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Virtual Population Analysis
Virtual population analysis (VPA) is a cohort modeling technique commonly used in fisheries science for reconstructing historical fish numbers at age using information on death of individuals each year. This death is usually partitioned into catch by fisheries and natural mortality. VPA is virtual in the sense that the population size is not observed or measured directly but is inferred or back-calculated to have been a certain size in the past in order to support the observed fish catches and an assumed death rate owing to non-fishery related causes. Virtual population analysis was introduced in fish stock assessment by Gulland in 1965 based on older work. The technique of cohort reconstruction in fish populations has been attributed to several different workers including Professor Baranov from Russia in 1918 for his development of the continuous catch equation, Professor Fry from Canada in 1949 and Drs. Beverton and Holt from the UK in 1957. Because cohort reconstruction is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cohort (statistics)
In statistics, epidemiology, marketing and demography, a cohort is a group of research subject, subjects who share a defining characteristic (typically subjects who experienced a common event in a selected time period, such as birth or graduation). Comparison with period data Cohort data can oftentimes be more advantageous to Demography, demographers than period data. Because cohort data is honed to a specific time period, it is usually more accurate. It is more accurate because it can be tuned to retrieve custom data for a specific study. In addition, cohort data is not affected by tempo effects, unlike period data. However, cohort data can be disadvantageous in the sense that it can take a long amount of time to collect the data necessary for the cohort study. Another disadvantage of cohort studies is that it can be extremely costly to carry out, since the study will go on for a long period of time, demographers often require sufficient funds to fuel the study. Demography ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fisheries Science
Fisheries science is the academic discipline of managing and understanding fisheries. It is a multidisciplinary science, which draws on the disciplines of limnology, oceanography, freshwater biology, marine biology, meteorology, conservation, ecology, population dynamics, economics, statistics, decision analysis, management, and many others in an attempt to provide an integrated picture of fisheries. In some cases new disciplines have emerged, as in the case of bioeconomics and fisheries law. Because fisheries science is such an all-encompassing field, fisheries scientists often use methods from a broad array of academic disciplines. Over the most recent several decades, there have been declines in fish stocks (populations) in many regions along with increasing concern about the impact of intensive fishing on marine and freshwater biodiversity. Fisheries science is typically taught in a university setting, and can be the focus of an undergraduate, master's or Ph.D. progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Mortality
Fish mortality is a parameter used in fisheries population dynamics to account for the loss of fish in a fish stock through death. The mortality can be divided into two types: * Natural mortality: the removal of fish from the stock due to causes not associated with fishing. Such causes can include disease, competition, cannibalism, old age, predation, pollution or any other natural factor that causes the death of fish. In fisheries models natural mortality is denoted by (M).Sparre, P.; Ursin E.and Venema S. C. (1989). Introduction to tropical fish stock assessment. Part 1- Manual. FAO Fisheries Technical Paper No. 3061. Rome, FAO. p. 337. * Fishing mortality: the removal of fish from the stock due to fishing activities using any fishing gear. It is denoted by (F) in fisheries models. (M) and (F) are additive instantaneous rates that sum up to (Z), the instantaneous total mortality coefficient; that is, Z=M+F.Gulland, J.A. (1969). Manual of Methods for fish stock assessment. Part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Stocks
Fish stocks are population, subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the Population dynamics of fisheries, stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored. Stocks fished within biologically sustainable levels decreased from 90% in 1974 to 62.3% in 2021. Concepts The stock concept All species have geographic limits to their distribution, which are determined by their Physiological tolerance, tolerance to natural environment, environmental conditions, and their ability to competition, compete successfully with other species. In ocean, marine environments this may be less evident than on land because there are fewer topography, topographical boundaries, however, discontinuities still exist, produced for example by mesoscale and sub-mesoscale circulations that m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fedor Baranov
Fedor Ilyich Baranov (Russian: Фёдор Ильич Баранов) (1 April 1886 – 30 July 1965) was a founder of fisheries science, and has been called the "grandfather of fisheries population dynamics". He is best known for setting the foundations for quantitative fisheries science (including the Baranov catch equation) as well as for his contributions to development of fishing technology. Life and career Baranov graduated as a marine engineer from St. Petersburg Polytechnical Institute in 1909. He had a keen interest in fishing, and made his career in this area, first in improving fishing techniques but soon also in setting the foundations for the theory of fishing and fishery production. In 1915, Baranov was appointed as a professor at the Department of Commercial Fisheries of the Moscow Agricultural Academy. Baranov was the first head of the Department of Industrial Fisheries, an institute created as a part of the Moscow Institute of Fisheries (Moskovskiy Tekhnicheskiy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ray Beverton
Raymond (Ray) John Heaphy Beverton CBE FRS (29 August 1922 – 23 July 1995) was an important founder of fisheries science. He is best known for the book ''On the Dynamics of Exploited Fish Populations''Beverton, R. J. H., and Holt, S. J. 1957. On the Dynamics of Exploited Fish Populations. Fishery Investigations Series II. Ministry of Agriculture, Fisheries and Food, London. 533 pp. (1957) which he wrote with Sidney Holt. The book is a cornerstone of modern fisheries science and remains much used today. Beverton's life and achievements are described in detail in several obituaries written by prominent figures in fisheries science. Achievements Much of the foundations of quantitative fisheries science were laid out in ''On the Dynamics of Exploited Fish Populations'' which Ray Beverton and Sidney Holt wrote at the Fisheries Laboratory, Lowestoft (UK). In his review of the 1993 reprint of the book, Ray Hilborn writes "It is remarkable how the book has stood the test of time an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidney Holt
Sidney J. Holt (28 February 1926 – 22 December 2019) was a British biologist who was a founder of fisheries science. He was best known for the book ''On the Dynamics of Exploited Fish Populations'' which he published with Ray Beverton in 1957.Beverton, R. J. H., and Holt, S. J. 1957. On the Dynamics of Exploited Fish Populations. Fishery Investigations Series II. Ministry of Agriculture, Fisheries and Food, London. 533 pp. The book is a cornerstone of modern fisheries science and remains much used today. Holt served with the FAO in 1953 and with other UN agencies for another 25 years.Anderson, E. (2011"Standing on the shoulders of giants"''ICES Insight,'' 48: 4–11. After his retirement in 1979, Holt remained active in work related to the International Whaling Commission and conservation of whales in general, also publishing his views about whaling and fisheries management in academic journals. Achievements Much of the foundations of quantitative fisheries science were laid out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Dynamics Of Fisheries
A fishery is an area with an associated fish or aquatic population which is harvested for its commercial or recreational value. Fisheries can be wild or farmed. Population dynamics describes the ways in which a given population grows and shrinks over time, as controlled by birth, death, and migration. It is the basis for understanding changing fishery patterns and issues such as habitat destruction, predation and optimal harvesting rates. The population dynamics of fisheries is used by fisheries scientists to determine sustainable yields. The basic accounting relation for population dynamics is the BIDE (Birth, Immigration, Death, Emigration) model, shown as: : ''N''1 = ''N''0 + ''B'' − ''D'' + ''I'' − ''E'' where ''N''1 is the number of individuals at time 1, ''N''0 is the number of individuals at time 0, ''B'' is the number of individuals born, ''D'' the number that died, ''I'' the number that immigrated, and ''E'' the number that emigrated between time 0 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
