries, finfish mariculture and bivalve mariculture-to estimate 'sustainable supply curves' that account for ecological, economic, regulatory and technological constraints. We overlay these supply curves with demand scenarios to estimate future seafood production. We find that under our estimated demand shifts and supply scenarios (which account for policy reform and technology improvements), edible food from the sea could increase by 21-44 million tonnes by 2050, a 36-74% increase compared to current yields. This represents 12-25% of the estimated increase in all meat needed to feed 9.8 billion people by 2050. Increases in all three sectors are likely, but are most pronounced for mariculture. Whether these production potentials are realized sustainably will depend on factors such as policy reforms, technological innovation and the extent of future shifts in demand.
Fuel use and greenhouse gas emissions of world fisheries
Food production is responsible for a quarter of anthropogenic greenhouse gas (GHG) emissions globally. Marine fisheries are typically excluded from global assessments of GHGs or are generalized based on a limited number of case studies. Here we quantify fuel inputs and GHG emissions for the global fishing fleet from 1990–2011 and compare emissions from fisheries to those from agriculture and livestock production. We estimate that fisheries consumed 40 billion litres of fuel in 2011 and generated a total of 179 million tonnes of CO2-equivalent GHGs (4% of global food production). Emissions from the global fishing industry grew by 28% between 1990 and 2011, with little coinciding increase in production (average emissions per tonne landed grew by 21%). Growth in emissions was driven primarily by increased harvests from fuel-intensive crustacean fisheries. The environmental benefit of low-carbon fisheries could be further realized if a greater proportion of landings were directed to human consumption rather than industrial uses.
Disturbance of the Marine Benthic Habitat by Commercial Fishing: Impacts at the Scale of the Fishery
Commercial fishing is one of the most important human impacts on the marine benthic environment. One such impact is through disturbance to benthic habitats as fishing gear (trawls and dredges) are dragged across the seafloor. While the direct effects of such an impact on benthic communities appear obvious, the magnitude of the effects has been very difficult to evaluate. Experimental fishing-disturbance studies have demonstrated changes in small areas; however, the broader scale implications attributing these changes to fishing impacts are based on long-term data and have been considered equivocal. By testing a series of a priori predictions derived from the literature (mainly results of small-scale experiments), we attempted to identify changes in benthic communities at the regional scale that could be attributed to commercial fishing. Samples along a putative gradient of fishing pressure were collected from 18 sites in the Hauraki Gulf, New Zealand. These sites varied in water depth from ∼17 to 35 m and in sediment characteristics from ∼1 to 48% mud and from 3 to 8.5 μg chlorophyll a/cm3. Video transects were used for counting large epifauna and grab/suction dredge and core sampling were used for collecting macrofauna. After accounting for the effects of location and sediment characteristics, 15-20% of the variability in the macrofauna community composition sampled in the cores and grab/suction dredge samples was attributed to fishing. With decreasing fishing pressure we observed increases in the density of echinoderms, long-lived surface dwellers, total number of species and individuals, and the Shannon-Weiner diversity index. In addition, there were decreases in the density of deposit feeders, small opportunists, and the ratio of small to large individuals of the infaunal heart urchin, Echinocardium australe. The effects of fishing on the larger macrofauna collected from the grab/suction dredge samples were not as clear. However, changes in the predicted direction in epifaunal density and the total number of individuals were demonstrated. As predicted, decreased fishing pressure significantly increased the density of large epifauna observed in video transects. Our data provide evidence of broad-scale changes in benthic communities that can be directly related to fishing. As these changes were identifiable over broad spatial scales they are likely to have important ramifications for ecosystem management and the development of sustainable fisheries.
A Pilot Study on the Application of Acoustic Data Collected from a Korean Purse Seine Fishing Vessel for the Chub Mackerel
This paper describes the first use of acoustic data collected during normal fishing operations from a South Korean commercial fishing vessel. Acoustic data (120 kHz) were collected from a purse seine fishing vessel while targeting chub mackerel ( Scomber japonicus) between 13 September and 7 October 2014 in the southern West Sea and near Jeju Island. Acoustic backscatter data from 21 fishing events were used to delineate fish school characteristics and to estimate the chub mackerel biomass which was compared with the catch. With regard to the fish school description, the volume back scattering strength (S V ) and thickness of the fish schools presented differently. The average and standard deviation of S V was −47.3 ± 2.1 dB. The fish lengths varied greatly and some schools were inordinately long (average and standard deviation length of 137.0 ± 329.6 m). The fish school area largely altered. The average distributional depth and the distance between fish school and sea bottom were 31.8 m and 42.7 m, respectively, indicating that the fish schools attracted by light were mainly located close to the water surface. On average, the chub mackerel biomass was 1.7 times larger than the catch. The correlation between the chub mackerel biomass and the catch was low positive ( r  = 0.3, p  < 0.05). This paper presented that available echo sounders installed fishing vessels can be used for helping in the chub mackerel resources management in South Korea.
Evolution of global marine fishing fleets and the response of fished resources
Previous reconstructions of marine fishing fleets have aggregated data without regard to the artisanal and industrial sectors. Engine power has often been estimated from subsets of the developed world, leading to inflated results. We disaggregated data into three sectors, artisanal (unpowered/powered) and industrial, and reconstructed the evolution of the fleet and its fishing effort. We found that the global fishing fleet doubled between 1950 and 2015—from 1.7 to 3.7 million vessels. This has been driven by substantial expansion of the motorized fleet, particularly, of the powered-artisanal fleet. By 2015, 68% of the global fishing fleet was motorized. Although the global fleet is dominated by small powered vessels under 50 kW, they contribute only 27% of the global engine power, which has increased from 25 to 145 GW (combined powered-artisanal and industrial fleets). Alongside an expansion of the fleets, the effective catch per unit of effort (CPUE) has consistently decreased since 1950, showing the increasing pressure of fisheries on ocean resources. The effective CPUE of most countries in 2015 was a fifth of its 1950s value, which was compared with a global decline in abundance. There are signs, however, of stabilization and more effective management in recent years, with a reduction in fleet sizes in developed countries. Based on historical patterns and allowing for the slowing rate of expansion, 1 million more motorized vessels could join the global fleet by midcentury as developing countries continue to transition away from subsistence fisheries, challenging sustainable use of fisheries’ resources.