• Title/Summary/Keyword: Natural mortality rate

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Effects of Changes in Fishing Effort on Yield of Kuwait's Commercial Fish Stocks

  • LEE J. U.
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.23 no.6
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    • pp.475-483
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    • 1990
  • An assessment of Kuwait's commercial fish stocks: hamoor (Epinephelus tauvina), zobaidy (Pampus argenteus), nakroor (Pomadasys argenteus) and sheiry (Lethrinus nebulosus), was conducted using length-frequency data, mean growth and mortality estimates obtained during 1981$\~$1988. The length-cohort analysis indicated that increases in fishing effort would not lead to long-term gains in yield of the stocks at the current estimate of natural mortality rate (M). At high M which was assumed arbitrarily, some benefit in yield could be obtained, especially for hamoor and sheiry. At low M, the yield of all stocks decreased with increased fishing effort. Increases in fishing effort resulted in significant dec-line in spawning stock size for all the stocks. Yield-per-recruit analysis indicated that, un-der low M assumption, a higher yield can be obtained for zobaidy and nakroor by reducing fishing effort. At moderate M, decreases in fishing effort brought gains in yield per recruit of the stocks, but it was not substantial compared with the present level of M. At high M, most of the stocks reached the maximum yield-per-recruit. Overall, increased fishing effort either will not be associated with large long-term gains in yield or, in some stocks, might cause a decline from the present level.

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Simulation-based Yield-per-recruit Analysis of Pacific cod Gadus macrocephalus in Southeastern Korean Coastal Waters (모의실험을 통한 동남해안 대구(Gadus macrocephalus)의 가입당 생산 분석)

  • Cha, Hyung Kee;Jung, Sukgeun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.45 no.5
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    • pp.493-498
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    • 2012
  • We derived biological reference points for Pacific cod Gadus macrocephalus in southeastern Korean waters by applying a yield-per-recruit analysis based on a daily simulation that adopted size-dependent fecundity, growth, and natural mortality functions. This showed that the yield per recruit of Pacific cod can be maximized at an instantaneous rate of fishing mortality (F)=0.37 $yr^{-1}$ under the current regulations, where the minimum catch size ($L_c$)=30 cm in total length (TL). The maximum economic yield was estimated to be attained at $L_c$=35-45 cm TL, if F>1 $yr^{-1}$ but at $L_c$=35-40 cm TL, if F<1 $yr^{-1}$. Despite great uncertainty in the stock assessment, to develop fisheries management plans for the sustainable exploitation of Pacific cod in southeastern Korean waters, it is necessary to estimate F using capture-recapture or other expedient methods.

Length based estimation population numbers of Nile tilapia (Oreochromis niloticus) stock in Lake Hayq, Ethiopia

  • Alemken Berihun;Minwyelet Mingist;Abebe Getahun;Degsera Aemro
    • Fisheries and Aquatic Sciences
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    • v.27 no.4
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    • pp.207-212
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    • 2024
  • The study was conducted at Lake Hayq, one of the lakes of Wollo, Ethiopia. Data were collected at the landing sites for 365 days (June 8, 2022 to June 7, 2023). The basic information gathered in the fishing part of the Lake was Nile tilapia caught by fishermen, the total number of tilapia and the increase in fishing effort. The aim of the research was to estimate the size of the Nile tilapia population and the fishing mortality rate in length groups for Nile tilapia stocks occurring in the lake. A Jones length-based cohort analysis model was used to estimate Nile tilapia population. The estimated Nile tilapia population was over 46.8 Million tilapia per year. The model estimates that more than 13.3 million 8-10 cm Nile tilapia are caught in fisheries each year.

In Silico Docking Studies of Selected Flavonoids - Natural Healing Agents against Breast Cancer

  • Suganya, Jeyabaskar;Radha, Mahendran;Naorem, Devi Leimarembi;Nishandhini, Marimuthu
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.19
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    • pp.8155-8159
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    • 2014
  • Background: Breast cancer is the serious health concern in India causing the highest mortality rate in females, which occurs due to uncontrolled cell division and can be metastasize to other parts of the human body. Interactions with estrogen receptor (ER) alpha are mainly responsible for the malignant tumors with regulation of the transcription of various genes as a transcription factor. Most of the drugs currently used for the breast cancer treatment produce various side effects and hence we focused on natural compounds which do not exhibit any toxic effect against normal human cells. Materials and Methods: Structure of human ER was retrieved from the Protein Data Bank and the structures of flavonoid compounds have been collected from PubChem database. Molecular docking and drug likeness studies were performed for those natural compounds to evaluate and analyze the anti-breast cancer activity. Results: Finally two compounds satisfying the Lipinski's rule of five were reported. The two compounds also exhibited highest binding affinity with human ER greater than 10.5 Kcal/mol. Conclusions: The results of this study can be implemented in the drug designing pipeline.

Natural History of Early Gastric Cancer: a Case Report and Literature Review

  • Iwai, Tomohiro;Yoshida, Masao;Ono, Hiroyuki;Kakushima, Naomi;Takizawa, Kohei;Tanaka, Masaki;Kawata, Noboru;Ito, Sayo;Imai, Kenichiro;Hotta, Kinichi;Ishiwatari, Hirotoshi;Matsubayashi, Hiroyuki
    • Journal of Gastric Cancer
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    • v.17 no.1
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    • pp.88-92
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    • 2017
  • Early detection and treatment decrease the mortality rate associated with gastric cancer (GC). However, the natural history of GC remains unclear. An 85-year-old woman was referred to our hospital for evaluation of a gastric tumor. Esophagogastroduodenoscopy identified a 6 mm, flat-elevated lesion at the lesser curvature of the antrum. A biopsy specimen showed a well-differentiated tubular adenocarcinoma. The depth of the lesion was estimated to be intramucosal. Although the lesion met the indications for endoscopic resection, periodic endoscopic follow-up was performed due to the patient's advanced age and comorbidities. The mucosal GC invaded into the submucosa 3 years later, and finally progressed to advanced cancer 5 years after the initial examination. The patient died of tumor hemorrhage 6.4 years after the initial examination. In this case, mucosal GC progressed to advanced GC, eventually leading to the patient's death from GC. Early and appropriate treatment is required to prevent GC-related death.

The Effects of the Spat Planting Time and Environmental Factors in the Arkshell, Scapharca broughtonii Schrenck Culture (피조개(Scapharca broughtonii Schrenck) 양식시 살포시기와 환경 특성의 영향)

  • Kim, Jeong-Bae;Lee, Sang-Yong;Jung, Choon-Goo;Jung, Chang-Su;Son, Sang-Gyu
    • Journal of Aquaculture
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    • v.20 no.1
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    • pp.31-40
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    • 2007
  • To find out the effect of the spat planting time and environmental factors in the arkshell, Scapharca broughtonii (Schrenck), we investigated the growth, survival rate of arkshell and habitat characteristics in Gamak Bay, Yeoja Bay and Saryang Island. We planted artificial spats of arkshell in Gamak Bay and Yeoja Bay at November 2004, and also planted domestic and Chinese natural spats in Saryang Island at March 2005. We measured growth, survival rate of arkshell, physiochemical parameters of the water mass (water temperature, salinity, dissolved oxygen, nutrients and chlorophyll a) and characteristics of the sediment (oxygen penetration depth, oxygen microprofiles, ignition loss and chemical oxygen demand) by monthly. The cumulative survival ratio of arkshell in Gamak Bay was the highest at December, whereas the ratio of arkshell in Yeoja Bay was recorded as 0% at October. The monthly growth rates of arkshell length in Gamak Bay and Yeoja Bay were the highest in May and the growth rate of the Korean arkshell in Saryang Island was higher than Chinese ones significantly. The high mortality (> 65%) of the arkshell in Yeoja Bay during summer probably caused by high water temperature, inflow of low salinity water, and low dissolved oxygen concentration in sediment. The concentrations of nutrient and sediment COD were considered to play an important role in the monthly survival ratio of arkshell in Gamak Bay and Sarayng Island. We suggest that the growth and mortality of arkshell might be influenced to the planting time of spat and the habitat characteristics.

Causative Substance and Time of Mortality Presented to Emergency Department Following Acute Poisoning: 2014-2018 National Emergency Department Information System (NEDIS) (급성 중독으로 응급실에 내원하여 사망한 환자의 원인물질 및 시간 분포)

  • Lee, Hyeonjae;Choa, Minhong;Han, Eunah;Ko, Dong Ryul;Ko, Jaiwoog;Kong, Taeyoung;Cho, Junho;Chung, Sung Phil
    • Journal of The Korean Society of Clinical Toxicology
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    • v.19 no.2
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    • pp.65-71
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    • 2021
  • Purpose: The purpose of this study was to investigate the cause of acute fatal poisoning and the time of death by analyzing the National Emergency Department Information System (NEDIS) of South Korea. Methods: The NEDIS data from 2014 to 2018 excluding non-medical visits were used for this study. The patients with acute poisoning were extracted using diagnostic codes. The toxic substances were classified into pharmaceuticals, pesticides, gases, artificial poisonous substances, and natural toxic substances. Patients were classified according to the time of death, place of death, and region. In each case, the most causative substances of poisoning were identified. Results: There were 380,531 patients including poisoning-related diagnoses, of which 4,148 (1.1%) died, and the WHO age-standardized mortality rate was 4.8 per 100,000. Analysis of 2,702 death patients whose primary diagnosis was acute poisoning, the most common cause of poisoning death was pesticides (62%), followed by therapeutic drugs, gas, and artificial toxic substances. Herbicides were the most common pesticides at 64.5%. The proportion of mortality by time, hyperacute (<6 h) 27.9%, acute (6-24 h) 32.6%, subacute (1-7 d) 29.7%, and delayed period (>7 d) were 9.8%. Conclusion: This study suggests that the most common cause of poisoning death was pesticides, and 60% of deaths occurred within 24 hours. The 71% of mortality from pesticides occurred within 6-24 hours, but mortality from gas was mostly within 6 hours. According to the geographic region, the primary cause of poisoning death was varied to pesticides or pharmaceuticals.

Biomass estimation of sailfin sandfish, Arctoscopus japonicus, in Korean waters (한국 연근해 도루묵, Arctoscopus japonicus의 자원량 추정)

  • Lee, Sung-Il;Yang, Jae-Hyeong;Yoon, Sang-Chul;Chun, Young-Yull;Kim, Jong-Bin;Cha, Hyung-Kee;Choi, Young-Min
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.42 no.5
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    • pp.487-493
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    • 2009
  • Available ecological and fishery data of sailfin sandfish, Arctoscopus japonicus, was examined to ascertain its population dynamic parameters in Korean waters. The instantaneous coefficient of total mortality (Z) was estimated to be 1.361/yr, and annual survival rate (S) was 0.256. The estimated instantaneous coefficient of natural mortality (M) was 0.482/yr, and the instantaneous coefficient of fishing mortality (F) for recent years was calculated to be 0.879/yr from Z and M values. Age at first capture was estimated to be 1.958 years. These parameters, in conjunction with catch landings data between 1991 and 2008, were used to estimate annual biomass using a biomass-based cohort analysis. The biomass of A. japonicus was estimated at approximately 7,600 mt in 1991, but since 1994 decreased to below 4,000 mt by 2001. After 2002 they started to increase gradually, and showed the level of more than 5,000 mt in recent years.

Electron Microscopic Alterations in Pediculus humanus capitis Exposed to Some Pediculicidal Plant Extracts

  • El Akkad, Dina M.H.;El-Gebaly, Naglaa Saad M.;Yousof, Hebat-Allah Salah A.;Ismail, Mousa A.M.
    • Parasites, Hosts and Diseases
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    • v.54 no.4
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    • pp.527-532
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    • 2016
  • Head lice, Pediculus humanus capitis, infestation is an important public health problem in Egypt. Inadequate application of topical pediculicides and the increasing resistance to the commonly used pediculicides made the urgent need for the development of new agents able to induce irreversible changes in the exposed lice leading to their mortality. The aim of the present work is to evaluate pediculicidal efficacy of some natural products such as olive oil, tea tree oil, lemon juice, and ivermectin separately in comparison with tetramethrin-piperonyl butoxide (licid), as a standard pediculicide commonly used in Egypt. The effects of these products were evaluated by direct observation using dissecting and scanning electron microscopes (SEM). Results showed that after 1 hr exposure time in vitro, absolute (100%) mortalities were recorded after exposure to 1% ivermectin and fresh concentrate lemon juice. The mortalities were decreased to 96.7% after exposure to tea tree oil. Very low percentage of mortality (23.3%) was recorded after 1 hr of exposure to extra virgin olive oil. On the other hand, the reference pediculicide (licid) revealed only mortality rate of 93.3%. On the contrary, no mortalities were recorded in the control group exposed to distilled water. By SEM examination, control lice preserved outer smooth architecture, eyes, antenna, respiratory spiracles, sensory hairs, and legs with hook-like claws. In contrast, dead lice which had been exposed to pediculicidal products showed damage of outer smooth architecture, sensory hairs, respiratory spiracles and/or clinching claws according to pediculicidal products used.

Effect of Dietary Essential Oils on Growth, Feed Utilization and Meat Yields of White Leg Shrimp L. vannamei

  • Kim, J.D.;Nhut, T.M.;Hai, T.N.;Ra, C.S.
    • Asian-Australasian Journal of Animal Sciences
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    • v.24 no.8
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    • pp.1136-1141
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    • 2011
  • Effect of dietary essential oils on growth, feed utilization and meat yields of white leg shrimp L. vannamei was investigated. White shrimp fry weighing 0.62 g were kept in one of 12 tanks (75 head/500 L holding tank) in a closed recirculation system. Four experimental diets, a commercial diet (control), phytoncide oil (PO), oregano oil (OO) and fermented garlic liquid (GL) were fed for 16 weeks. The mean water quality values for the whole experimental period were $27.8{\pm}1^{\circ}C$, $7.6{\pm}0.3$, $15.5{\pm}0.3$ g/L and $6.1{\pm}0.3$ mg/L for water temperature, pH, salinity and dissolved oxygen, respectively. At the end of the trial, 10 shrimp per tank were randomly sampled and meat yields (%) were evaluated after peeling the shell and removing the head. After a 16 week feeding trial, final weight of shrimp ranged from 21.9 g to 23.6 g. Feed conversion was not significantly different among groups (p>0.05), which was the lowest (1.95) in the control and highest (2.30) in the PO. Specific growth rate was also not significantly different (p>0.05) and ranged from 3.18% to 3.25%. Average daily gain of 0.2 g was obtained in all treatments. Mortality varied from 35.1% for control to 44.9% for OO. Meat yields maintained constant at 52.1% for control to 53.0% for PO. The study suggested that natural essential oils could not exert any improvement in growth performance, mortality and meat yields of white leg shrimp.