FISHERY BULLETIN: VOL. 82. NO. 2 



Moreover, we observed so little overlap of lengths 

 from different spawned groups that few individu- 

 als could have been incorrectly aged and basic 

 conclusions on apparent growth and mortality 

 would be little affected by such error. As Geoghe- 

 gan and Chittenden (1982) found for Stenotomus 

 caprinus, length-frequency analysis can be a 

 superior method to age L. fasciatus because 1) 

 little spawning occurs in other than one major 

 discrete period each year, 2) length frequencies 

 within spawned groups are reasonably described 

 by a normal distribution, 3) growth of large and 

 small fish within a spawned group appears uni- 

 form since the variance was generally constant 

 between cruises, and 4) life span is short so age 

 determination need be applied only to a few ages, 

 the ideal situation for using length frequencies 

 (Lagler 1956; Tesch 1971). Ross (1978) successfully 

 used scales and otoliths to determine age of North 

 Carolina fish, but we were not able to do so in 

 limited trials and did not pursue these methods 

 further because it seemed unnecessary. 



Larimus fasciatus reach slightly larger sizes at 

 age off North Carolina than apparent sizes we 

 found in the northwestern Gulf. Von Bertalanffy 

 predictions of size at age off North Carolina (Ross 

 1978) were 153 mm (121.3 mm SL) at age 1, 188 mm 

 ( 151.1 mm SL) at age II, and 209 mm (168.0 mm SL) 

 at age III compared with quadratic and von Ber- 

 talanffy predictions of 130-150 mm at age I and 

 155-180 mm at or approaching age II for the 

 northwestern Gulf. Our finding that growth is 

 greatest in the spring and summer agrees with 

 Ross (1978). 



Maximum Size, Life Span, and Mortality 



The largest L. fasciatus we found in the north- 

 western Gulf (182 mm) is smaller than most 

 maximum sizes reported from the north central 

 Gulf (Louisiana: 208 mm by Hildebrand 1954, 

 195 mm ?L by Dunham 1972, and Mississippi: 202 

 mm by Franks et al. 1972, 189 mm by Christmas 

 and Waller 1973, 187 mm in our data), and much 

 smaller than those reported from the Atlantic 

 coast of the United States (New York to Florida: 

 220 mm by Wilk and Silverman 1976, Chesapeake 

 Bay: 215 mm ?L by Hildebrand and Schroeder 

 1928, off North Carolina: 205 mm ?L by Hilde- 

 brand and Schroeder 1928, 206 mm ?L by Hilde- 

 brand and Cable 1934, and 225 mm = 182 mm SL 

 by Ross 1978). The largest record is a 271 mm 

 specimen collected off Mississippi (Franks 1970). 

 The larger size off the Atlantic coast of the United 



360 



States may reflect greater longevity there, espe- 

 cially from about Cape Lookout or Cape Hatteras 

 north where zoogeographic change in population 

 dynamics may occur (White and Chittenden 1977). 

 Ross (1978) collected age III fish off North 

 Carolina, but the oldest fish we collected only ap- 

 proached age II. 



The appearance of larger L. fasciatus in the 

 north central Gulf than in the northwestern area 

 follows a pattern apparent in a variety of species 

 (Murphy and Chittenden footnote 7) including C. 

 nothus, P. burti, S. caprinus, Brevoortia patronus, 

 and Micropogonias undulatus. These authors 

 suggested this could reflect 1) small but funda- 

 mental percentage composition and population 

 dynamics differences between these areas, 2) 

 greater biomass at all ages in the north central 

 Gulf, not necessarily population dynamics differ- 

 ences, so that greater numbers of large fish might 

 be captured there even if percentage compositions 

 did not vary, and/or 3) probable permanent emi- 

 gration from the northwestern to the north central 

 Gulf by larger, older, spawning or postspawning 

 fish as they approach age I. They suggested the 

 last explanation applied to C. nothus, P. burti, and 

 probably other fishes, and that it would be man- 

 ifested as between area population dynamics dif- 

 ferences. The following findings also suggest that 

 L. fasciatus too more or less permanently emi- 

 grates from the northwestern to the north central 

 Gulf as spawning and age I approaches 1) the 

 plateaus in length formed in August and seeming 

 cessation of somatic growth in later stages of 

 gonad development, and 2) the appearance in the 

 northwestern Gulf in July 1981 of an abundant 

 fall-spawned group approaching age II. This older 

 spawned group, and parallel spawned groups in 

 other years, was absent or rare in all other months 

 even though our data were based on 71 cruises and 

 3,390 tows over 4 yr. 



Because larger, older L. fasciatus probably 

 emigrate to the north central Gulf, the typical 

 maximum life span of 1-2 yr we observed for the 

 northwestern area may be a little low for a stock 

 that ranges over both areas. With the exception of 

 the very large specimen that Franks (1970) found, 

 the largest individuals reported from the north 

 central Gulf are only 189-208 mm as noted. This is 

 not much larger than our largest specimen (182 

 mm) from the northwestern area, which was 20 mo 

 old. Moreover, these maximums are similar to von 

 Bertalanffy predictions of mean sizes at age II 

 (165-185 mm) or at age III (175-195 mm) that we 

 found, and sizes of 188 and 204 mm Ross (1978) 



