186 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
REPORT ON MEASUREMENTS OF PLAICE 
~~ MADE DURING THE YEAR 1910. 
By JAS. JOHNSTONE. 
1. INTRODUCTION cs Gen ae ays 732 186 
2. TABLES af os ee AA iy sie 189 
3. APPENDIX ON STATISTICAL METHODS ... 207 
1. Introduction. 
The measurements of plaice caught by the Officers 
of the Committee in the course of the routine trawling 
experiments have been continued on much the same lines 
as in the year 1909. For various reasons the number of 
fish dealt with is not so great as in 1909—altogethe 
35,000 plaice have been measured on board the -vessels, 
and in the laboratories at Liverpool and Piel. The general 
objects of the investigation are to provide data for a study 
of the utility of trawl-mesh restrictions; for a study of 
the variation in the prevalent lengths of plaice on the 
various fishing grounds and at various seasons through- 
out the year; and indirectly for a study of migration 
paths and seasons. In last year’s report I gave an 
outline of the preliminary results then apparent from the 
data, and it will not be necessary to do this again. It is 
expected that the Lancashire Fisheries Committee will 
continue this work and that it may be extended so as to 
include several fishing grounds lying, strictly speaking, 
outside their proper area. So far as the grounds sampled 
during the past year are concerned the scale of the 
experiments is probably sufficient—that is to say, the 
numbers of plaice measured are probably great enough 
to yield reliable estimates. The chief defect of the 
investigations of 1910 is that pointed out in last year’s 
Report, that is, not nearly enough plaice are examined 
