COMM. B — DEC. 1903 — APPEND. D 
IL. 
Annexe D 
Some Ideas involved in the Experiments with Nets, showing the 
Necessity for such Experiments 
. Hauls with nets form the basis or ground-work on which all results and con- 
clusions must be founded. Hence the necessity of concentrating the attention 
on nets for a time. 
Statistics, whether from research steamers or commercial trawlers, give 
only the quantities or numbers of fish actually caught; but we are 
now well aware that a very large proportion escape. Hence, the statistics by 
themselves cannot be relied upon to give a measure of the real „fish-wealth“ 
in any region of the sea, but must be supplemented by experiments with nets 
on the lines shewn in the programme. 
(a) 
(b) 
Dr. Wemyss Fulton has shown that greater numbers of fish pass through 
the meshes of the cod-end of ordinary trawls than are retained. Many 
more must pass through the larger meshes in the front part of the trawl 
and it is probable that less than 10 percent of the fish, both large and 
small, which enter the net are really retained there. This, the actual 
fishing-capacity of trawls, has not yet been investigated. 
It is possible that although the largest specimens of any species, say the 
haddock or plaice, may have decreased in numbers, yet that the inter- 
mediate-sized specimens having now more room and food, have really 
increased — in numbers (see Mc. Intosh and Masterman, “British Marine 
Food-Fishes” pp 99—100) or in size (see Petersen, “What is Over-fishing?”, 
Jour. M. B. A. vol. VI, part 4, Advance Copy). This effect of severe fishing, 
is by no means to be regretted if these intermediate-sized fish are better 
as food. 
Such intermediate-sized fish have obviously a better chance of escaping 
from a net than larger fish; hence if the catches from any long-fished 
region are now less than they used to be, this possibility, which is not 
shown by statistics, may account in part for the decrease. It is necessary, 
therefore, to make special investigations with nets in order to ascertain 
the actual proportion of these intermediate-sized and small fish on any 
particular ground, and to ascertain whether that proportion alters with 
the years. 
(c) Decrease in numbers of fish is not necessarily “overfishing”. “Over- 
fishing” takes place when the “stock” of fish left in the sea is not able 
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