EFFECTS OF TEMPERATURE ON THE DEVELOPMENT AND SURVIVAL OF EGGS OF 4 COASTAL CALIFORNIA FISHES

Laboratory experiments were conducted to determine the effects of temp erature on egg development and survival of four fish species found off southern California. Our objectives were to further understanding of natural spawning patterns and to aid in identifying and ageing field-c ollected specimens. An egg-staging procedure was devised and eggs were observed every two hours during development at a range of temperature s (8-28 degrees C). Barred sand bass, Paralabrax nebulifer, eggs survi ved to hatching and produced viable embryos at the highest temperature range (16-28 degrees C), reflecting this species' summer spawning sea son. Fantail sole, Xystreurys liolepis, eggs also hatched at a higher temperature range (16-24 degrees C). This species spawns primarily fro m summer through fall. Eggs of the two species with winter-spring spaw ning peaks, white croaker Genyonemus lineatus, and California halibut, Paralichthys californicus, had lower temperature-tolerance ranges (12 -20 degrees C). Developmental rate at a specific temperature did not s ignificantly differ between species, whereas within tolerance limits, temperature strongly affected rate of development for all species. Tim e to hatching for all species was inversely related to temperature, an d the relationship was approximately exponential. Species-specific dif ferences in egg-stage sequence were observed; embryonic organogenesis in relation to germ-ring migration and blastopore closure was faster f or barred sand bass and fantail sole than for white croaker and Califo rnia halibut.