Only meager data are available concerning bioluminescence in the 

 Bering Sea and northern part of the Worth Pacific Ocean. The few re- 

 ports available indicate that the majority of displays occur from April 

 through September J although the water probably is highly luminous at 

 times during autumn and winter. Noctiluca and other luminous dino- 

 flagellates are the principal light producers during stmmer, when 

 maximum bioluminescence apparently occurs; copepods and euphausiids 

 seem to cause the majority of displays dirring other seasons. Shoals of 

 luminescent salps and medusae have been reported in the warmer waters of 

 the North Pacific. 



The maximum amount of biolviminescence in the region most probably 

 occurs in the zone where the Oyashio and Kuroshio meet. One observer, 

 while traveling across the front between the two currents, noted the sea 

 as a tremendous arc of "phosphorescence" which lighted up the ship as 

 though a green floodlight had been turned on. 



In the western Aleutian Islands bioluminescence is pronounced during 

 summer and early autumn (July through October). Both sheet and spark 

 types have been observed during this period. The copepod Metridia has 

 caused strong greenish bioluminescence in the coastal waters of the 

 various islands of the Aleutians in the summer. Noctiluca reaches a 

 peak of abundance in late summer and is responsible for displays in the 

 surface waters off Attn, Kiska, and other islands. 



Reports of bioluminescence are fragmentary in the northeastern part 

 of the North Pacific. However, bioluminescence undoubtedJ.y is much less 

 frequent in the open ocean than near the coasts. Glowing-ball type 

 biolxuninescence increases in frequency southward to the Hawaiian Islands. 

 Many species of luminescent medusae occur in the central Pacific. 



Along the California coast many sheet-type displays occur during 

 spring and summer when red water is produced by large numbers of lumin- 

 escent dinoflagellates. Red water also may develop in winter when 

 unusually warm water conditions occur. Luminous water observed just 

 south of Monterey contained large numbers of dinoflagellates. The water 

 may be highly luminescent off San Diego and San Rrancisco in November. 

 This luminescence often is due to concentrations of salps or pyrosomes 

 and at times to ctenophores. 



Along the coast of southern California and Baja California, fish 

 schools are located with the aid of bioluminescence. The kind of fish, 

 depth, and direction of movement all are revealed by the bioluminescence 

 created when they move tlirough large concentrations of bioluminescent 

 organisms. Nets drawn through the water often retrieve a very luminous 

 slime made up of innumerable dinoflagellates. 



28 



