Abstract
An occupational hazard peculiar to fishermen, is an injury from a sharp fish spine. Such spines can cause envenomation injury, infectious sequelae or trauma to anatomical structures. The management of two fishermen with penetrating ratfish (Chimaera) spine injuries to the lower limb is described. Both were managed by removal of the spine under general anaesthesia. In the second patient, the spine was embedded adjacent to the left femoral artery, highlighting the potential for major haemorrhage and supporting the use of surgical wound exploration when important structures may be involved. Herein, we describe the first report in English of Chimaera spine injury. In addition, we surveyed nine northeast Atlantic deep-sea fishermen to gain information on exposure to, and injuries from, this type of fish. The most commonly identified species was Chimaera monstrosa. Five fishermen reported injuries to their feet or hands from Chimaera spines and two had sought medical attention. The evidence indicates that deep-sea trawler fishermen of the northeast Atlantic frequently encounter Chimaera species and can suffer dangerous penetrating wounds from its dorsal spine.
Introduction
There are numerous species of fish that can inflict painful and even fatal wounds to those who invade the marine world. An occupational hazard peculiar to fishermen, is injury from a sharp defensive spine carried by certain fish. Such injuries can range from trivial abrasions to deep penetrating wounds with damage to important anatomical structures. Although there have been well-documented descriptions of envenomation injury and infectious sequelae from defensive spines, there are relatively few reports in the literature of deep penetrating wounds to fishermen.1,2
Penetrating injuries to fishermen from species including garfish (Belone belone), needlefish and weever fish (Trachinus) have been described in the literature.3–5 To our knowledge, there has been only one published report of human injury from Chimaera species. In this instance, a fisherman suffered the inflammatory effects of an envenomous injury to his leg by the dorsal fin spine of Chimaera monstrosa, also known as ratfish or rabbitfish. 6 There have been no such cases described in English and no reports of Chimaera spine wounds requiring surgical exploration.
C. monstrosa are a shark-like, cartilaginous fish of the Chimaera (Chimaeroid) order. Three Chimaera families are recognized: namely Chimaeridae (e.g. C. monstrosa), Hydrolagus and Rhinochimaera.
At maturity, Chimaeras range from approximately 40 to 150 cm in total length, with larger fish inhabiting deeper waters.7,8 Of particular interest to healthcare professionals is the dorsal fin spine carried by all Chimaera species, which is traumatogenic as well as mildly poisonous. 9 The hazardous sting projects just in front of the first dorsal fin; the second dorsal fin is much longer, less prominent and has no spiny appendage (See Appendices: Figure 1 available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC1). Chimaeras have a worldwide distribution, generally occurring on the sea floor and close to land since none are oceanic. 10 Of the approximately 33 Chimaera species, five are known to inhabit waters around Scotland: C. monstrosa, Harriotta raleighana, Hydrolagus affinis, Hydrolagus mirabilis and Rhinochimaera atlantica.8,11 These species are usually found in small groups beyond the continental shelf, and inhabit a variety of depths down the continental slope. C. monstrosa is the commonest of these species in the northeast Atlantic and is found at depths of approximately 170-1700 m.7,11 Generally considered to be an unwanted bycatch, Chimaera flesh is unpalatable but there is some commercial interest in the oil of Chimaeras and their use as fish meal.7,12
Evans found the C. monstrosa spine to be composed of an oval cartilaginous matrix coated with a layer of dentine. He demonstrated a shallow groove on the posterior aspect of the spine armed with small denticles, and the anterior aspect is relatively smooth.9,13 The length of the dorsal spine of adult C. monstrosa is approximately 85 mm. 10
We describe two patients with deep penetrating soft tissue injury from Chimaera spines; both patients were managed by surgical exploration under general anaesthesia. Within this report, we also include a survey of deep-sea fishermen fishing out of Lochinver, the only port on the west coast of Scotland that accommodates deep-sea (i.e. >200 m trawling depth) vessels. The purpose of the questionnaire was to investigate the occurrence of Chimaera-related injuries in this group of fishermen.
Patient reports
The Western Isles Hospital (WIH), Stornoway, on the Isle of Lewis off Northwest Scotland has treated two foreign deep-sea fishermen for penetrating lower limb injuries sustained from the dorsal fin spine of Chimaera species.
Patient one
A 40-year-old French fisherman presented to WIH following a penetrating Chimaera spine injury to his left foot. The fisherman had been working onboard the fishing boat when, at around midnight, a fish spine of a ‘Chimère’ went through his leather boot into his left foot. He experienced severe pain and received two doses of co-amoxiclav 625 mg and diclofenac 100 mg en route to hospital. Some 21 hours after this injury, the fisherman arrived in the accident and emergency department with a discoloured left foot and the Chimaera spine-end projecting from a wound on the lateral side of his left fifth toe. It was not possible to remove the spine under local anaesthesia and therefore underwent general anaesthesia. The spine had penetrated through the soft tissues of the fifth toe and into the plantar surface of the base of the fourth toe. The spine was removed intact and the tract irrigated with saline and cefuroxime. A four-strand 1/0 prolene ‘seton’ drain was inserted through the tract. Postoperative recovery was uneventful and the patient was discharged back to France on oral cefuroxime, with plans for the drain be removed within three to four days.
Patient two
A Portuguese fisherman, also 40-years-old, presented to WIH with a penetrating Chimaera spine injury to his left thigh. While handling a Chimaera aboard the vessel, the fisherman was impaled by the fish's dorsal fin spine and it embedded into the anterior aspect of his left thigh. The patient was transferred from the offshore fishing boat by coastguard helicopter to WIH. During transfer, Entonox gas was used for analgesia. On arrival at hospital the patient had palpable peripheral pulses and was generally comfortable. A plain radiograph demonstrated an intact spine deep in the left thigh soft tissues (See Appendices: Figure 2 available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115DC1).
The patient received intravenous cefuroxime and metronidazole preoperatively. Under general anaesthesia, the wound was surgically explored and the Chimaera spine was found to have penetrated into the subsartorial canal with the sharp tip adjacent to the femoral artery. The spine was safely removed. Immediate postoperative recovery was uneventful, with intravenous cefuroxime and metronidazole given prior to discharge home.
Chimaera injury survey
Methods
A questionnaire was designed by the authors and translated into French and Spanish (See Appendices for English version: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2). FishBase (www.fishbase.org) photograph images were used to identify Chimaera species. 14 The study aims and content of the questionnaire were explained to the English-speaking contacts at the two seafood merchants based at Lochinver. Chimaera inhabit the continental slope, which is only accessed by deep-sea trawlers, as a consequence Lochinver was selected for study as it is the main harbour on the Northwest Scottish coast for deep-sea trawler boasts fishing the Northeast Atlantic. The trawlers are generally manned by non-British crews; hence the questionnaires were translated into French and Spanish, the most common native languages of the trawlermen. Questionnaires in the appropriate language, along with stamped addressed envelopes, were distributed by the seafood merchants to fishermen willing to participate during September-November 2008. Returned questionnaires were analysed by the authors.
Results
Nine fishermen returned a completed questionnaire; four captains, four deck crew and one petty officer. By nationality three were French, four Spanish, one from Senegal and in one the nationality was not recorded. The length of a fishing career in the northeast Atlantic ranged from three months to 18 years (mean 6 years). All respondents had encountered one or more Chimaera species. The ‘Hebrides’ fishing zone (See Appendices: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2) was the region most commonly sited for encountering Chimaeras. The most commonly identified species was C. monstrosa, with seven positive identifications out of the nine respondents. Five respondents (three French and two Spanish fishermen) claimed to encounter Chimaera species ‘once per day on average’ and all these considered Chimaeras as ‘dangerous’.
Five of the respondents reported personal injury by Chimaera species, while three denied injury and one response was not clear. All five who reported such injuries had been injured on multiple occasions. The fisherman who reported the most injuries was a French captain. He had fished for 18 years from Lochinver and estimated that he had sustained as many as 12 injuries by Chimaeras. All five fishermen with injuries attributed this to the Chimaera dorsal spine. One of those, the petty officer, also reported injury from the nose and teeth of Chimaeras. All of those injured, had sustained wounds to their feet and two of the five also reported injury to their hands. Two of the five had sought medical treatment for their injuries; one reached treatment within one hour, while the other did not do so until several ‘days’ after the event. Both these wounds had been bleeding.
Only one respondent reported a subsequent scar and he also attributed chronic pain to the injury. All nine respondents reported the use of protective gloves and eight regularly wear protective footwear.
Discussion
There are many traumogenous fish that inhabit the world's oceans. Fishermen are exposed to a variety of unfamiliar hazards and may suffer unusual injuries. This is the first report of Chimaera spine injuries in the English literature. Geographical isolation from emergency healthcare services can mean that casualties at sea suffer a poorer outcome when compared with similar patterns of injury on land. The two patients described in this paper illustrate the traumatic sequelae of injury from defensive fish spines; it is clear that the dorsal fin spines (8-9 cm in length) can penetrate deep into soft tissues. 10 The second patient, where the sharp spine was found adjacent to the femoral artery, highlights the potential for damage to major blood vessels and we recommend careful wound exploration where important structures may be involved.
The small number of completed questionnaires reflects both the turnover of fishing boats at Lochinver and the considerable time constraints upon the fishermen when docked in harbour. A limitation, common to questionnaire-based studies, is the possibility of respondent bias, but we saw no evidence of this in this small study. From the returned questionnaires and the two patient reports, it is clear that fishermen who trawl the deep waters lying to the west of the British Isles encounter Chimaera species, especially C. monstrosa, and occasionally suffer soft tissue limb injuries from the dorsal spine. While Chimaera species are currently considered to be an unwanted bycatch, the commercial potential for shortnosed Chimaeridae (e.g. C. monstrosa) is being reviewed for the Atlantic ocean.12,14 Should interest in Chimaeras develop, there may be an increase in the human exposure to these hazardous fish spines and consequently an increase in spine-related injuries presenting to healthcare services.
Footnotes
Acknowledgements
The authors thank Inver Peche Ltd and Euroscot Seafoods Ltd, Lochinver for their participation during the survey; Ayrshire Language Services for matters of translation and Dr Chevonne Laurenson (NAFC Marine Centre, Scotland) for advice on matters of marine biology and methods. The authors acknowledge Dr Nils Magerøy and Dr Siegfried Ehrich for copies of their original articles and Erling Svensen (UWPhoto ANS, Norway) (Chimaera monstrosa – See Appendices: Figure 1 available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC1), V Tičina (Institute of Oceanography and Fisheries, Split, Croatia) (Chimaera monstrosa – See Appendices: available online at 
), Alberto Garazo Fabregat (Harriotta raleighana – See Appendices: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2), Rógvi Mouritsen (Hydrolagus affinis – See Appendices: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2), Dr Keiichi Matsuura (Kanagawa Prefectural Museum of Natural History, Japan) (Hydrolagus mirabilis – See Appendices: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2) and Dr Andrey Dolgov (Polar Research Institute of Marine Fisheries and Oceanography, Russia) (Rhinochimaera atlantica – See Appendices: available online at http://smj.rsmjournals.com/cgi/content/full/smj.2011.011115/DC2) for images included with permission. The authors also acknowledge Emoscopes, Wikimedia Commons, for the UK shipping forecast zones illustration (GNU Free Documentation License). The authors declare no conflict of interest, and there was no funding to this work.