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| Registros recuperados: 10 | |
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| 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 |
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| 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 |
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| Perrotta, R.G.; Madirolas, A.; Viñas, M.D.; Akselman, R.; Guerrero, R.A.; Sánchez, M.F.; López, F.; Castro Machado, F.; Macchi, G.J.. |
| In August 1996 acoustic methods were employed to estimate mackerel (Scomber japonicus) abundance in the Buenos Aires, Argentina shelf area of "El Rincón" (4,287 mn2), located between 39°- 40° 30' S. Results showed a biomass estimate of 77,260 t. ASIMRAD EK-500 equipment operated with a 38 KHz split-beam transducer was used. Midwater fishing trawls were employed to identify echotraces and to collect mackerel samples.Trawls 4 and 5 were the most successful. Samples included only adult fish (310-470 mm Lt and ages ranging 2-11). Length and weight growth parameters and mortality rates were estimated. Analysis of the stomach contents revealed that mackerel was feeding exclusively on zooplankters over 2 mmlength. The analysis of the characteristics (dimensions... |
| Tipo: Journal Contribution |
Palavras-chave: Abundance; Biomass; Population structure; Zooplankton; Environmental conditions; Echo surveys; Biomass; Population structure; Zooplankton; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_6115; Http://aims.fao.org/aos/agrovoc/c_15490; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/2529 |
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| Perrotta, R.G.; Viñas, M.D.; Madirolas, A.; Reta, R.; Akselman, R.; Castro Machado, F.; Garciarena, A.D.; Macchi, G.J.; Moriondo Danovaro, P.; Llanos, V.; Urteaga, J.R.. |
| Between September 1st and 6th a research cruise was carried out in the Buenos Aires shelf area of "El Rincon" 39°40'-41°30'S, Argentine Sea SW Atlantic. The total area studied was 2,527.8 nautical mile2. Knowledge of the commercial fleet location at the time of the survey allowed to intensify sampling in a 'miniarea' of 52,8 nautical mile2. The acoustic assessment of chub mackerel (Scomber japonicus) biomass was 49,511.9 t, 94 of which corresponded to this last area. Fish samples coming from fishing trawls included only adult individuals of 240-460 mm total length (TL) and ages ranging 2-11 years. The limit age was estimated at 13 years and natural and total mortality rates at 0.23 and 0.54, respectively. Oceanographic conditions were those typical of the... |
| Tipo: Journal Contribution |
Palavras-chave: Population characteristics; Echo surveys; Mackerel fisheries; Fishery oceanography; Biomass; Environmental conditions; Fishery oceanography; Biomass; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_2938; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 2003 |
URL: http://hdl.handle.net/1834/2418 |
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| Perrotta, R.G.; Garciarena, A.D.; Madirolas, A.; Cabreira, A.. |
| Chub mackerel (Scomber japonicus) landings corresponding to November 2003-January 2004 and November 2004-January 2005 fishing seasons were analyzed at the Mar del Plata port (Argentina, SW Atlantic). Fourty one samples were taken to measure total length exclusively and 4 sub-samples to record individual data (total length, weight, sex, sexual stage, age according to otoliths reading). Total length ranged 20-50 cm (1 and 8 years old). The most abundant sizes, between 32-37 cm, corresponded to ages 3 and 4, respectively. Most of the fish caught were adult (95%) and mature (85%) specimens. Length-weight, length-age relations were calculated and length-growth, weight-growth parameters estimated. The catch per unit of effort, of high variability (0-2,455 kg... |
| Tipo: Journal Contribution |
Palavras-chave: Landing statistics; Biological sampling; Growth; Fishing effort; Echo surveys; Biomass; Growth; Biomass; Fishing effort; Http://aims.fao.org/aos/agrovoc/c_3394; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_24027. |
| Ano: 2009 |
URL: http://hdl.handle.net/1834/3455 |
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| Casarsa, L.; Madirolas, A.. |
| The normal behavioral patterns of several fish species is altered during trawling affecting the fish spatial distribution. Sonar methods were carried out in this research work in order to study the reaction of reproductive concentrations of the Argentine hake (Merluccius hubbsi) during mid-water and bottom fishing trawls. Observations made from a trawl sonar mounted on the headrope of an ENGEL (35 m) bottom trawl, showed that this species concentrates at the lower-central sector of the net mouth. During daytime trawls fish schools with a vertical distribution exceeding ten meters were observed entering the trawl within the first two meters from the bottom. Some observations during pelagic trawls carried out at night, showed no specific pattern at the net... |
| Tipo: Journal Contribution |
Palavras-chave: Behaviour; Bottom trawling; Sonar; Echo surveys; Vertical distribution; Behaviour; Http://aims.fao.org/aos/agrovoc/c_868. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/2517 |
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| Registros recuperados: 10 | |
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