344 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



amounts together with brown, pink, or white 

 shrimp, but due to difficulty in distinguishing them 

 from the hitter species, are never differentiated by 

 the fishing industry. 



Species having potential commercial value in- 

 clude the royal red shrimp, Hymenopenaeus ro- 

 bustus Smith, a deep-water species, and the rock 

 shrimps, genus Sicyonia, particularly S. brevirostris 

 Stimpson, which frequently attains high densities 

 in many areas. 



This report treats exclusively the larger, more 

 abundant varieties, namely, the brown, pink, and 

 white shrimp. These are sought on the continental 

 shelf and in contiguous inshore waters from the 

 Florida Kej-s counterclockwise around the Gulf 

 to the Yucatan Peninsula. Coastal, bathymetric, 

 and seasonal distribution depends upon the species 

 ajid, to some extent, the general locale. Although 

 all three species occur throughout the Gulf, brown 

 and white shrimp are most abundant along the 

 northern and western coasts, whereas pink shrimp 

 tend to concentrate to the south and east. A 

 major task now confronting biologists is determin- 

 ing whether primary shrimp stocks are homogene- 

 ous over their ranges, or whether they comprise 

 discrete subpopulations overlapping in space, 

 time, or both. 



The question of population definition is prompted 

 in part by the unique life history of common 

 penaeid shrimps. In general, eggs are fertilized 

 and spawned in the oceanic habitat of the parent 

 shrimp. After a very short incubation period, a 

 small larva or nauplius emerges. Rapid growth 

 accompanied by gross morphological changes en- 

 sues, the larva, now a component of the zooplank- 

 ton, being quickly carried shoreward into broad 

 and shallow estuaries. Transformation to adult 

 likeness and habits occurs somewhat before or as 

 the larva enters inshore waters. Here the shrimp, 

 now a postlarva or juvenile, maintains rapid 

 growth for the next 2 or 3 months. As maturation 

 approaches, it departs from the "nursery" grounds, 

 returning to the parental offshore habitat where its 

 life cycle is completed. The average life span of 

 tlxe more important penaeids is thought to approx- 

 imate 18 months although there are indications 

 that many female shrimp continue to breed to a 

 more advanced age, tending to make this estimate 

 somewhat low. Pink shrimp captured as large 

 and mature adults have been maintained in aquaria 

 at the Bureau of Commercial Fisheries Biological 



Laboratory, Galveston, Tex., for periods exceeding 

 1 year. 



In reconsidering the problem of stock homoge- 

 neity, questions arise concerning the relationship 

 between offshore aggregations and the utilization 

 of inshore waters by their progenj'. Are there 

 discrete offshore populations that can be consist- 

 ently defined in terms of specific inshore waters 

 which nurture their offspring? That is, do indi- 

 vidual shrimp, after their sojourn in specific in- 

 shore waters, return to reproduce in their natal 

 offshore areas; or do most juveniles migrate coast- 

 ally toothersuitableoffshorehabitat, their progeny, 

 in turn, being nurtured in inshore waters adjacent 

 thereto? Or is there a more or less random inter- 

 play between subgroups making up a given stock 

 and the inshore areas their developing progeny 

 occupy, such relationship being tempered to a 

 large degree by varying oceanographic conditions? 

 The fact that mortality in inshore waters is being 

 increasingly compounded b_y artificial factors, 

 especially by intensified harvest of subadult 

 shrimp, dictates the need for a better understanding 

 of each stock's spatial relatic-nships. 



TYPES OF FISHERIES 



Each of the common Gulf shrimps is subject to 

 utilization over a broad spectrum of life history 

 stages. Large and small shrimp are utilized for 

 food while the small ones are also important as 

 sport fishing bait. In practically all inshore and 

 offshore waters, commercial and noncommercial 

 fisheries heavily exploit shrimp ranging from small 

 juveniles to the largest adults. The degree to 

 which activities of either interest prevail in a par- 

 ticular area depends largely upon local statutes. 



Some States, for example, permit extensive 

 commercial and noncommercial harvesting of small 

 shrimp for human consumption, whereas others 

 stringently enforce closed-season and minimum- 

 size laws. Development of markets made possible 

 by machinery that permits economical processing 

 of small-size ("cocktail") shrimp has stimulated 

 demands for this product. In inshore waters 

 where size laws restrict commercial harvest of 

 immature shrimp for table use, bait shrimp fish- 

 eries are now firmly established. These have ex- 

 hibited such phenomenal growth in recent years 

 that in some areas their collective income fre- 

 quently exceeds that of the adjacent offshore 

 fishery. 



