276 PLANKTON STUDIES IN RELATION TO 



From a comparison of the tables it will be seen that the reverse 

 condition was not brought about entirely by the decrease of the Phaco- 

 cystis, but also by the increasing number of the Copepods in the 

 samples. 



During this cruise, through lack of time, only one position could be 

 worked in the Bristol Channel (Sample No. 18, Table I), which showed 

 phytoplankton in excess of zooplankton. The same condition was 

 observed in a sample taken at Sevenstones five days later. The 

 positions of the stations on this cruise and the general distribution of 

 samples taken during April, 1906, can be readily understood on refer- 

 ence to the Distribution of Species Chart No. 1. 



Throughout the early part of April, 1907, from the fishermen's 

 reports it appeared that fairly regular catches had been landed from 

 the Bristol Channel south-west of the Wolf, and also from twenty to 

 thirty miles S.W. of the Lizard. Many fishermen declared, however, 

 that the water lying within a ten-mile or wider limit from the coast 

 from off Plymouth to Land's End, was in that particular condition 

 which they termed " stinking," and of a most unsuitable condition for 

 the presence of mackerel.* 



In order to obtain observations in this affected area, and also to trace 

 the varying proportions of zooplankton and phytoplankton on the 

 fishing ground, a cruise was taken from Plymouth to ten miles S.W. 

 of the Wolf, and from thence to twenty miles north of the Longships, 

 somewhat earlier than in 1906, viz. April 16th, 17th. The analyses of 

 the tow-nettings taken (see Samples Nos. 41-8, Table II) show a some- 

 what similar condition to that observed in 1906, with certain impor- 

 tant exceptions. The main differences lie in the excess of phyto- 

 plankton extending farther westward past the Lizard (see Samples 

 Nos. 41-5, Table II). This condition was largely due to Fhaeoajstis ; 

 zooplankton occurring in excess of phytoplankton only in the sample 

 taken farthest west, viz. ten miles S.W. of the Wolf (No. 48, Table II). 

 A more important feature, however, appears to lie in the conditions 

 observed in the Bristol Channel samples (Nos. 46, 47, Table II), where 

 zooplankton occurred decidedly in excess of phytoplankton. For a 

 synoptic view of these observations, showing the positions of stations, 

 the reader is referred to Distribution of Species Chart No. IV. 



Now in drawing a comparison between the condition exhibited by 

 the plankton and that by the fishery in April 1906 and 1907, it will be 

 seen that in the former year, phytoplankton appearing in excess of zoo- 

 plankton in the Bristol Channel, the fishery there was unprofitable ; 

 whereas the reverse obtaining S.W. of the Wolf, fair catches were 



* See note on "Stinking Water," p. 289. 



