per m2, now reduced to about 1.0 per m2. These aggregations form in and around geologic structures, such as undersea canyons and seamounts, where water movement and mixing is high, ensuring dense prey concentrations. The aggregations are not necessarily for spawning or feeding; the fish are thought to cycle through metabolic phases (active or feeding and inactive or resting) and seek areas with ideal hydrologic conditions to congregate during each phase. They lose almost all pigmentation while inactive, when they are very approachable. Predators include large, deep-roving sharks, cutthroat eels, merluccid hakes, and snake mackerels. When active, juveniles feed primarily on zooplankton such as mysid shrimp, euphausiids (krill), mesopelagic and benthopelagic fish, amphipods, and other crustaceans; mature adults consume smaller fish, predominantly of the Butterflyfish and Lanternfish families, and squid, which make up to 20% of their diet. The diet of the orange roughy is depth-related, with adult diets inversely related to that of juveniles. For example, juvenile consumption of crustaceans is lowest at but increases with depth, while crustaceans in the adult diet peak at and decrease with depth. The consumption of fish is the opposite: juvenile consumption decreases with depth while adult consumption increases. This inverse feeding pattern may be an example of resource-partitioning to avoid intraspecific competition for the available food at depths where prey is less abundant. The orange roughy's metabolic phases are thought to be related to seasonal variations in prey concentrations. The inactive phase conserves energy during lean periods. Orange roughy can live for over 200 years. Reproduction Orange roughy are oceanodromous (wholly marine), pelagic spawners: that is, they migrate several hundred kilometers between localized spawning and feeding areas each year and form large spawning aggregations (possibly segregated according to gender) wherein the fish release large, spherical eggs in diameter, made buoyant by an orange-red oil globule) and sperm en masse directly into the water. The fertilized eggs, (and later larvae) are planktonic, rising to around to develop, with the young fish eventually descending to deeper waters as they mature. Orange roughy are also synchronous, shedding sperm and eggs at the same time. The time between fertilization and hatching is thought to be 10 to 20 days; fecundity is low, with each female producing only 22,000 eggs per kg of body weight, less than 10% of the average for other species of fish. Females rarely produce more than 90,000 eggs in one lifetime. Spawning