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Thursday, 10 March 2011 16:57

Health Problems and Disease Patterns

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Work in the fishing and fish-processing industry shows a clear differentiation according to gender, with the men traditionally doing the actual fishing while the women work at fish processing on shore. Many of the persons working on fishing vessels may be looked upon as unskilled; the deckhands, for instance, receive their training in the work on board. The navigators (captain, skipper and mate), the machine room personnel (engineer, machinist and stoker), the radio operators and the cooks all have different educational backgrounds. The main assignment is to fish; other tasks include loading of the vessel, which is done on the open sea, followed by the fish processing, which takes place to various stages of completion. The only common exposure of these groups occurs during their stay on board the vessel, which is in constant motion both while they are working and resting. Fish processing on shore will be dealt with later.


The most dangerous work tasks for the individual fishers are related to the setting out and hauling in of the fishing gear. In trawler fishing, for example, the trawl is laid out in a sequence of tasks involving the complicated coordination of different types of winches (see “Major sectors and processes” in this chapter). All operations take place at great speed, and teamwork is absolutely essential. While setting the trawl, the connecting of the trawl doors to the warp (wire ropes) is one of the most dangerous moments, as these doors weigh several hundred kilograms. Other parts of the fishing gear are also too heavy to be handled without the use of derricks and winches while shooting the trawl (i.e., heavy gear and bobbings move freely around before being hoisted overboard).

The whole procedure of setting and hauling aboard the trawl, purse seine and nets is carried out using wire cables which pass across the working area often. The cables are at high tension, as there is often an extremely heavy pull from the fishing gear in a direction opposite of the forward motion of the fishing vessel itself. There is a great risk of getting entangled by or falling onto the fishing gear and thus being drawn overboard, or of falling overboard when laying out the fishing gear. There is a risk of crushing and trapping injuries to fingers, hands and arms, and the heavy gear may fall or roll and thus injure legs and feet.

Bleeding and gutting the fish are often done manually and take place on the deck or on a shelterdeck. The pitching and rolling of the vessels make injuries to the hands and fingers common from knife cuts or from pricks of fish bones and spines. Infections in wounds are frequent. Long-line and hand-line fishing involve the risk of wounds to fingers and hands from the hooks. As this type of fishing is becoming more and more automated it is becoming associated with dangers from line haulers and winches.

The method of managing fishing by limiting the amount caught from a restricted natural resource area also influences the injury rate. In some places pursuit quotas allocate to the vessels certain days when they are allowed to fish, and the fishers feel they have to go fishing at these times whatever the weather.

Fatal accidents

Fatal accidents at sea are easily studied through mortality registers, as accidents at sea are coded on the death certificates as water transport accidents according to the International Classification of Diseases, with an indication as to whether the injury was sustained while employed on board. Death rates from work-related fatal accidents among workers in the fishing industry are high, and higher than for many other occupational groups on shore. Table 1 shows the mortality rate per 100,000 for fatal accidents in different countries. The fatal injuries are traditionally classified as (1) individual accidents (i.e., individuals falling overboard, being swept overboard by heavy seas or being fatally injured by machinery) or (2) individuals lost as a result of vessel casualties (e.g., because of foundering, capsizing, missing vessels, explosions and fires). Both categories are related to the weather conditions. Accidents to individual crew members outnumber the others.

Table 1. Mortality figures on fatal injuries among fishermen as reported in studies from various countries


Study period

Rates per 100,000

United Kingdom



United Kingdom



United Kingdom






New Zealand






















The safety of a vessel depends on its design, size and type, and on factors such as stability, freeboard, weather-tight integrity and structural protection against fire. Negligent navigation or errors of judgement may result in casualties to vessels, and the fatigue which follows long spells of duty may also play a role, as well as being an important cause of personal accidents.

Better safety records of more modern vessels may be due to the combined effects of improved human and technical efficiency. Training of personnel, proper use of flotation support apparatus, suitable clothing and the use of buoyant overalls may all increase the probability of rescue of persons in the event of an accident. More widespread use of other safety measures, including safety lines, helmets and safety shoes, may be needed in the fishing industry in general, as discussed elsewhere in this Encyclopaedia.

Non-fatal injuries

Non-fatal injuries are also quite common in the fishing industry (see table 2). The body regions of injured workers most frequently mentioned are the hands, lower limbs, head and neck and upper limbs, followed by the chest, spine and abdomen, in decreasing order of frequency. The most common types of traumas are open wounds, fractures, strains, sprains and contusions. Many non-fatal injuries may be serious, involving, for instance, amputation of fingers, hands, arms and legs as well as injuries to the head and neck. Infections, lacerations and minor traumas of the hands and fingers are quite frequent, and treatment with antibiotics is often recommended by the ship’s doctors in all cases.

Table 2. The most important jobs or places related to risk of injuries

Job or tasks

On board vessels injury

On shore injury

Setting and hauling trawl, purse seine and other fishing gear

Entangled in the fishing gear or wire cables, crushing injuries, fall overboard


Connecting trawl doors

Crushing injuries, fall overboard


Bleeding and gutting

Cuts from knives or machines,
musculoskeletal disorders

Cuts from knives or machines,
musculoskeletal disorders

Long-line and hand-line

Wounds from hooks, entangled in the line


Heavy lifts

Musculoskeletal disorders

Musculoskeletal disorders


Cuts, amputations using knives or machines, musculoskeletal disorders

Cuts, amputations using knives or machines, musculoskeletal disorders

Trimming fillets

Cuts from knives, musculoskeletal disorders

Cuts from knives, musculoskeletal disorders

Work in confined spaces, loading and landing

Intoxication, asphyxia

Intoxication, asphyxia



Information on the general health of fishers and overviews of their illnesses are mainly obtained from two types of reports. One source is the case series compiled by ships’ doctors, and the other is the medical advice reports, which report on evacuations, hospitalizations and repatriations. Unfortunately, most if not all of these reports give only the numbers of patients and percentages.

The most frequently reported non-traumatic conditions leading to consultations and hospitalization arise as a result of dental conditions, gastro-intestinal illness, musculoskeletal conditions, psychiatric/neurological conditions, respiratory conditions, cardiological conditions and dermatological complaints. In one series reported by a ship’s doctor, psychiatric conditions were the most common reason for evacuating workers from trawlers on long-term fishing voyages, with injuries only coming in second place as a reason for rescuing fishers. In another series the most common illnesses which necessitated repatriation were cardiological and psychiatric conditions.

Occupational asthma

Occupational asthma is frequently found among workers in the fish industry. It is associated with several types of fish, but most commonly it is related to exposure to crustaceans and molluscs—for example, shrimp, crabs, shellfish and so on. The processing of fishmeal is also often related to asthma, as are similar processes, such as grinding shells (shrimp shells in particular).

Hearing loss

Excessive noise as a cause of decreased hearing acuity is well recognized among workers in the fish-processing industry. The machine room personnel on the vessels are at extreme risk, but so are those working with the older equipment in fish processing. Organized hearing conservation programmes are widely needed.


In some studies on fishers and sailors from the merchant fleet, high death rates because of suicide have been reported. There is also an excess of deaths in the category where the doctors were not able to decide whether the injury was accidental or self- inflicted. There is a widespread belief that suicides in general are underreported, and this is rumoured to be even greater in the fishing industry. Psychiatric literature gives descriptions of calenture, a behavioural phenomenon where the predominant symptom is an irresistible impulse for sailors to jump into the sea from their vessels. The underlying causes for the risk for suicide have not been studied among fishermen particularly; however, consideration of the psychosocial situation of the workforce at sea, as discussed in another article in this chapter, seems a not unlikely place to start. There are indications that the suicide risk increases when the workers stop fishing and go ashore both for a short while or definitely.

Fatal poisoning and asphyxia

Fatal poisoning occurs in incidents of fire on board fishing vessels, and is related to inhalation of toxic smoke. There are also reports of fatal and non-fatal intoxication resulting from the leak of refrigerants or the use of chemicals for preserving shrimp or fish, and from toxic gases from the anaerobic decay of organic material in unventilated holds. The refrigerants concerned range from the highly toxic methyl chloride to ammonia. Some deaths have been attributed to exposure to sulphur dioxide in confined spaces, which is reminiscent of the incidents of silo-filler’s disease, where there is exposure to nitrogen oxides. Research has similarly shown that there are mixtures of toxic gases (i.e., carbon dioxide, ammonia, hydrogen sulphide and carbon monoxide), along with low partial pressure of oxygen in holds on board ship and on shore, which have resulted in casualties, both fatal and non-fatal, often related to industrial fish such as herring and capelin. In commercial fishing, there are some reports of intoxication when landing fish that have been related to trimethylamine and endotoxins causing symptoms resembling influenza, which may, however, lead to death. Attempts could be made to reduce these risks through improved education and alterations to equipment.

Skin diseases

Skin diseases affecting hands are common. These may be related to contact with fish proteins or to the use of rubber gloves. If gloves are not used, the hands are constantly wet and some workers may become sensitized. Thus most of the skin diseases are contact eczema, either allergic or non-allergic, and the conditions are often constantly present. Boils and abscesses are recurrent problems also affecting hands and fingers.


Some studies, although not all, show low mortality from all causes among fishermen as compared to the general male population. This phenomenon of low mortality in a group of workers is called the “healthy worker effect”, referring to the consistent tendency for actively employed people to have more favourable mortality experience than the population at large. However, due to high mortality from accidents at sea, the results from many mortality studies on fishermen show high death rates for all causes.

The mortality from ischemic heart diseases is either elevated or decreased in studies on fishermen. Mortality from cerebrovascular diseases and respiratory diseases is average among fishermen.

Unknown causes

Mortality from unknown causes is higher among fishermen than other men in several studies. Unknown causes are special numbers in the International Classification of Diseases used when the doctor who issues the death certificate is not able to state any specific disease or injury as the cause of death. Sometimes deaths registered under the category of unknown causes are due to accidents in which the body was never found, and are most likely water transport accidents or suicides when the death occurs at sea. In any case an excess of deaths from unknown causes can be an indication, not only of a dangerous job, but also of a dangerous lifestyle.

Accidents occurring other than at sea

An excess of fatal traffic accidents, various poisonings and other accidents, suicide and homicide have been found among fishermen (Rafnsson and Gunnarsdóttir 1993). In this connection the hypothesis has been suggested that seamen are influenced by their dangerous occupation towards hazardous behaviour or a hazardous lifestyle. The fishermen themselves have suggested that they become unaccustomed to traffic, which could provide an explanation for the traffic accidents. Other suggestions have focused on the attempts of fishermen, returning from long voyages during which they have been away from family and friends, to catch up on their social life. Sometimes fishermen spend only a short time ashore (a day or two) between long voyages. The excess of deaths from accidents other than those at sea points to an unusual lifestyle.


The International Agency for Research on Cancer (IARC), which among other things has a role in evaluating industries in respect to the potential cancer risks for their workers, has not included fishing or the fish-processing industry among those industrial branches showing clear signs of cancer risk. Several mortality and cancer morbidity studies discuss the cancer risk among fishermen (Hagmar et al. 1992; Rafnsson and Gunnarsdóttir 1994, 1995). Some of them have found an increased risk for different cancers among fishermen, and suggestions are often given as to possible causes for the cancer risks which involve both occupational and lifestyle factors. The cancers which will be discussed here are cancer of the lip, lung and stomach.

Cancer of the lip

Fishing has traditionally been related to lip cancer. Previously this was thought to be related to exposure to tars used to preserve the nets, since the workers had used their mouths as “third hands” when handling the nets. Currently the aetiology of lip cancer among fishermen is considered to be the joint effect of exposure to ultraviolet radiation during outdoor work and smoking.

Cancer of the lung

The studies on lung cancer are not in accord. Some studies have not found increased risk of lung cancer among fishermen. Studies of fishermen from Sweden showed less lung cancer than the reference population (Hagmar et al. 1992). In an Italian study the lung cancer risk was thought to be related to smoking and not to the occupation. Other studies on fishermen have found increased risk of lung cancer, and still others have not confirmed this. Without information on smoking habits it has been difficult to evaluate the role of smoking versus the occupational factors in the possible cases. There are indications of the need to study separately the different occupational groups on the fishing vessels, as engine room personnel have elevated risk for lung cancer, thought to be due to exposure to asbestos or polycyclic aromatic hydrocarbons. Further studies are thus needed to clarify the relation of lung cancer and fishing.

Cancer of the stomach

Many studies have found elevated risk of stomach cancer in fishermen. In the Swedish studies the risk of stomach cancer was thought to be related to high consumption of fatty fish contaminated with organochlorine compounds (Svenson et al. 1995). At present it is uncertain what role dietary, lifestyle and occupational factors play in the association of stomach cancer with fishing.



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