How to train your ray

Posted: 27th February, 2017

A researcher at Living Coasts is training greedy fish to play nice and share their food. And the work taking place at Torquay's coastal zoo is highlighting just how smart fish can be.

Meg Davitt is a student at the University of Surrey, where she is studying Veterinary Biosciences. She is currently on a one-year placement at Living Coasts in order to carry out a research project.

Two species of stingray live in the charity zoo’s Mysterious Mangroves exhibit. There are three female blue spotted stingrays (Neotrygon kuhlii), also known as masked rays, and six blue-spotted ribbontail rays (Taeniura lymma) - four females and two males.

The species live in the same type of habitat in the wild, frequenting the coral reefs and mangroves of the tropical Indian and Western Pacific Oceans where the seabed is sandy and flat. They co-exist in the zoo’s tank quite nicely - most of the time.

Meg: “The ribbontail rays are a more dominant presence in the tank and so can be a little greedy during feeding times and not share the food fairly with the masked rays. They are all fed three times a day with a scatter feed, which is where the food is distributed all over the tank to encourage natural foraging behaviours. The ribbontail rays will often chase the masked rays away from the most favourable pieces of food, leaving them with the least favourable.”

This is where the training comes in. “I did some behavioural observations on the stingrays to find out which ones are the most dominant, in the hope that training these individuals first would solve the problem. From my observations, I discovered that there were three ribbontail rays responsible for chasing away the masked rays. These were three of the four females - Sandy, Alex and Holly.”

Once she had identified the troublemakers, Meg was able to start her husbandry training. “I chose to start with Sandy because she is the most dominant and did the most chasing. My observations showed where Sandy spent most of her time in the lead-up to feeds and also which food she preferred - sprats. This was useful information, as I decided to start training in that area of the tank and do the first few sessions using her favourite food. I employed a training target which is basically a black and white chequered circle on a pole.”

To begin with, Meg lowered the target into the tank in the area where Sandy spent most of her time, so that she and the other fish could get used to it. Luckily, the target didn’t seem to bother them too much and they happily swam around it or just ignored it.

“During the next session, I placed the target in the same location as before, but when Sandy swam near, I dropped a piece of food next to it. Eventually, she began to associate the presence of the target with food. Sandy would approach the target and press herself against it for her food reward. It only took three sessions to perfect the behaviour, which shows just how intelligent this species really is! Now, Sandy will follow the target, no matter where in the tank it is, and will press herself against it for a reward, move away and come back for the next piece of food.”

Since the training started, Sandy has chased the masked rays less often, so they are getting a fairer share of the scatter feed. Meg’s work is not done, however: “I’ll continue to train Sandy so that she doesn’t slip back into old habits, and I have just made a new target for Alex so that I can start training with her. If the success with Sandy is anything to go by, Alex will be trained in no time and I can start working with Holly!”

Clare Rugg, Operations Manager at Living Coasts, said: “This is a text-book example of how behavioural training can benefit animal husbandry. All the fish have better welfare as a result of the training. It shows how evidence-led science can identify both an issue and the way to solve it. All you need is patience, perseverance - and a circle on a stick!”

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