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| Registros recuperados: 15 | |
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| Wöhler, O.C.; Giussi, A.R.; Hansen, J.E.. |
| Sequential population analysis on Long Tail Hake (Macruronus magellanicus)from the Southwest Atlantic. Years 1985-1995. VPA on the Long Tail Hake (Macruronus magellanicus), based on data covering the years 1985 up to 1995, was performed to assess the current state of the stock. Simulation trials, inducing uncertainty about both the natural mortality rate and recruitment were also accomplished, to evaluate the risk of overfishing which is associated to different fishing alternatives, always under the assumption of a single and closed Long Tail Hake population. CPUE data were not appropriate for tunning, so the traditional VPA has been applied. During the period of study, stock biomass and spawning stock biomass showed an increased trend. Long and short-term... |
| Tipo: Journal Contribution |
Palavras-chave: Stock assessment; Fishery management; Catch/effort; Fishing mortality; Overfishing; Biomass; Sexual maturity; Stock assessment; Fishery management; Biomass; Overfishing; Sexual maturity; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_34068; Http://aims.fao.org/aos/agrovoc/c_7016. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/1875 |
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| Aubone, A.; Wöhler, O.C.. |
| With the purpose of easening its application, the theory of parameter estimation by the maximum likelihood method is presented. The theory is general and useful for linear and nonlinear models. The method is applied to the von Bertalanffy´s growth model for individual data and for mean values of length-at-age. Statistical tests to compare parameters from different population groups are presented. Problems caused by lack of verification of assumptions are discussed. An example of its application is given and results of nonlinear least squares estimations are compared to those obtained with Allen´s method. An example of application implemented on a calculus spreadsheet is attached. |
| Tipo: Journal Contribution |
Palavras-chave: Growth curves; Mathematical models; Mathematical models; Http://aims.fao.org/aos/agrovoc/c_24199. |
| Ano: 2000 |
URL: http://hdl.handle.net/1834/2541 |
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| Wöhler, O.C.. |
| Length and age at first maturity was estimated, and the distribution of the spawning stock of castaneta (Cheilodactylus bergi) was analyzed, with the aim of understanding the spawning activity and its relation with oceanographic parameters. Samples came from two research cruises carried out in the Argentine-Uruguayan Common Fishing Zone (CFZ) (SW Atlantic, between 34 degree and 39 degree 30'S), during the end of spawning period (May-June) of 1991 and 1993. Length at first maturity was estimated in 21.34 cm and 23.69 cm of total length, for males and females respectively. Age at first maturity estimated for sexes combinated corresponding to 2.60 years. A spawning area in the north (between 35 degree and 37 degree S) was determined, showing a high incidence... |
| Tipo: Journal Contribution |
Palavras-chave: Fishing grounds; Sexual maturity; Spawning seasons; Mortality; Environmental conditions. |
| Ano: 1997 |
URL: http://hdl.handle.net/1834/5795 |
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| Wöhler, O.C.. |
| Length and age at first maturity was estimated, and the distribution of the spawning stock of castaneta (Cheilodactylus bergi) was analyzed, with the aim of understanding the spawning activity and its relation with oceanographic parameters. Samples came from two research cruises carried out in the Argentine-Uruguayan Common Fishing Zone (CFZ) (SW Atlantic, between 34 degree and 39 degree 30'S), during the end of spawning period (May-June) of 1991 and 1993. Length at first maturity was estimated in 21.34 cm and 23.69 cm of total length, for males and females respectively. Age at first maturity estimated for sexes combinated corresponding to 2.60 years. A spawning area in the north (between 35 degree and 37 degree S) was determined, showing a high incidence... |
| Tipo: Journal Contribution |
Palavras-chave: Fishing grounds; Sexual maturity; Spawning seasons; Mortality; Environmental conditions. |
| Ano: 1997 |
URL: http://hdl.handle.net/1834/5793 |
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| Wöhler, O.C.; Marí, N.R.. |
| Basic aspects concerning southern blue whiting (Micromesistius australis) fishing by the Argentine fleet in the period 1989-1995 are analized. Catch and effort statistics, fleet operation modalities and spatial and temporary characteristics of fishing activities are included. The basic information to perform this analysis was collected from the fishing statistics provided by the Subsecretaría de Agricultura, Ganadería y Pesca of Argentina and from reports of the Observers Program on board of the commercial fleet. It was in 1989, when the first ship for surimi production entered the fishery, that southern blue whiting catches carried out by the Argentine fleet became important. As of 1989 catches increased in a steady way to stabilize at near 100,000 annual... |
| Tipo: Journal Contribution |
Palavras-chave: Catch statistics; Fishing grounds; Catch/effort; Fishing grounds; Http://aims.fao.org/aos/agrovoc/c_2947. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/2528 |
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| Wöhler, O.C.. |
| Growth parameters based on age assignation, length-weight relationship and mortality rates of castañeta Cheilodactylus bergi were studied. Samples came from landings at Mar del Plata Port(Buenos Aires province, Argentina) during 1989, and from a research cruise carried out in the Argentine-Uruguayan Common Fishing Zone(CFZ) during 1991. Castañeta is a longeval demersal species. The growth parameters of von Bertalanffy special model were: 1) Lý 31.95,34.69, 32,30; 2) K 040, 033, 039; and 3) t0 0.00, -0.16, 0.03 corresponding to males, females and all fish respectively. The rates of total mortality (Z) were 0.18, 0.16 and 0.17 for males, females and all fish, respectively. Because of the low rate of exploitation during the study, this values can be used as... |
| Tipo: Journal Contribution |
Palavras-chave: Growth; Mortality; Length-weight relationships. |
| Ano: 1997 |
URL: http://hdl.handle.net/1834/5792 |
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| Gorini, F.L.; Di Marco, E.; Wöhler, O.C.. |
| Fishery statistics of austral demersal fishes in the Southwest Atlantic (1980-2002 period). A synthesis of the information available about catches of austral demersal fishes and fishing efforts reported by different fleets that operated in the SW Atlantic between 34° S-58° S in the 1980-2002 period is made. Species included in the analysis were southern blue whiting (Micromesistius australis), patagonian hoki (Macruronus magellanicus), patagonian toothfish (Dissostichus eleginoides), red cod (Salilota australis), southern hake (Merluccius australis) and ling (Genypterus blacodes). Annual and monthly catches, fishing grounds, number of vessels that participated in the fisheries, main landing ports and other characteristic of interest are presented. When it... |
| Tipo: Journal Contribution |
Palavras-chave: Demersal fisheries; Landing statistics; Catch statistics; Fishing effort; Demersal fisheries; Fishing effort; Http://aims.fao.org/aos/agrovoc/c_2173; Http://aims.fao.org/aos/agrovoc/c_24027. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/2559 |
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| Wöhler, O.C.; Hansen, J.E.; Giussi, A.R.; Cordo, H.D.. |
| Period 1985-2001. A stock assessment of Patagonian hoki of the Southwest Atlantic was carried out by using data from the years 1985-2001. A cohort analysis, fitted with some survey abundance indices was used in an adaptive conceptual framework. Simulation trials were performed to project the evolution of the fishery, to evaluate the risk of over-fish the stock under different exploitation levels, and to estimate Biologically Acceptable Catches (BAC). Both total biomass and spawning stock biomass showed increasing trends resulting from four strong year classes (1993, 1995, 1996 and 1998). Total biomass at the beginning of 2001 was estimated to be 2.5 million tons, and spawning stock biomass at the spawning time (August) was estimated to be around 1.28... |
| Tipo: Journal Contribution |
Palavras-chave: Stock assessment; Fishery management; Biomass; Risks; Demersal fisheries; Stock assessment; Fishery management; Biomass; Demersal fisheries; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_2173. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/2525 |
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| Wöhler, O.C.; Giussi, A.R.; García de la Rosa, S.B.; Sánchez, M.F.; Hansen, J.E.; Cordo, H.D.; Alvarez Colombo, G.L.; Incorvaia, I.S.; Reta, R.; Abachián, V.E.. |
| An assessment survey on the austral fish was carried out during the summer 1997 on both the shelf and slope off southern Argentina. The cruise covered 101,508 nm2 between 45° and 54° 30'S and depths between 50 and 400 m. The survey did not include the area controlled by the United Kingdom. Considering the total area as an undivided stratum, a random sampling was used to estimate demersal fish biomass and a delta distribution-based model to evaluate mean densities. Out of the forty five species caught 28 were bony fish and 17 elasmobranch. Four cephalopod mollusc species were also identified. A biomass of 3.2 million tons (CI(95o/o): 1.90 - 6.06 millions) proved that longtail hake was the most abundant resource within the region followed by common hake... |
| Tipo: Journal Contribution |
Palavras-chave: Demersal fisheries; Fishery surveys; Biomass; Population structure; Feeding; Parasitism; Environmental conditions. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/5782 |
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| Registros recuperados: 15 | |
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