316 SECTIONAL TRANSACTIONS.—D. 
of animals, while the winter drift carries old weed to the islands from which 
the animals have to a great extent disappeared. 
REPORTS OF RESEARCH COMMITTEES (12.45). 
AFTERNOON. 
Dr. S. M. Manton.—Peripatus (2.15). 
Dr. D. S. Rartr.—Fishing intensity and stock replenishment in the haddock 
(2.45). 
Investigations into the factors governing fecundity in North Sea haddock 
have shown that, in fish of the same age, egg production is proportional 
to a power of length slightly greater than the cube, while in fish of the same 
length the older the specimen the greater the number of eggs produced, 
the difference being most noticeable in two-year-olds as compared with 
three-year-olds. At the age of two, moreover, only about ro per cent. of the 
females and 60 per cent. of the males of a year class mature. At three 
about 75 per cent. of the females and 95 per cent. of the males are spawners, 
and it is not till the age of five in males and six in females that all surviving 
members of a brood have ripened. 
Such is the efficiency of the modern trawl that haddock come under its 
influence when they are about eighteen months old. Only a negligible 
percentage escapes capture to reach large size. "The brunt of stock replenish- 
ment falls upon small fish of two and three years of age, for which task they 
are of greatly inferior capabilities. } 
Dr. Henry Woop.—The relationship between the herring caught on the 
Scottish drift-net grounds and those caught by trawl on the Fladen 
ground (3.15). 
The herring population in Scottish waters is made up of at least two 
distinct race components, spring spawners and autumn spawners, which 
differ not only in their spawning times, but also to some extent in their 
distribution. Morphologically they are distinguishable from each other 
by differences in the numbers of vertebrz and keeled scales. The first 
shoals which appear on the drift-net grounds in May and June in search of 
food are mixed, containing varying proportions of the two components. 
About mid-July a redistribution of the shoals takes place. Maturing autumn . 
spawners migrate to coastal areas and spawn in August and September. 
At the same time a large concentration of herring takes place on the Fladen 
ground, where spawning does not take place. These two communities, 
which incorporate closely allied components, remain apart throughout the 
rest of the drift-net fishery, so that the results of the trawl fishery for 
herring on the Fladen ground have no effect on the drift-net catches until 
the following May and June, when the shoals in quest of food are due to 
return again to grounds which lie within range of the drifter fleets. 
Dr. S. G. Gippons.—Copepods with reference to herring fishery problems 
(3.45). : 
Introductory remarks on the group. Food value owing to oil. Copepods 
form main food of the herring in Scottish waters in’summer and, of all 
Copepods, Calanus is by far most abundant. Study of Calanus therefore 
useful and necessary, and the possibility at once arises of correlating plankton 
