نتایج جستجو برای: fishing mortality proxy
تعداد نتایج: 325174 فیلتر نتایج به سال:
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...
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...
There is an urgent need to quantify the impacts of artisanal fisheries and define management practices that allow for the recovery and conservation of exploited stocks. The extent of illegal catch is particularly critical as a driver of overexploitation in artisanal fisheries. However, the lack of data at proper spatial scales limits the evaluation of illegal fishing and effectiveness of manage...
Attaining maximum sustained yield (MSY) is a central goal in U.S. fisheries management. To attain MSY, fishing mortality is maintained at FMSY and biomass at BMSY. Replacing FMSY and BMSY by “proxies” for FMSY and BMSY is commonplace. However, these proxies are not equivalent to FMSY and BMSY. The lack of equivalency is an important issue with regard to whether MSY is attained or whether biomas...
The purpose of this paper was to detail some important biological aspects of T. tonggol in coastal waters of Hormuzgan Province(Persian Gulf and Oman Sea). A total monthly data of 4383 individuals ranging from 25 to 124 cm fork length were collected from April 2015 to March 2016. The data were analyzed with FiSAT II software using the ELEFAN1 package to estimate the population parameters. Th...
Fisheries models are generally built to assess the dynamics of a resource with a given fishing mortality which level can be decided by some “decision maker” and/or which can be an observed process, e.g. times series proportional to some observed values of fishing effort. In these cases, the resource dynamics is represented “conditionally to” fishing mortality. This mortality must be therefore p...
in this study, 160 fishes were randomly collected from commercial catch by a cone net in babolsar port from january to october 2010. the biological features of specimens were measured. 2 + years old fishes made the dominant age group with 33.75% and 1 + and 5 + years old had the least frequency (8.75%). relationship between length and weight indicated negative allometric growth pattern (b=2.581...
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...
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...
OBJECTIVE To investigate long-term trends in mortality rates for accidents to fishing vessels in the UK fishing industry from 1948 to 2008; to investigate the circumstances and causes of these fishing vessel accidents and trends in fishing vessel losses. MATERIAL AND METHODS Examination of paper death inquiry files, death registers, marine accident investigative files, annual casualty and dea...
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