Abstract
In November 2012, an emaciated adult female Hawaiian monk seal (Monachus schauinslandi) was found with a large fishing hook in the left commissure of the mouth and trailing monofilament line with a wire leader. The oral cavity was malodorous with severe lingual edema. Due to its emaciated status, dull mentation and apparent dehydration, the seal was hospitalized for supportive care and ancillary diagnostics. Examination under sedation revealed severe necrosis of the rostral third of the tongue, with glossopharyngeal edema that precluded complete oral examination. Radiographs ruled out any additional foreign objects in the upper gastrointestinal tract. A mild anemia was noted on complete blood count (CBC); biochemistry was within normal limits.
Under general anesthesia, two deep glossal lacerations involving 50% thickness of the tongue were identified; one transverse laceration at the mid-body of the tongue, and one that extended sagittally from the mid-body of the tongue to the left commissure. Endoscopic examination confirmed that the trauma was confined to the lingual region. The necrotic rostral third of the tongue was excised to healthy tissue adjacent to the frenulum. The sagittal laceration was closed with a double layer of 0-PDS (polydioxanone). Buccal mucosa from the left commissure was slid to cover the base of the tongue. Glossal muscle was excised to close the transverse laceration with glossal mucosa. It was unclear if the seal would be able to effectively prehend food. Post-operatively the animal was supported with parenteral fluids, anti-inflammatories, antibiotics and vitamins. The patient was obtunded in the 24 hours following recovery. Two days post-operatively, a small tube feeding was administered. The patient caught and consumed live prey on day four.
Pre-release CBC revealed a normocytic, normochromic, regenerative anemia. The patient demonstrated a consistent ability to capture live fish, and was satellite tagged and released 13 days after hospitalization. Post-release observational and telemetry data suggested appropriate movements, yet changes in body condition were difficult to distinguish. Assessment 13 days after release revealed a slight increase in body condition, resolving anemia and marked leukocytosis (41.1 K/µL) with 10% unclassified, phagocytically active mononuclear cells. A steady improvement in body condition was documented thereafter, suggesting that this individual is capable of successful foraging. This is the first report of severe lingual trauma and subsequent partial glossectomy in a Hawaiian monk seal and supports the need for early reporting of hooking incidents.
In the Main Hawaiian Islands (MHI), reports of ingestion of fishing hooks by Hawaiian monk seals are increasing.2 Many incidental hooking injuries are superficial (i.e., confined to the lip), uncomplicated and treatable in field settings with manual restraint. From 1980–2011, two of 86 seals examined with hooks were hospitalized and one was found dead.2 However, the number of hooking injuries increased markedly in 2012, necessitating hospitalization of three seals and causing two mortalities. While the population of endangered Hawaiian monk seals is declining overall, the subpopulation in the Main Hawaiian Islands is growing.1 This suggests that seal and fishing gear interactions will continue to rise and that rehabilitation capacity must expand.
Acknowledgements
This work was conducted under NMFS Permit 932-1905 and was accomplished with the help of the Waikiki Aquarium, Honolulu Zoo, Hawaiian Monk Seal Response Team Oahu, Dolphin Quest, and NOAA Fisheries Marine Mammal Health and Stranding Response Program. In particular, the authors would like to thank Dr. Deborah Fauquier, Dr. Shawn Johnson, Dr. Ben Okimoto, Dr. Gabby Schrader, Trevor Spradlin and Jaclyn Taylor for their support.
* Presenting author
Literature Cited
1. Baker, JD, Harting, AL, Wurth, TA, Johanos, TC. 2011. Dramatic shifts in Hawaiian monk seal distribution predicted from divergent regional trends. Mar Mam Sci 27: 78–93.
2. Pacific Islands Fisheries Science Center, unpublished data.