Browsing by Author "Cordo, H.D."

Now showing 1 - 6 of 6
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    Descripción macroscópica de los ovarios del abadejo manchado (Genypterus blacodes). Escala de maduración
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Machinandiarena, Laura; Villarino, M.F.; Cordo, H.D.; Macchi, Gustavo J.; Pájaro, Marcelo
    The macroscopic ovaric stages of pink cuskeel (Genypterus blacodes) females from the Argentine Sea (SW Atlantic) are described. They were classified in five stages of development based on changes in the appearance and size of the ovary: juvenile (I), developing (II), spawning (III), spent (IV) and resting (V).
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    Estimación de un índice de abundancia anual de gatuzo (Mustelus schmitti) a partir de datos de la flota comercial argentina. Período 1992-2008
    (INIDEP, 2011) Pérez, M.; Massa, A.M.; Cordo, H.D.
    Patagonian smoothhound (Mustelus schmitti) is one of the predominant cartilaginous fishes of the Argentine Sea (SW Atlantic Ocean). It is caught, mainly, in the coastal multispecific fishery with nearly other 30 bony and cartilaginous species. The group is known as ‘variado costero’. In this work the smoothhound abundance indices (CPUE) and standardized efforts for the 1992-2008 period in the area between 34~’S-42~’S were estimated. The General Lineal Model (GLM) and data derived from the argentine commercial fleet were used. Other aspects that could affect estimates and trends of the annual indices were also analyzed. Mean CPUE values estimated with the GLM, considered as annual standardized abundance indices, show an increasing trend as of 2000; the highest relative levels correspond to the last three years of the study period
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    Estructura y abundancia del stock reproductor del abadejo (Genypterus blacodes) del Mar Argentino en el período 1995-2000
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Cordo, H.D.
    The structure and abundance of Ling spawning stock were analized from basic biological and oceanographic data recorded during research surveys carried out by INIDEP between 1995 and 2000, to assess the juveniles fraction of common hake stock (January) and of Argentine patagonian squid (February). Jointly both surveys covered the main spawning area of Ling between 44º S and 48º S and approximately between the mouth of San Jorge Gulf (60º W) and 200 m isobath (65º 30’ W) during the summer season (mid-December to mid-March). Size structures and maturity stages confirmed the presence of a spawning unit in the area covered by the surveys. This enabled the estimate of an annual index of Ling spawning stock abundance. Abundance shows a decreasing trend since 1995, even when it seems to stop during 2000. Nevertheless, abundance estimates during 2000 represent 58% of the corresponding figure for 1995. This represents a significant decrease in the reproductive stock over a relatively short period of time. A possible solution to put an end to the decreasing trend would be to establish a fishing ban area, complementary to that created to protect hake juveniles, extended only during Ling reproductive season, namely every year between December 15 and March 15.
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    Evaluación de merluza de cola (Macruronus magellanicus) en el Atlántico Sudoccidental. Período 1985-2001
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2007) Wöhler, O.C.; Hansen, J.E.; Giussi, A.R.; Cordo, H.D.
    Period 1985-2001. A stock assessment of Patagonian hoki of the Southwest Atlantic was carried out by using data from the years 1985-2001. A cohort analysis, fitted with some survey abundance indices was used in an adaptive conceptual framework. Simulation trials were performed to project the evolution of the fishery, to evaluate the risk of over-fish the stock under different exploitation levels, and to estimate Biologically Acceptable Catches (BAC). Both total biomass and spawning stock biomass showed increasing trends resulting from four strong year classes (1993, 1995, 1996 and 1998). Total biomass at the beginning of 2001 was estimated to be 2.5 million tons, and spawning stock biomass at the spawning time (August) was estimated to be around 1.28 million tons. The exploitation rate was low (0.19) and showed a decreasing trend in relation to previous years. The fishing mortality rate producing sustainable total catches in the long term, i.e., BAC corresponded to yields between 160 and 306 thousand tons during 2002, depending on future levels of recruitment
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    Evaluación de polaca (Micromesistius australis) en el Atlántico Sudoccidental. Período 1987-2001
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2007) Wöhler, O.C.; Hansen, J.E.; Cassia, M.C.; Cordo, H.D.
    Period 1987-2001. A diagnosis of the current state of Southern blue whiting (Micromesistius australis) stock in the Southwest Atlantic was carried out on the basis of catches corresponding to the period 1987-2001 as reported by the Argentine fleet and also by vessels operating around Malvinas Islands. Abundance and current fishing mortality rates were estimated, and the biomass evolution in the long term resulting from some possible exploitation strategies based on different management strategies were projected. A sequential population analysis calibrated under a conceptual adjustable framework with five independent abundance indices was carried out. The effects on the biomass estimates were analysed by adopting different selection patterns and calibration indices as well as taking into account the under-declaration and discard of catches. Results indicated that the declining trend of Southern Blue Whiting observed in previous studies has continued, but it has been less marked than in preceding years. Total biomass estimates at the beginning of 2001 ranged between 566 and 622 thousand tonnes, whether the under-reporting or discards of catches by the Argentine fleet were taken into account or not. Accordingly, the spawning biomass at the onset of spawning ranged between 403 and 442 thousand tonnes. These values would correspond to 27-29% of the virgin biomass. Current fishing mortality was estimated as 0.27, corresponding to a relatively high exploitation rate (0.56). Projections aimed at four possible management objectives showed that biologically acceptable catches would range 22-84 thousand tonnes in 2002. Catches in the Southwest Atlantic should not exceed 50 thousand tonnes during 2002 in order to stop the declining trend of Southern blue whiting biomass.
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    Evaluación del recurso abadejo y recomendaciones sobre su explotación a partir del año 2002
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2007) Cordo, H.D.
    Ling (Genypterus blacodes) resource was assessed by means of an age structured production model fitted with stock abundance indices from catch per unit effort data (CPUE) obtained from the commercial fishing fleet. Reproductive stock was assessed in the same way with CPUE data from the fishery research vessel. A short-term analysis of collapse risk as a function of 1999 and 2000 fishing mortalities was carried out with the results, and also a long-term analysis with the assumption of a variable fishing mortality (F) with two recruitment hypotheses. Results show that the present state of the Ling resource has worsened with respect to the last assessment. Considering the best of all cases, the Br/Kr relationship decreased from 0.55 to 0.33, indicating that the reproductive stock is near the acceptable limit assumed in this paper. Risk analysis pointed out that catch should be kept at a level of 16,000 t year-1 in the long term to maintain collapse risk within acceptable levels ( 10%). This would imply decreasing total allowable catch levels, currently at 19,000 t year-1. Nevertheless, since Ling is in great proportion, a by-catch of the common hake fishery, catch levels are regulated to a great extent by the effort directed to hake. In addition, it was observed that Ling catch by longliners increased from 137 t in 1998 to 3.088 t in 2001. This implies an increase in fishing effort oriented to Ling. From the above discussion it is inferred as necessary to limit fishing effort oriented to Ling particularly that exerted during the first quarter of the year around the reproductive area. Based on results from this and other reports, some proposals for management of the species starting from the year 2002 are indicated.