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| Registros recuperados: 18 | |
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| Rodrigues, K.A.; Macchi, G.J.. |
| Spawning and reproductive variables of the northern hake stock were analyzed using macroscopic and histologic gonad information derived from samples collected in May 2009. The study includes estimates of batch fecundity, spawning frequency, oocyte dry weight and size at first maturity. During May 2009 the reproductive activity of the northern hake stock took place mainly near the 50 m isobath, north of 37° S. Spawning occurred within a temperature range of 9 °C-15 °C that coincided with a bottom thermal front. Size at first maturity, much lower than that reported at the beginning of the 1980s, showed differences between males (27.16 cm TL) and females (32.84 cm TL). The reproductive frequency was estimated at one spawning every 13 days and mean batch... |
| Tipo: Journal Contribution |
Palavras-chave: Stocks; Spawning populations; Histology; Fecundity; Gadoid fisheries; Merluccius hubbsi; Marine environment. |
| Ano: 2011 |
URL: http://hdl.handle.net/1834/4883 |
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| Ehrlich, M.D.; Macchi, G.J.. |
| Hake Merluccius hubbsi fecundity was estimated with the gravimetric method using ovaries with hydrated oocytes without post-ovulatory follicles. Samples were obtained in three research cruises in the Argentine Sea, off Chubut Province, SW of Peninsula Valdes between 42°S and 45°S, near Isla Escondida, during December 1993, 1994 and 1996, time which coincides with the most important reproductive activity. Relative fecundity values were 722 plus or minus 107, 606 plus or minus 60 and 533 plus or minus 26 oocytes per gram of female without ovaries, respectively. Partial fecundity was adjusted to a potential model for total length and weight without ovaries, corresponding: F=0.9988 Lt3.294 and F=197.91 P1.1585 for 1994 and F=6.9785 Lt2.816 and F=552.22 P0.9889... |
| Tipo: Journal Contribution |
Palavras-chave: Fishery surveys; Juveniles; Fecundity; Gadoid fisheries; Stock assessment; Stock assessment; Juveniles; Fecundity; Http://aims.fao.org/aos/agrovoc/c_24251; Http://aims.fao.org/aos/agrovoc/c_25393; Http://aims.fao.org/aos/agrovoc/c_15725. |
| Ano: 2003 |
URL: http://hdl.handle.net/1834/2415 |
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| Pájaro, M.; Macchi, G.J.; Ehrlich, M.D.. |
| Batch fecundity and spawning frequency of Argentine hake inhabiting Patagonian waters south of 41° S were estimated using monthly samples collected during the December 2000-March 2001 reproductive season and at the end of the March 2002 spawning period. Batch fecundity was fitted to a power function of total length and a linear function of ovary-free female weight with values ranging between 100,000 (32 cm total length) and 2,300,000 (87 cm total length) hydrated oocytes. Batch and relative fecundity showed variations during the spawning season with a marked decrease towards the end of the reproductive period (March). The spawning frequency, which ranged between 0.10 and 0.15, was estimated from the proportion of females with day-1 postovulatory follicles... |
| Tipo: Journal Contribution |
Palavras-chave: Spawning seasons; Ovaries; Hake fisheries; Ovaries; Http://aims.fao.org/aos/agrovoc/c_5456. |
| Ano: 2006 |
URL: http://hdl.handle.net/1834/1566 |
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| Perrotta, R.G.; Madirolas, A.; Viñas, M.D.; Akselman, R.; Guerrero, R.A.; Sánchez, M.F.; López, F.; Castro Machado, F.; Macchi, G.J.. |
| 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... |
| Tipo: Journal Contribution |
Palavras-chave: Abundance; Biomass; Population structure; Zooplankton; Environmental conditions; Echo surveys; Biomass; Population structure; Zooplankton; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_6115; Http://aims.fao.org/aos/agrovoc/c_15490; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 1999 |
URL: http://hdl.handle.net/1834/2529 |
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| Perrotta, R.G.; Viñas, M.D.; Madirolas, A.; Reta, R.; Akselman, R.; Castro Machado, F.; Garciarena, A.D.; Macchi, G.J.; Moriondo Danovaro, P.; 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... |
| Tipo: Journal Contribution |
Palavras-chave: Population characteristics; Echo surveys; Mackerel fisheries; Fishery oceanography; Biomass; Environmental conditions; Fishery oceanography; Biomass; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_2938; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 2003 |
URL: http://hdl.handle.net/1834/2418 |
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| Perrotta, R.G.; Pertierra, J.P.; Viñas, M.D.; Macchi, G.J.; Tringali, L.S.. |
| 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... |
| Tipo: Journal Contribution |
Palavras-chave: Mackerel fisheries; Biomass; Catch/effort; Environmental conditions; Economic models; Commercial fishing; Biomass; Environmental conditions; Http://aims.fao.org/aos/agrovoc/c_926; Http://aims.fao.org/aos/agrovoc/c_32980. |
| Ano: 1998 |
URL: http://hdl.handle.net/1834/2465 |
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| Registros recuperados: 18 | |
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