

termination would probably be as accurate from 

 intensive length frequencies alone. The long 

 spawning season and multiple-spawned group 

 compositions complicate age determination. 

 Exact age determination may be difficult for the 

 few fish age II or older. The few fish of these ages 

 might not be distinct in length frequencies and a 

 spawned group probably could not be assigned. 

 Growth and mortality estimates for C. nothus 

 should be based upon individual spawned groups 

 to avoid misinterpretation. 



Maximum Size, Life Span, 

 and Mortality 



The largest specimen of C. nothus that we cap- 

 tured (190 mm SL = 230 mm TL) is similar to the 

 maximum sizes typically reported (Hildebrand 

 and Cable 1934; Gunter 1945; Hildebrand 1954; 

 Christmas and Waller 1973; Chittenden and 

 McEachran 1976). The only published records of 

 fish much >190 mm SL include a specimen 315 

 mm SL (380 mm TL) from the Gulf of Mexico off 

 Mississippi (Franks et al. 1972), a few specimens 

 to 259 mm SL (312 mm TL) from industrial fish 

 catches in the gulf (Thompson 1966), and Ma- 

 hood's (1974) report of two fish 255 mm SL (308 

 mm TL) from the Atlantic Ocean off Georgia. 

 Net avoidance and/or behavioral change to a 

 midwater life-style probably does not explain the 

 absence of C. nothus >190 mm SL off Texas, be- 

 cause we collected many C. arenarius to 283 mm 

 SL. Large C. nothus apparently do not occupy 

 water deeper than 46 m off Texas, because twice 

 monthly day and night collections at 55-100 m in 

 the period June 1979- August 1980 have not cap- 

 tured larger fish (Chittenden, unpubl. data). The 

 absence of large C. nothus off Texas might indi- 

 cate movement to rough, normally untrawled 

 substrate or possibly a spawning or postspawn- 

 ing movement to the northcentral gulf. Large C. 

 nothus to 225-250 mm SL occur in deep water in 

 the northcentral gulf (E. Gutherzand B. Rohr ), 

 but the comparative percentage of these large 

 fish needs further study. Based on our data and 

 the published literature, however, it appears 

 that C. nothus does not exist in significant num- 

 bers at sizes >190 mm SL. Even Mahood's(1974) 

 data indicate that only 4% of his specimens were 

 >188 mm SL. 



6 E. Gutherz and B. Rohr, Fishery Biologists, Southeast 

 Fisheries Center Pascagoula Laboratory, National Marine 

 Fisheries Service, NOAA, Pascagoula, MI 39567, pers. com- 

 mun. January 1981. 



FISHERY BULLETIN: VOL. 80, NO. 3 



The maximum life span of C. nothus is only 1- 

 1.5 yr off Texas, although it might be as long as 2 

 yr in the northcentral gulf or off the southeast 

 United States. A value of ti. = 1-1.5 yr seems 

 reasonable for Texas waters because fish >160- 

 180 mm SL (the average size at age I) made up 

 <l-0.5% of our catch. Our estimate is supported 

 by the absence of fish with more than one annu- 

 lus and by the complete disappearance of fish 

 after age I. This agrees with Chittenden and 

 McEachran's (1976) estimate that the life span is 

 little more than 1 yr. A ti value as large as 2.0 yr 

 seems tenable only for Mahood's (1974) data and, 

 possibly, for the northcentral gulf where some 

 fish reach larger sizes than we observed. 



Our observed mortality estimates agree with 

 theory (White and Chittenden 1977; Royce 1972: 

 238) that the total annual mortality rate is 90- 

 100% if the life span is only about 1-2 yr. Our best 

 estimate that 1 — S is 99% may be a slight over- 

 estimate, particularly if large fish exhibit sig- 

 nificant spawning or postspawning migration to 

 the northcentral gulf. However, it seems un- 

 likely that many fish survive beyond 2 yr and 

 that 1 - Sis <90%. This is supported by Mahood's 

 (1974) data which suggest a 96% mortality rate 

 for C. nothus off the southeast coast of the United 

 States, assuming that all his specimens >188 

 mm SL were age II fish. The high mortality rate 

 that we have found explains why few C. nothus 

 had an annulus. Most fish probably die before or 

 while a mark forms on the scales. 



Distribution and Availability 



The disappearance of large C. nothus that we 

 found during winter agrees with Mahood (1974, 

 table 8), who reported only six specimens (of 947 

 fish) >130 mm SL (160 mm TL) from October 

 through April, and with Hildebrand and Cable 

 (1934), who reported no C. nothus captured off 

 Beaufort Inlet, N.C., during winter although 

 they were rather common in summer. The dis- 

 appearance of large C. nothus during the colder 

 months and their subsequent reappearance in 

 spring probably reflects an offshore overwinter- 

 ing movement of large fish. This interpretation 

 is supported by 1) reanalysis of Chittenden and 

 McEachran's (1976, fig. 10) data on distribution 

 of C. nothus in mid-January (Fig. 5) which indi- 

 cates that fish > 140 mm SL were most abundant 

 in deep water, and 2) Miller's (1965) report that 

 large C. noth us occurred in deep water from Feb- 

 ruary through April. 



498 



