Consulta: creatorFacets:"Hansen, J.E."
Registros recuperados: 25
Data/hora: 10/06/2024 04:59:24

Características morfométricas y merísticas del bonito argentino
Provedor de dados: 20
Autores: Hansen, J.E.
Collete and Chao (1975) reviewed the systematic and morphology of the Genus Sarda and relatives ((Tribe Sardini), including into their analysis a few S.sarda from the SW Atlantic. Before that, Demir (1964)dealt with the meristic data of the same species from the Black Sea. This paper in concerned with the featuring of the bonito caught in Argentina, from both a morphometric and a meristic point of view. The study made the differences reported by Collette and Chao (op.cit.)among W and E S.sarda populations to be more conspicuous, because our samples had even lower values han those from the NW.
Tipo: Journal Contribution
Palavras-chave: Meristic counts; Morphometry.
Ano: 1988
URL: http://hdl.handle.net/1834/1966

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

Recomendación de capturas biológicamente aceptables de anchoíta patagónica (Engraulis anchoita, 41º S-48º S) durante 2012
Provedor de dados: 20
Autores: Hansen, J.E.; Buratti, C.C.; Garciarena, A.D.
Advise on Biologically Allowable Catch (BAC) for Southern Argentine anchovy (Engraulis anchoita, 41° S-48° S) during 2012. To assess the evolution since 1990 and the current status of Argentine anchovy Southern stock, an Age Structured Population Model (ASPM) was used. Modeling of catches according to a four-month period pulses allowed to predict annual yields so as to get them close to the nominal catches officially recorded. Some independent indexes of stock abundance (eight acoustic estimates of total biomass and five estimates of spawning stock biomass obtained with the Daily Egg Production Method) and the proportion of individuals per age group assessed during the same cruises were used to calibrate the fitting. No stock-recruitment function but a...
Tipo: Journal Contribution
Palavras-chave: Stock assessment; Yield; Statistical models; Age composition; Clupeoid fisheries.
Ano: 2013
URL: http://hdl.handle.net/1834/5508

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

Diferencias entre parámetros vitales de las poblaciones bonaerense y patagónica de anchoíta argentina.
Provedor de dados: 20
Autores: Hansen, J.E.
Two pelagic cruises were carried out by R/V"Cap.Oca Balda" in the spring of 1988 and the following summer. Anchovy samples were taken in order to increase the knowledge on the differences between two main stocks of the species, inhabiting the Argentine Sea from 35°S southwards, with distributional boundary situated at about 41°S. Length-weight relationships were statistically different among populations. Weight-at-length values calculated for the summer cruise were higher tha sprin estimates, and they were also higher within Northern individuals. The differences were not statistically significant between stocks, but there are reasons to believe that if ages 1 and 6 of both stocks had been represented those differences would have been increased. Mortality...
Tipo: Journal Contribution
Palavras-chave: Length-weight relationships; Growth; Mortality; Size distribution; Growth; Mortality; Http://aims.fao.org/aos/agrovoc/c_3394; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1994
URL: http://hdl.handle.net/1834/1933

Aspectos generales de la pesca del bonito (Sarda sarda)en la Argentina
Provedor de dados: 20
Autores: Hansen, J.E.
Basic aspects of the fising of Bonito in Argentina such as: catch statistics, fleet and gears, season and fishing grounds, and catch per unit effort (CPUE)are analized. FAO World Catch Statistics show that none of the different populations of Sarda sarda or other species of the Genus may support a highly productive fishery Exceptions are Sarda chilensis and S.sarda from the Black Sea, which us exploited by Turkey. On the basis of available information it may be inferred that the Bonito of Argentina has more competitors and a narrower thophic spectrum than that from the Black Sea.
Tipo: Journal Contribution
Palavras-chave: Landing statistics; Fishing gear; Fishing vessels; Catch/effort; Fishing gear; Fishing vessels; Http://aims.fao.org/aos/agrovoc/c_2946; Http://aims.fao.org/aos/agrovoc/c_2954.
Ano: 1987
URL: http://hdl.handle.net/1834/2009

Estimación de parámetros poblacionales del efectivo de sardina fueguina (Sprattus fuegensis) de la costa continental Argentina.
Provedor de dados: 20
Autores: Hansen, J.E.
Patagonian sprat is probably the only pelagic fish species having a considerable biomass within the Argentine Seasouth of 45ºS. There are two populations, the first inhabiting mainly the coastal region around Malvinas Islands and the other close to the coast off Santa Cruz and Tierra del Fuego Provinces, including the fuegian channels. Some results of two seasonal (autumn and spring) patagonian sprat assessment surveys carried out during 1996 are shown. The autumn cruise covered the area between 50° and 55°S, from the continental coast up to 60 m depth, whereas the spring survey extended upto 90 m depth including Le Maire Strait and part of the Beagle Channel. During both seasons, in waters ranging 6.2 - 8.8°C temperature, the species distributed very...
Tipo: Journal Contribution
Palavras-chave: Fishery surveys; Length-weight relationships; Sexual maturity; Growth; Mortality; Growth; Sexual maturity; Mortality; Http://aims.fao.org/aos/agrovoc/c_3394; Http://aims.fao.org/aos/agrovoc/c_7016; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1999
URL: http://hdl.handle.net/1834/2530

Parámetros biológicos relevantes para las pesquerías de anchoíta argentina (Engraulis anchoita). Estimaciones resultantes de reunir datos de campañas de investigación (1993 a 2008) y de muestras de capturas comerciales (1986 a 2009)
Provedor de dados: 20
Autores: Hansen, J.E.
The aim of this paper was to accurately estimate population parameters of northern (“bonaerensis”, latitude &lt; 41° S) and southern (“patagonic”, latitude 41° S) Argentine anchovy stocks and to describe some aspects of their behaviour. The research surveys allowed to obtain data on length, total weight, sex, maturity and age of 27,853 specimens of the northern and 12,787 of the southern stocks. Besides, 20,717 age determinations stemmed from commercial landing samplings of the northern stock were established. Sex proportion in the northern population was 0.50 : 0.50; the southern showed a slight predominance of males (0.52 : 0.48). Data derived from cruises and commercial landings showed statistical differences in the growth ratio of the northern stock...
Tipo: Journal Contribution
Palavras-chave: Pelagic fisheries; Stocks; Population characteristics; Growth; Natural mortality; Sexual maturity; Engraulis anchoita; Marine environment.
Ano: 2011
URL: http://hdl.handle.net/1834/4884

Resultados de una campaña de investigación sobre la anchoíta (Engraulis anchoita)del sector bonaerense en el otoño de 1983. Distribución, abundancia y algunos aspectos biológico-pesqueros
Provedor de dados: 20
Autores: Hansen, J.E.; Gru, D.L.; Perrotta, R.G.
An extensive area of the continental shelf -between 37°20' and 34°40'S - was reviewed through hidroacoustical methods in order to evaluate the anchovy biomass. Within the area of highest concentration, further data on anchovy abundance were recorded, and fish samples were taken. Large anchovy shoals were located at about 170 nm from Mar del Plata, mainly in zones with sharp changes in oceanographic conditions. The distribution of the species was not uniform, but "contagious", and the log-normal distribution provided the best fit for the echo-integrator recorded data. The biomass was estimated at 1,061,727 tons (Confidence limits in between 921,010 and 1,223,930 tons). Some parameters of the population were estimated, such as: lenght-weight relationship,...
Tipo: Journal Contribution
Palavras-chave: Length-weight relationships; Sex ratio; Age composition; Growth curves; Echo surveys; Mortality; Age composition; Sex ratio; Mortality; Http://aims.fao.org/aos/agrovoc/c_29093; Http://aims.fao.org/aos/agrovoc/c_7014; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1986
URL: http://hdl.handle.net/1834/2038

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

Precisión en las evaluaciones por área barrida de algunos peces demersales costeros entre los 34º S Y 42º S, Atlántico Sudoccidental
Provedor de dados: 20
Autores: Hansen, J.E.; Hozbor, N.; Lagos, N.; Martos, P.
To estimate the biomass of six species, the stratified design used at present for demersal coastal fish stocks is compared against other design alternatives. Density data (t mn-2 between 34ºS and 42ºS, from the coast line to 50m depth, corresponding to whitemouth croaker (Micropogonias furnieri), patagonian smoothhound (Mustelus schmitti), stripped) weakfish (Cynoscion guatucupa), angular angel shark (Squatina guggenheim), brazilian flathead (Percophis brasiliensis) and skate (Sympterygia bonapartii) collected in surveys carried out in spring and winter in the Argentine Sea (SW Atlantic), were analyzed. The spatial distribution of the species was strongly contagious and influenced by bottom salinity. Different marine zones that showed special salinity...
Tipo: Journal Contribution
Palavras-chave: Stock assessment fishery surveys coastal fisheries stratification spatial analysis modelling demersal fish Micropogonias furnieri; Mustelus schmitti; Cynoscion guatucupa; Squatina guggenheim; Percophis brasiliensis; Sympterygia bonapartii PSW; Argentina; Buenos Aires ASW; Uruguay swept area marine environment.
Ano: 2010
URL: http://ocenadoc/1554veasecualser

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

Distribución, evaluación acustica y estructura poblacional de la anchoíta. Resultados de las campañas del año 1993
Provedor de dados: 20
Autores: Hansen, J.E.; Madirolas, A.
Two pelagic surveys to study were carried out during 1993. Those surveys covered the regions inhabited by either the bonaerensis stock in october (34-41°S)and the patagonian stock in November - December (41-45°30'S). Pre-stratified random sampling designs, including two random steps to allocate the transects, were adopted to perform the acoustic sampling by echo integration. A midwater trawl net (9-16 m vertical opening, 10 mm mesh-sized codend)was used to collect fish samples. The biomass of the northern stock was acoustically estimated to be about 1,45 million tons, whereas that of the southern stock was almost 740,000 t. Young anchovies, up to two-year old, allow for most of theose abundance values within each stock. The arrays of individuals at the sea...
Tipo: Journal Contribution
Palavras-chave: Pelagic fisheries; Geographical distribution; Biomass; Mortality; Echo surveys; Stock assessment; Geographical distribution; Biomass; Stock assessment; Pelagic fisheries; Mortality; Http://aims.fao.org/aos/agrovoc/c_5083; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_5659; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1996
URL: http://hdl.handle.net/1834/1955

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

Distribución estacional y estructura poblacional del bacalao austral (Pisces, Moridae, Salilota australis) en la zona económica exclusiva argentina entre los 45°S y 56°S durante 1992 y 1993
Provedor de dados: 20
Autores: Cassia, M.C.; Hansen, J.E.
The Patagonian cod (Salilota australis) inhabits the SW Atlantic from 38°S up to 55°S, as well as the Pacific Ocean from 40°S up to 57°S. The annual catches of this species by both the Argentine fleet and those operating around the Malvinas Islands have significantly increased during the decade 1990-2000, peaking to 16,556 t in 1996. After this, a marked decrease in landings was noticed, and during 2003 the catch was 7,924 t. Seasonal distribution, concentration grounds, and population structure of the Patagonian cod from the Argentine Sea are described, and the mean densities of the species are seasonally related to latitude, temperature and depth, on the basis of data from surveys carried out by the INIDEP research vessels in 1992 and 1993. Highest mean...
Tipo: Journal Contribution
Palavras-chave: Gadoid fisheries; Seasonal distribution; Population density; Population structure; Biomass; Population structure; Biomass; Population density; Http://aims.fao.org/aos/agrovoc/c_6115; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_6112.
Ano: 2005
URL: http://hdl.handle.net/1834/1561

Composición por tallas y edades de las capturas comerciales de anchoíta bonaerense obtenidas entre 1990 y 2011
Provedor de dados: 20
Autores: Hansen, J.E.; Garciarena, A.D.
As part of the research programs performed yearly at the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP, Mar del Plata, Argentina) some important basic data about the commercial fisheries usually included in internal reports are registered. This formal paper is a review and summary of size and age composition estimates of commercial catches (discards included) of Northern Argentine anchovy (34ºS-41ºS) obtained between 1990-2011. The basic data resulting from the examination of 521 samples from fishing vessels included 62,466 fish length measurements and 26,667 valid age readings from which the corresponding 22 annual age-length keys were built. The annual estimates of the individual total length-total weight relation parameters and of...
Tipo: Journal Contribution
Palavras-chave: Pelagic fisheries; Stock assessment; Commercial fishing; Catch composition; Age composition; Size distribution; Clupeoid fisheries.
Ano: 2013
URL: http://hdl.handle.net/1834/5502

Algunos resultados de las campañas primaverales de evaluación anual de anchoíta bonaerense efectuadas entre 1993 y 1996.
Provedor de dados: 20
Autores: Hansen, J.E.; Madirolas, A.
Information resulting from four spring acoustic surveys carried out between 1993 - 1996 to assess bonaerensis anchovy (Engraulis anchoita) biomass (34°- 41°30´S) is presented. Annual estimates, successively higher, went from 1.5 to 5.3 millon tons and the respective coefficient of  variability that followed the same trend ranged between 7.4.  and 28.0. . In general terms, the largest abundances were those recorded within the coastal strata off the Río de la Plata followed by those of the most southern stratum. Nevertheless, during the 1996 survey, the latter showed very high biomass values and, consequently, the largest mean. The region corresponding to the main commercial anchovy fishing ground during the season  represented, in any case, relatively low...
Tipo: Journal Contribution
Palavras-chave: Echo surveys; Biomass; Sexual maturity; Growth; Mortality; Biomass; Growth; Sexual maturity; Mortality; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_3394; Http://aims.fao.org/aos/agrovoc/c_7016; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1999
URL: http://hdl.handle.net/1834/2531

Factores oceanográficos relacionados con la abundancia relativa de anchoíta (Engraulis anchoita) sobre la plataforma bonaerense (34°S-41°S) durante la primavera
Provedor de dados: 20
Autores: Martos, P.; Hansen, J.E.; Negri, R.M.; Madirolas, A.
Research has been conducted to study the relationship between some physical variables and the relative abundance of the northern stock of the Argentine anchovy (Engraulis anchoita) within the main area of distribution of the stock during springtime. Basic data were recorded during four research surveys mainly aimed at the acoustic assessment of the stock between 34°S and 41° 30'S (Buenos Aires prov., Argentina - Uruguay). The cruises were always carried out in October from 1993 to 1996. Several environmental variables were simultaneously input into a General Linear Model to analyze the variations on fish abundance; however, the model did not account for more than 17-20% of the total variance. Nevertheless most of those factors (sea surface temperature,...
Tipo: Journal Contribution
Palavras-chave: Clupeoid fisheries; Seasonal distribution; Abundance; Stocks; Fronts; Salinity gradients; Stocks; Http://aims.fao.org/aos/agrovoc/c_28772.
Ano: 2005
URL: http://hdl.handle.net/1834/1559

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

Revisión y síntesis de las estimaciones acústicas de abundancia de anchoíta (Engraulis anchoita) efectuadas entre 1993 y 2008
Provedor de dados: 20
Autores: Madirolas, A.O.; Hansen, J.E.; Cabreira, A.G.
The annual research planning of the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP, Mar del Plata, Argentina) includes at least two surveys to estimate the total biomass of Argentine anchovy Northern and Southern stocks. The assessment is performed using hydroacoustic techniques and the Daily Egg Production Method. In this paper the results of the acoustic estimates obtained during the 1993-2008 period are summarized. Besides, the studies performed to determine the characteristics of the species behavior such as vertical migrations or avoidance reactions to vessels that would produce uncertainty about estimates absolute value are discussed.
Tipo: Journal Contribution
Palavras-chave: Pelagic fisheries; Stocks; Echo surveys; Echo integrators; Abundance.
Ano: 2013
URL: http://hdl.handle.net/1834/5493

Estudios de distribución de la anchoíta (Engraulis anchoita)en un área de extensión reducida. I. Densidades mínimas de muestreo para la estimación de algunos parámetros poblacionales
Provedor de dados: 20
Autores: Gru, D.L.; Hansen, J.E.
Results of a research cruise carried out to estimate some biological parameters of anchovy (Engraulis anchoita), during the major spawning season, were analyzed in order to determine the minimum number of samples required to obtain unbiased values. Twelve samples of fishes were taken within an area of 607 nm². Size (total length)distributions, slope of the length-weight relationship, sex ratio and age population structure were considered. Results suggest that those parameters should be estimated by eight or more samples (corresponding to 76 nm² each).
Tipo: Journal Contribution
Palavras-chave: Length-weight relationships; Size distribution; Sex ratio; Age composition; Biological sampling; Age composition; Sex ratio; Http://aims.fao.org/aos/agrovoc/c_29093; Http://aims.fao.org/aos/agrovoc/c_7014.
Ano: 1986
URL: http://hdl.handle.net/1834/2029

Applying a non-parametric bootstrap technique to assess the accuracy of biomass estimates of argentine anchovy (Engraulis anchoita) northern stock (34º S-41º S) with the Daily Egg Production Method. 1993-2008 period
Provedor de dados: 20
Autores: Pájaro, M.; Hansen, J.E.; Leonarduzzi, E.
Engraulis anchoita northern stock reproductive biomass (SSB) during the 1993-2008 period was estimated applying the Daily Egg Production Method (DEPM) and accuracy of estimates assessed using a bootstrap technique (SW Atlantic Ocean, Argentine Sea). The basic data were collected in different research surveys carried out in late Spring, at the peak of the spawning season. The aim of this work was to build reliable confidence intervals around the estimates of the mean reproductive biomass applying a non-parametric bootstrap method. Resampling methods are becoming increasingly popular as statistical tools as they are robust and do not require the assumption of any particular distribution of the basic data. This is especially relevant when assessing the DEPM...
Tipo: Journal Contribution
Palavras-chave: Spawning; Stocks; Fecundity; Biomass; Statistical analysis.
Ano: 2013
URL: http://hdl.handle.net/1834/5494

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

Muestreo bioestadístico de pescado en el puerto de Mar del Plata. Anchoíta (Engraulis anchoita). Período 1986-1990
Provedor de dados: 20
Autores: Hansen, J.E.
This paper deals with the commercial landings of bonaerensis anchovy at the Port of Mar del Plata (Buenos Aires province,Argentina), during the years 1986 to 1990. The mean catch was 15,501t per year. A total of 59 fish samples were taken for total length distributions (N=20164), and 24 sub-samples (N=2370) were analyzed to record individual data (length, weight, sex, sexual stage, age fromotoliths reading). The numer of fish per kg ranged between 28 and 53(mean=34.6). The mean size was 156.63 mm, and the most abundant fish in the landings were those being 3 and 2 years old, as it was also recorded during the period 1980-1985. Ordinary length-weight relationships by season were fitted, and the results were as follows:1) Autumn-Winter: W=8.5* 10-7* L3.392;...
Tipo: Journal Contribution
Palavras-chave: Length-weight relationships; Size distribution; Sexual maturity; Clupeoid fisheries; Biological sampling; Age composition; Commercial land use; Cohort analysis.
Ano: 1997
URL: http://hdl.handle.net/1834/5794

Características poblacionales de la anchoíta (Engraulis anchoita)del Mar Argentino. Parte I. El largo medio al primer año de vida, crecimiento y mortalidad
Provedor de dados: 20
Autores: Hansen, J.E.; Cousseau, M.B.; Gru, D.L.
A total of 7263 otoliths were collected from anchovy samples taken during two pelagic cruises which were carried out in the Spring of 1978. An statistical analysis of back calculated length distributions of one-year-old fish (L1)was made. The L1 mean values taken by geographical latitude form a cline, with higher values in the northern samples, and decreasing Southwards. Within this latitudinal gradient two main anchovy populations can be identified, one in the region of Buenos Aires Province and the other in Patagonian waters. The L1 of the females is significatively larger than that of the males for the former population, whereas in the Patagonian area differences between sexes are not significant. The parameters of the von Bertalanffy Growth curves, as...
Tipo: Journal Contribution
Palavras-chave: Stock identification; Otolith reading; Growth curves; Mortality; Mortality; Http://aims.fao.org/aos/agrovoc/c_4945.
Ano: 1984
URL: http://hdl.handle.net/1834/2043