Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Developing quality assurance practices for PIT tagging in the Mekong River (#184)

Thanasak Poomchaivej 1
  1. CK Power Company Limited, Dindaeng, BANGKOK, Thailand

The barrier effect of dam construction can limit fish migrations and threaten the ability for fish to complete essential life history stages by limiting access refuge, feeding, spawning or dispersal habitat. The importance of understanding the fish movement is to understand the role fish play in broader ecosystem processes. The aquatic monitoring technology has a substantial role to play in this progression. Critical to collecting the fish movement data is developing cost-effective, accurate and scientifically robust technology. Traditionally, tagging has been used to understand movements in and around dams. A technology with significant promise for application in the Mekong is Passive Integrated Transponder (PIT) tagging as a method to quantify fish migrations. But the technology has been rarely used in the Lower Mekong Basin, only two species from the Mekong River have been previously assessed to determine the suitability and there have been no large-scale field trials. Furthermore, no studies have been undertaken to validate whether the critical requirements for tagging studies (Tag retention, Low mortality, Low impact on behavior) are valid for PIT tags in the region. there is little information on the potentially negative biological impacts of the tags themselves to Mekong fish species. If tagging influences fish survival or behavior, then the results can be called into question. Here I report on the results of a PIT tag retention trial was performed for selected Mekong species. A range of species, from different sizes, were implanted with different-sized tags to determine any influences on growth or survival. The results indicated that survival and retention rates increased proportionally with fish size. We also determined that survival and retention was influenced more by fish length, than weight. The data provides an excellent basis for the practical application of fish, in large tropical rivers, to enhance maximum survival of tagged fish.