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| Registros recuperados: 25 | |
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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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| Wöhler, O.C.; Giussi, A.R.; Hansen, J.E.. |
| Sequential population analysis on Long Tail Hake (Macruronus magellanicus)from the Southwest Atlantic. Years 1985-1995. VPA on the Long Tail Hake (Macruronus magellanicus), based on data covering the years 1985 up to 1995, was performed to assess the current state of the stock. Simulation trials, inducing uncertainty about both the natural mortality rate and recruitment were also accomplished, to evaluate the risk of overfishing which is associated to different fishing alternatives, always under the assumption of a single and closed Long Tail Hake population. CPUE data were not appropriate for tunning, so the traditional VPA has been applied. During the period of study, stock biomass and spawning stock biomass showed an increased trend. Long and short-term... |
| Tipo: Journal Contribution |
Palavras-chave: Stock assessment; Fishery management; Catch/effort; Fishing mortality; Overfishing; Biomass; Sexual maturity; Stock assessment; Fishery management; Biomass; Overfishing; Sexual maturity; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_34068; Http://aims.fao.org/aos/agrovoc/c_7016. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/1875 |
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| Pájaro, M.; Hansen, J.E.; Leonarduzzi, E.. |
| Engraulis anchoita northern stock reproductive biomass (SSB) during the 1993-2008 period was estimated applying the Daily Egg Production Method (DEPM) and accuracy of estimates assessed using a bootstrap technique (SW Atlantic Ocean, Argentine Sea). The basic data were collected in different research surveys carried out in late Spring, at the peak of the spawning season. The aim of this work was to build reliable confidence intervals around the estimates of the mean reproductive biomass applying a non-parametric bootstrap method. Resampling methods are becoming increasingly popular as statistical tools as they are robust and do not require the assumption of any particular distribution of the basic data. This is especially relevant when assessing the DEPM... |
| Tipo: Journal Contribution |
Palavras-chave: Spawning; Stocks; Fecundity; Biomass; Statistical analysis. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5494 |
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| Hansen, J.E.. |
| Collete and Chao (1975) reviewed the systematic and morphology of the Genus Sarda and relatives ((Tribe Sardini), including into their analysis a few S.sarda from the SW Atlantic. Before that, Demir (1964)dealt with the meristic data of the same species from the Black Sea. This paper in concerned with the featuring of the bonito caught in Argentina, from both a morphometric and a meristic point of view. The study made the differences reported by Collette and Chao (op.cit.)among W and E S.sarda populations to be more conspicuous, because our samples had even lower values han those from the NW. |
| Tipo: Journal Contribution |
Palavras-chave: Meristic counts; Morphometry. |
| Ano: 1988 |
URL: http://hdl.handle.net/1834/1966 |
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| Hansen, J.E.; Cousseau, M.B.; Gru, D.L.. |
| A total of 7263 otoliths were collected from anchovy samples taken during two pelagic cruises which were carried out in the Spring of 1978. An statistical analysis of back calculated length distributions of one-year-old fish (L1)was made. The L1 mean values taken by geographical latitude form a cline, with higher values in the northern samples, and decreasing Southwards. Within this latitudinal gradient two main anchovy populations can be identified, one in the region of Buenos Aires Province and the other in Patagonian waters. The L1 of the females is significatively larger than that of the males for the former population, whereas in the Patagonian area differences between sexes are not significant. The parameters of the von Bertalanffy Growth curves, as... |
| Tipo: Journal Contribution |
Palavras-chave: Stock identification; Otolith reading; Growth curves; Mortality; Mortality; Http://aims.fao.org/aos/agrovoc/c_4945. |
| Ano: 1984 |
URL: http://hdl.handle.net/1834/2043 |
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| Hansen, J.E.; Garciarena, A.D.. |
| As part of the research programs performed yearly at the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP, Mar del Plata, Argentina) some important basic data about the commercial fisheries usually included in internal reports are registered. This formal paper is a review and summary of size and age composition estimates of commercial catches (discards included) of Northern Argentine anchovy (34ºS-41ºS) obtained between 1990-2011. The basic data resulting from the examination of 521 samples from fishing vessels included 62,466 fish length measurements and 26,667 valid age readings from which the corresponding 22 annual age-length keys were built. The annual estimates of the individual total length-total weight relation parameters and of... |
| Tipo: Journal Contribution |
Palavras-chave: Pelagic fisheries; Stock assessment; Commercial fishing; Catch composition; Age composition; Size distribution; Clupeoid fisheries. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5502 |
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| Cassia, M.C.; Hansen, J.E.. |
| The Patagonian cod (Salilota australis) inhabits the SW Atlantic from 38°S up to 55°S, as well as the Pacific Ocean from 40°S up to 57°S. The annual catches of this species by both the Argentine fleet and those operating around the Malvinas Islands have significantly increased during the decade 1990-2000, peaking to 16,556 t in 1996. After this, a marked decrease in landings was noticed, and during 2003 the catch was 7,924 t. Seasonal distribution, concentration grounds, and population structure of the Patagonian cod from the Argentine Sea are described, and the mean densities of the species are seasonally related to latitude, temperature and depth, on the basis of data from surveys carried out by the INIDEP research vessels in 1992 and 1993. Highest mean... |
| Tipo: Journal Contribution |
Palavras-chave: Gadoid fisheries; Seasonal distribution; Population density; Population structure; Biomass; Population structure; Biomass; Population density; Http://aims.fao.org/aos/agrovoc/c_6115; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_6112. |
| Ano: 2005 |
URL: http://hdl.handle.net/1834/1561 |
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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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| 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... |
| Tipo: Journal Contribution |
Palavras-chave: Stock assessment; Fishery management; Biomass; Risks; Demersal fisheries; Stock assessment; Fishery management; Biomass; Demersal fisheries; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_24026; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_2173. |
| Ano: 2007 |
URL: http://hdl.handle.net/1834/2525 |
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| Hansen, J.E.. |
| This paper deals with the commercial landings of bonaerensis anchovy at the Port of Mar del Plata (Buenos Aires province,Argentina), during the years 1986 to 1990. The mean catch was 15,501t per year. A total of 59 fish samples were taken for total length distributions (N=20164), and 24 sub-samples (N=2370) were analyzed to record individual data (length, weight, sex, sexual stage, age fromotoliths reading). The numer of fish per kg ranged between 28 and 53(mean=34.6). The mean size was 156.63 mm, and the most abundant fish in the landings were those being 3 and 2 years old, as it was also recorded during the period 1980-1985. Ordinary length-weight relationships by season were fitted, and the results were as follows:1) Autumn-Winter: W=8.5* 10-7* L3.392;... |
| Tipo: Journal Contribution |
Palavras-chave: Length-weight relationships; Size distribution; Sexual maturity; Clupeoid fisheries; Biological sampling; Age composition; Commercial land use; Cohort analysis. |
| Ano: 1997 |
URL: http://hdl.handle.net/1834/5794 |
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| Hansen, J.E.. |
| The aim of this paper was to accurately estimate population parameters of northern (“bonaerensis”, latitude < 41° S) and southern (“patagonic”, latitude 41° S) Argentine anchovy stocks and to describe some aspects of their behaviour. The research surveys allowed to obtain data on length, total weight, sex, maturity and age of 27,853 specimens of the northern and 12,787 of the southern stocks. Besides, 20,717 age determinations stemmed from commercial landing samplings of the northern stock were established. Sex proportion in the northern population was 0.50 : 0.50; the southern showed a slight predominance of males (0.52 : 0.48). Data derived from cruises and commercial landings showed statistical differences in the growth ratio of the northern stock... |
| Tipo: Journal Contribution |
Palavras-chave: Pelagic fisheries; Stocks; Population characteristics; Growth; Natural mortality; Sexual maturity; Engraulis anchoita; Marine environment. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/4884 |
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| Registros recuperados: 25 | |
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