How small can they go? Microelectronic tags for movement ecology of small aquatic organisms

Abstract Miniaturization and optimization of batteries and electric components, as well as new technological innovations, are driving increased use of microelectronic tags to study animals in the wild that are smaller than ever before. Here, we provide an overview of the different alternatives to common electronic tagging and tracking tools used for aquatic research and discuss the research opportunities afforded by these micro tags and the challenges for investigators. We are optimistic that the miniaturization of tags will create opportunities for novel ecological inquiry. A key advance will be to allow investigators to address broader questions at an ecosystem scale about aquatic environments that span small-bodied adult fishes and life stages (i.e., juveniles). However, even the new developments have limitations in what can be tagged, how long tags will last, and their detection distance. Moreover, investigators will need to better understand how to effectively instrument the smallest animals with surgical implants or attachments of tags to maintain fish welfare and minimize alterations of behavior or survival. Collaboration with engineers will be important to assess where the field can go next for miniaturization, which will help to further advance the understanding of small species and early life stages in rivers, lakes, estuaries, and oceans.