would be most applicable to the marking of 

 small shrimp. The number of individuals 

 marked by this method at any one time would 

 be limited only by the quantity of available 

 shrimp and capacity of storage facilities. 



At present, only three colors, red, 

 green, and blue, are available for use as 

 shrimp -marking agents. Simultaneous use of 

 identical colors on groups of shrimp of like 

 size in neighboring areas ;ould lead to complete 

 confusion of results. It is strongly urged that 

 all shrimp -marking experiments be subject to 

 judicious and cooperative planning by the vari- 

 ous fishery-research agencies prior to 

 commencement of field operations. 



ACKNOWLEDGMENTS 



The author is indebted to Dr. Gordon 

 Gunter, Director, Gulf Coast Research Labor- 

 atory, and the late Mr . William Herzog for 

 valuable suggestions and assistance during the 

 early phases of this study. The writer is also 

 grateful for the courtesies extended by members 

 of the Gulf Fishery Investigations, U. S. Fish 

 and Wildlife Service, Galveston, Texas. 



SUMMARY 



1 . Results of tests on the marking of 

 commercial shrimp, Penaeus setiferus , P. 

 aztecus, and P. duorarum, with biological 

 stains are presented. 



2 . Experiments were conducted on cap- 

 tive shrimp held in storage tanks and aquariums 

 supplied with circulating sea water . 



3. Ninety-nine tests involving more 

 than 26 stains were conducted during the period 

 from June 1955 through June 1956. 



4. Shrimp ranging in size from 30 mm. 

 to 175 mm. were subject to one or more of 

 three staining methods; immersion, injection, 

 and feeding . 



5. The immersion technique has been 

 consistently unsuccessful with the stains used. 



6. Fast Green FCF (National Anilin4 

 Niagara Sky Blue 6B, Trypan Red, and Trypan 



Blue have proved effective with the injection 

 technique. Each of these stains has remained 

 fast for more than 100 days and through at least 

 one shedding period. Trypan Red and Trypan 

 Blue have been retained for over 200 days . 



7. Trypan Red is the only fast marking 

 agent found among stains administered by the 

 feeding method. It is effective throu^out the 

 experimental size ranges, and is considered 

 satisfactory for marking shrimp under a length 

 of 80 mm. Distinctive coloration was retained 

 for more than 233 days and through at least 

 three ecdyses. 



8. A high incidence of cannibalism a- 

 mong captive shrimp makes determination of 

 experimental mortality difficult. Evidence from 

 control experiments indicates that when recom- 

 mended procedures are followed there is little 

 difference between mortalities of marked and 

 normal shrimp. 



9. Whether these stains will remain 



fast for extended periods under natural conditions 

 can only be determined by field tests. 



10. Since only three colors, red, blue, 

 and green, have been found satisfactory as mark- 

 ing agents, the value of these marking techniques 

 in a field program will depend largely upon 

 judicious and cooperative planning by the vari- 

 ous shrimp investigations. 



REFERENCES 



Carranza, J. 



1953. Metodos para marcar peces de 

 pequeno tamano de utilidad en 

 estudio de problaciones. Ann. 

 Escuela National Cienclas Biol. 

 7{1-4):111-128. 



Conn, H . 

 1953. 



EXinn, A. 

 1951. 



Biological stains. 6th edn., 367 pp. 

 Biotech Publications, Geneva, N.Y. 



and CM. Cocker 



Notes on marking live fish with bio- 

 logical stains. Copeia 1951 (l):28-3l. 



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