Milton et al.: Reproductive biology and egg production of three species of Clupeidae 



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Figure 4 



Monthly variation (±95% confidence limits) in (A) 

 condition, (B) visceral fat index, (C) hepatosomatic 

 index and (D) proportion spawning of female 

 Spratelloides delicatulus from Kiribati between 

 November 1988 and May 1991. 



8000-. 



50 



100 



150 



Figure 5 



The relationship between batch fecundity and 

 fish weight for (A) Amblygaster sirm, (B) 

 Herklotsichthys quadrimaculatus and (C) 

 Spratelloides delicatulus from Kiribati. 



Discussion 



The reproductive cycles of A. sirm, H. quadrima- 

 culatus, and S. delicatulus in Kiribati are similar to 

 that reported for temperate multiple-spawning 

 clupeoids (Hunter and Goldberg, 1980; Gil and Lee, 

 1986; Shelton, 1987; Alheit, 1989). Most studies on 

 multiple spawning clupeoids have been on 

 engraulids; these species spawn many batches of 

 eggs each year and have variable batch fecundity 

 (Alheit, 1989). Our results for H. quadrimaculatus 



and S. delicatulus from Kiribati agree with previ- 

 ous reproductive studies of these species in tropical 

 areas (McCarthy, 1985 1 ; Moussac and Poupon, 1986; 

 Milton and Blaber, 1991). In the tropics, both spe- 

 cies spawn throughout the year, but have periods 

 when spawning activity is greater. In more temper- 

 ate parts of their range, the reproductive season of 

 both H. quadrimaculatus and S. delicatulus is 

 shorter and coincides with increases in water tem- 

 perature in early summer (Williams and Clarke, 

 1983; Lewis et al., 1983; Conand, 1988). 



