Evaluation of Biological Stains, Inks, and 

 Fluorescent Pigments as Marks for Shrimp 



by 



EDWARD F. KLIMA, Fishery Biologist (Research) 



ABSTRACT 



Studies were made in the laboratory to find marking materials that can be used 

 to distinguish groups of shrimp in mark- recapture experiments designed to estinnate 

 rates of population growth and mortality. A series of combination n-iarks, formed 

 by injecting various biological stains and fluorescent pigments, was developed. 

 These marks are permanent and do not affect survival. 



INTRODUCTION 



Mark-recapture experiments provide a sim- 

 ple and direct nneans for estin-iating growth 

 and mortality in fish and shellfish populations. 

 Recent developnnent of the stain- injection tech- 

 nique of marking has greatly improved our 

 ability to estin-iate these vital paranneters in 

 stocks of penaeid shrinnp. Petersen disk tags, 

 which have been used to mark shrimp, nnay 

 affect survival and growth, whereas nnarking 

 with stains has no discernible effect. 



Until recently, the staining technique has 

 been sonnewhat limited by the small number of 

 suitable stains available. Of those tested by 

 Dawson (1 957) and Costello ( 1 964), only Trypan 

 blue, Niagara sky blue 6B, Trypan red, and 

 fast green FCF were retained pernnanently in 

 the gills of shrimp. Trypan red is not suitable 

 for use as a nnarking agent, however, because 

 it does not contrast sufficiently with the 

 shrimp's natural coloration to permit shrimp 

 so marked to be easily identified by fishernnen. 

 Shrinnp nnarked with Trypan blue and Niagara 

 sky blue 6B cannot be differentiated from one 



another and therefore cannot be used to iden- 

 tify groups that n-iight overlap spatially during 

 a particular study. The objective of this in- 

 vestigation was to increase the number of 

 distinguishable marks that can be used sinnul- 

 taneously in mark-recapture experiments. 



Accordingly, laboratory tests were under- 

 taken to find additional materials for marking 

 shrimp and to deternnine the effect of these 

 marks on shrinnp survival. In the first few 

 experinnents, shrimp were held in groups of 

 2 or more in large tanks supplied with either 

 fresh or recirculating filtered sea water. In 

 later experiments, they were kept in small 

 individual connpartments. The experimental 

 shrinnp ranged in total length from 55 to 179 

 nnm. --sizes that would nornnally be involved 

 in mark- recapture studies. They were caught 

 in Galveston Bay and included the three species 

 fished commercially in the northern Gulf of 

 Mexico, namely, the white, brown, and pink 

 shrimps, Penaeus setiferus , P^. aztecus , and 

 P. duorarum, respectively. 



TYPES OF MARKS 



Permanent, nonlethal nnarks that can be 

 easily detected by casual observers are de- 

 sirable for quantitative mark- recapture 

 studies designed to provide estimates of nnor- 

 tality and growth rates. Marks that do not 

 fulfill all of these qualifications may satisfy 

 the less demanding requirements of studies 

 undertaken to obtain general infornnation on 

 shrinnp movements. 



PRIMARY MARKS 



Primary marks are formed upon injection 

 of pignnents (e.g., fast green FCF, Niagara sky 

 blue 6B, and Trypan blue) that rennain in the 

 gills of shrimp and differ sufficiently fronn the 

 animal's natural color to be easily detected 

 by fishermen. Aqueous solutions of biological 

 stains, commercial food colors, and inks were 



■"■Contribution No. 200, Bureau of Commercial Fisheries Biological Laboratory, Galveston, Tex. 



