A routine maintenance task on the fishing vessel Antarctic Discovery turned into a hazardous situation when decomposing fish waste was unintentionally pumped into a machinery space, resulting in four workers being sent to the hospital. This is the finding of a recent investigation by New Zealand's Transport Accident Investigation Commission (TAIC).
The incident happened on February 21, 2025, while the vessel was in dry dock in Lyttelton for routine maintenance. According to the TAIC report, two apprentice fitters entered the bow thruster machinery space to work on pipes located near a holding tank that contained a mix of rotting fish remains and seawater.
The investigation suggested that one of the workers may have unintentionally pressed an unmarked button that started the offal pump. This caused the tank's contents to be sprayed out through an open hose above the ladder entering the compartment, drenching the workers and quickly releasing hydrogen sulfide, a very toxic gas produced from decaying organic matter.
The apprentices managed to escape by climbing through the spilled waste and getting to fresh air. However, the vessel's superintendent went in to check things out and was quickly affected by the gas. When the chief engineer and second engineer entered the space, they collapsed and had to be rescued by crew members using breathing apparatus. All four were hospitalized but later recovered.
TAIC's Acting Chief Investigator, Tahlia Fisher, stated that the accidental start of the pump caused the incident, but the investigation also found serious safety failures that go beyond just the maritime sector.
The commission discovered that equipment nearby that could create hazards had not been shut down before maintenance started, even though the workers were focused on different machinery. They also concluded that the bow thruster machinery space should have been treated as a confined space due to its enclosed design and potential hazardous atmospheres, even if it wasn’t officially classified as one.
Additionally, the investigation pointed out the lack of coordination among various organizations working on the vessel during the dry dock period, emphasizing that overlapping responsibilities require better communication and shared safety management. Investigators also noted that safety-critical changes to the vessel did not have proper oversight, documentation, or formal approval processes.
TAIC acknowledged that the vessel's owner, Australian Longline Pty. Ltd., has already taken significant corrective actions since the incident. However, the commission still issued safety recommendations to both Australian Longline and Lyttelton Port Company to enhance the management of safety-critical systems and improve dry dock safety procedures.
Hydrogen sulfide is one of the most dangerous hazards in maritime operations, particularly on fishing vessels where decaying fish waste can build up in tanks, holds, and piping systems. At high concentrations, this gas can quickly incapacitate workers by affecting their sense of smell and impacting their respiratory and nervous systems, making confined-space procedures and atmospheric testing essential before entering such areas.
TAIC emphasized that the goal of this investigation is to enhance transport safety, not to assign blame, in order to prevent similar incidents from happening in the future.