MARE researcher is first author of article published in Scientific Reports (Nature)
MARE researcher Ashlie J. McIvor is first author of the article ‘Mark-recapture validates the use of photo-identification for the widely distributed blue-spotted ribbontail ray, Taeniura lymma’, recently published in the prestigious scientific journal Scientific Reports from group Nature. In the published study, the researchers used the dorsal spot patterns of blue-spotted ribbontails to identify specific individuals, comparing this method with more traditional ones.
The blue-spotted uge (Taeniura lymma), is a cartilaginous fish widely distributed throughout the coral reefs of the Indo-Pacific Ocean. This species of Uge owes its name to its conspicuous blue spots on the dorsal surface and two blue stripes along the dorsolateral edges of the tail.
The decline in shark populations globally, and the consequent decrease in predation, has led to speculation of an increase in blue-spotted uge populations. However, for this to be confirmed, more information needs to be gathered on the population trends of this species.
The ability to easily identify individuals of this species using photo-ID would greatly facilitate the collection of this information. In addition, photo-ID monitoring of regional populations of T. lymma can aid in understanding the species' behavioural and population responses to habitat degradation, as well as providing evidence-based management insights for small-scale fisheries that catch the species.
In this context, a team of researchers led by MARE researcher Ashlie J. McIvor compared the effectiveness of this innovative identification method with more traditional marking methods. To do this, the researchers not only assessed the accuracy of using unique dorsal spot patterns of blue-spotted grebes for individual identification, but also examined the longevity of these spot patterns to assess the suitability of using photo-ID for long-term monitoring. To guarantee the reliability of photo-ID, this method was combined with recapture tagging to ensure that our photo-ID assessments are based on verifiable recaptures.
This study showed that spotting patterns are unique to each individual of the T.lymma species with 90.3 per cent of individuals correctly identified using I 3 S photo matching software, from images taken up to 496 days apart. In comparison, traditional physical tagging methods showed a tag loss rate of 27 per cent and a maximum tag retention period of just 356 days. This means that photo-ID identification of azure-winged magpies proves to be an effective method, making it an important tool for monitoring populations of this species and better understanding its ecology, without resorting to more invasive methods.
The validation of photo-identification for blue-spotted puffins is extremely important, as it is a species dependent on coral reefs and has a wide distribution, making it possible to easily monitor behavioural and demographic changes in relation to coastal threats, such as human development and habitat degradation.
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