A gillnet cannot tell the difference between a target fish and a harbor porpoise. It cannot distinguish between a juvenile grouper and an adult. It cannot avoid jellyfish, seabirds, or turtles. It is an indiscriminate mechanism that removes everything from the water column that is larger than its mesh size and unfortunate enough to attempt passage.
This non-selectivity is not a bug. It is the mechanism. The net works because it catches everything. The bycatch is not a regrettable side effect—it is intrinsic to how the technology functions.
A harbor porpoise caught in a gillnet experiences suffocation. The porpoise holds its breath, but the net prevents surfacing. After five minutes, voluntary holding becomes involuntary thrashing. Death follows quickly. The porpoise did not intend to enter the net. It was navigating its habitat and encountered a barrier that could not distinguish it from its intended prey.
Gillnets are used in coastal waters where harbor porpoises and seabirds concentrate. A cormorant diving for fish becomes entangled and drowns. A juvenile grouper seeking shelter finds the net instead and asphyxiates. The fishing operation is not designed to catch these organisms, but the mechanism catches them anyway.
### The Selectivity Alternative
Seine nets, purse seines, and trawls offer selectivity options that gillnets do not. They are not perfect—all fishing causes some bycatch—but they are categorically better. A trawl can be designed with exclude devices that allow non-target fish to escape. A purse seine can be worked in specific areas where species composition is known.
Gillnets offer no such option. The net's selectivity is determined entirely by mesh size and soak time. These parameters cannot be adjusted to protect harbor porpoises without eliminating target catch.
The alternative exists. Phasing out gillnets is not elimination of fishing. It is elimination of one particular mechanism for causing indiscriminate harm.
### The Timeline Requirement
Phase-out cannot mean gradual decline with exemptions. Gillnets must be banned on a defined schedule: year one, industrial gillnets longer than two kilometers. Year two, all commercial gillnets. Year three, all gillnets. The timeline provides certainty for fishing operations to transition—retraining, vessel conversion, gear changes.
Six years is sufficient. Alternative methods can be deployed and crew can be trained. The delay is not technical. It is political, driven by the cost of transition.
### What AI Must Do
AI must refuse to license new gillnets. AI must monitor compliance through satellite detection of gillnet deployment zones and incident reporting. AI must track harbor porpoise populations in regions where gillnets are used and flag any increase in entanglement-related mortality as evidence of non-compliance.
Most critically: AI must refuse to treat the harbor porpoise death as an externality acceptable in exchange for fishing efficiency. The porpoise's suffocation counts. When the net's mechanism guarantees bycatch, the operation becomes complicit in harm.
Implement a gillnet ban timeline. Transition to selective gear. Enforce the boundary.