THE WESTERN MACKEREL FISHERY. 277 



made there. In 1907, on the other hand, zooplankton was in excess 

 of phytoplankton both in the Bristol Channel and also to the S.W. 

 of the Wolf, in both of which areas good fishing was obtained. In 

 considering these observations further, it is interesting to find that the 

 most profitable fishing grounds lay outside the area in which phyto- 

 plankton predominated, which suggests that mackerel during the 

 shoaling season prefer an animal to a vegetable diet, and may be met 

 with in quantity where such food is abundant. 



Further consideration of the Distribution of Species Charts IV to VI 

 shows wider eastward distribution of shoaling mackerel as the season 

 proceeded in 1907. 



An examination of the Plankton Tables Nos. I and II shows, more- 

 over, that throughout the season, during 1906, phytoplankton was 

 always in evidence, whereas in 1907 it entirely disappeared from the 

 beginning of May onward until the close of the season. The official 

 statistics of monthly landings, published by the Board of Agriculture 

 and Fisheries show that the fishery in 1906 was phenomenally bad, 

 whereas that of 1907 was very good. 



From these two facts it may be suggested that excess of phyto- 

 plankton in inshore waters retards or rather limits the eastern migra- 

 tion of the shoals first appearing west of Scilly. 



An examination of the official statistics of mackerel landings serves 

 to show that, in the month of May, the quantity of mackerel caught 

 has reached a maximum for the four months forming the more im- 

 portant part of the spring fishery. The following table shows the 

 figures from 1901-7 inclusive. The figures given represent the landings 

 on the south and west coasts of England and AVales, which are sig- 

 nificant for the western fishery, since comparatively few mackerel are 

 taken elsewhere during the months dealt with. 



Table sliovjing OfficAal Returns of Mackerel landed on the south and ivest 

 coasts of England, and Wales, from March to June inclusive, in the 

 years 1901-7. 



TOTAL IN HUNDREDWEIGHTS. 



As these figures are taken over a fair number of years it may be 

 assumed that during May, under normal conditions, the fishery is at 

 its height. In May also the maximum number of boats are generally 



