NOTE Work et al : Necropsy findings in sea turtles taken as bycatch in the Nortin Pacific 



877 



Results 



We performed necropsies on seven olive ridley (Lepido- 

 chelys olivacea), two green (Chelonia mydas). and two 

 leatherback sea turtles (Table 1). Turtles were caught 

 between 5.4-18.0°N and 148.5-161.3''W in the North 

 Pacific from February 1996 through June 2000. 



One leatherback sea turtle (identification |ID| 3) had 

 severe acute inflammation of the liver associated with 

 clumps of fibrin (Fig. 1, A and B), mild acute inflammation 

 of heart muscle, and mild diffuse pulmonary edema. No 

 bacteria or viruses were isolated from the liver The other 

 leatherback sea turtle (ID 4) had severe diffuse fibrosis of 

 the pancreas (Fig. IC) and a large subcapsular hematoma 

 of the liver. The lesions in both turtles were severe enough 

 to cause significant impairment of organ function and 

 probable morbidity Incidental microscopic lesions in four 

 of the seven olive ridley sea turtles included mild acute 

 heart muscle inflammation (ID 6), mild focal necrosis in 

 one lung (ID 7), parasite-induced necrosis in the stomach 

 wall (ID 8), and foreign material (probable ingesta) in the 

 bronchioles (ID 10). Microscopic lesions in the olive ridley 

 sea turtles were not severe enough to cause morbidity, and 

 no microscopic lesions were seen in the remaining turtles 

 including the green sea turtles. 



Cause of mortality for all sea turtles was drowning after 

 hooking; however, in only one case (olive ridley ID 11 ) was 

 there gross evidence of water in the lungs. Female ( 10/11) 

 and lightly hooked (9/11) animals predominated. Most 

 hooks were tuna 3.6-mm hooks (Table 1). In one deeply 

 hooked olive ridley turtle (ID 10), the hook perforated the 

 esophageal wall in two places at approximately half of the 

 length of the wall. In the other olive ridley sea turtle, ID 

 6 (classified as deeply hooked by the observer), the hook 

 perforated just caudal to the tongue. Both leatherback 

 sea turtles had been entangled by the leader; one had the 

 leader tightly wound around the right front flipper, the 



other had the leader around the neck, where it had caused 

 lacerations . 



Bait (sama; Cololabias saira) was seen in the esophagus 

 of four olive ridley sea turtles; one turtle contained three 

 fish, indicating ingestion from more than one hook. Other 

 items in olive ridley stomachs included cowfish, pyroso- 

 mas, pelagic snails, bird feathers, and small fragments of 

 plastic. Stomachs from both leatherback turtles and from 

 one green turtle contained pyrosomas exclusively. 



Discussion 



Only two sea turtles were classified as deeply hooked; most 

 turtles had no visible lesion indicative of hooking either 

 to the observer present on board when the turtles were 

 hauled into the boat, or to the observer and us at the time 

 of necropsy. Turtles that scored as lightly hooked but that 

 died later would suggest that deep or light hooking may 

 not be satisfactory criteria for the probability of short-term 

 survival in the species we studied. Similarly, Polovina et 

 al. (2000) and Parker et al. (in press) obsei"ved that there 

 was no significant difference in distance or speed of travel 

 between deeply and lightly hooked loggerhead turtles 

 that were caught by the North Pacific longline fishery and 

 then marked with satellite tags, and followed for several 

 months. Hence, deep versus light hooking may not be a 

 useful indicator of long-term survival for these species. 



The preponderance of females in our study was notice- 

 able. Markedly skewed sex ratios in wild sea turtles are 

 more commonly encountered among hatchlings (Gonzales 

 et al., 2000), presumably due to incubation well below or 

 above the pivotal temperature (Mrosovsky and Yntema, 

 1980). Studies of immature green sea turtles stranded 

 with fibropapillomatosis in Hawaii revealed a sex ratio of 

 close to 1:1 (Koga and Balazs, 1996). Ross (1984) in Oman 

 reported sex ratios of adult green sea turtles to be closer to 



