15 SEPTEMBER 1999
EFFECT OF TEMPERATURE ON INCUBATION TIME AND DEVELOPMENT OF ATLANTIC COD (GADUS MORHUA) EGGS AND LARVAE
M. Pryor, J. A. Brown-1998
Bulletin of the Aquaculture Association of Canada, 98-2 (contributing papers Aquaculture Canada '98): 38-40
Abstract:
Incubation time of Atlantic cod (Gadus morhua) eggs was shorter at high (7.0-8.0 C) and medium (3.0-4.0 C) temperatures than at low temperature (0.0-1.0 C). Developmental time was 40% longer at the low temperature. There was no significant difference between dry weights of eggs incubated at these temperatures. There were significant differences in egg diameters between the treatments; diameter increased proportionately with temperature. Larval development was slowest at 0.0-1.0 C; yolksac absorption took nearly twice as long as in the other treatments. Larval growth was significantly different between treatments. Total length was greatest at the lowest temperature both at 50% hatch and at the end of the yolksac stage. Yolksac width at 50% hatch was significantly greater at 3.0-4.0 C. Larval dry weights at 50% hatch and the end of the yolksac stage were not significantly different among the treatments. It appears that while incubation time decreases with increasing temperature, the larvae are smaller which may indicate they are of poorer quality and less able to survive mass rearing conditions. Further study is needed to determine the viability of larvae reared at these temperatures so that proper rearing conditions can be determined.
(Marine Institute of Memorial University of Newfoundland, St. John's, NF, Canada A1C 5R3)