EARLY DEVELOPMENTAL STAGES OF PINK SHRIMP, PENAEUS 

 DUORARUM, FROM FLORIDA WATERS 



By Sheldon Dobkin, Marine Laboratory 

 University of Miami 



Study of tlie life histoiy of penaeid slirimps has 

 received great impetus in the past 25 yeai-s with 

 tlie increased commercial importance of many of 

 tlie species. The species of most impoi-t<ince com- 

 mercially Mong to the genus Fenaeus and the 

 developmental stages of several membei-s of this 

 genus have been described. 



Tiiree species of Penaeits are fished commer- 

 cially along the South Atlantic and Gulf coasts of 

 the United States. Of these, P. xetiferm has re- 

 ceived the most study; its early life history has 

 been described by Pearson (1939). Tlie larval 

 development of P. duomrum and P. azfeeux has 

 i^ot l)een described ; however, some information on 

 the po8tlar\'al and juvenile phases of their life 

 histon- is available (Williams, 1953, 1955, 1959). 



The pink shrimp, P. duoranim.. supports a 

 valuable fisheiy in Florida and accounts for ap- 

 proximately three-quarters of the slu'imp landed 

 in the State. The object of this study was to pro- 

 vide detailed descriptions of the egg and larval 

 stages of this shrimp. 



The author expresses appreciation to Drs. C. P. 

 Idyll, G. L. Vos.s, and A. C. Jones, of the Marine 

 Laboratory. Univei-sity of Miami, for helpful 

 advice during the course of this study and for 

 critical reading of the manuscript; and to T. J. 

 Costello and H. L. Cook, of the Bureau of 

 Commercial Fisheries, and E. S. Iversen, of the 

 Marine Laboratory, for valuable suggestions. 

 Tlie autlior is indebted to Mrs. D. E. Dimitriou, 

 A. E. Jones, D. I. Dubrow, and J. H. Tweedy for 

 their help in tliis study, and to Mrs. E. S. Iversen 

 for inking the drawings of the early stages. 



Note. — This work was conducted In the Marine Laboratory of 

 the University of Miami. Miami, Fla., for the Bureau of 

 Commercial Fisheries with Saltonstall-Kennedy funds under 

 Contract No. 14-17-008-78. 



Approved for publication. July S, 1960. Fishery Bulletin 190. 



METHODS AND MATERIALS 



PLANKTON COLLECTIONS 



To obtain the eggs and larvae of penaeid 

 shrimps, which are planktonic, more than 500 

 plankton samples were taken between January and 

 December, 1959, in Florida Bay and in the Dry 

 Tort.ugas areas and adjacent watei-s. These col- 

 lections were made from research vessels of the 

 Univei-sity of Miami Marine Lalwratory and from 

 commercial trawlei-s. Tows were made at all 

 times of day and night and at several water depths 

 (see table 1). The depth at which the nets were 

 fished was determined by applying the wire angle 

 measured by an inclinometer to the known amount 

 of wire out. Three-quarter meter (mouth diam- 

 eter) "Discovery""-type nets were used in most 

 instances with either a No. 10 mesh silk bolting or 

 a Xo. -2 mesh nylon cod end. A 1-foot (mouth 

 diameter) "Turtox" net of Xo. 6 mesh silk bolting 

 cloth was also used. 



Plankton tows were generally of 30 minutes' 

 duration except when other considerations, such 

 as the necessity for making hydrographic observa- 

 tions, caused the net to lie brouglit up sooner. A 

 towing speed of approximately 31/2 knots was 

 maintained in most cases. The i)lankton was pre- 

 served in 3-percent formalin buffered with hexa- 

 metliylenamine and stored in Ifi-ounce jars. 



REARING EXPERIMENTS 



Four rearing experiments were conducted from 

 late March througli July 1059. In these experi- 

 ments, large females (ajiproximately 1'20 to 170 

 mm. total length) with opaque ova were removed 

 fi-om the regular commercial hauls of a shrimp 

 trawler on the Dn- Tortugas fishing grounds and 

 taken to the laboratory. The shrimp were kept 



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