نتایج جستجو برای: growth and fishing indices

تعداد نتایج: 16941550  

2009

This paper formulates a simple biomass growth model of a fishery. The property rights regime is of the unregulated local common property type with a fixed number of fishermen and where the fish stock is exploited in a myopic profit-maximizing manner. Within this resource management setting it is demonstrated that more modern fishing technology has a two-sided profitability effect, and where the...

2010
Kelly R. Stewart Rebecca L. Lewison Daniel C. Dunn Rhema H. Bjorkland Shaleyla Kelez Patrick N. Halpin Larry B. Crowder

Biodiverse coastal zones are often areas of intense fishing pressure due to the high relative density of fishing capacity in these nearshore regions. Although overcapacity is one of the central challenges to fisheries sustainability in coastal zones, accurate estimates of fishing pressure in coastal zones are limited, hampering the assessment of the direct and collateral impacts (e.g., habitat ...

2017
Thomas Klefoth Christian Skov Anna Kuparinen Robert Arlinghaus

In passively operated fishing gear, boldness-related behaviors should fundamentally affect the vulnerability of individual fish and thus be under fisheries selection. To test this hypothesis, we used juvenile common-garden reared carp (Cyprinus carpio) within a narrow size range to investigate the mechanistic basis of behavioral selection caused by angling. We focused on one key personality tra...

C.I. Zhang C.W. Lee D.E. Hay H. Fazli,

There have been recent changes in the Caspian Sea ecosystem, such as those due to changes in sea level or those caused by the invasive ctenophore, Mnemiopsis leidyi. It is believed that these changes had significant impacts on the absolute and relative abundance of the commercially important anchovy kilka (Clupeonella engrauliformis) and common kilka (C. cultriventris caspia) leading to decline...

C.I. Zhang, C.W. Lee, D.E. Hay, H. Fazli,

There have been recent changes in the Caspian Sea ecosystem, such as those due to changes in sea level or those caused by the invasive ctenophore, Mnemiopsis leidyi. It is believed that these changes had significant impacts on the absolute and relative abundance of the commercially important anchovy kilka (Clupeonella engrauliformis) and common kilka (C. cultriventris caspia) leading to decline...

Journal: :Ecological applications : a publication of the Ecological Society of America 2006
James N Sanchirico Urmila Malvadkar Alan Hastings James E Wilen

Discussions on the use of marine reserves (no-take zones) and, more generally, spatial management of fisheries are, for the most part, devoid of analyses that consider the ecological and economic effects simultaneously. To fill this gap, we develop a two-patch ecological-economic model to investigate the effects of spatial management on fishery profits. Because the fishery effects of spatial ma...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی 1391

مطالعات قبلی بازار بیمه را به صورت کلی در نظر می گرفتند اما در این مطالعه صنعت بیمه به عنوان متغیر مستفل به بیمه های زندگی و غیر زندگی شکسته شده و هم چنین بیمه های زندگی به رشته های مختلف بیمه ای که در بازار بیمه ایران سهم قابل توجهی دارند تقسیم میشود. با استفاده از روشهای اقتصاد سنجی داده های برای دوره های 48-89 از مراکز ملی داده جمع آوری شد سپس با تخمین مدل خود بازگشتی برداری همراه با تعدادی ...

Journal: :علمی شیلات ایران 0
فرود بساک کاهکش f kahkesh وحید یاوری v yavari غلامرضا اسکندری g eskandary غلامحسین محمدی g mohammadi

the effects of weight and length of barbus grypus broodstock on fingerlings reproductive characteristics and growth were investigated. we chose three female treatments  including weight and length groups (1) 2212.5±479g,  62.68±6.7cm, (2) 4518±780g,  79.12±4.36cm  and (3) 7712.5±1171g, 92.62±3.13cm. the same male broodstock were used for all the treatments with the weight and length size of 140...

Journal: :پژوهش های حبوبات ایران 0
امیری ده احمدی امیری ده احمدی پارسا پارسا نظامی نظامی گنجعلی گنجعلی

in order to evaluate the effects of drought stress at different phenological stages on growth indices of chickpea (cicer arietinum l.) cultivar jam, an experiment was carried out at the research greenhouse of faculty of agriculture, ferdowsi university of mashhad, using a completely randomized design with four replications. drought stress was applied by preventing irrigation until the soil mois...

Journal: :Ecology letters 2006
Matthew R Walsh Stephan B Munch Susumu Chiba David O Conover

Some overharvested fish populations fail to recover even after considerable reductions in fishing pressure. The reasons are unclear but may involve genetic changes in life history traits that are detrimental to population growth when natural environmental factors prevail. We empirically modelled this process by subjecting populations of a harvested marine fish, the Atlantic silverside, to exper...

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