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    • Article

      A simple method of tagging prawns 

      LM Rodriguez - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The recognition of individual animals is crucial to many aspects of research. Prawns (Penaeus monodon) present unique difficulties in this respect since they molt regularly. Thus, almost all tagging and marking methods developed for prawns so far have proven inadequate. Some tags or marks are lost during molting; others cause injury to the prawns. A new and efficient method has been developed at the Igang Seafarming Station of the Aquaculture Department.

      Rectangular brass tags measuring 5 mm by 20 mm and numbered consecutively are used. The prawn is held gently but firmly at the base of the carapace with the left hand while the right hand slips the brass tag around the stalk of the unablated eye and presses the tag gently. All tagging must be made under water to avoid stress.

      From May 29 to September 7 to a total of 348 unilaterally-ablated adult female prawns were tagged on the unablated eyestalk in 5 batches to enable individual observations on gonadal maturation, molting, and growth. Periodic examinations were made four times a month to coincide with the different phases of the lunar cycle. On each examination, survival and recovery rates were recorded. The data included death due to immediate mortality during ablation and loss to cannibalism for the duration of the experiments.

      In all five tagging experiments, most of the prawns recovered had their tags intact. These included even dead and molting animals.

      The eyestalk tagging method is suitable for prawns because the tags can be attached without causing injury and has no effect on the rate of growth, maturity, molting and behavior of the animal. The tags are identifiable and permanent; they remain attached to the animal even after death.
    • Article

      A simple method of tagging prawns 

      LM Rodriguez - Natural and Applied Science Bulletin, 1976 - University of the Philippines
      The recognition of individual animals is crucial to many aspects of research. Prawns present unique difficulties in this respect since they molt regularly. Thus almost all tagging and marking methods developed for prawns so far have proven inadequate. Some are lost during molting; others cause injury to the prawns. A new and efficient method has been developed at the Igang Sea Farming Station of the Aquaculture Department.

      Brass tags measuring 5 mm by 20 mm and numbered consecutively are encircled around the eyestalk like a small bracelet. The prawn is gently held at the base of the carapace by the left hand while the right hand slips the brass tag over the eye. The tag is gently pressed around the eyestalk to prevent its slipping out. All tagging is done under water to avoid stress.