Three fishermen die of suspected suffocation while cleaning boat's fish hold at Tadadi port in Uttara Kannada

Who the victims are

The dead have been named in reports as Naushad, 48, Ameen, 40, and Aman, 26. One report gives Aman's age as 18, so the accounts differ on that detail. Reports also differ on the name of the port: most place it at Tadadi in Kumta taluk near Gokarna, while one calls it Tadri near Bhatkal. One of the two rescued men was taken for treatment to a hospital in Manipal, according to a report, and no names have been given for the survivors.

The danger of fish holds

Boats keep the catch in insulated compartments below the deck, and after the catch is unloaded, residues of fish, ice melt and water can remain. Organic matter that rots in a closed, poorly ventilated space can use up the oxygen and give off gases such as hydrogen sulphide and ammonia, which are harmful when they are breathed in even in small amounts. A person who goes in may be overcome in a matter of moments, and a colleague who goes in to help can be affected too. This is a general feature of confined spaces on boats, and the actual cause in this case will be known only after the investigation and the post-mortem.

Hydrogen sulphide, which is produced when protein rots, smells like rotten eggs at low levels, but at higher levels it dulls the sense of smell, so a person may stop noticing it just as it becomes dangerous. At high concentrations it can make a person collapse almost at once. Ammonia irritates the eyes and lungs. Even without any poisonous gas, a closed space where organic matter is decaying can run short of oxygen, which causes confusion and loss of consciousness without much warning.

Police have said they are trying to establish which gases were involved and what the circumstances were. In cases of this kind the questions usually include whether the hold had been opened and ventilated, whether the crew had any breathing equipment or a rope and harness, who was told to clean it and for whom the crew worked, and what the post-mortem and the tests of samples show. The case has been registered at Gokarna police station.

Safety guidance for work in enclosed spaces, which applies to fishing boats, is consistent on a few points. The compartment should be opened and ventilated for a long time before anyone enters, and fresh air should be pushed in with a blower or fan while people are working inside. Nobody should go in alone, and a person should stay outside with a rope or harness on the person who enters, ready to raise the alarm and to pull them out. Anyone who feels dizzy, sees spots or has a headache should leave at once. Rescuers should not rush in without breathing equipment, because many of the people who die in such accidents are those who try to help.

If someone is found unconscious in a closed compartment, the first step is to call for help, using the emergency number 108 for an ambulance in Karnataka, and to ventilate the space. A person should enter only with proper breathing equipment, and a casualty who is brought out into fresh air and is not breathing needs cardiopulmonary resuscitation until medical help arrives.

Deaths of workers at sea and in ports often leave families without an earner. The police case is expected to establish whether any lapse by the owner of the boat or at the port contributed to the deaths. The reports available so far do not mention any compensation announced for the families.

The coastal communities of Uttara Kannada rely on fishing, and the port at Tadadi is one of the working harbours in the district. The tragedy has raised the question of how much training and equipment crews have for cleaning and maintaining their boats.