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Hypleurochilus fissicornis is a resident species of the intertidal and subtidal zones of Mar del Plata, Argentina. The specific reproductive biology was studied by means of both microscopic and macroscopic analyses. A total of 212 males and 223 females were analysed. Specimens were dissected and their gonads and livers were removed. The gonadosomatic and hepatosomatic indexes and the condition factor were calculated on a monthly basis. Hypleurochilus fissicornis breeds in rocky intertidal areas, and exhibits low fecundity with benthic eggs and parental care. Size at first maturity (L50) was estimated at 53.66 and 55.83 mm total length for females and males, respectively. The spawning season takes place between December and April. [ABSTRACT FROM AUTHOR]

The reproductive potential of red porgy in coastal waters of Buenos Aires Province (Argentina) and Uruguay (34°-39°S) was studied by means of a macroscopic and histological analysis of the gonads. Length and age at first maturity were determined, and fecundity, spawning frequency and egg quality were estimated. The spawning season extended from spring through summer between October and January with a peak of spawning in December. Length and age at maturity for sexes combined was 24.5 cm TL and 1.54 years, respectively. Batch fecundity ranged from 6,974 (25 cm TL) to 110,725 (39 cm TL) hydrated oocytes and showed significant linear relationships with total length and ovary-free weight. Relative fecundity ranged from 16 to 172 oocytes per female gram (ovary free). Spawning frequency was 58.5% during January 2011, indicating that females spawned once every 1-2 days at the peak of the spawning season. The life history of red porgy in Argentina and Uruguay was characterized by a young age at first maturity and partial, almost daily, spawning in a bounded time period, a life history strategy that would facilitate population expansion or colonization of new areas, and high population recovery rates or growth (r). [ABSTRACT FROM AUTHOR]

The reproductive biology of the Jenyns's sprat Ramnogaster arcuata in the Río de la Plata area was studied using macroscopic and histological analysis of ovaries. Samples were collected during two research surveys carried out in June 1998 and June 1999. In addition monthly occurrences of this species from historical data were analysed. Jenyns's sprat specimens were mainly observed in open waters of the estuary during winter months. Most of the females collected during June 1998 and 1999 were in the spawning stage. This pattern differs from fish that reproduce in the estuarine waters of the Río de la Plata, which spawn during spring and summer. These results suggest that conditions of productivity and larval retention in the estuary also remain during winter months. This characteristic might be useful for R. arcuata larvae in avoiding competition with other estuarine spawners. Jenyns's sprat is a multiple spawner with indeterminate annual fecundity. A preliminary estimate of spawning frequency (N = 220) indicated a daily percentage of females with postovulatory follicles of 17.35%, which suggests that this species spawns on average once every six days. Batch fecundity, estimated from counts of hydrated oocytes from 40 females, ranged from 669 to 2026 hydrated oocytes in 1998 and from 570 to 1830 hydrated oocytes in 1999. Batch fecundity was fitted to a linear function of total body weight (without ovary) in 1999. Mean relative fecundity was 234 hydrated oocytes per female gram (ovary free) in 1998 and 155 hydrated oocytes per female gram (ovary free) in 1999, and no significant relationship was observed between this parameter and female size. The dry weight of 100 hydrated oocytes ranged between 3.9 and 6.3 mg, these values being significantly higher than those estimated for other species of the Río de la Plata estuary. [ABSTRACT FROM PUBLISHER]