continental shelf bivalves and its paleoecologic significance 

 Paleobiology 6:331-340. 



1981. Repeating layers in the moUuscan shell are not always 

 periodic J. Paleontol. 55:1076-1082. 



Kennish, M. J. 



1980. Shell microgrowth analysis. Mercenaria mercenaria as 

 a type example for research in population dynamics. In D. 

 C. Rhoads and R. A. Lutz (editors), Skeletal growth of aquatic 

 organisms: Biological records of environmental change, p. 

 255-294. Plenum Press, N.Y. 

 Kennish, M. J., and R. K. Olsson. 



1975. Effects of thermal discharges on the microstructural 

 growth of Mercenaria merce7iaria. Environ. Geol. 1:41-64. 

 Pannella, G., and C. MacClintock. 



1968. Biological and environmental rhythms reflected in 

 molluscan shell growth. Paleontol. Soc. Mem. 2:64-80. [J. 

 Paleontol. 42 (Suppl. to No. 5)]. 

 Peterson, C. H. 



1982. Clam predation by whelks (Biisycon spp.): experimen- 

 tal tests of the importance of prey size, prey density, and sea- 

 grass cover. Mar. Biol. (Berl.) 66:159-170. 



Peterson, C. H., and W. G. Ambrose, Jr. 



1985. Potential habitat dependence in deposition rate of 

 presumptive annual lines in shells of the bivalve Protothaca 

 staminea. Lethaia 18:257-260. 

 Peterson, C. H.. P. B. Duncan, H. C. Summerson, and G. W. 

 Safrit, Jr. 



1983. A mark-recapture test of annual periodicity of internal 

 growth band deposition in shells of hard clams, Mercenaria 

 mercenaria, from a population along the southeastern United 

 States. Fish. Bull., U.S. 81:765-779. 



Peterson, C. H., H. C. Summerson, and P. B. Duncan. 



1984. The influence of seagrass cover on population structure 

 and individual growth rate of a suspension-feeding bivalve, 

 Mercenaria mercenaria. J. Mar. Res. 42:123-138. 



Rhoads, D. C., and R. A. Lutz (editors). 



1980. Skeletal growth of aquatic organisms: Biological records 

 of environmental change Plenum Press, N.Y., 750 p. 

 Rhoads, D. C., and G. Pannella. 



1970. The use of molluscan shell growth patterns in ecology 

 and paleoecology. Lethaia 3:143-161. 



Rosenberg, G. D., and S. K. Runcorn (editors). 



1975. Growth rhythms and the history of the earth's rotation. 

 John Wiley and Sons, Lond., 559 p. 

 Sutherland, J. P., and R. H. Karlson. 



1977. Development and stability of the fouling community at 

 Beaufort, North Carolina. Ecol. Monogr. 47:425-446. 

 Thayer, G. W. 



1971. Phytoplankton production and the distribution of 

 nutrients in a shallow unstratified estuarine system near 

 Beaufort, N.C. Ches. Sci. 12:240-253. 



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 Jr. 

 1973. A hydrographic atlas of large North Carolina sounds. 

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 p. (U.S. Fish Wildl. Serv., Data Rep. 20, 130 p.) 



Charles H. Peterson 



P. Bruce Duncan 



Henry C. Summerson 



Brian F. Real 



Institute of Marine Sciences 



University of North Carolina at Chapel Hill 



Morehead City, NC 28557 



STANDING STOCK OF JUVENILE 



BROWN SHRIMP, PENAEUS AZTECUS, 



IN TEXAS COASTAL PONDS 



The increased demand for timely information con- 

 cerning management of shrimp stocks has renewed 

 interest in developing reliable methods of predicting 

 brown shrimp, Penaeus aztecus, crop size for the off- 

 shore Gulf of Mexico fishery. Advance information 

 regarding shrimp abundance would also enable 

 elements of the shrimp industry to prepare for a 

 potentially good or poor harvest. Studies exploring 

 the feasibility of predicting the annual abundance 

 of brown shrimp off the Tfexas coast, initiated in 1960 

 (Baxter 1963), are based on the premise that post- 

 larval and juvenile shrimp abundances are propor- 

 tionally related to the subsequent commercial 

 harvest (Berry and Baxter 1969). 



A "good" predictor is one that is precise, timely, 

 and cost effective The abundance of postlarval 

 shrimp as they move from the Gulf of Mexico into 

 coastal bays is determined from semiweekly collec- 

 tions made by the National Marine Fisheries Ser- 

 vice, Galveston, at the entrance to Galveston Bay be- 

 tween late February and early May (Baxter 1963). 

 The postlarval shrimp index gives the earliest but 

 least reliable indication of potential harvest. A more 

 accurate but less timely prediction is derived from 

 landings of the bait shrimp fishery. Statistics for bait 

 shrimp landings since 1960 provide the basis for a 

 predictive model developed by K. N. Baxter (Klima 

 et al. 1982) defining the relationship between the bait 

 abundance index and subsequent offshore catch. 

 However, this prediction is not available until mid- 

 June, just prior to the seasonal opening, because 

 recruitment of brown shrimp into the bait fishery 

 does not begin until May (Chin 1960). A third possi- 

 ble indicator is the standing stock size of juvenile 

 shrimp in estuarine nursery areas measured before 

 shrimp emigrate and become vulnerable to the bait 

 fishery. This would provide an estimate earlier in the 

 season than the bait index and may be a more ac- 

 curate predictor than the postlarval abundance 

 Predictive capability increases with each successive 

 life stage because of the decreased time span be- 

 tween the estimate and subsequent commercial 

 harvest. 



Tb examine the relationship between juvenile 

 brown shrimp standing stock and offshore harvest, 

 and to determine the suitability of juvenile brown 

 shrimp abundance as a predictor, we conducted a 

 mark-recapture study in Galveston Bay, TX, during 

 the first week of June 1983. In this report we sum- 

 marize the results of our study, compare estimates 



FISHERY BULLETIN: VOL. 83, NO. 4, 1985. 



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