AbStr3Ct. — Collections were made 

 for gulf butterfish Peprilus burti 

 along a cross-shelf transect at depths 

 of 5-100 m in the Gulf of Mexico off 

 Texas from October 1977 to July 

 1980. Butterfish mature at 100-160 

 mm fork length as they approach age 

 I. Spawning occurs primarily from 

 September through May, but length 

 frequencies indicate it concentrates, 

 or is most successful, in distinct 

 "Winter" (late January-mid-May) 

 and "Fall" (early September-late 

 October) periods that coincide with 

 downcoast, alongshore currents (to- 

 ward Mexico). Gonad data and per- 

 sistence of small fish indicate spawn- 

 ing in winter, but at a low level. 

 Spawning probably occurs offshore 

 and upcoast toward the northcentral 

 Gulf. Surface currents of the cyclonic 

 shelf gyre probably transport eggs/ 

 larvae inshore and downcoast to re- 

 cruit to the bottom in water 5-27 m 

 deep, used as nurseries by butterfish 

 when they are 2-5 months old. But- 

 terfish disperse offshore as they ma- 

 ture and congregate in 36-100 m 

 depths when they are 9-12 months 

 old. They average 130-146mm in 

 fork length at age I in the north- 

 western Gulf, but 120-124 mm at age 

 I and about 170 mm at age II in the 

 northcentral Gulf. Estimates for the 

 von Bertalanffy growth parameters 

 L„, K, and t were 164 mm, 1.99/ 

 year, and -0.20 years, respectively, 

 for pooled northwestern Gulf Winter 

 cohorts and 141mm, 2.69/year, and 

 - 0.06 years, respectively, for pooled 

 Fall cohorts. Somatic growth ceases 

 as spawning approaches in the north- 

 western Gulf, but fish from the 

 northcentral Gulf show large annual 

 size increments. Butterfish reach 

 about 200 mm in fork length, the 

 largest ones occurring in the north- 

 central Gulf. Apparent maximum 

 ages are 1-1.5 years in the north- 

 western Gulf, and 2-2.5 years in the 

 northcentral Gulf. Differences in pop- 

 ulation attributes suggest complete 

 mortality at age I in the northwest- 

 ern Gulf or some unknown combina- 

 tion of an offshore and permanent 

 contranatant spawning or postspawn- 

 ing emigration of adults to the north- 

 central Gulf. The genus Peprilus 

 shows zoogeographic differences in 

 population dynamics near Cape Hat- 

 teras, North Carolina. 



Manuscript accepted 1 October 1990. 

 Fishery Bulletin, U.S. 89:101-116 (1991). 



Reproduction, Age and Growth, 

 and Movements of the Gulf 

 Butterfish Peprilus burti* 



Michael D. Murphy 



Florida Marine Research Institute, Florida Department of Natural Resources 

 100 Eighth Avenue SE. St. Petersburg. Florida 33701 



Mark E. Chittenden Jr. 



Department of Wildlife and Fisheries Sciences. Texas A&M University 

 College Station, Texas 77843 



Present address: Virginia Institute of Marine Science, School of Marine Science 

 College of William and Mary, Gloucester Point, Virginia 23062 



The gulf butterfish Peprilus burti 

 ranges in the Gulf of Mexico (Gulf) 

 from the Yucatan Peninsula to Tam- 

 pa Bay, Florida (Horn 1970) and may 

 occur along the U.S. southeast Atlan- 

 tic coast, depending upon its system- 

 atic status and range extensions 

 during cold spells (Caldwell 1961, 

 Collette 1963, Horn 1970, Persch- 

 bacher et al. 1979). This abundant 

 species is important in the industrial 

 fishery and is commonly discarded by 

 the shrimp fishery in the northern 

 Gulf (Roithmayr 1965, Franks et al. 

 1972, Gutherz et al. 1975, Chittenden 

 and McEachran 1976). Recent ex- 

 ploratory surveys have found large, 

 commercially valuable concentra- 

 tions of P. burti in the northern Gulf 

 (Vecchione 1987). A preliminary bio- 

 mass estimate for this area is 177,000 

 MT per 10,164 square miles (Gledhill 

 unpubl.). 



The life history and population 

 dynamics of this species have not 

 been described in detail, only as brief 

 notes in numerous faunal studies in- 

 cluding Gunter (1945), Hildebrand 

 (1954), Miller (1965), Franks et al. 

 (1972), Christmas and Waller (1973), 

 Chittenden and McEachran (1976), 

 and Allen et al. (1986). The paucity 



'Contribution No. 1625 of the Virginia Insti- 

 tute of Marine Science, College of William and 

 Mary. 



of information reflects difficulty in 

 age determination. Allen et al. (1986) 

 found that hard parts such as oto- 

 liths, scales, opercula, and vertebrae 

 were not useful in age determination. 

 In this paper we use an extensive 

 set of length frequencies to infer age 

 of P. burti and to describe size and 

 age at maturity, spawning seasonal- 

 ity and areas, recruitment, seasonal 

 distribution and movements, growth, 

 maximum size and age, and weight- 

 length, girth-length, and total, fork, 

 and standard length relationships. 

 We also discuss hydrographic condi- 

 tions associated with spawning areas 

 and recruitment, and zoogeographic 

 differences in population dynamics in 

 Peprilus near Cape Hatteras, North 

 Carolina. 



Methods 



Collections for Peprilus burti were 

 made along a cross-shelf transect in 

 the Gulf off Freeport, Texas (Fig. 1) 

 from October 1977 through July 1980 

 aboard a chartered shrimp trawler 

 using twin 10.4-m (34-ft) shrimp 

 trawls with a tickler chain and 4.4-cm 

 stretched mesh in the cod end. Initial 

 stations were located at depths of 9, 

 13, 16, 18, 22, 27, 36, and 47m. 

 Sampling was expanded to include 

 stations at 5 and 24 m after 

 November 1978 and at 55, 64, 73, 82, 



101 



