322
THE BIOLOGY OF FISHES
.
of the ground shes, Cod, Haddock and Plaice, are Well: i
above the average, perhaps as the result of the, for
_
comparative peace during the years 1915—1918.
But
this cannot be taken as the whole explanation, since the
Plaice, the most ground—loving of them all and the one“
supposed to be the most subject to the attacks of the trawlers,
is the one that shows the least difference from the average.
‘
,.
Previous to 1908 the quantities of every species showed
a great variation, from 10 to Over 60 per cent., in the annual ;
catch, but here again the Plaice showed the least variation.
Since the beginning of these statistics in the year 1903, the
Plaice has shown remarkable conStancy in the
'
landed year by year, the yearly uctuation being only about
cent. over ten years.
ÿ‘}
The outstanding feature of the sheriesin all bountries
»
is the 'îprominent part taken by the Herring and other j
CluPeids.
in the North Sea region we see that over
;
60 per cent. of the total quantities landed consists of Herring.
In spite of the most rig0rous pursuit by all kinds of enemie’s, Ï:Ê=
there
no
sign of diminution. Byu— means of the scalestudies it has been found recently that as many as twenty
_
year—groups may be represented in the catche‘ë"; thus a
particularly good year like 1904 mayeontinue to be
‘nentiin'the annual Catches right to 1922.
"
In spite of the
persecution, therefore, aÏvery' large proportion of Herring }
must escape and contribute to the qùantities
years...
…
,
_
;
…_
'i
,
.
…The Hadd0d<=h the; most
»
: =:
quant1tres taken are
When the
have
.,
Ï
L£rgequ@tiyïibeen credited to
the
too many ’
‘:
small Sh‘.»
recognise thatthe
natural
than the shing by
Forjexa—rplç3, lit Was pointed eur in the Statistical
Bulletin
for theyeai* 1908, that the years
:
;-WÔUÏd
bé good Years if0ï Îh€ Cod
of the .NthhSeas
owing [Simply to the
_
_
?
-theyeàsgïgoô, 1907
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