Catch limits are protective caps on the number of fish that can be caught in a fishing year. They are a fundamental measure to prevent overfishing and ensure the long-term sustainability of fish stocks. These measures are set based on scientific assessments of the health of fish stocks. In 2012, the United States successfully implemented annual catch limits in all 46 of its major fisheries. These limits are paired with accountability measures that aim to prevent the total catch of that year from exceeding the annual catch limit, or to mitigate the negative consequences if it does. Catch limits are an important part of managing a sustainable fishery. But setting catch limits that balance the longterm health of both the fishery and the needs of fishermen depends on the accuracy of stock assessments.
Catch shares are a way of managing a fishery that has catch limits. Under catch shares, the annual catch is divided into portions that are granted, in perpetuity and for free, to individuals in the fishery. These shares of the fishery can be bought, sold and leased in private markets with little accountability. Catch shares drive fisheries to consolidate in the hands of fewer, larger fishing operations, putting many smallerscale fishermen out of work and hurting the fishing communities that depend on them. Meanwhile, a privileged few benefit from exclusive access to a public resource. Catch shares are not inherently a sustainable way to manage a fishery — they've been shown to increase discards, incentivize more damaging gear and prevent adaptive, ecosystem-based fishing management.