Paternity testing in rays

Source: M. Janse, Burgers' Zoo
Employees from Burgers' Zoo and Gendika have worked together to develop a paternity test for young rays. The test determines the identity of the father as an aid in the prevention of inbreeding-a very important issue in zoo populations.
The genetic health of a population is essential, especially in breeding programmes for animal species threatened with extinction. To this end, it is necessary to know the identity of the mother and the father of each animal. The mothers of the white-spotted eagle rays kept at Burgers’ Zoo are a given, as this species bears live young. The fathers, on the other hand, are unknown. Ten years ago, Burgers’ began with four spotted eagle rays: four females and two males. Many more have been born since, and have been featured in this newsletter. At the time of the study, there were ten females and ten males.

A part of each ray’s poisonous sting, which grows back quickly, was taken for paternity research. A very specialised technique revealed the identity of the young rays’ fathers. One of the males had fathered five of the young, and the other had fathered fifteen: proof that both males were sexually active. One pair of twin rays was even discovered to have been fathered by two different males. This is called multiple paternity, a phenomenon described before in only one other species of ray, the thornback (Raja clavata).

Paternity testing using the poisonous sting in captive white-spotted eagle rays Aetobatus narinari: a non-invasive tool for captive sustainability programmes.

M. Janse, A.L. Kappe en B.L.M. van Kuijk

Journal of Fish Biology (2013) volume 82