| Summary: | Tagging studies provide an important window to the life history of exploited fish species. With the ease of application and visible recovery, dart tags with external streamers allow for the widest possible public participation in both marking and recapturing fish. This dissertation examined the performance of a single barbed plastic dart and double barbed nylon dart tag in red snapper (Lujanus campechanus) held at the Aquarium of the Americas research facility in New Orleans, LA, and red drum (Sciaenops ocellatus ) held at the University of Miami RSMAS Experimental Fish Hatchery in Miami, FL. An assessment of differences in biological compatibility of the two dart tags revealed differences in surface microstructure of the dart materials which influence the ability for tissue to adhere to the anchor. However, the two tags did not show a significant difference in inflammatory response of tissue surrounding the tag. The double-barb design has a higher mechanical holding power than the single barb-design for both fish species. The dart tags did not affect growth or condition of either species. The red snapper suffered substantial mortality due to opportunistic pathogens that used the tag entrance wound to enter the fish. Tag loss from red drum revealed that assumed immediate tag shedding demonstrated a dynamic structure, and occurred over a prolonged period. A well-defined reduction in tag attrition demonstrated that this loss was clearly not type II shedding. A three parameter, nonlinear tag shedding mode is presented that more captures the dynamics of prolonged type I shedding, expresses type I shedding as a rate, and provides an estimate of the breakpoint between type I and type II (long term) shedding processes. This approach reduced bias and provided more accurate estimates of type I and type II shedding. The effect of bias in estimates of survivorship based on long term tag loss of the two tag designs when introduced into spawning potential ratio models was examined. Conclusions and recommendations were presented regarding the future role of large scale tagging programs and risk exposure using dart tags.
|
|---|