FISHERY BULLETIN: VOL. 80. NO. 3 



Table 4.— Analyses of total weight-standard length, girth-standard length, and standard length-total 

 length relationships for C. nothus. Lengths and girths are in millimeters and weights are in grams. 



significant ata =0.01. Coefficients of determina- 

 tion (100 r 2 ) were 97% for girth-standard length 

 relationships but 99% for total weight-standard 

 length and standard length-total length relation- 

 ships. All relationships were based on fish whose 

 standard length range was 26-188 mm. 



DISCUSSION 



Spawning 



Our findings on C. nothus reproduction agree 

 with the limited literature. The finding of spawn- 

 ing from May to late October is consistent with 

 reports of 1) fish about 35-40 mm TL (26-30 mm 

 SL) or smaller from June to December (Hilde- 

 brand and Cable 1934; Hoese 1965; Christmas 

 and Waller 1973; Mahood 1974), 2) ripe individ- 

 uals in mid-May (Miller 1965) and throughout 

 August (Gunter 1945; Hildebrand 1954), and 3) 

 late-developing specimens in August and Sep- 

 tember (Mahood 1974). Our finding of peak 

 spawning in late summer agrees with Gunter 

 (1945) and Chittenden and McEachran (1976), 

 and with the dominance of a late summer- 

 spawned group in Mahood (1974, fig. 13). The 

 small size at maturity is consistent with Miller's 

 (1965) report of running ripe females only 135- 

 140 mm TL (110-114 mm SL), although the small- 

 est fish that Mahood (1974) collected in late- 

 developing or spent condition was 205 mm TL 

 (168 mm SL). Our finding of May-, August-, and 

 September-spawned groups is similar to the 

 spring peak and late summer or fall peak of 

 reproduction reported for C. nothus (Mahood 

 1974) and for C. arenarius (Shlossman and Chit- 

 tenden 1981). The latter workers suggested that 

 the spawning periodicity of C. arenarius was 

 timed to coincide with the two major periods of 

 rising sea level in the northern Gulf of Mexico 

 each year when surface currents could transport 

 eggs and/or larvae to inshore or estuarine nurs- 

 eries. Spawning of C. nothus in the Gulf of Mexi- 

 co probably is timed also to take advantage of 



such current transport. We have observed that 

 C. nothus exhibits two distinct peaks of spawning 

 within the August-September major spawning 

 period. It is not yet clear 1) whether multiple- 

 spawned group production consistently occurs 

 within the late summer reproduction period, 

 which would imply spawning keyed to regu- 

 lar intraperiod cues, or 2) whether multiple- 

 spawned group production in the late summer 

 period reflects irregular happenstances such as 

 the increased survival and recruitment that 

 could occur if reproduction at times coincided 

 with unusually favorable current transport 

 (Hjort 1914, 1926; Nelson et al. 1977), or if a criti- 

 cal larval period (Marr 1956; May 1974) irregu- 

 larly coincided with an unusually great food 

 supply. 



Growth and Age Determination 



Our estimates that C. nothus in the northern 

 Gulf of Mexico reach 130-190 mm SL and aver- 

 age 150 mm or more when they disappear at age 

 I agree with Chittenden and McEachran (1976) 

 and Chittenden (1977) that C. nothus reaches 

 120-150 mm SL (150-185 mm TL) at age I. Gun- 

 ter's (1945) estimate that fish 75-110 mm SL (93- 

 138 mm TL) taken in May were about 1 yr old is 

 low and may have been based on fish that actu- 

 ally would not have reached age I until the major 

 spawning period of August-September. None of 

 these cited workers, though, recognized the mul- 

 tiple-spawned group composition of this species 

 and their estimates of age could be in error. Our 

 estimates for C. nothus agree with estimates for 

 C. nebulosus of 157-165 mm SL at age I (Pearson 

 1929; Moody 1950; Tabb 1961), although lower 

 estimates of 116 and 130 mm SL have been re- 

 ported (Klima and Tabb 1959; Moffett 1961). The 

 growth of C. nothus also agrees with estimates 

 for C. regalis of 143-180 mm SL at age I (Merri- 

 ner 1973). Seasonal growth of August-September 

 spawned C. nothus appears comparable to that of 

 C. nebulosus and C. regalis. Pearson (1929) found 



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