Studies on rearing of lingcod Ophiodon elongatus

Experiments were conducted to determine the influence of environmental factors on growth and survival of larval lingcod as a prerequisite for development of practical methods for production of juveniles for restocking depleted populations. The time to 50% hatch of lingcod eggs decreased from 48 days at 8 degrees C to 24 days at 14 degrees C. The survival of young unfed larvae was significantly improved in darkness at a salinity of 20 parts per thousand compared with light at 30 parts per thousand. The larvae were able to ingest both cysts and nauplii of Artemia equally well at light intensities of 0.0004 mu E m(-2) s(-1) and 0.03 mu E m(-2) s(-1). It is concluded that survival of lingcod larvae during the critical early stages can be improved by keeping them in darkness or at low light intensity to reduce their swimming activity and by reducing salinity. The proportion of essential fatty acids in enriched Artemia remained below that found in lingcod or copepods indicating that further improvements can be made in diet quality.