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  • 1
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    Variaciones de la abundancia numérica y biomasa del zooplancton de red en el Golfo San Jorge (año 1985) (2007)
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP)
    Details
    Publication Date: 2021-05-19
    Description: 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 importance, as well as their total biomass.
    Description: Publisher permission
    Description: Published
    Description: zooplancton, distribución por tamaño, densidad poblacional, biomasa
    Keywords: Zooplankton ; Biomass ; Population density ; Zooplankton ; Biomass ; Size distribution ; Population density
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 2
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    La caballa (Scomber japonicus) y las condiciones ambientales en el area bonaerense de El Rincón (39°- 40°30' S), agosto 1996. (2008)
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero
    Details
    Publication Date: 2021-05-19
    Description: 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 and density) of the mackerel shoals allowed to detect two areas of concentration above and below 40°S latitude. The northern area was characterized by relatively small schools of medium density similar to those of the Mar del Plata area. In the southern zone, large schools of high density that account for almost 92 of the total biomass were found.Differences between both areas were also detected when plankton distribution was analyzed. Higher abundances of the dinoflagellate Alexandrium tamarense corresponded to the southern area. On the contrary, higher zooplankton biomass was detected northerly of 40°S. From an oceanographic standpoint, the presence of mackerel was associated to relatively higher salinity values. As a result of the different data analyzed it is suggested that,during this time of the year, the species shows a migratory pattern from the intermediate shelf to coastal areas.
    Description: Publisher permission
    Description: Published
    Description: Scombridae, Scomber japonicus, caballa, zooplancton, relevamientos ecoicos, condiciones ambientales, biomasa, abundancia, estructura poblacional
    Keywords: Biomass ; Population structure ; Zooplankton ; Environmental conditions ; Abundance ; Biomass ; Population structure ; Zooplankton ; Environmental conditions ; Echo surveys
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 3
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    Una aplicación de los estudios ambientales para orientar la pesqueria de la caballa Scomber japonicus en Mar del Plata (2008)
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero
    Details
    Publication Date: 2021-05-19
    Description: 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 pushed by waters from the median shelf. A fishing strategy according with sea surface temperature is proposed to lead the commercial fleet.
    Description: Publisher permission
    Description: Published
    Description: Scombridae, Scomber japonicus, caballa
    Keywords: Biomass ; Environmental conditions ; Mackerel fisheries ; Biomass ; Catch/effort ; Environmental conditions ; Economic models ; Commercial fishing
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 4
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    La caballa (Scomber japonicus) y las condiciones del ambiente en elárea "El Rincón" 39°40'-41°30'S del Mar Argentino. Septiembre 2000 (2008)
    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero
    Details
    Publication Date: 2021-05-19
    Description: 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 winter season, characterized by the vertical homogeneity of the water column in temperature and salinity. The isotherms and isohalines distributed parallel to the 50 m isobath with values progressively decreasing from the coast towards the slope. Salinity values allowed to detect two hydrographic regimes: that of the San Matias Gulf 33.8-34.4 located to the West and covering more than half of the study area and the one of the Shelf Waters 33.5-33.79 occurring towards the East. A positive gradient in chlorophyll a concentration was observed in N-S sense and from the coast towards the shelf break. The highest densities of phytoplankton, with dominance of diatoms, were observed in the southern sector. Low concentrations of Alexandrium tamarense and Prorocentrum minimum, two potentially noxious dinoflagellates, were detected. The highest zooplankton biomass associated to the highest salinity values and salinity gradients, represented mostly by Calanoides cf. carinatus, was also detected in the southern sector. The western sector, influenced by the San Matias Gulf regime and characterized by high densities of both, phytoplankton and zooplankton, may constitute a potentially favourable feeding ground for chub mackerel.
    Description: Publisher permission
    Description: Published
    Description: Scombridae, Scomber japonicus, caballa
    Keywords: Fishery oceanography ; Biomass ; Environmental conditions ; Population characteristics ; Echo surveys ; Mackerel fisheries ; Fishery oceanography ; Biomass ; Environmental conditions
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 5
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    El zooplancton del hábitat reproductivo de la población bonaerense de anchoíta (Engraulis anchoita), con especial énfasis en crustáceos (2014)
    Details
    Publication Date: 2021-05-19
    Description: 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 different taxa and oceanographic conditions: Río de la Plata River (ARP), coastal (AC), and shelf (AP). Although predominance of copepods less than 1 mm total length was observed in the three areas, the largest abundances were registered in ARP and AC, Argentine anchovy reproductive habitat. The high abundance, wide distribution and size structure of Oithona nana, O. helgolandica, and Paracalanus parvus turn the species into key prey for the different E. anchoita ontogenic stages.
    Description: Las campañas de evaluación de la población bonaerense de anchoíta (Engraulis anchoita) han permitido realizar estudios sobre la comunidad zooplanctónica de la plataforma bonaerense desde 1995. En este trabajo se presentan los resultados más relevantes respecto de la estructura taxonómica y por talla de la comunidad, áreas faunísticas y especies "clave" en relación con las condiciones hidrográficas y sistemas frontales de la región. Se analizan, además, las consecuencias que esos resultados podrían tener en la ecología trófica de la anchoíta. Los grupos taxonómicos estudiados incluyeron copépodos, cladóceros, apendicularias, quetognatos, anfípodos y eufáusidos. El análisis multivariado aplicado a datos cuantitativos permitió distinguir claramente tres áreas faunísticas con distintas especies representativas y condiciones oceanográficas: Río de la Plata (ARP), costera (AC) y de plataforma (AP). A pesar de que se observó predominancia de copépodos de talla inferior a 1 mm de largo total en las tres áreas, las mayores abundancias se registraron en ARP y AC, hábitat reproductivo de la anchoíta. La gran abundancia, amplia distribución y estructura de tallas de Oithona nana, O. helgolandica y Paracalanus parvus convierte a estas especies en presas clave para los distintos estadios ontogénicos de E. anchoita.
    Description: Published
    Description: Engraulidae
    Description: Engraulis anchoita
    Description: anchoíta
    Description: zooplancton
    Description: biogeografía
    Description: fauna
    Description: frentes
    Description: relaciones tróficas
    Description: abundancia
    Description: pesquerías pelágicas
    Keywords: Zooplankton ; Biogeography ; Fauna ; Fronts ; Trophic relationships ; Abundance ; Pelagic fisheries
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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