SEA-FISHERIES LABORATORY. 929 
to. distribute themselves over a fairly large tract of sea 
bottom. I think this must happen very seldom indeed; 
should it happen, such exceptional captures would 
surely not be considered as indicative of other than an 
exceptional density of marked fishes apart from 
unmarked ones. But it must almost always be the case 
that a number of marked (or unmarked) fish liberated on 
a certain spot distribute themselves very rapidly and 
uniformly over all the tract of sea-bottom inhabited by 
the population of which they formed a sample. I have 
seen no indications that marked plaice, when liberated, 
segregate themselves, or distribute themselves in a 
different manner from that in which the population 
from which they were taken behaved; and it is 
incumbent on anyone who advances such a criticism to 
give instances where this has occurred, or to show 
a priort that it is hkely to happen. Experiment 4 of 
1907* dealt with 120 marked plaice, which were 
liberated between Great Ormes Head and Point Lynus 
in October of 1907. In November of that year a very 
intense fishery began in the same area, and lasted for 
two months, and on some days from 20 to 30 smacks 
trawled there. Yet only about 30 of these plaice were 
returned to me, and I regard this small proportion of 
recapture as indicative of a wide distribution of the 
marked fish over the whole area exploited. Let anyone 
who urges this segregation of marked fish as an 
objection to the results deduced mark some 100 plaice, 
and then, immediately after liberating them, attempt to 
trawl them up again. I should be greatly surprised if 
he succeeded in getting back even a small proportion 
after several days of fishing. 
* «Ann. Rept. Lancashire Sea-Fish. Laby.’’ for 1907, Liverpool, 
1908," p2.09, 1-11: 
