FISHERY BULLETIN: VOL 79, NO. 4 



present in 11 mo ( Figure 5). The apparent values of 

 1 - S were 100% within each month when A'', was 

 zero. In six other months the youngest group in the 

 ratio Nf/N^j was incompletely recruited off 

 Freeport, so that the following mortality rates 

 would be underestimates: 1) June 1978, 99.2%, 

 spring fish; September 1978, 98.9% , spring fish; 2) 

 May 1979, 99.5%, spring fish; June 1979, 99.9%, 

 spring fish; August 1979, 99.0% , spring fish; and 3) 

 December 1978, 98.8% , late summer fish. Because 

 the youngest spawned group in the ratio strongly 

 showed incomplete recruitment, realistic mortal- 

 ity estimates were not possible for the following 

 months: 1) spring groups. May 1977, Port Aransas; 

 2) late summer gi'oups, September, October, and 

 November 1977, Port Aransas; 3) spring groups. 

 May 1978, Freeport; and 4) late summer groups, 

 December 1977, September 1979, Freeport. Fol- 

 lowing the first procedure of Robson and Chapman 

 (1961), we calculated an average value of 1 - S = 

 99.79% by pooling identifiable Ng and A^^ values 

 from each month except the seven in which the 

 youngest spawned group strongly showed incom- 

 plete recruitment. 



Our observed estimates agree with the theory 

 (Royce 1972:238) that the total annual mortality 

 rate is about 90% if the lifespan is about 2 yr and 

 approaches 100% if 1 yr. Our high mortality esti- 

 mates are consistent with maximum sizes and 

 length frequencies in many published faunal 

 studies based on trawling in estuarine and gulf 

 waters. Theoretical values that 1 - S = 80-90% 

 based on lifespans of 2-3 yr appear to be lowest 

 tenable values even if the data include recre- 

 ational or trammel/gill net caught fish. 



TOTAL WEIGHT-, GIRTH-, AND 



STANDARD LENGTH-TOTAL LENGTH 



RELATIONS 



Total weight-total length, girth-total length, 

 and standard length-total length relationships are 

 presented in Table 4. Regressions of total weight 

 on total length were significantly different in 

 elevation between sexes (F = 5.38; 1, 1,501 df; 

 a = 0.05) but not in slope (F = 2.41; 1, 1,500 df; 

 a - 0.05). Calculated slopes significantly exceeded 

 p = S.Oata = 0.5 (data pooled, t = 18.85; males, 

 t = 15.10; females, t = 14.85). 



GENERAL DISCUSSION 



The fact thatC. arenarius produces two distinct, 

 664 



major spawned groups each year may be impor- 

 tant to its systematic status, management, and to 

 understanding its population fluctuations. 



The temporal separation of the spawned groups 

 implies reproductive isolation, the extent of which 

 remains to be determined. The existence of the 

 two spawned groups — and their systematic 

 status — must be considered in resolving the 

 status of C. arenarius. Ginsburg (1929), Mohsin 

 (1973), and Weinstein and Yerger (1976) did not 

 indicate the spawned groups studied. The two 

 spawned groups may be separate populations or, 

 possibly, separate species. That should be deter- 

 mined and considered in management because 

 fishing could affect them differently. 



The production of two major spawned groups 

 each year would minimize year to year population 

 fluctuations even though C. arenarius is short 

 lived and little more than an annual crop. As De- 

 Vries and Chittenden (footnote 6) noted for C 

 nothus, each spawned group buffers population 

 stability as a multiple year class structure buffers 

 longer lived species. Ricker reproduction curves 

 (Ricker 1954, 1975) might be useful to simulate 

 fluctuations of multiple spawned-group stocks. 



Many aspects of the life history and population 

 dynamics of C arenarius differ from C. regalis in 

 the Middle Atlantic Bight north of Cape Hatteras, 

 but C. arenarius appears similar to C. regalis 

 south of Cape Hatteras. In general, it appears that 

 for C. arenarius: 1) spawning lasts from March 

 through September but mainly occurs in two 

 peaks, a spring period (March-May) and a late 

 summer period (August-September); 2) maturity 

 is reached at 140-180 mm TL as they approach age 

 I and spawn; 3 ) maximum size typically is 350-375 

 mm TL, but most fish are much smaller so that C. 

 arenarius is not a major commercial food fish; 4) 

 maximum age typically is 1-2 yr, or 3 yr at most; 5) 

 total annual mortality rate is 80-90% or more, our 

 best estimate being 99%f , and 6) fish reach 210-280 

 mm TL at age I. 



The life history of C regalis in the Middle Atlan- 

 tic Bight is more difficult to enumerate, because it 

 makes north-south and onshore-offshore migra- 

 tions (Pearson 1932; Nesbit 1954; Wilk 1979). 

 Moreover, at least two intermixing populations 

 may occur there (Nesbit 1954; Perlmutter et al. 

 1956; Seguin 1960), although stocks remain un- 

 defined (Joseph 1972; Merriner 1973; Wilk 1979). 

 However, it appears that C. regalis north of Cape 

 Hatteras 1) spawn from May to August with one 

 peak period about April- June (statements of sev- 



