Table 5. --Comparative survival of shrimp receiving no mark, Injected with distilled water, or 



marked with a mixture of two dyes 



Material 



suitable marks. Higher concentrations of the 

 fluorescent solvent tended to mask the green 

 dye. The fluorescent secondary mark could be 

 detected under ultraviolet light for up to 45 

 days after marking, but soon thereafter began 

 to fade. Consequently, this combination mark 

 is suitable only for short-ternn studies. 



Tattooing 



A secondary mark of ink or fluorescent 

 pigment was also applied by tattooing in the 



manner described by Dunstan and Bostick 

 (1956). A 1-percent suspension of a fluores- 

 cent pignnent in castor oil, or one part 

 Sanford's ink to three parts castor oil, was 

 tattooed into shrimp between the second and 

 third abdominal segments. Within a short 

 tinne, these secondary marks were lost and 

 an infection was observed at the injection site; 

 therefore, this method of marking is not 

 suitable for shrinnp. 



SUMMARY 



Prior to this study, fast green FCF, Niagara 

 sky blue 6B, and Trypan blue were the only 

 stains proved suitable for nnarking shrimp in 

 studies of growth and mortality. Laboratory 

 experinnents were therefore made to find addi- 

 tional materials that could be used as shrimp- 

 marking agents. 



None of the 65 staining nnaterials tested was 

 found to provide fully satisfactory primary 

 marks. Many of the stains were either lethal 

 or faded within 1 week. Combinations of Trypan 

 red and Trypan blue produced marks in the 

 gills that could only be identified by trained 

 observers and would therefore have limited 

 practical use. Green and blue machine inks 

 produced marks that faded but could still be 



used in short-term marking studies designed 

 to provide general infornnation on shrimp 

 movements. 



Various inks and fluorescent materials were 

 tested for use as secondary marks in combina- 

 tion with the suitable biological stains. Red 

 and blue checkwriter inks were found to be 

 satisfactory for possible use as secondary 

 marks in field studies designed to obtain gen- 

 eral information on movements. Although the 

 inks remained visible up to 84 days after 

 marking, they frequently migrated into the 

 gills and masked the primary stain. A com- 

 bination of fast green FCF and the fluorescent 

 solvent Fluorographic produced a combination 

 mark adequate for short-term studies. 



