Mann et al,: Reproduction and recruitment of Mugil curema 



817 



between August and January. Mullet from the 

 Margarita zone were small (4 to 36 cm in SL) 

 and mostly immature (>80%). Because size at 

 maturity of white mullet is 24 cm (Marin and 

 Dodson, unpubl. data), most of the adults in 

 the lagoon were probably in their first spawn- 

 ing cycle. Similarly, mullet from the Cariaco 

 Gulf zone also appeared to be young adults in 

 their first spawning cycle. In contrast, mullet 

 from the Chacopata zone were larger and 

 generally in more advanced stages of gonadal 

 development. This finding suggests that the 

 Chacopata mullet were part of a prespawning 

 aggregation, and the location of the aggrega- 

 tion agrees with the more offshore location of 

 the Chacopata fishery. 



Because white mullet spawn offshore (Ja- 

 cot, 1920; Anderson, 1957; Ditty and Shaw, 

 1996), the small proportion of mature fish 

 in the coastal fisheries from July to April is 

 likely explained by the migration of adults to 

 the offshore spawning grounds. If this is so, 

 reproduction is not indicated by an increase in 

 the frequency of fish in advanced stages, but 

 rather is associated with the disappearance of 

 maturing and mature fish from coastal areas. 

 The disappearance of fish in advanced stages 

 from coastal areas as the spawning season ap- 

 proaches was also reported by Angell (1973) 

 and Moore (1974). The analysis of birth dates 

 of juveniles sampled in the La Restinga La- 

 goon indicates that successful spawnings are 

 concentrated in the periods of increased up- 

 welling and also coincide with the end of the 

 rainy season. The spawning season may or may 

 not be concentrated at these times but larvae 

 that hatch during upwelling events are most 

 likely to successfully recruit to the lagoon. 



Although reproduction in tropical fishes 

 is often protracted, peaks in successful 

 spawning may nevertheless be initiated by 

 environmental cues (Redding and Patino, 

 1993). The white mullet possibly uses tem- 

 perature or other signals associated with 

 upwelling to synchronize its spawning with 

 upwelling events. The variations in the tim- 

 ing of recruitment of white mullet in differ- 

 ent geographical regions may be the result 

 of variation in the timing of favorable condi- 

 tions that enhance survival. Such conditions 

 may include increased primary production 

 (Ferraz-Reyes, 1983; Miiller-Karger et al., 

 1989) or hydrographic mechanisms likely to 

 facilitate transport of larvae to coastal nurs- 

 ery areas (Blaber, 1987), so that survival is 

 increased. Populations likely have adequate 

 time to adapt to environmental conditions in 

 particular areas because local hydrographic 

 patterns develop over geological time scales 

 (Bakun, 1986; Sinclair, 1988; Heath, 1992). 



Uj 



a. 

 o 



jlllu. 



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miiL 



noc 



n = 416 



iDnDnc 



JlDnnnnnn n n n 



_dQ 



jmd 



jaa 



n = 103 



jm 



nn_ 



nnnr,n 



nnn^nnnnnOnn r. 



n = 88 



,nnnn) 



nflnn 



Innr 



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n = S7 



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Jim 



iiliiiii. 



ilii ..III 



lUlllliIh^ 



^■lIUImlBllkMlL 



JUI.Ulill. 



-■Illl 



n = 66 



Mar-05 



Mar-19 



Apr-02 



Apr-14 



Apr-30 



May-14 



May-28 



Jun-11 



Jun-25 



Jljl-08 



Jul-23 



Aug-05 



Aug-20 



Sep-03 



Sep-17 



Oct-02 



OcM5 



Ocl-29 



Nov-10 



Nov-26 



Dec- 10 



Dec-28 



Jan-08 



Jan-21 



Feb-04 



Mar-04 



Mar-18 



Apr-01 



Apr-15 



Apr-29 



May-13 



May-25 



Jun-10 



Jun-25 



Jul-08 



Jul-22 



1992 



1993 



10 30 50 70 90 110 130 150 170 190 210 



Standard length (mm) 



Figure 8 



Semimonthly size distributions of juvenile white mullet from March 1992 

 to July 1993 in La Restinga Lagoon. The abundance for each size class is 

 presented as the Log CPUE + 1. From top to bottom, open bars represent 

 cohort 1, black bars represent cohort 2, gray bars represent cohort 3, and 

 black bars represent cohort 4. Cohorts were identified by discontinuities 

 in size distributions of juveniles, n = number offish sampled. 



