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Registros recuperados: 15
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Análisis y diagnóstico del diseño de muestreo de las campañas de evaluación de merluza (Merluccius hubbsi) al norte y al sur de los 41°S (Zona Comun de Pesca Argentino-Uruguaya y Mar Argentino). Años 1996-1999 OceanDocs
Hernandez, D.R.; Bezzi, S.I.; Ibañez, P.M..
Gain contribution by stratification in hake (Merluccius hubbsi) biomass estimation with respect to a simple random sampling based on the same sample size is analyzed. Considering as objective hake biomass assessment, curves which relate precision reached in estimations to the sample size are established. Data were from total hake biomass surveys carried out from 1996 through 1999 hake management units distributed North and South of 41°S Argentine Sea are analyzed separately. Stratification used at present allows to obtain very variable gains in precision associated to biomass with estimations, in the North management unit, with a maximun of 88 in 1996 and no gain in 1997. The South management unit presents also variable results but always with important...
Tipo: Journal Contribution Palavras-chave: Gadoid fisheries; Fishery surveys; Biomass; Statistical sampling; Stock assessment; Biomass; Stock assessment; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_24251.
Ano: 2003 URL: http://hdl.handle.net/1834/2401
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Aplicación de un modelo dinámico de biomasa para evaluar el efectivo sur de merluza. Período 1986-1998 OceanDocs
Irusta, G.; Hernandez, D.R..
The status of hake (Merluccius hubbsi) resource south of 41°S in the Argentine Sea was evaluated with the Biomass Dynamic Model of Pella and Tomlinson. Results indicate that the population was overexploited and in a low biological production level (B99 BMSY1 because, as of 1998, catches always exceeded the surplus production corresponding to each year and the (MSY) Maximum Sustainable Yield. In 1993 increase of landings accelerated declination of biomass. For 1999 the MSY was estimated at 244,773 t and the replacement catch at 147,389 t. Landings corresponding to 1998 surpassed the MSY in 145,000 t and the replacement catch in 242,611 t.
Tipo: Journal Contribution Palavras-chave: Gadoid fisheries; Stock assessment; Overfishing; Biomass; Yield; Stock assessment; Biomass; Overfishing; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_34068.
Ano: 2003 URL: http://hdl.handle.net/1834/2425
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Beneficio económico de la caballa (Scomber japonicus) con relación a la temperatura superficial del mar en el área de Mar del Plata. OceanDocs
Perrotta, R.G.; Hernandez, D.R..
The temperature that limits the presence of schools of Argentine chub mackerel Scomber japonicus was found to be around 19°C in the Mar del Plata area Buenos Aires prov., Argentina. At higher values, most shoals leave coastal waters in direction to the mid-shelf. An inverse relationship was observed between catches per unit of effort CPUE and sea surface temperature. The highest CPUE values corresponded to temperatures lower than 19°C. Beyond that value, the possibility of obtaining a CPUE higher than the unit is nearly null and the low standard deviation means it is unlikely to reach high CPUE values. The economic profit per minute of each daily cruise was estimated using a case study carried out with a single vessel pilot with mean structural and...
Tipo: Journal Contribution Palavras-chave: Catch/effort; Surface temperature; Fishery management; Commercial fishing; Mackerel fisheries; Fishery management; Http://aims.fao.org/aos/agrovoc/c_24026.
Ano: 2002 URL: http://hdl.handle.net/1834/2543
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Estratificación de la flota industrial de buques fresqueros y estimación de los rendimientos OceanDocs
Bertolotti, M.I.; Pagani, A.N.; Hernandez, D.R.; Buono, J.J..
In order to increase knowledge about the ice chilling fleet and to explain the relationship between structural variables and yields, a simplified model was developed. The fleet was classified in three homogeneous strata. Stratum I includes the smallest ships, with a catch composition equal to that of the large coastal fishing vessels. The stratum yields decreased in 1997 and 1998. Strata II and III have common hake as the main target of catches. Yields of those strata showed a continuous decrease as of 1994/1995. Therefore, the species was replaced by other fish originally caught by other fleets. These two last strata are more vulnerable to overfishing of traditional coastal and demersal fisheries.
Tipo: Book Section Palavras-chave: Fishery economics; Overfishing; Fish catch statistics; Yield; Fishing vessels; Overfishing; Fishing vessels; Http://aims.fao.org/aos/agrovoc/c_34068; Http://aims.fao.org/aos/agrovoc/c_2954.
Ano: 2001 URL: http://hdl.handle.net/1834/2586
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Estratificación y análisis de la eficacia y la eficiencia de la flota costera de pequeña escala perteneciente a la Sociedad de Patrones Pescadores del puerto de Mar del Plata. OceanDocs
Errazti, E.; Hernandez, D.R.; Bertolotti, M.I.; Buono, J.J..
This chapter includes an economic analysis of the small scale fleet of the Mar del Plata harbour, Buenos Aires Province, Argentina. The original study was carried out at the request of the Skippers Fisheries Society to find out the relative efficacy and efficiency of homogeneous groups of associated vessels. Based on the information available, to tune the observed data, assess the relative efficacy and estimate the relative economic efficiency of the fleet, an ad hoc model was designed. Length, gross registered tonnage, engine power and number of crew members were considered and analyzed as structural variables for 1995, 1996 and 1997. No changes in variables for the period were observed so, the efficacy and efficiency analysis was carried out for the year...
Tipo: Book Section Palavras-chave: Fishing vessels; Fishery economics; Coastal fisheries; Yield; Mathematical models; Fishing vessels; Coastal fisheries; Mathematical models; Http://aims.fao.org/aos/agrovoc/c_2954; Http://aims.fao.org/aos/agrovoc/c_1696; Http://aims.fao.org/aos/agrovoc/c_24199.
Ano: 2001 URL: http://hdl.handle.net/1834/2585
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Estratificación y estimación de los rendimientos de la flota de buques procesadores congeladores arrastreros. OceanDocs
Bertolotti, M.I.; Hernandez, D.R.; Pagani, A.N.; Castañeda, M.F..
In order to better understand the behaviour of the trawler processing freezer fleet in the Argentine Sea, an analysis of yields and structural characteristics for the 1989-98 period was carried out. The relationship between structural variables and yield expressed in kilos per day was explained with a simplified asymptotic model. The fleet was divided into four homogeneous strata. Common hake is the target of stratum I and stratum II which are deeply affected by overfishing of the species. As of 1993, in stratum III, common hake was replaced by other pelagic and demersal species, mainly hoki. In fleet stratum IV southern blue whiting and hoki were caught. Catches of the latter increased during the last three years.
Tipo: Book Section Palavras-chave: Trawlers; Factory ships; Yield; Mathematical models; Fish catch statistics; Trawlers; Factory ships; Mathematical models; Http://aims.fao.org/aos/agrovoc/c_7880; Http://aims.fao.org/aos/agrovoc/c_10732; Http://aims.fao.org/aos/agrovoc/c_24199.
Ano: 2001 URL: http://hdl.handle.net/1834/2584
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Evaluación de corvina rubia (Micropogonias furnieri) en el área del Río de la Plata y Zona Común de Pesca argentino-uruguaya por medio de un modelo de dinámica de biomasa OceanDocs
Carozza, C.R.; Hernandez, D.R.; Perrotta, R.G..
Whitemouth croaker (Micropogonias furnieri)has a broad distribution along the Atlantic coast of the Americas, from Mexico to the south of the Province of Buenos Aires, Argentina. At the southern end of distribution, Argentina and Uruguay catch the species with different commercial fleet types bay or creek, coastal and off-shore and modalities of bottom trawling with doors and paired trawling. Maximum catches of both countries, that reached 60,000 t, were registered between 1995 and 1997. After that period a remarkable decrease was observed, specially in Argentina where catches remained at around 6,000 t over a total of 30,000 t for both countries. The commercial fleet was divided in three categories and the total area of study in three subareas: El Salado,...
Tipo: Journal Contribution Palavras-chave: Stock assessment; Catch/effort; Risks; Biomass; Depleted stocks; Mathematical models; Coastal fisheries; Commercial fishing; Stock assessment; Biomass; Mathematical models; Coastal fisheries; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_24199; Http://aims.fao.org/aos/agrovoc/c_1696.
Ano: 2004 URL: http://hdl.handle.net/1834/1503
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Influencia de las interacciones con el factor Año en los índices anuales de abundancia obtenidos por modelos lineales generales utilizando datos de Captura por Unidad de Esfuerzo OceanDocs
Hernandez, D.R.; Perrotta, R.G..
The problem in the definition of a relative annual abundance index using a General Linear Model is posed. The possible factors generating changes in the catch per unit effort (CPUE) are discussed and the parameterization of the model is analyzed, in particular the Sigma-restrictive parameterization. This report considers the problem caused by the presence of interactions of first order that include the factor Year in the model. It has been mathematically demonstrated that in the presence of these interactions, the index series is not proportional to the abundance annual mean of the resource. An approach of practical order to evaluate the possible effect of the interactions that include the factor Year in the index is considered using the percentage of...
Tipo: Journal Contribution Palavras-chave: Stock assessment; Catch/effort; Mathematical models; Abundance; Fishing vessels; Stock assessment; Mathematical models; Fishing vessels; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24199; Http://aims.fao.org/aos/agrovoc/c_2954.
Ano: 2006 URL: http://hdl.handle.net/1834/2511
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Introducción al análisis Bayesiano OceanDocs
Hernandez, D.R..
An introduction to the Bayesian Analysis is presented and conceptual aspects highlighted. Initially, the probability concept is analyzed from its objective perspective such as frequency, and from its subjective perspective such as degree of belief. It is discussed how, within the context of Bayesian statistics, probability as degree of belief allows to give sense to the probability of a hypothesis and, therefore, enables to resolve problems of scientific interest that could not be otherwise addressed. The likelihood concept is discussed and the Bayes formula, which integrates a priori information and knowledge with information provided by current data demonstrated. Basic concepts of the Decision Theory within the Bayesian perspective are introduced. The...
Tipo: Book Palavras-chave: Statistical analysis; Statistical models; Fishery resources; Stock assessment; Prediction; Probability theory; Statistical analysis; Stock assessment; Fishery resources; Prediction; Http://aims.fao.org/aos/agrovoc/c_7378; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_2942; Http://aims.fao.org/aos/agrovoc/c_29367.
Ano: 2007 URL: http://hdl.handle.net/1834/2560
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Morphological identification of two southwest Atlantic loliginid squids: Loligo gahi and Loligo sanpaulensis OceanDocs
Pineda, S.E.; Hernandez, D.R.; Brunetti, N.E.; Jerez, B..
Morphological characters of two loliginid squids, Loligo gahi and Loligo sanpaulensis, in the SW Atlantic region off Argentina were studied to obtain a diagnostic criterion for their identification. Emphasis was placed on the taxonomic characters suitable to identify individuals in the whole size range. Considering the uncertainty associated to the correct identification of juveniles, their taxonomic status was confirmed using electrophoretic studies. Discrimination between species based on morphological characters proved to be more effective than meristic counts. A discriminant function that allows an easy separation of the two species is presented. The function, composed of two indices: fin width mantle length (FW/ML)and gladius width mantle length...
Tipo: Journal Contribution Palavras-chave: Meristic counts; Morphometry; Electrophoresis; Electrophoresis; Http://aims.fao.org/aos/agrovoc/c_2523.
Ano: 2002 URL: http://hdl.handle.net/1834/1583
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Muestreo de desembarque de caballa (Scomber japonicus) en el puerto de Mar del Plata (38° S) y determinación de niveles de captura en el área El Rincón; período 1989-2003 OceanDocs
Perrotta, R.G.; Garciarena, A.D.; Hernandez, D.R..
Chub mackerel caught by the commercial fleet in El Rincón (39°-41° 30’ S) and Mar del Plata (38° S) areas was analyzed. In 2001 and 2002 samples from El Rincón were obtained from landings or collected by scientific observers on board the commercial ships. Samples from Mar del Plata were acquired during the 2001-2002 and 2002-2003 fishing seasons, on board two vessels of the small purse-seine fleet. Landings were mostly adults and only a small fraction of juveniles was observed (< 5%). Length growth parameters from El Rincón samples were estimated, and length-weight and length-age relationships were fitted by Least Squares. The results were as follows: L(mm) = 538.4; k (years-1) = 0.122; t0 (years) = -4.92; Pt = 4*10-7 * Lt 3.536. Natural mortality was...
Tipo: Journal Contribution Palavras-chave: Landing statistics; Catch/effort; Growth; Commercial fishing; Length-weight relationships; Growth; Http://aims.fao.org/aos/agrovoc/c_3394.
Ano: 2007 URL: http://hdl.handle.net/1834/2516
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Nematodes parásitos como indicadores biológicos de Macruronus magellanicus OceanDocs
Incorvaia, I.S.; Hernandez, D.R..
A wide distributional range species can constitute many populations or fishing stocks which can be whole or partly overlapped within their distribution area, reason why they must be clearly identified. Therefore, proper identification of stocks is necessary for fisheries management, as this is the unit to which the fishing effort should be applied. The parasitological method is one of the systems currently used to determine stock. Nematodes parasites of Macruronus magellanicus (longtail hake) collected during surveys enmarked between 45º S-55º S in the Southwest Atlantic were studied. Nematodes that could be used as biological indicators were selected. Mean abundance values of L3 Anisakis simplex and Hysterothylacium aduncum were estimated. Three different...
Tipo: Journal Contribution Palavras-chave: Indicator species; Abundance; Endoparasites; Endoparasites; Indicator species; Http://aims.fao.org/aos/agrovoc/c_10603; Http://aims.fao.org/aos/agrovoc/c_35790.
Ano: 2006 URL: http://hdl.handle.net/1834/1565
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Stock assessment of the bluemouth (Helicolenus dactylopterus) in Azorean waters during the 1990-2002 period, applying a biomass dynamic model OceanDocs
Perrotta, R.G.; Hernandez, D.R..
Bluemouth (Helicolenus dactylopterus), a benthic fish mostly inhabiting at depths between 500 m and 600 m, represents a highly valuable economic resource for local fishermen at the Azores Islands (NE Atlantic). Nominal catches of bluemouth increased from 1990 through 1994, and declined afterwards reaching in 1999 the lowest value recorded. Standardized catch per unit effort (CPUE) was used as an index for stock relative abundance; a General Linear Model, considering several factors that may have affected the fishing efficiency of commercial vessels, was run to obtain this CPUE index. These factors were: fleet type, year, month, and boat size; the last three factors were found to be statistically significant. A discrete version of the Schaefers Biomass...
Tipo: Journal Contribution Palavras-chave: Stock assessment; Catch/effort; Risks; Mathematical models; Stock assessment; Mathematical models; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24199.
Ano: 2005 URL: http://hdl.handle.net/1834/1563
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Uso de técnicas geoestadísticas en la estimación de la abundancia de vieira patagónica (Zygochlamys patagonica). OceanDocs
Lasta, M.L.; Hernandez, D.R.; Bogazzi, E.; Burgos, G.; Valero, J.; Lucifora, L.O..
To evaluate absolute biomass, a research cruise was conducted on three scallop (Zygochlamys patagonica)beds (38°S-56°W, September 1998). The estimated bed surface was 1,162 nm(2). Sampling stations were regularly spaced at 5 nm intervals. A total of 118 trawls were performed with a non-selective dredge 2,5 m wide (efficiency 16-21. ). Trawls duration and speed were 10 minutes and 3 nm.h(-1)respectively. Samples were taken to estimate total and commercial (greater or equal than 55 mm total height)scallop weight and size frequency distribution. Coefficients of variation (CV)of the estimated biomass were calculated for each bed using geoestatistical techniques and a simple random sampling alternative with the same number of samples. The CVs for total scallop...
Tipo: Journal Contribution Palavras-chave: Fishery surveys; Scallop fisheries; Biomass; Abundance; Biomass; Http://aims.fao.org/aos/agrovoc/c_926.
Ano: 2001 URL: http://hdl.handle.net/1834/1870
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Variaciones interanuales (1995-2000) de la temperatura y la salinidad registradas en los meses de enero en el golfo San Jorge y aguas adyacentes (43°S-47°S). OceanDocs
Louge, E.; Reta, R.; Santos, B.A.; Hernandez, D.R..
Temperature and salinity interannual variations are analyzed south ofthe hake (Merluccius hubbsi)spawning grounds area, in the San Jorge Gulf and adjacent waters Argentine Sea, SW Atlantic. The study period comprises the months of January 1995-2000. Results of cruises carried out on board of INIDEP research vessels to assess hake juveniles were studied. Statistically significant increase of temperature from 1997 was observed. Change trends over a period of 20 years at a global climate scale are discussed. Mean salinity did not show variations except for 2000 when it was slightly higher probably due to the scarce influence of the Patagonian Current in the area. Temperature and salinity fields showed a horizontal gradient south of the Gulf (thermohaline...
Tipo: Journal Contribution Palavras-chave: Salinity; Temperature; Shelf fronts; Thermocline; Environmental factors; Nursery grounds; Climatic changes; Environmental factors; Salinity; Temperature; Nursery grounds; Http://aims.fao.org/aos/agrovoc/c_2594; Http://aims.fao.org/aos/agrovoc/c_6751; Http://aims.fao.org/aos/agrovoc/c_7657; Http://aims.fao.org/aos/agrovoc/c_25438.
Ano: 2004 URL: http://hdl.handle.net/1834/1500
Registros recuperados: 15
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