MANOOCH; REPRODUCTIVE CYCLE OF RED PORGY 



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Gonad Index 



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MONTHS 



Figure 4.-Mean gonad indices for female Pagrus pagriis for 

 each month compared with photoperiod and bottom 

 temperatures. 



for the banded sunfish, Enneacanthus obesus. 

 Pagrus pagrus spawns between January and 

 April, when photoperiod increases rapidly, but 

 when bottom temperatures fluctuate irregularly. 

 Gonads were in spent and resting stages during 

 maximum photoperiod, May to August, and began 

 developing as photoperiod decreased. The graphs 

 suggest that seasonal increase in photoperiod in 

 late winter and early spring initiates final matu- 

 ration of ovaries and ultimately, the spawning of 

 P. pagrus. 



Eggs and Young 



Red porgy eggs are pelagic, spherical, without 

 appendages and contain a single oil droplet. Pre- 

 served eggs were generally yellow to orange in 

 color, they measured 0.31 to 0.94 mm in diameter 

 and the oil droplet was 0.20 to 0.32 mm in diameter. 



This size description is similar to the unfertilized 

 eggs of another sparid, Stenotomus chrysops, 

 which were 0.66 to 0.95 mm and had an oil droplet 

 0.17 to 0.40 mm in diameter (Finkelstein 1969). I 

 induced three females (355-560 mm TL) to release 

 ova in aquaria in March 1975. These eggs appeared 

 transparent and were noticeably larger than those 

 described above. Since I considered these eggs to 

 be most representative of mature, unfertilized 

 eggs, I recorded size for 10 eggs from each fish. 

 Their mean size was 0.88 mm in diameter and 

 ranged from 0.64 to 0.92 mm; the oil droplet aver- 

 aged 0.25 mm in diameter. Very little difference 

 was found in egg size for each fish. 



Prejuvenile red porgy were collected in April off 

 South Carolina. An 18-mm specimen had minute 

 spines along the dorsal and ventral outlines of the 

 body, and five to six vertical pigment bands 

 (Figure 5). These bars appeared red on stressed 

 adults. Ranzi (1969) described young P. pagrus 

 from the Bay of Naples and referred to the vertical 

 bands in specimens 13 mm and larger. 



Forty-four juvenile P. pagrus ranging in length 

 from 42 to 59 mm {X = 51 mm) were collected by 

 trawl off Charleston in relatively shallow water 

 (9-20 m); bottom temperatures ranged from 17.5° 

 to 18.5°C. The fish were also collected in April, 

 indicating spawning may occur slightly earlier in 

 that area compared with Onslow Bay and Raleigh 

 Bay, N.C. 



SUMMARY AND CONCLUSIONS 



Red porgy spawn in North Carolina waters from 

 January through April with a peak in spawning 

 activity between March and April. Maturation of 

 gonads and spawning appear to be correlated with 

 increased photoperiod. Spawning fish were col- 

 lected over irregular bottom ranging from 21 to 

 100 m in depth. Bottom temperatures at these 

 depths ranged from 16.4° to 21.5°C. Collection of 

 relatively large juveniles off Charleston in April 

 indicates that spawning may occur earlier there. 



Some female P. pagrus attain sexual maturity 

 as 2-yr-old fish; however, the majority mature at 3 

 yr. AH of the fish examined had reached sexual 

 maturity by the fourth year. Approximately 50% 

 of the females were mature at 304 mm TL, and 75% 

 were mature at 334 mm. All fish 364 mm or more in 

 length were sexually mature. Evidently, some of 

 the age II and III fish experience regular, seasonal 

 maturation of gonads but do not spawn that first 

 year. This conclusion is based upon several fish I 



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