Fecundidad y frecuencia reproductiva de las poblaciones bonaerense y patagónica de anchoíta Argentina Engraulis anchoita.

Abstract

Fecundity and spawning frequency were estimated in the northern(off Buenos Aires Province)and southern (patagonian)argentine anchovy Engraulis anchoita populations in 1993, during the peak of the spawning season. Relative fecundity, expressed as eggs per ovary-free weight was 574±21 (CI 95. ) and 605±49 (CI 95. ) in the northern and southern populations. The difference was not statistically significant between stocks (P0.13). Relative fecundity was higher in anchovies larger than 130 mm. The mean batch fecundity for the northern and southern populations was 13675±856 (CI 95. ) and21677±2.753 (CI 95. ) respectively. Batch fecundity (F)expressed as alinear function of ovary-free weight (W)was: F=-1310+649 * W(northern), F=-5935+786 * W (southern). The daily spawning incidence was estimated in 12,6. ±3.3 (CI 95. ) for the northern population and 15,5. ±8.5 (CI 95. ) for the southern. The females spawned about every 7.9 and 6.5 days respectively. A low incidence of alpha and bethastages atresia in ovaries was founded in both populations (less than 2. yolked oocytes affected). Relative egg production for anchovies ages 1-2 and ages 2-3 were estimated to contribute 74. and 64. to egg production in the northern and southern stocks during the peak of the spawning season. It was observed a direct relationship between collections with male-dominated schools and females with hidrated and recent post-ovulattory follicles.