Bycatch can include juvenile fish, non-target fish species, sharks and rays, marine mammals, seabirds, turtles, and invertebrates such as corals. Currently, bycatch discussion focuses on population-level effects: how many Endangered, Threatened, and Protected species were caught, whether that's affecting stock sustainability, whether it violates fisheries regulations. Those are important questions to ask, but for animal welfare we are asking something different: what did those individual animals experience?

Bycatch animals experience the same stressors as target species. So the first priority should be preventing unwanted catch from happening in the first place. This can include more selective gear, changes in fishing location or timing, real time information (e.g. underwater cameras) and escape devices.

In cases where bycatch does happen, welfare includes how they are handled, retained or released. Animals should be handled as little as possible and released in a way that gives them the best chance of survival. If kept onboard, they should be held in species-specific holding tanks just like for target species.

If bycatch reduction is going to be taken seriously as a conservation goal, understanding the welfare dimensions gives additional reasons to act and additional metrics for evaluating whether gear modifications actually work.