Scripps Institution of Oceanography

Our knowledge of the biology of oceanic cephalopods is extremely limited. The population sizes, distribution patterns, breeding seasons, life histories, and growth rates are virtually unknown. In view of the fact that these organisms are undoubtedly abundant and ecologically important, both as predators and prey, this state of ignorance is unfortunate. Part of the reason for this lack is attributable to the great difficulty of adequately sampling the adults. The larvae and some juveniles, however, can be caught, in the types of plankton nets and trawls generally in use. Therefore the possibility exists that the times and places of spawning, and the developmental history of many species, may be determined from zooplankton surveys. Using this approach presupposes that a sufficiently extensive area is surveyed and that the sampling is intensive in both space and time. It is also necessary that enough specimens of the adults and intermediate-sized ranges be available for accurate identification of the larvae. This is best done by tracing the morphological changes through progressively smaller individuals. The Marine Life Research Group at Scripps Institution of Oceanography (SIO) has available a very large collection of zooplankton samples taken by the California Cooperative Oceanic Fisheries Investigations (CalCOFI) in the California Current. This program has surveyed a large portion of this current system by monthly cruises for a period of ten years. It is from these samples that the data in this report are derived.