Embryology and early larval development of orange roughy (Hoplostethus atlanticus Collett)

Abstract

Orange roughy (Hoplostethus atlanticus Collett) egg development is described from fertilisation in a series of 29 stages based on morphological criteria. Two early larval stages are also described. Observations were made of eggs obtained from strip-fertilisation using trawl-caught adults and from plankton net samples of eggs caught off the east coast of New Zealand, and then cultured on-board ship. Live eggs of each stage are described and illustrated with line drawings and photographs and age-at-stage data are presented. The mean development times from fertilisation to hatching were 278 h at 8°C, 235 h at 10°C, and 146 h at 12°C. Eggs cultured at 6°C did not hatch. The mean length of the larvae at hatching was 5.33 mm notochord length. Most criteria used in staging are readily observable with a standard dissecting microscope at x25 magnification using transmitted light. Damaged eggs are common in egg production surveys for orange roughy. The staging of damaged eggs is described. Orange roughy eggs can be sorted easily from plankton samples collected during egg production surveys for orange roughy biomass, and staged on-board ship before preservation. © 1998, Copyright Taylor & Francis Group, LLC.