SEA-FISHERIES LABORATORY. 277 



same net, through May and June to July 1st, and then 

 by the yacht's hauls again in August, we find the 

 following results : — 



There is a well-marked, but possibly exceptional, 

 early Copepod maximum of short duration from April 

 1st to 5th. This reaches in a haul 3,000 nauplii, 1,600 

 juveniles and 955 adults, is apparently due to a swarm of 

 Oithona, and is actually earlier than the phyto-plankton 

 increase which usually starts and dominates the vernal 

 maximum. 



The Copepoda are more abundant in the surface 

 nets than in the Nansen nets hauled at from 20 to 10 

 faths. in the earlier part of April (March 27th to 

 April 8th), but the reverse is the case in the later part of 

 the month (April 13th to 26th). This is not incompatible, 

 however, with a general correspondence between the 

 surface and the deeper hauls, the two rising or falling 

 more or less together. 



There is a marked decrease of Copepoda (as well as 

 of the phyto-plankton) during the few days preceding 

 April 9th, a period of relatively hot and very fine weather 

 for the time of year. The sea-temperature falls again 

 between the 9th and the 13th, and at that period the 

 Diatom and Dinoflagellate maxima begin. 



In August, when, compared with April, the total 

 catch is very small (0'2c.c, say, as against 4 c.c), and 

 the Diatoms are at their minimum, the Copepoda are 

 fairly numerous, ranging up to about a thousand adults 

 and five thousand nauplii in a haul. 



The vertical hauls with the Nansen net show the 

 same Oithona increase on April 1st to 5th, and also an 

 even greater increase of Copepoda a few days later on 

 April 14th to 23rd. The latter reaches a height of 5,396, 

 of which 5,000 are Oithona. We are inclined, however, 



