CalCOFI Reports, Vol. 30, 1989 - California Cooperative Oceanic ...

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LAVANIEGOS-ESPEJO ET AL.: EL NINO EFFECTS ON GULF OF CALIFORNIA EUPHAUSIIDS
CalCOFl Rep., Vol. 30,1989
likely for N. dfjcilis because they did not find significantly
fewer adults in August 1957 than in April
1957, within the 0-140-m depths sampled. Because
of the extensive presence of oxygen-deficient
waters in the gulf, information on the depth distributions
of gulf euphausiids is needed.
Among these species, Nyctiphanes simplex
showed the longest reproductive period in 1957: at
least February through June (Brinton and Townsend
1980). Even though 1983 larvae were found
throughout a large range of surface temperature
(20"-23"C), they were most abundant to the north,
where temperature was lowest (figures 4,14; appendix
1). This supports the possibility that the warming
event of 1983 had a negative effect on calyptopis
recruitment. Brinton and Townsend (1980) reported
that the best calyptopis recruitment in 1957
occurred in waters of 17"-18"C (10-m depth), which
is cooler than any part of the gulf covered in 1983.
Calyptopis distribution in April 1957 was very similar
to that of April 1984, but surface water temperature
was slightly warmer in 1984. However,
temperature distribution at 30-m depth in spring
1984 resembled that at 10-m depth in April 1957,
with