Every year, commercial fisheries capture an estimated 0.9 to 2.5 trillion wild fishes for human and animal consumption. This figure doesn’t even account for illegal catches or discards, meaning the true numbers are likely higher.

Currently, the vast majority of these animals suffer significantly during slaughter. They typically die via asphyxiation in air or ice or evisceration while fully conscious. These methods are widely considered inhumane because they don’t render fishes immediately insensible to pain, stress, and suffering.

While humane stunning — rendering an animal unconscious immediately — is becoming more common in aquaculture for species like salmons and trouts, legislation and guidance for wild-caught fishes remain virtually non-existent. Beyond welfare, stress during slaughter can negatively affect the quality of the final food product, suggesting that humane methods could offer economic benefits to commercial fishers.

This article aimed to catalog existing scientific research on humane stunning for wild-caught fishes to identify knowledge gaps and feasibility for commercial fisheries. The authors conducted systematic mapping, a type of review that gathers and organizes a large amount of evidence to create a categorized overview of what information currently exists on a broad topic. They searched seven academic databases and 20 specialist organization websites for relevant studies published in English and Spanish.

The authors looked for studies involving wild fishes caught on a commercial scale. They focused on stunning methods recognized by the World Organization for Animal Health, such as electrical and percussive stunning. After screening thousands of records, the final review included 133 articles covering 223 unique studies. The authors then carried out a narrative evaluation, describing the studies’ implications for fish welfare, flesh quality, and practical implementation.

A Lack Of Real-World Data

The review reveals that research into humane slaughter for wild fishes is severely lacking compared to the magnitude of the problem.

Focus On Farmed Species

While the review targeted wild-caught species, 95% of the identified studies were actually conducted on farmed fishes, particularly rainbow trouts and Atlantic salmons.

Only 12 studies tested stunning methods on fishes caught directly from the wild, and only seven of those took place on board actual fishing vessels.

Method Effectiveness

Electrical stunning was the most researched method (75% of studies), followed by percussive stunning (32% of studies). However, protocols developed for farmed animals may not work for wild ones. For example, one study found that wild Atlantic cods required different electrical settings than farmed cods, possibly due to the damage or stress from trawling affecting their skin’s electrical resistance.

Immobilization Isn’t Stunning

A critical finding is that some commercial vessels use electricity to “electro-immobilize” fishes rather than stun them. This temporarily paralyzes the animals, making them safer and easier for crew to handle, but the fishes remain fully conscious and sensible to pain.

Flesh Quality

The impact on flesh quality is mixed. While some methods improved quality, others, such as in-water electrical stunning for Atlantic herrings, damaged the fillets to the point where they were commercially unacceptable. Even when they improve welfare, methods that negatively affect flesh quality are likely to be rejected by the industry.

Limitations

The authors noted that their search was limited to English and Spanish documents, meaning relevant studies in other languages may have been missed. Additionally, the terminology used in the field is inconsistent. Researchers use various terms like “electro-narcosis” or “electro-sedation” without clear definitions, making it difficult to compare results across studies. Finally, because most studies were lab-based, it’s unclear whether the high welfare standards achieved in controlled environments can be replicated on the moving deck of a commercial trawler.

Potential For Impact

This review underscores that the welfare of wild-caught fishes is a neglected area with massive potential for impact.

• Call for species-specific research: There’s no “one-size-fits-all” solution. Advocates can push for funding applied research to determine the correct stunning parameters for different species and environments.
• Challenge “immobilization”: Be aware that electricity used on fishing boats doesn’t guarantee better welfare at slaughter. Advocates should scrutinize industry claims to ensure that electrical systems are causing true unconsciousness, not just temporary paralysis that masks suffering.
• Push for commercial feasibility trials: Success in the lab doesn’t always translate to the ocean. To win industry support, advocates need to demonstrate that humane stunning is practical, safe for workers, and economically viable on board vessels.

This summary was drafted by a large language model (LLM) and closely edited by our Research Library Manager for clarity and accuracy. As per our AI policy, Faunalytics only uses LLMs to summarize very long reports (50+ pages) that are not appropriate to assign to volunteers, as well as studies that contain graphic descriptions of animal cruelty or animal industries. We remain committed to bringing you reliable data, which is why any AI-generated work will always be reviewed by a human.