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Shrimp tagged with the Atkins -type tag have been held with a con- 

 trol group for 3\ months in a salt-water pond. During this time, they passed 

 through a series of molts. Growth of tagged shrimp was comparable to that 

 of untagged individuals. Comparisons of the more obvious differences be- 

 tween the Atkins-type tag and the Petersen tag revealed the following: 



Weight - The Atkins -type tag 

 is slightly heavier than water and 

 weighs only one -eighth as much 

 as the Petersen tag (Atkins tag 

 and nylon line, 0. 0292 g. ; Peter- 

 sen tags and pin, 0. 233 g. ). 



Water resistance - The ob- 

 long plastic strip of the Atkins - 

 type tag trails the shrimp dorso- 

 posteriorally to the point of at- 

 tachment. In this position, and 

 with its small size, it presents a 

 very narrow surface to the flow 

 of water, probably creating less 

 water resistance than the Peter- 

 sen tag. 



Attachment - The time re- 

 quired to attach each tag is ap- 

 proximately equal. Both tags are 

 attached to the shrimp through the 

 first abdominal somite. The Atkins- 

 type tag is attached to the shrimp 

 with 3 -pound -test monofilament 

 nylon line, diameter 0. 3 mm. 

 while the Petersen tag is affixed 

 with a nickel pin, 0. 9 mm. in 

 diameter. It appears that the 

 relatively thick, rigid pin causes 

 more tissue damage than the thin, 

 pliable nylon line. 



Indications are that the 

 Atkins tag, relatively streamlined, 

 lightweight, and flexible, is an im- 

 provement over the Petersen tag 

 and may be particularly useful for tagging small-sized shrimp. Final evalu- 

 ation, however, must await experiments which compare survival rates of 

 shrimp tagged with Atkins tags, with those of unmarked shrimp and shrimp 

 tagged with Petersen disks. 



The position of attachment for the 

 Atkins tag on shrimp and the mod- 

 ified needle used to insert the mono- 

 filament nylon harness. 



89 



