Ocean research and the great fisheries . 22 „ c „ 40 to 60 22 to 33 „ D , 60 to 80 „ 33 to 43 „ E „ 80 to 100 „ 43 to 54 „ i „ 100 to 200 „ 54 to 109 „ 1 1 over 200 over 109 It must always be remembered that these statistics take noaccount at all of small fish thrown overboard (many ofwhich must be dead), but only of small fish landed. In ^ The Trade categories large , medium , and small do not help shows that in Grimsby large fish mean anything between 9 and28 inches. Medium fish are 9 to 13 inches ; and small fish from 5| to11| inches. 42 THE STOCK OF PLAICE deciding whether or
Ocean research and the great fisheries . 22 „ c „ 40 to 60 22 to 33 „ D , 60 to 80 „ 33 to 43 „ E „ 80 to 100 „ 43 to 54 „ i „ 100 to 200 „ 54 to 109 „ 1 1 over 200 over 109 It must always be remembered that these statistics take noaccount at all of small fish thrown overboard (many ofwhich must be dead), but only of small fish landed. In ^ The Trade categories large , medium , and small do not help shows that in Grimsby large fish mean anything between 9 and28 inches. Medium fish are 9 to 13 inches ; and small fish from 5| to11| inches. 42 THE STOCK OF PLAICE deciding whether or not to bring his small plaice to shorea skipper will always be guided by two considerations : (1) Isthere a fair chance of filling up with bigger fish ? (2) Is therea demand ashore for fish of that size ? If a big demand forsmaller sizes of plaice has grown up since 1906 the statisticsmay mean little more than that plaice which were once thrownaway are now eaten, particularly in the fried-fish shops. ?Brede Bugt. Faxe Buqt Fae roeBanU: F^eroe 1^ Shetland |s Orkney I^rjf* Fig. 3.—Marking Exiieriments from Iceland showing that in the springthe mature plaice wander from colder waters (Vopnatiord and 8kjalfandiBay) to the southern and western shores in order to find suitable spawningconditions. (Dr. Hjort after Dr. Schmidt.) The plaice in the North 8ea donot appear to migrate, to such an extent as in Icelandic waters. Marking Experiments Many experiments have been made with marked plaice inorder to discover what percentage of the plaice population iscaught in the trawls every year. A certain number of fish,say one hundred or one thousand, are marked with labels andhberated on a particular ground. In the year after they arecast adrift a certain number of these marked plaice (say 10 to40 per cent.) will be recaptured in a certain area. If it isassumed that the marked fish have distributed themselvesuniformly amongst the unmarked fish, the inference is drawn(a
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