The hazard foremost in most people's minds, although it may not be the most prevalent, when involved in electric fishing is that of receiving an electrical shock. Electric fishing equipment uses a variety of output waveforms - direct current, rectified alternating current, alternating current, square-wave current (condenser discharge), and pulses of current. The hazard is related to the magnitude of the current, the duration of the shock and the current waveform. As an example, direct current (DC) causes a severe shock when the circuit is made or broken but not while the current is steady. By contrast, a 50 or 60Hz alternating current will produce a continuous painful shock. It also requires about three or four times more direct current than alternating current for a lethal shock.
The process of being shocked from energized conductors has been well described by Bernstein (1973, 1974) and Hartley (1975) but basically falls into three categories of electrocution listed below in descending order of severity.
Ventricular fibrillation is described as an unco-ordinated, asynchronous contraction of the ventricular muscle fibres of the heart in contrast to their normal co-ordinated and rhythmic contraction (Bernstein, 1974). The greatest risk of ventricular fibrillation occurs when an electric shock is received and the path of the current is through the chest (eg between two arms or one arm and a leg). The heart's natural rhythm is stopped and replaced by an asynchronous quivering. This is extremely dangerous and death can occur in minutes unless correctional steps are taken immediately. A defibrillator must be used to restore a stable pulse. Cardiopulmonary resuscitation (CPR) can be used to stabilize the patient until they can be defibrillated, but it is only a stalling tactic and will not restore the correct pulse by itself.
Respiratory arrest can be caused by shocks or blows to the head. The respiratory control centre is contained at the base of the skull and can be deactivated by a shock or blow in this area. CPR or artificial respiration can help in certain cases.
Asphyxia is caused by the chest muscles contracting and not releasing. Current from an electric shock which is above a certain level (ie 0.005A at 60Hz) can cause a person if he is grasping a live wire to be unable to let go (Bernstein, 1974). This can be sufficient to cause the chest muscles to restrict and in turn asphyxiate the victim.
Although injury resulting directly from the electric current is considered the most prevalent, the potential for secondary, electric fishing related injuries, such as scrapes, bruising, falls or drowning, is equally, if not more significant.
Next to electrical shock another common risk and hazard is death by drowning, When an individual is in the water where electrical current is present, it is possible for relatively low currents to induce drowning. These currents make it impossible to swim. The body of a person drowned because of electrocution will appear to a pathologist as that of a normal drowning victim. There have been several articles dealing with the effects of electrical currents on people in water (Dalziel and Lee, 1968; Lee, 1980).
Injury by a mechanical means or secondary injury caused by electrical shock (eg a shock causing a person to lose their footing and then injure themselves) can be initiated by different hazards. These hazards can take the form of fire, noise fatigue, slippery footing, poor boating practice, poor boat design, improper clothing or insufficient training, amongst others. The common denominator is that all can be eliminated by using common sense, following proper safety protocol and using well-designed, safe, equipment. ‘There is no substitute for a competent and experienced crew who work together as a team in a safe and reliable manner’ (Hartley, 1975).
