The return of "Stumpy" the whale shark: two decades and counting

Few fish capture the human imagination like whale sharks (Rhincodon typus). Each is born with unique body pigmentation - a natural patterning of lines and spots that is retained throughout its life and may therefore be used to identify individuals (eg Norman 1999; Arzoumanian et al. 2005). Through the combination of photographed encounters and spot-pattern matching, a whale shark may be "tagged" without physical contact or interference. These non-invasive tagging methods, including the digital images captured by citizen scientists, are key to monitoring the return rate and site fidelity of individuals of this long-lived species at global aggregation sites (Holmberg et al. 2008; Davies et al. 2013). Information can also be gathered on other aspects of their natural history, such as changes in growth or body condition, identification of commensal species, and large-scale migration patterns.