Abstract

Entanglement of sea turtles in fishing gear is a global problem that impacts all species.¹ One of the most frequent causes of morbidity due to fishing gear interaction is front flipper entanglement. Fishing line entanglement causes deep lacerations and strangulation of the affected flipper, leading to significant distal swelling, ischemic necrosis, bone fracture and self-amputation.

In Hawaii, a large percentage of green turtle strandings are directly caused by hook and line fishing interactions.² Most commonly these present as front flipper entanglement injuries. Historically, these were treated surgically with amputation of the affected flipper at the scapulohumeral joint. Avoiding amputation would be preferred for the individual turtle, the population, and for cost savings.

Vascularization of the limb distal to the strangulation injury has been shown to be a key prognostic indicator for potential viability of the flipper.³ This work led to the development of a conservative approach of rehabilitation therapy to treat affected flippers at the Maui Ocean Center Marine Institute (MOCMI).

This approach includes the integration of low level light therapy (laser), massage therapy, and targeted pulsed electromagnetic field (PEMF) therapy. Laser therapy speeds the healing process, promotes tissue regeneration, and relieves pain and inflammation.⁵ Photobiomodulation (PBM) is the term used to describe the mechanistic/therapeutic response to light energy (photons).⁶ Illuminating mitochondrial cytochrome c oxidase accelerates electron transfer, and induces a complex chain of physiological reactions in damaged tissues. These reactions increase ATP production, modulate the release of reactive oxygen species, and signal the release of transcription factors.⁶ Clinically, this alleviates pain, promotes and accelerates wound healing, and resolves inflammation and edema caused from strangulation injuries. Therapeutic massage involves using manual techniques (pushing strokes and manual compressions from distal to proximal) to increase blood and lymph flow to the treated area. As a result, swelling is reduced by removing metabolic wastes and increasing the supply of oxygen and nutrients distal to the strangulation. The Assisi loop is a portable therapeutic device that delivers PEMF to target tissues. PEMF is a micro-current signal that stimulates cellular repair by upregulating endogenous anti-inflammatory molecules.

Patient selection criteria for non-surgical conservative therapy included ruling out significant comorbidities and assessing vascular viability via positive doppler flow ultrasound of the brachial, radial and/or ulnar arteries.^3,4 In the acute inflammatory stage, therapeutic goals were: pain management, reduction in swelling/inflammation, control of infection, and topical wound therapy. In the recovery stage, therapeutic goals were: improve circulation, improve range of motion, build strength and support wound recovery. Daily, patients were removed from the pool for wound therapy followed by multimodal rehabilitation therapy.

From 2020 through 2021, 40 sea turtles were admitted to MOCMI for front flipper injuries due to strangulation from fishing gear entanglement. 20 patients underwent surgery for a forelimb amputation, and 20 turtles were treated with the non-invasive multimodal integrative rehabilitation therapy protocol. All 40 turtles were successfully released into the wild. Long term post release survival information is pending.

Acknowledgements

The authors thank Dr. Michelle Barbieri for her guidance. Special thanks to the entire staff and volunteers at the Maui Ocean Center Marine Institute and the National Association and Atmospheric Administration Pacific Island Regional Fisheries Science Center Marine Turtle Biology and Assessment Program for their contributions to this study and their efforts in sea turtle rehabilitation and conservation. Rescue and rehabilitation activities were conducted under the USFWS Permit # TE-72088A-2. Additional acknowledgement to our partners at Multi Radiance Medical Laser for timely advice and consultation.

Literature Cited

1.  Asmutis R. 2004. Gerry E. Studds Stellwagen Bank National Marine Sanctuary Marine Mammal Entanglement Working Group Action Plan.

2.  Chaloupka M, Work TM, Balazs GH, et al. 2008, Cause-specific temporal and spatial trends in green sea turtle strandings in the Hawaiian Archipelago (1982–2003). Marine Biology 154: 887–898.

3.  Franchini D, Valastro C, Ciccarelli S, Ricciardi M, Lenoci D, Corrente M, Di Bello A. 2020. Assessment of residual vascularization of the limb as a prognostic factor to avoid sea turtle flipper amputations. Journal of Wildlife Disease 56:145–156.

4.  Gaynor JS, Muir WW, eds. 2015 Handbook of Veterinary Pain Management, 3rd. ed. Elsevier Health Sciences. Ch. 5 Pain behaviors and pain assessment scale.

5.  Kuffler DP. 2016 Photobiomodulation in promoting wound healing: a review. Regen Med. 11:107–122.

6.  Fulop A, et al. 2010 A meta-analysis of the efficacy of laser phototherapy on pain relief. Clin J pain. 26:729–736