Doryteuthis opalescens completes its life cycle in roughly six to nine months. There is no reservoir of older adults to buffer a bad year, so recruitment in one season determines the fishery in the next. The species spawns over sand in shallow water, attaching capsules of eggs in dense mats that divers describe as covering whole patches of bottom.
Cool, productive upwelling conditions favour the squid. During strong El Nino events, when upwelling weakens and the water warms, landings have fallen by more than an order of magnitude within a season and then recovered as conditions returned. Californian landings in the strongest years have exceeded 100,000 tonnes, making squid the state's largest fishery by weight.
Management reflects this volatility. Rather than setting a quota per stock assessment in the way a long-lived groundfish is managed, California caps the seasonal catch and closes weekends to allow undisturbed spawning. What is not settled is how much of the variation is genuine population change and how much is squid redistributing to cooler water outside the fishing grounds.