Abstract
Loggerhead sea turtles (Caretta caretta) are migratory animals that come to the Northwestern Mediterranean Sea mainly in spring and summer, at the time when long-line fisheries have their highest activity. Therefore, interaction with long-line fisheries is considered the main threat to loggerhead sea turtles in this area. It is estimated that around 15,000 turtles are incidentally caught every year in the Spanish Mediterranean Sea.1,4 One of the aims of the Foundation for the Conservation and Rescue of Marine Animals (CRAM) is to rescue, treat, and release all types of marine wildlife, including marine turtles. During its 10 years of existence, approximately 470 turtles have been registered at the rescue centre, of which 291 arrived with hooks (286 alive), with 272 successfully treated and released back into the wild.
Most of the hooks seen during these 10 years are located in mid-esophagus, just cranial to the s-bend. Very few references about hook removal in sea turtles exist.2,3 However, the ideal technique should be minimally invasive, causing no further damage to the animal and allowing for a quick recovery and release back into the wild. Surgery and opening of the skin of the neck should be avoided, since healing in these animals takes a long time.
At CRAM we have developed a simple technique to remove these hooks from the turtles’ esophagus orally, without having to resort to surgery in most cases. The animal is first heavily sedated with an intravenous injection of 10–15 mg/kg ketamine (Imalgene 1000; Merial Laboratorios SA, Barcelona, Spain) and 0.1–0.2 mg/kg diazepam (Diazepan-Prodes; Prodes SA, Sant Just Desvern, Barcelona, Spain). The mouth is then opened using a canine mouth gag, allowing visualization of the hook attached to the wall of the esophagus. Using straight, long, forceps, and with the fishing line still attached to the shank, the hook and the wall of the esophagus are slightly prolapsed for a better view of the affected area. This can be performed very easily in these species since the esophagus is quite mobile. The point of the hook is then pushed back into the lumen of the esophagus making a small new hole in the wall. A piece of string is attached to the barb of the hook, so it can be held from the mouth. The shank of the hook is cut with tongs, while the barb is held by the string. Using forceps, the remainder of the hook is then completely passed through the wall of the esophagus, causing no damage to the area.
This noninvasive technique is only possible in uncomplicated cases where there is no secondary damage caused by the hook and when the hook is located cranial to the s-bend. Fortunately, over the past 10 years, the vast majority of turtles seen at CRAM present in this manner. This ensures release of turtles 5–7 days following treatment, thus, allowing successful migration to warmer waters by autumn.
Literature Cited
1. Aguilar, R., J. Mas, and X. Pastor. 1995. Impact of the Spanish swordfish longline fisheries on the loggerhead sea turtle Caretta caretta population in the western Mediterranean. In: Richardson J. J., T.H. Richardson (eds.). Proc of the 12th An Workshop on Sea Turtle Biology and Conservation. NOAA Technical Memorandum NMFS-SEFSC-361. 1–6.
2. Hyland R.J. 2002. Surgical removal of a fish hook from the esophagus of a turtle. Aust Vet J. 80:54–56.
3. Jaeger G.H., M.A. Wosar, C.A. Harms, and G.A. Lewbart. 2003. Use of a supraplastron approach to the coelomic cavity for repair of an esophageal tear in a loggerhead sea turtle. JAVMA. 223(3):353–355.
4. Mayol J., J. Muntaner, and R. Aguilar. 1988. Incidencia de la Pesca Accidental sobre las Tortugas Marinas en el Mediterráneo Español. Butlletí de la Societat d’Història Natural de les Balears. 32:19–31.