Cooperative Fish and Wildlife Research Units Program: Missouri
Education, Research and Technical Assistance for Managing Our Natural Resources

Huber, A. F., W. A. Fitzsimmons, and J. T. Westhoff. 2023. The Smaller, the Better? First evaluation of growth and mortality in crayfish internally tagged with p-Chips. Journal of Crustacean Biology 43: 1-10.


Small-bodied aquatic organisms present a challenge to researchers seeking to uniquely mark individuals for scientific study. Microtransponder tags, such as p-Chips, represent the smallest electronic animal tags available to meet this need. However, the use of p-Chips to tag freshwater crayfish has not been explored. Therefore, the goal of this study was to determine the effects of p-Chip tagging on growth and survival of crayfish in a controlled laboratory environment. Furthermore, we investigated potential influences from variables such as sex, reproductive form, and the number of molt events on mortality. We internally tagged woodland crayfish Faxonius hylas (12.2 to 26.6 mm carapace length; CL) with either one p-Chip (single-tag) or one p-Chip and one Visual Implant Elastomer tag (double-tagged) and observed the effects over a period of 90 days. Survival probability over time was not statistically different among tagging groups, sex, and reproductive form. The survival rates were similar across all tagging groups, with 75% in the control group, 77% in the double-tagged group, and 78% in the single-tag group. However, a strong correlation was observed between survival and the number of molt events. Additionally, there was a negative correlation between survival and crayfish size (CL), indicating a higher risk of mortality for larger individuals. There were no statistically significant differences in growth among the tagging groups. We conclude that p-Chips are a viable tagging option for the study of crayfish given their size, readability, and retention through molting cycles. However, we recommend that future studies repeat this experiment using smaller individuals to determine the minimum crayfish size compatible with p-Chip tagging. Additionally, it is important to test p-Chips with other crayfish species and compare the growth and mortality of crayfish tagged with p-Chip in natural habitats.