Dee and Parrish: Reproductive and trophic ecology of Mynpristis amaena 



52! 



mens taken between 2000 and 0200 hours 

 contained identifiable prey items. From 62 

 guts collected in the daytime, only four 

 (taken at 0730 hours) contained more than 

 one identifiable food item. At Puako, all 

 11 guts collected between 2300 and 0930 

 hours contained identifiable prey items, all 

 of which might reasonably be the result of 

 night or dawn feeding. Eleven specimens 

 taken between 1000 and 1300 hours con- 

 tained some food, much of it only uniden- 

 tified crustacean parts. Sixteen specimens 

 collected between 1100 and 1500 hours 

 contained no identifiable prey. Of 61 speci- 

 mens from the NWHI, only nine (collected 

 between 0800 and 1100 hours) contained 

 identifiable prey, mostly considerably di- 

 gested. The remaining 52 specimens, col- 

 lected between 1000 and 1600 hours, were 

 empty or contained well digested, uniden- 

 tifiable material. 



Reproduction 



The GSI of each sex collected during reproductive 

 periods throughout the year from JA and Puako com- 

 bined indicated an increase in the range of 153-156 

 mm SL for females (Fig. 1) and in the range of 149- 

 156 mm SL for males (Fig. 2). Based on histological 

 examination of developing oocytes in JA females, five 

 developmental stages were identified (Table 1). 



Sexual maturity was defined based on the presence 

 of ovaries with oocytes in the late yolk granule stage 

 for females (>0.4 mm diameter; see Fig. 3) and on 

 the presence of mature sperm in males (Fig. 4). The 

 11 ovaries and five testes examined histologically 

 indicated that first sexual maturity occurred near 

 154 mm SL for females and 149 mm SL for males. 

 The results were consistent with those 

 from visual examination of 24 total gonads 

 (males and females) from Puako. 



When GSI of mature specimens (larger 

 than 145 mm SL) from JA was plotted 

 against month of capture, with data from 

 all months except September, spawning 

 peaks were discernible in January, April, 

 May, and October; the major peak was in 

 April (Fig. 5). Based on visual examina- 

 tion, GSI, and histology, no gravid indi- 

 viduals were recorded among specimens 

 collected during any other month. 

 (Samples were rather small in some 

 months.) 



The fecundity estimated from the 12 

 ovaries sampled at JA ranged from 12,400 

 mature ova for a 156-mm SL fish to 69,200 

 for a 181-mm SL fish (Appendix B). Re- 

 gressions were performed with fecundity, 

 F, in number of mature eggs as a function 

 of standard length, SL, in millimeters, and 

 alternatively as a function of whole wet 

 body weight, W, in grams. The fit was 



