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| Alvarez Colombo, G.L.; Viñas, M.D.. |
| Themisto gaudichaudii, the most abundant and widely distributed hyperiid amphipod in Argentine shelf waters, provides a source of food for several species of economical value such as the anchovy, mackerel, hake, and squid. Predictive dry weight-length and volume-length regression were established in order to provide an indirect estimation of the individual body mass from a measurement of body length. Samples were collected in San Jorge Gulf and fixed with a 4 o/o formaldehyde solution. The possible effect of formaldehyde fixation on dry weight and volume is discussed. |
| Tipo: Journal Contribution |
Palavras-chave: Dry weight; Length-weight relationships. |
| Ano: 1994 |
URL: http://hdl.handle.net/1834/1928 |
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| Perrotta, R.G.; Pertierra, J.P.; Viñas, M.D.; Macchi, G.J.; Tringali, L.S.. |
| Both mackerel mean biomass and mean fishing effort in Buenos Aires (Argentina) shelf during the period 1990-91/1994-95 were estimated. Those values were 85,792 t and 42,051 minutes, respectively. However, the best economic profit from the fishery (about $15,390,036)($1=U$S1) was estimated to take place at 28,000 minutes. It was observed a waste in fishing effort of the commercial fleet related with sea surface temperatures of 19°C or more. Moreover, adult mackerel find better trophic conditions on the continental shelf (depth 50m), while larvae originated from massive spawning in late November-early December, i.e., during the main fishing season, find their optimum at lower depths. Mackerel shoals enter and leave fishing grounds in a counterclockwise way... |
| Tipo: Journal Contribution |
Palavras-chave: Mackerel fisheries; Biomass; Catch/effort; Environmental conditions; Economic models; Commercial fishing; Biomass; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 1998 |
URL: http://hdl.handle.net/1834/2465 |
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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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| Viñas, M.D.; Marrari, M.; Di Mauro, R.; Cepeda, G.D.; Padovani, L.N.. |
| The information gathered in Argentine anchovy (Engraulis anchoita) Northern population assessment cruises allowed to perform studies on the zooplankton community of the Buenos Aires shelf since 1995. In this work the most relevant results as regards the taxonomy and size structure of the community, faunistic areas, and 'key' species in relation to the hydrographic conditions and frontal systems of the region are presented. Besides, the consequences those results might have on Argentine anchovy trophic ecology are analyzed. The taxonomic groups studied included copepods, cladocerans, appendicularians, chaetognaths, amphipods, and euphausiids. The multivariate analysis applied to quantitative data allowed to clearly distinguish three faunistic areas with... |
| Tipo: Journal Contribution |
Palavras-chave: Zooplankton; Biogeography; Fauna; Fronts; Trophic relationships; Abundance; Pelagic fisheries. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5497 |
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| Pérez Seijas, G.M.; Ramirez, F.C.; Viñas, M.D.. |
| A study was made on numercial and biomass variations of the zooplankton of the San Jorge Gulf (Argentina), based on samples from five cruises performed during 1985. The sampling was included within a proagramme for the biology and fishery evaluation of the shrimp Pleoticus muelleri. San Jorge, a large gulf of the northern patagonian shelf, comprises major fishery activities. Some fish species of economical importance depend on copepods for their feeding, like anchovy (Engraulis anchoita)or partially on middle-size plankters, like mackerel (Scomber japonicus). As a way for determining the trophic disponibility at the gulf, a study was made in order to express the numerical abundance of copepods, euphausiids and amphipods and other items of lesser... |
| Tipo: Journal Contribution |
Palavras-chave: Zooplankton; Biomass; Size distribution; Population density; Zooplankton; Biomass; Population density; Http://aims.fao.org/aos/agrovoc/c_15490; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_6112. |
| Ano: 1987 |
URL: http://hdl.handle.net/1834/2006 |
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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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