نتایج جستجو برای: natural and fishing mortality

تعداد نتایج: 16915710  

2004
Telmo Morato William W. L. Cheung Tony J. Pitcher

Based on life history and ecological characteristics, several authors have placed seamount fishes at the extreme end of the vulnerability spectrum. However, it was still unclear if there is justification for the generalization that seamount fishes overall possess specific life-history characteristics that render them more vulnerable to fishing than other species. In this contribution, we test t...

2004
A. Jamie F. Gibson Ransom A. Myers

We review and evaluate methods of estimating reference fishing mortality rates from spawner-recruit (SR) data to obtain maximum sustainable yield. Using Monte Carlo simulations, we found that a reference fishing mortality rate derived from the maximum likelihood estimates of the SR parameters was less biased than reference fishing mortality rates obtained using the mode of the marginal probabil...

2016
Bjørn A. Krafft Ludvig A. Krag Arill Engås Sigve Nordrum Inge Bruheim Bent Herrmann

Antarctic krill (Euphausia superba) is an abundant fishery resource, the harvest levels of which are expected to increase. However, many of the length classes of krill can escape through commonly used commercial trawl mesh sizes. A vital component of the overall management of a fishery is to estimate the total fishing mortality and quantify the mortality rate of individuals that escape from fis...

1998
M. Virtala S. Kuikka E. Arjas

The Metropolis–Hastings algorithm was applied to a standard Virtual Population Analysis using a simulated data set containing catch data from 10 age groups over a 10-year period. Posterior distributions of fishing mortalities and population sizes are studied under different prior assumptions. The results demonstrate the usefulness of obtaining distributions of plausible parameter values instead...

The present study considered the situation of kilka stocks in last decades by using overfished biomass threshold, fishing effort ratio and fishing mortality proxy during 1991-2010. The CPUE index of anchovy and mixed-species of kilka indicated an undepleted from 1991 to 2000. In 2000, the CPUE ratio declined to close to the “in danger” region, and subsequently collapsed to “overfished” region f...

2009
Kate Richerson Phillip S. Levin Marc Mangel

Ecosystem-based fishery management (EBFM) requires taking account of indirect effects (such as habitat destruction, incidental mortality, and competition between the fishery and marine mammals or birds) and dealing with non-commensurate values (such as yield from the fishery and production of offspring by the birds or mammals competing for the same resource). The perspective of EBFM requires th...

2008
Paul A. Breen David R. Schiel

Ministry of Agriculture and Fisheries. Fisheries Research Centre P.O. Box 297. Wellington, New Zealand Present address: Department of Zoology. University of Canterbury Christchurch J. New Zealand Population Structure, Ageing, and Fishing Mortality of the New Zealand Abalone Haliotis iris Abstract. Populations of the New Zealand (NZ) black-footed abalone Haliotis iris were examined in two import...

2014
Anna Kuparinen Jeffrey A. Hutchings

Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics int...

پایان نامه :دانشگاه بین المللی امام خمینی (ره) - قزوین - دانشکده مهندسی معماری و شهرسازی 1388

nowadays,tourism industry considered as one of the main sources of income of a country.unfortunately and despite of owning plenty of cultural historical and natural attractions, iran has not reached to a proper position in this field. besides, the historical cities of a country are considered as the income resource and national wealth of it. qazvin with a rich cultural precedent, have suitable ...

2000
SYLVIE GUÉNETTE

In the midst of several management failures, marine reserves are seen as a potential management tool to control overexploitation. In the literature, both modelling and empirical work have demonstrated that closing an area to fishing would lead to an increase in biomass and mean body size within the reserve. Benefits, in the form of increased catch, outside the reserves are sometimes shown using...

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