SEA-FISHERIES LABORATORY. 79 
Under the first category may be grouped the following, 
amongst other, investigations :— 
(a) Trawling observations and experiments with 
various nets on different grounds, measuring and 
marking experiments with fish set free and subse- 
quently re-captured ; 
(b) Researches into the lfe-histories of fishes, their 
rates of growth, spawning periods, seasonal migra- 
tions, feeding grounds, etc. 
(a) and (b) involve work at sea. These investiga- 
tions were devised for the purpose of ascertaining 
the need of regulations or to test existing bye-laws. 
Without such experimental results the statistical 
data collected officially are of little use as a guide 
to administration. 
(c) Plankton work so far as it includes a study of 
the distribution and occurrence (both quantitative 
and qualitative) of fish eggs and larvae. 
(c) also involving work at sea, gives valuable 
information as to the spawning grounds of fish, their 
seasons and variations in relation to physical con- 
ditions and the fate of the young fish. 
(d) The study of sewage pollution with respect to 
the shell-fish beds, including both topographical 
surveys and sampling on the shore and the sub- 
sequent bacteriological research in the laboratory. 
(d) is necessary for sound administration which 
ought to involve not merely restriction, but also 
measures of cultivation and purification. The Local 
Government Board and the Local Health Authorities 
may take steps to prevent the distribution of polluted 
shell-fish, but this is not enough. Such administrative 
