Consulta: creatorFacets:"Wöhler, O.C."
Registros recuperados: 15
Data/hora: 05/06/2024 18:22:41

Evaluación de la polaca (Micromesistius australis) del Atlántico sudoccidental, período 1987-1999.
Provedor de dados: 20
Autores: Wöhler, O.C.; Cordo, H.D.; Cassia, M.C.; Hansen, J.E.
Taking into account the commercial catches by the Argentine fleet and other fleets that operated around Malvinas Islands (SW Atlantic) in the 1987-1999 period, the current state of southern blue whiting (Micromesistius australis) is assessed. A sequential analysis (Cohort Analysis) tuned, in an ADAPT conceptual framework with six independent indices of abundance, was performed for the southern blue whiting stock of the SW Atlantic. Commercial catch data of the Argentinian fleet and other fleets that operate around Malvinas Islands were used.The indices included catch per unit of effort of different fleets and data from Argentine-British research surveys. The analysis showed that the decreasing trend in biomass observed in previous studies went on during...
Tipo: Journal Contribution
Palavras-chave: Stock assessment; Fishing mortality; Biomass; Demersal fisheries; Statistical analysis; Gadoid fisheries; Stock assessment; Biomass; Demersal fisheries; Statistical analysis; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_2173; Http://aims.fao.org/aos/agrovoc/c_7378.
Ano: 2002
URL: http://hdl.handle.net/1834/2546

Evaluación pesquera del bacalao austral (Salilota australis) del Atlántico Sudoccidental
Provedor de dados: 20
Autores: Wöhler, O.C.; Cassia, M.C.; Hansen, J.E.
Information about the austral cod Salilota australis caught in the Patagonian shelf including the area around Malvinas Islands (SW Atlantic)as well as some data from annual research surveys carried out as of 1992 to 1998 were analyzed. On this basis, the fishery was studied and the abundance of the stock inhabiting the area under Argentine control was estimated. To calculate the optimum yield as a function of both age-at-first catch and fishing mortality, the Yield-per-Recruit model was used. Some biological reference points were also identified and an exploitation strategy based on low risk of collapse recommended. Austral cod landings, although small, showed an increasing trend as of 1990 that reached a maximum of 14,900 tons in 1998. Most of the catches...
Tipo: Journal Contribution
Palavras-chave: Stock assessment; Landing statistics; Fishing mortality; Fishing grounds; Risks; Demersal fisheries; Biomass; Stock assessment; Demersal fisheries; Biomass; Fishing grounds; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_2173; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_2947.
Ano: 2001
URL: http://hdl.handle.net/1834/1866

Aspectos de la biologia reproductiva de la castaneta (Cheilodactylus bergi) en la zona comun de pesca Argentino-Uruguaya
Provedor de dados: 20
Autores: 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

Aspectos de la biologia reproductiva de la castaneta (Cheilodactylus bergi) en la zona comun de pesca Argentino-Uruguaya
Provedor de dados: 20
Autores: 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

Análisis secuencial de la población de polaca (Micromesistius australis) en el período 1987-1997 ajustado con valores de rendimiento por unidad de esfuerzo de pesqueros comerciales.
Provedor de dados: 20
Autores: Wöhler, O.C.; Cordo, H.D.; Hansen, J.E.; Cassia, M.C.
The current status of southern blue whiting Micromesistius australis stock is described. A single, closed fish population is assumed to inhabit the SW Atlantic. Based on catch data corresponding to years 1987-1997, a sequential analysis on the stock is carried out (Cohort Analysis). Under an adaptative framework, catch per unit of effort data from commercial vessels are used to fit the model. Two commercial fleets are used in the fitting, i.e. Polish vessels (1987-1994)and Argentine surimi factory vessels (1991-1997). Results indicate that both, total stock biomass and spawning stock biomass would have declined. Total biomass would have decreased from a maximum close to 1.4 million tons in 1990 down to 0.5 mt in 1997 whereas the current spawning stock...
Tipo: Journal Contribution
Palavras-chave: Stock assessment; Fishery management; Catch/effort; Recruitment; Biomass; Demersal fisheries; Demersal fisheries; Stock assessment; Fishery management; Biomass; Http://aims.fao.org/aos/agrovoc/c_2173; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926.
Ano: 2001
URL: http://hdl.handle.net/1834/1867

Análisis secuencial de la población de merluza de cola (Macruronus magellanicus)en el atlantico sudoccidental período 1985-1995.
Provedor de dados: 20
Autores: 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

Identificación de las primeras marcas de crecimiento en los otolitos de juveniles de castañeta Cheilodactylus bergi (Pisces:Cheilodactylidae).
Provedor de dados: 20
Autores: Wöhler, O.C.
Hyaline or slow growth rings were identified in juvenile castañeta otoliths Cheilodactylus bergi, with the aim of establishing an objective criteria for age determination in this life stage.Samples were obtained from four research cruises carried out between 1988 and 1991 in the north-patagonian continental shelf and Argentine-Uruguayan Common Fishing Zone (CFZ)(SW Atlantic, between 34° and 47°S). Through measurement of sagitta otoliths, the existence of three hyaline rings was determined. The one closer to the nucleusis formed during the first winter in the fish life or when larval metamorphosis occurs (1-2 months after spawning peak). The second ring was related to the transitional period between postlarvae and juvenile. This involves a habitat change,...
Tipo: Journal Contribution
Palavras-chave: Age determination; Otoliths; Juveniles; Age determination; Otoliths; Juveniles; Http://aims.fao.org/aos/agrovoc/c_24110; Http://aims.fao.org/aos/agrovoc/c_27091; Http://aims.fao.org/aos/agrovoc/c_25393.
Ano: 1997
URL: http://hdl.handle.net/1834/1925

Crecimiento y mortalidad de la castañeta Cheilodactylus bergien la zona común de pesca Argentino-Uruguaya
Provedor de dados: 20
Autores: 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

Evaluación de polaca (Micromesistius australis) en el Atlántico Sudoccidental. Período 1987-2001
Provedor de dados: 20
Autores: Wöhler, O.C.; Hansen, J.E.; Cassia, M.C.; Cordo, H.D.
Period 1987-2001. A diagnosis of the current state of Southern blue whiting (Micromesistius australis) stock in the Southwest Atlantic was carried out on the basis of catches corresponding to the period 1987-2001 as reported by the Argentine fleet and also by vessels operating around Malvinas Islands. Abundance and current fishing mortality rates were estimated, and the biomass evolution in the long term resulting from some possible exploitation strategies based on different management strategies were projected. A sequential population analysis calibrated under a conceptual adjustable framework with five independent abundance indices was carried out. The effects on the biomass estimates were analysed by adopting different selection patterns and calibration...
Tipo: Journal Contribution
Palavras-chave: Fishery management; Biomass; Demersal fisheries; Stock assessment; Biomass; Fishery management; Demersal fisheries; Stock assessment; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_2173; Http://aims.fao.org/aos/agrovoc/c_24251.
Ano: 2007
URL: http://hdl.handle.net/1834/2526

Estadística pesquera de peces demersales australes en el Atlántico Sudoccidental (período 1980-2002)
Provedor de dados: 20
Autores: 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

Aplicación del método de máxima verosimilitud a la estimación de parámetros y comparación de curvas de crecimiento de von Bertalanffy.
Provedor de dados: 20
Autores: 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

Evaluación de merluza de cola (Macruronus magellanicus) en el Atlántico Sudoccidental. Período 1985-2001
Provedor de dados: 20
Autores: 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

Estimación del nivel óptimo de mortalidad por pesca y riesgo de sobreexplotación de la castañeta (Cheilodactylus bergi)
Provedor de dados: 20
Autores: Wöhler, O.C.; Cordo, H.D.
Patagonian scallop (Zygochlamys patagonica King &amp; Broderip, 1832): A new fishery in the Argentine continental shelf. Yield-per-recruit model was applied to the stock of castañeta (Cheilodactylus bergi)in the Argentine-Uruguayan Common Fishing Zone (Southwest Atlantic, among 34° and 39°30' S), in order to estimate the range of F0.1 values resulting from the uncertainty in the parameters of the model. Simulations with variations in natural mortality and recruitment were carried out, in order to estimate the risk of overfishing associated with different fishing mortality levels. The criterion that spawning stock biomass be mantained over 35. of its unexploited level was adopted. For an optimum age of first capture of 4 years, the range of calculated F0.1...
Tipo: Journal Contribution
Palavras-chave: Fishing mortality; Overfishing; Biomass; Yield; Biomass; Overfishing; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_34068.
Ano: 1999
URL: http://hdl.handle.net/1834/1873

Aspectos de la pesca de la polaca (Micromesistius australis) por parte de la flota argentina en el período 1989 - 1995
Provedor de dados: 20
Autores: 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

Resultados de la campaña de evaluación de peces demersales australes efectuada en el verano de 1997.
Provedor de dados: 20
Autores: 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