Missing limbs no obstacle for resilient turtles

Rehabilitated turtles which had their front or hind limb amputated, are able to cover the same distances across the Mediterranean as fully-bodied turtles, according to a study published in science journal Xjenza.

The study was based on the GPS tracking of the amazing journeys of Tama, Carmine, Doris, Allison and Janis, five loggerhead turtles rescued in Maltese waters and rehabilitated at the Aquaculture Directorate at Fort San Luċjan.

Tama, the sole adult male and a victim of a multiple injuries caused by a propeller, was missing a front left flipper on release.

Doris and Carmine, both juveniles, were missing one of their rear flippers following severe injuries one involving entanglement in ropes and nylon. Janis, rescued with a hook in the gullet, and Alison, who was entangled in a fishing line, were not missing any flippers on release.

The turtles spent between just seven months and four years at the rehabilitation centre, depending on the severity of their injuries. Tama had spent the longest time in captivity while Alison had spent the shortest time.

The study assessed whether specimens suffering from loss of different flippers behaved differently from fully able specimens, and whether turtles who have undergone amputation of one or more of their flippers differed in the migratory routes and speeds.

The GPS tracking showed that the five turtles covered similar mean distances (11.2–22.4 km/day), despite differences in their age and physical abilities. “These results suggest that despite their physical limitations, turtles having missing limbs moved at speeds and covered distances comparable to their fully able counter parts,” the authors of the study conclude.

The study showed differences in the route taken by the different turtles.

Following their release, two of the turtles spent most of their time in the sea south of the Maltese Islands, while one (Janis) spent most of its time in the Malta-Sicily channel and North East of the Maltese Islands. Alison spent a few days in the Malta-Sicily channel, but then headed south soon after the first few weeks of tracking. Carmine headed west towards Tunis immediately after release then proceeded to the north-west of the Mediterranean towards Sardinia and continued further towards Spain.

Tama, the adult missing a front flipper and who had spent the longest time in rehabilitation, recorded a maximum travelling speed comparable to Alison, a full-bodied juvenile, and Doris, a juvenile turtle missing one of its hind flippers.

Carmine, who was also missing a rear hind flipper, recorded the highest travelling speed and registered the largest distance travelled per day over the tracking period. The maximum distance recorded for this turtle was not a one-off, as it actually travelled almost an equal distance on the day after registering the maximum distance travelled. Probably this was because the turtle was travelling in open waters where speeds achieved are much higher than those in shallow coastal waters.

All turtles in the study spent some time in shallower Tunisian and Libyan waters, which suggests that these areas are important foraging and mating grounds

The results confirmed that the rehabilitation of these five marine turtles and their return to their natural environment was a success, in particular for Tama, Carmine and Doris in spite of their long period of rehabilitation. The study was conducted by Vince Attard, Celine Ferlat and Martina Cutajar from Nature Trust and by Anthony Gruppetta from St. Simon Veterinary Practice.