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| Leonarduzzi, E.. |
| Age and growth rates of southern anchovy larvae (Engraulis anchoita)were estimated by analysis of daily increments in sagittal otoliths under light microscopy. Samples were collected during 2002 with a bongo net, in the Buenos Aires province, Argentine Sea (SW Atlantic). Otoliths corresponding to 251 larvae (size range 3.5 u 12.2 mm SL)were analyzed. Growth rate estimated as slopes by linear regression of length-age data were 0.50, 0.40, and 0.42 mm/day, and these values corresponded to larvae collected in spring, summer and autumn. Larval growth were significantly distinct between the year seasons (ANCOVA, p<0.01). Recent larval growth expressed as mean growth rates during the last 4 days of the larvae was not correlated with surface temperature. The... |
| Tipo: Theses and Dissertations |
Palavras-chave: Fish larvae; Growth; Otoliths; Seasonal variations; Daily variation; Growth; Otoliths; Fish larvae. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/1484 |
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| Brown, D.R.; Leonarduzzi, E.; Averbuj, A.; Livore, J.P.. |
| Argentine anchovy (Engraulis anchoita) eggs and larvae abundance distribution patterns in the Argentine northpatagonian littoral during January-April 2001 were analyzed. As the season progressed, a process of decline in the reproductive activity was observed. Larval growth and mortality rates were established. Age determinations were performed analyzing otoliths daily increments. The 0.43 mm day-1 growth rate average did not show space-time differences, fact attributed to the homogeneity of the thermal field. The 0.32 d-1 January natural mortality rate was determined by exponential decline. Mortality rates, estimated with the mortality-aggregation model, were considered dependent on the larval size. The value ranges (d-1) were 0.07-0.49, 0.05-0.61 and... |
| Tipo: Journal Contribution |
Palavras-chave: Fish larvae; Growth; Otoliths; Mortality. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5500 |
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| Leonarduzzi, E.; Di Marco, E.J.; Pájaro, M.. |
| The daily spawning females fraction (S) of Argentine anchovy (Engraulis anchoita) in relation to the year, length, proportion of females, temperature and salinity variables was studied using generalized linear models. Samples were collected during eleven research surveys carried out in the main spawning seasons and areas during 1993-2008 (Southwest Atlantic Ocean, Argentine Sea). The aim of this work was to identify the factors that affect the spawning activity. No temporary differences were observed and an S 0.12 average value was estimated. The poor explanatory percentage of the models analyzed did not allow to clearly detect the variables that could affect S. Length and temperature were the only variables that related positively, which suggests that... |
| Tipo: Journal Contribution |
Palavras-chave: Pelagic fish; Reproduction; Biomass; Spawning; Mathematical models. |
| Ano: 2013 |
URL: http://hdl.handle.net/1834/5492 |
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| Leonarduzzi, E.; Massa, A.E.; Manca, E.A.. |
| The biochemical composition and energy content of muscle, liver and gonads of Merluccius hubbsi females during the reproductive cycle were assessed. Adult females (44-50 cm total length) were caught in the Patagonian area (43~' S-45~' S). Condition factor (K) and hepatosomatic index (HSI) were estimated. Proteins and lipids in each tissue were determined. Besides, water and ashes content in muscle was analyzed. In all tissues the biochemical components underwent variations during the reproductive cycle. During the process gonads showed a significant drop in protein and lipid content (P < 0.01). In muscle, a decrease in proteins (P < 0.01) and lipids in the postspawning period was observed; the percentage of both components increased during the... |
| Tipo: Journal Contribution |
Palavras-chave: Chemical composition Reproductive cycle Proteins Lipids Merluccius hubbsi PSW; Argentina marine environment. |
| Ano: 2012 |
URL: http://hdl.handle.net/1834/4908 |
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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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