Atlantic mackerel are caught in enormous quantities by purse seine and mid-water trawl. Their welfare during capture and killing is largely unaddressed in current fishery management.
Mackerel capture welfare is a largely invisible issue despite involving some of the largest animal welfare events by individual numbers. When a purse seine closes on a school of mackerel, millions of sentient animals enter a process that leads to slow death from asphyxiation, crushing, and suffocation over hours. Rapid killing methods — such as immediately transferring fish to refrigerated sea water (RSW) systems with high carbon dioxide or through stunning before transfer — are technically feasible but rarely applied. The welfare case for improving capture methods in high-volume fisheries like mackerel is compelling given the numbers involved. Market certification schemes like the MSC do not currently include fish welfare criteria — a significant gap that advocates are beginning to challenge.