Ocean research and the great fisheries . med—and a deformed fish larva always dies veryquickly. The sea temperature at a depth of 50 fathoms on thisside of the Atlantic does not fall so low as 32° F. until one iswell north of Iceland, and round the British coast it is between46° F. and 50° F. On the main herring spawning-ground to thesouth-west of Norway it is between 46° F. and 42° F. Thedanger of the eggs suffering from the effects of cold on this sideof the Atlantic is accordingly much more remote than on theAmerican side, where the 32° F. line at 50 fathoms passes wellsouth of Newfoundland
Ocean research and the great fisheries . med—and a deformed fish larva always dies veryquickly. The sea temperature at a depth of 50 fathoms on thisside of the Atlantic does not fall so low as 32° F. until one iswell north of Iceland, and round the British coast it is between46° F. and 50° F. On the main herring spawning-ground to thesouth-west of Norway it is between 46° F. and 42° F. Thedanger of the eggs suffering from the effects of cold on this sideof the Atlantic is accordingly much more remote than on theAmerican side, where the 32° F. line at 50 fathoms passes wellsouth of Newfoundland, westward towards the Nova ^ Cf. Mnmial of Fish Culture, p. 226-7 ; British Food Fishes, p. 455 ; Migra-tions of Fish. 2 Herring eggs with a diameter of 0-035 and 0039 inch run respectively1,578,000 and 1,150,000 to the quart. The Norwegian eggs run 347,000 to thequart with a diameter of 0-058 inch. In America the average is 541,000 to thequart (average diameter 0-050 inch). a Cf. p. 187 below (fig. 20). PLATE XV. HERRING EGGS ON SEAWEED (Photograph by Mr. A. Scott.) Magnified about 5 times. P. 156 EGGS AND FEY OF THE HEEEING 157 The Spawning Grounds In 18601 Dr. Boeck made certain experiments for the Nor-wegian Government. He netted the channel between Eaagoand Faejo in Yordingborg Bay (Great Belt) with a hne of netsstretching towards Hauskeskaer ; he also made another chainof nets, which stood for the most part on rocks, with one endreaching the channel. All the nets in the channel caughtmany ripe herrings ; those on the rocks caught none, exceptwhere they projected into the channel. With the dredgehe raised large lumps of herring ova attached to and mixedwith gravel. He concluded that in calm weather the herringsfavourite spawning places w^ere large level places at the bottomof the sea coverecl with rough gravel. In 1803 Dr. Walker, of Edinburgh University, had also foundthat the eggs were deposited on a gravelly bottom at about10 to 12 fathoms. In 18
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