نتایج جستجو برای: natural and fishing mortality
تعداد نتایج: 16915710 فیلتر نتایج به سال:
This paper presents the results of study on age, growth, mortality rates and yield-per-recruit of Beluga (Huso huso) living in Caspian Sea. The mean length of successive years, mortality rates and yield-per-recruit studies indicated that at present the resource is under heavy fishing pressure. For the female Beluga growth was regarded as comprising of three stages, and the von Bertalanffy param...
Between 1978 and 1980, we investigated and compared the dietary intake of fish meat, platelet function, rheological properties of blood and mortality rate due to thrombotic cardiovascular diseases between the residents of fishing and farming villages. Notable finding is that the dietary intake of EPA in the residents of fishing village was nearly 3 times (2.5 g/day) higher than that (0.9g/day) ...
United States and Canadian governments have responded to legal requirements to reduce human-induced whale mortality via vessel strikes and entanglement in fishing gear by implementing a suite of regulatory actions. We analyzed the spatial and temporal patterns of mortality of large whales in the Northwest Atlantic (23.5°N to 48.0°N), 1970 through 2009, in the context of management changes. We u...
The biological indicators of Chrysichthys walkeri (Claroteid catfishes) in lake Volta were investigated for their sustainable management. A total 846 samples collected from the March to December 2020. recorded length fish was analyzed using TropFishR. von Bertalanffy parameters including asymptotic (L∞), growth rate (K), and performance index (Φ) estimated as 28.88 cm, 0.42 per year, 2.54 respe...
Fishery management plans ignore the potential for evolutionary change in harvestable biomass. We subjected populations of an exploited fish (Menidia menidia) to large, small, or random size-selective harvest of adults over four generations. Harvested biomass evolved rapidly in directions counter to the size-dependent force of fishing mortality. Large-harvested populations initially produced the...
Abrupt shifts in natural resources and their markets are a ubiquitous challenge to human communities. Building resilient social-ecological systems requires approaches that are robust to uncertainty and to regime shifts. Harvesting diverse portfolios of natural resources and adapting portfolios in response to change could stabilize economies reliant on natural resources and their markets, both o...
A challenge for conservation science is predicting the impacts of co-occurring human activities on ecological systems. Multiple anthropogenic and natural stressors impact ecosystems globally and are expected to jeopardize their ecological functions and the success of conservation and management initiatives. The possibility that two or more stressors interact synergistically is of particular con...
Ribbonfish, Trichiurus lepturus (Linnaeus, 1758), is an important component of subsistence fisheries throughout its tropical and subtropical distribution. The catch rate of ribbonfish has increased seven-fold in a decade in the Persian Gulf and Oman Sea. We collected monthly biological samples from T. lepturus, to estimate growth and mortality parameters, and identify species reproductive patte...
the speech act of disagreement has been one of the speech acts that has received the least attention in the field of pragmatics. this study investigates the ways power relations, social distance, formality of the context, gender, and language proficiency (for efl learners) influence disagreement and politeness strategies. the participants of the study were 200 male and female native persian s...
Growth, onset of maturity and investment in reproduction are key traits for understanding variation in life-history strategies. Many environmental factors affect variation in these traits, but for fish, hypoxia and size-dependent mortality have become increasingly important because of human activities, such as increased nutrient enrichment (eutrophication), climate warming and selective fishing...
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