SPATIAL AND TEMPORAL VARIATION IN THE GROWTH-RATE OF ELEPHANTFISH (CALLORHINCHUS-MILII)

Growth rate estimates were obtained for elephantfish using length-freq uency and tagrecapture data from the east coast of South Island during 1966-88. Elephantfish hatch from egg cases at about 10 cm fork length (FL) during May-July. Females grow faster than males after their firs t year and growth is fastest in summer. In 1966-68, elephantfish in Pe gasus Bay grew faster than in Canterbury Eight, resulting in modal len gth differences that were maintained for the first 3 years of life. Th is suggests there are at least two distinct juvenile nurseries. Maximu m observed lengths were 76 cm FL for males and 97 cm FL for females. L ength-frequency analyses identified 5-8 male age classes and 8-9 femal e age classes, but longevity probably exceeds these values. Growth rat es of 0+ elephantfish in Pegasus Bay in 1983-84 and Canterbury Eight i n 1988 were 33-56% greater than in 1966-58. The faster growth rate mea nt male age at maturity was 4+ in the 1960s and 2+ to 3+ in the 1980s. If female length at maturity was the same in the 1980s as in the 1960 s, then female age at maturity would have been 5+ to 6+ in the 1960s a nd 4+ to 5+ in the 1980s. The increased growth rates and earlier matur ity may have led to an increase in elephantfish stock productivity bet ween the 1960s and 1980s.