Similar work, somewhat less detailed and 

 less specific as to the factors that deter- 

 mine distribution, has been reported for the 

 Euphausiidae of the eastern tropical Pacific 

 (Brinton, 1962). Bathymetric distributions of 

 euphausiids (Brinton, 1962) and chaetognaths 

 (Alvarino, 1964a) have been well sunnmarized 

 for the Pacific as a whole, but more for the 

 North Pacific than the eastern tropical Pacific. 



For want of repetitive cruises at succes- 

 sive periods in most parts of the eastern 

 tropical Pacific, few attempts have been made 

 to describe and analyze changing species dis- 

 tributions, whether determined by distribution 

 of water masses or by distribution of simple 

 properties. Most of this work has been done in 

 the northernmost part of the eastern tropical 

 region (area 3 and adjacent waters), where 

 repetitive cruises have been made under the 

 auspices of CalCOFI. Differences in distribu- 

 tion of species between the warm period that 

 occurred from about 1957 to 1959 and the 

 earlier cooler period have been described and 

 partly interpreted by Balech (I960) for phyto- 

 plankton, Alvarino (1964b) for chaetognaths, 

 Brinton (1960, 1962) for euphausiids, and 

 Radovich (1961) for fishes. Probably the most 

 detailed contribution of this kind is that of 

 Berner and Reid (196l), who explained chamges 

 in the distribution of the pelagic tunicate, 

 Doliolum denticulatum , on the basis of its 

 responses to sea temperature and major non- 

 seasonal changes in temperature which oc- 

 curred between 1949 and 1959, together with 

 seasonal changes in surface currents. 



Several other oceanographically detailed con- 

 tributions are available for the same region. 

 The study of Johnson (I960) on the distribution 

 of pelagic larvae of spiny lobster is partic- 

 ularly interesting because it showed that re- 

 cruitment of lobsters must depend upon fea- 

 tures of circulation which retard the flushing 

 out of larvae with the California Current. 

 Distributions of calanoid copepod species have 

 been charted for repetitive cruises in the 

 California Current by Fleminger (1964). 

 Ahlstrom (1959) dealt with vertical distribu- 

 tion of pelagic eggs and larvae of 46 species 

 of fish in the same area. Studies of changing 

 distribution of the pelagic crab, Pleuroncodes 

 planipes , again in the California Current area, 

 are being made at the Scripps Institution of 

 Oceanography (Longhurst, MS.^). 



The best-described species distributions 

 for the eastern tropical Pacific as a whole 

 are those of the yellowfin and skipjack tunas, 

 which have been made known not by ocean- 

 ographic work (except for larvae) but from the 

 records of commercial fishing (e.g., Alverson, 

 1960); charts are available for each quarter- 



^ Longhurst, Alan R. The pelagic phase of Pleuroncodes 

 planipes, Stimpson (Crustacea, Galatheidae) in the Cali- 

 fornia Current. (Scripps Institution of Oceanography, 

 University of Callfomia, 1965). 



year since the beginning of 1951. Knowledge of 

 ocean features whichdetermine these distribu- 

 tions is still incomplete. Both temperature 

 (which regulates range limits) and food supply 

 (standing crops of animals at lower trophic 

 levels, which probably determine distributions) 

 are involved; salinity does not appear to be a 

 factor (Blackburn, 1965). No attempt is made 

 here to review several other works in which 

 connections between ocean conditions and dis- 

 tribution or abundance of fishes were suspected 

 or demonstrated. 



ACKNOWLEDGMENTS 



Alan R. Longhurst, Carl J. Lorenzen, Milner 

 B. Schaefer, and William H. Thomas read 

 and commented on the manuscript. 



LITERATURE CITED 



AHLSTROM, ELBERT H. 



1959. Vertical distribution of pelagic fish 

 eggs and larvae off California and Baja 

 California: U.S. Fish Wildl. Serv. Fish. 

 Bu!l. 60: 107-146. 



ALVARINO, ANGELES. 



1964a. Bathymetric distribution of 

 chaetognaths. Pac. Sci. 18(1): 64-82. 

 1964b. Zoogeografia de los Quetognatos, 

 especialmente de la region de Cali- 

 fornia. Ciencia, M^x. 23(2): 51-74. 

 ALVERSON, FRANKLIN G. 



1960. Distribution of fishing effort and re- 

 sulting tuna catches from the eastern 

 tropical Pacific by quarters of the year, 

 1951-1958. Inter-Amer. Trop. Tuna 

 Comm., Bull. 4(6): 321-446. [Englishand 

 Spanish.] 



BALECH, ENRIQUE. 



1960. The changes in the phytoplankton 



population off the California coast. 



Calif. Coop. Oceanic Fish. Invest. Rep. 



7: 127-132. 



BENNETT, EDWARD B., and MILNER B. 



SCHAEFER. 



1960. Studies of physical, chemical, and 

 biological oceanography in the vicinity of 

 the Revilla Gigedo Islands during the 

 "Island Current Survey" of 1 957. Inter- 

 Amer. Trop. Tuna Comm., Bull. 4(5): 

 219-317. [English and Spanish.] 



BERNER, LEO D., and JOSEPH L. REID. 



1961. On the response to changing tempera- 

 ture of the temperature -limited plankter 

 Doliolum denticulatum Quoy amd 

 Gaimard 1835. Limnol. Oceanogr. 6: 

 205-215. 



BIERI, ROBERT. 



1959. The distributions of the planktonic 

 chaetognatha in the Pacific and their 

 relationship to water masses. Limnol. 

 Oceanogr. 4: 1-28. 



15 



