Browsing by Author "Perrotta, Ricardo G."

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    Análisis de la utilización de la captura por unidad de esfuerzo de pescadilla de red (Cynoscion guatucupa) como índice de abundancia anual. Período 1992-2004
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Perrotta, Ricardo G.; Ruarte, Claudio
    The stripped weakfish (Cynoscion guatucupa) caught in Brazil, Uruguay and Argentina (SW Atlantic) has a wide latitudinal distribution (22° S-43° S). In Argentina there are two main fishing areas, the Argentine-Uruguayan Common Fishing Zone and 'El Rincón', southern zone of the Buenos Aires littoral. The importance of the species makes it necessary to define an annual abundance index that would allow to diagnose the state of the stock. The model adjusted to calculate the index is the General Linear Model. The factors used were Year, Quarter, Length, Stratum (4 categories) and sub-areas (5 categories), all statistically significant. The problem generated by the presence in the model of first order interactions that include the Year factor is discussed. The importance of said interactions is assessed pursuant to the percentage of variance explained considering the model with and without such interactions. It is concluded that the catch per unit of effort series reflects space-temporal changes in the fleet activity not proportional to the biomass.
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    La caballa (Scomber japonicus) y las condiciones del ambiente en el área "El Rincón" (39°40'-41°30' S) del Mar Argentino. Septiembre, 2000
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Perrotta, Ricardo G.; Viñas, M.D.; Madirolas, A.; Reta, Raúl; Akselman, Rut; Castro Machado, Federico; Garciarena, A. David; Macchi, Gustavo J.; Moriondo Danovaro, Paula; 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 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.
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    Características biológicas y de la pesca del savorín Seriolella porosa (Pisces: Centrolophidae) del Mar Argentino
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2002) Garciarena, A. David; Perrotta, Ricardo G.
    Length growth parameters were calculated and total length-weight and total length-fork length relationships, which showed no differences between sexes, were fitted for the South Atlantic bream (Seriolella porosa). Length at first maturity was also calculated. The results were as follows: L (mm)= 490.96k years-¹) = 0.154; t0 (years)= -3.915; W(g) = 4*10-6)*TL³.1989; FL(mm) = 0.8917*TL1.0006);L sub 50 (mm)= 290.61. Natural mortality was estimated at 0.274 and limit age at 11 years. Samples were taken during research surveys carried out in 1999 and 2000 in the Argentine Sea (Atlantic SW). Sagittae otoliths of 374 specimen were used for age determination. Total fish length ranged from 226 mm to 550 mm (1-14 years). Commercial landing data of trawl fleets for the period 1990-2000 were analyzed. Catch per unit effort (CPUE) (kg/h) was calculated and standardized using a General Linear Model. All the variables considered in the analysis year, month, fishing rectangle, fleet and horse power were significant. The CPUE showed an increasing tendency through the years.
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    Las condiciones oceanográficas en el área marplatense (37° 00' S-38° 24' S) y su relación con la distribución de la caballa (Scomber japonicus). Octubre-noviembre de 1999
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Reta, Raúl; Perrotta, Ricardo G.; Garciarena, A. David
    Results obtained during a research cruise carried out along the coastal area of Mar del Plata (Buenos Aires, Argentina) in November 1999 are presented. The objective of the research cruise was to estimate chub mackerel (Scomber japonicus) abundance with acoustic methods and establish its relation to the hydrographic conditions. The information gathered was complemented with data of catches obtained by a commercial vessel that operated simultaneously in the study area. Environmental data from other research cruises and satellite information were also taken into account to obtain contemporary sea surface temperature and wind speed and direction data. The main species of catches of the research cruise and commercial vessel were horse mackerel (Trachurus lathami) and anchovy (Engraulis anchoita). No chub mackerel was detected during the acoustic assessment; however, the species was caught by the commercial vessel in the southern part of the study area and near the thermohaline front. Chub mackerel yields were very low if compared to those regularly recorded in the area and time the purse-seine fleet operates and that are typical of an advanced fishing season (January). The advection of estuarine waters from the de la Plata river, conditioned by the winds field, generated the displacement of low salinity waters over the coastal area that surpassed the regular southern limits. The positive anomalies of sea surface temperature in the region, that reached values close to 3 °C, could have caused the partial exclusion of chub mackerel in the coastal region of Mar del Plata.
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    Distribución y estructura de tallas de la palometa (parona signata, carangidae) y el pampanito (stromateus brasiliensis, stromateidae) en relación con las condiciones oceanográficas en la Zona Común de Pesca (34° s-38° s) y estimación de la longitud de primera madurez sexual. Julio de 2001
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Perrotta, Ricardo G.; Guerrero, Raúl A.; Carozza, Claudia R.; Quiroga, Pedro; Macchi, Gustavo J.
    Samples were obtained using bottom trawl nets during a coastal research cruise carried out on board of the RFV “Dr. E. L. Holmberg” between 3rd. and 16th. July 2001. The spatial distribution of surface and bottom temperature and salinity fields was analyzed at the oceanographic stations sampled in each trawl position. The analysis allowed to characterize the oceanographic conditions of the area during the sampling period and to compare them to the historic seasonal mean. 669 leatherjack specimens of 9-55 cm total length (TL) caught at depths ranging 5-29 m and 1,372 butterfish individuals of 6-40 cm total length (TL) caught at depths ranging 4-29 m were sampled. Length at first sexual maturity for both sexes was also estimated. Results were: leatherjack: L50 (cm) = 30.06 and butterfish: L50 (cm) = 23.12. It is worth mentioning that the presence of adult leatherjack near Mar del Plata (Buenos Aires prov., Argentina) suggests that the resource may become one of the target species for the coastal fleet.
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    Estimación de un índice de abundancia anual estandarizado para pescadilla de red (Cynoscion guatucupa), mediante la aplicación de un modelo lineal general; período 1992-2003
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2007) Ruarte, Claudio; Perrotta, Ricardo G.
    The stripped weakfish (Cynoscion guatucupa) has a wide latitudinal distribution (22° S-43° S) and it is object of fishery in Brazil, Uruguay and Argentina (SW Atlantic). In this last country, it is mainly captured in the coastal region of Buenos Aires Province by means of a fleet, which has between 20 m and 30 m length. In Argentina, the average landings in the last 5 years were 9,900 t. It is the second commercial species among the coastal groups. There are two main fishery areas of this species: the Argentinean-Uruguayan Common Fishing Zone (AUCFZ) and the El Rincón area, in the South of bonaerense littoral. Due to the importance of this species, it is necessary to define an index of annual abundance to allow a suitable diagnosis of the fishery condition. The General Linear Model is a suitable model to calculate this index. The factors used in this work were: year, trimester, 4 length categories and 5 sub areas. All of them were significant and reflect spatial-temporal changes in the abundance of this species. The model explained 34% of the total variability in the AUCFZ and 46% in the El Rincón. In general, the trends of catch per unit effort (CPUE) were similar and increasing in both areas, registering a greater increase in the internal areas. On the other hand, the fleet displacements between the areas and the reduction of the total fishery area caused a rise in the annual CPUE and a fall of the captures. These captures were dominated by adults but with an important presence of juveniles in the coastal zone off Mar del Plata city.
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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
    (Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Hernández, Daniel R.; Perrotta, Ricardo 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 explained variance of the model with and without these interactions. Some methodological rules are also defined to attenuate several problems generated by the mentioned interactions: (1) evaluating if type of fleet, included as categories of the factor Ship, has experienced modifications throughout the period of study that could have generated changes in the efficiency of fishing units; (2) allowing for the possibility of working with indexes pondered by Area; (3) using the most convenient categorization for the factor Month (month, bimonthly, quarterly, fishery season, etc.), considering the seasonal distribution of the resource and the activity of the fleet, as well as the limitations generated by the presence of empty cells in the design. Two application examples are presented
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    Modificación del análisis de cohortes de Pope para extender su aplicación a un rango más amplio de valores de mortalidad natural y mortalidad por pesca
    (Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2008) Hernández, Daniel R.; Perrotta, Ricardo G.
    Pope's Cohorts Analysis was modified to extend its application to a wider range of natural mortality, M and fishing mortality, F rate values. The modified method maintains the simplicity of the one established by Pope and does not require to resolve any non lineal equation in each cohort reconstruction process. The relative errors obtained when estimating the number of individuals per age (maximum and mean in absolute value) showed acceptable levels within the five domains (M and F pairs of values) analyzed in this work. The new method can be adapted to a particular situation (M and F values range) simply solving an optimization problem (minimization of the maximum relative error absolute value) easily achieved using a calculation sheet or considering the approximation corresponding to any of the domains herein analyzed.
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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
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2007) Perrotta, Ricardo G.; Garciarena, A. David; Hernández, Daniel 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 estimated at 0.30 and age limit at 10 years. The standardized catch per unit effort (CPUE) annual mean (kg h-1) for the 1990-2002 period was calculated by means of a General Linear Model which justified 41% of total variance. The most significant variables resulted to be the seasonal pattern of exploitation of the resource (month), and its pronounced concentration in the exploitation area (fishing position). Values of the standardized CPUE annual mean fluctuated with trends that were similar to those registered between 1993 and 2002. Due to fluctuations in the Chub mackerel abundance and the possible negative effect caused by the activity of large ships in El Rincón, a maximum annual catch of 13,000 t for 2003 is suggested for this area as a precautionary measure.
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    Muestreo de desembarque de caballa (Scomber japonicus) en el puerto de Mar del Plata, período noviembre 2003-diciembre 2004 y resultados de la campaña de estimación de la biomasa de diciembre de 2004
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Perrotta, Ricardo G.; Garciarena, A. David; Madirolas, A.; Cabreira, Ariel G.
    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 h-1), decreased as sea surface temperature increased. To estimate the species biomass in the fishing area a research cruise was carried out between 17-20 December 2004. Measurements, obtained with acoustic methods, reached a total of 11,678 t. The highest concentrations were found at a temperature of around 17.4 ºC and salinity of 33.62 psu. During the acoustic tracking, unusual concentrations of anchovy for the season were detected.