نتایج جستجو برای: natural and fishing mortality
تعداد نتایج: 16915710 فیلتر نتایج به سال:
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...
the objectives of this study were to determine the age, growth, mortality and exploitation of a commercially important fish of northeastern mediterranean sea, mullus barbatus from the karatas coast of iskenderun bay during september 2002 and april 2003. a total of 212 specimens of red mullet were collected by monthly sampling using traditional bottom trawl net by commercial vessel (coskun reis,...
the aim of this paper is eliminating cr(vi) by natural hap. hap is a inexpensive material which is used from bovine critical bone ash in order to remove heavy metal ions like cr(vi). some experiments in different ph are performed (ph=2,3,7). maximum adsorption was appeared at ph=2, dosage=0.3 gr, c0=10 mg/l. cr(vi) removal depends on ph value and initial amount of cr(vi) result of experiments w...
Clupeidae particularly Engraulidae is one of the most valuable supplies in the Persian Gulf, which plays an important role in the ecological and nutritional chain. The present study was done during from October 2015 to September 2016 with the aim of determining the amount of reserves of anchovies and adjusting its sustainable harvest pattern in Qeshm Island. Sampling was carried out in the sout...
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Overfishing of sharks is a global concern, with increasing numbers of species threatened by overfishing. For many sharks, both catch rates and underwater visual surveys have been criticized as indices of abundance. In this context, estimation of population trends using individual demographic rates provides an important alternative means of assessing population status. However, such estimates in...
A population of young blacktip sharks was monitored over three years to determine their mortality rates using a series of acoustic listening stations. Based on these data it was possible to use several mortality estimators, including indirect life -history based methods and direct methods such as the Kaplan-Meier and SURVIV methods, to estimate natural, fishing and total mortality. Kaplan-Meier...
To interpret long-term trends in age and size at maturation, new statistical methods have recently been devised for estimating probabilistic maturation reaction norms based on data collected for the management of fisheries. Here we apply these methods to three Newfoundland stocks of American plaice (NAFO Divisions 2J3K, 3LNO, 3Ps) and report a clear long-term shift in the maturation reaction no...
Most reintroduction and restocking programs consist of releasing captive-raised juveniles. The usefulness of these programs has been questioned, and therefore, quality control is advisable. However, evaluating restocking effectiveness is challenging because mortality estimation is required. Most methods for estimating mortality are based on tag recovery. In the case of fish, juveniles are tagge...
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