LIFE HISTORY OF LAKE HERRING OF LAKE HURON 299 



average temperature of the aquarium water was the same as that of the water in the 

 sea, but abundant food was supplied continuously. The haddock and whiting Hved 

 well to the end of the third j^ear; the codling did not do well after the beginning of the 

 third summer, nor the saithe after the completion of the second autumn. Growth 

 was continuous throughout the year, the ma-ximum occurring from May to October, 

 the minimum in March. In all cases where fish were transferred to the aquarium 

 during the season of greatest growth a false winter mark appeared on the scales. 

 Thompson concludes that abundant proof was obtained of the unfailing formation 

 of normal winter markings on each occasion that the fish passed through one or two 

 winters in captivity, although growth did not actually cease, as occurs in the sea. 

 The annulus was a slighter check in the aquarium than in the sea fish. 



Creaser (1926, p. 37) writes: "A series of bluegills {Helioperca incisor), sunfishes 

 (Eupomotis gibhosus), and large-mouthed basses {Aplites salmoides) collected in 

 February had scales with margins like those of late fall. When these fishes began 

 to grow in the laboratory a typical annulus was formed Dy the resumption of scale 

 growth. This production of an annidus after a period of growth cessation has also 

 been shown for the green sunfish {Apomotls cyanellus)." (Work on the green sunfish 

 was done by a student of Prof. Frank Smith, University of Illinois.) 



Johnston (1905 and 1907) is probably the first to test successfully the age hypo- 

 thesis by marking wild fish in the field. Atlantic salmon were marked during the 

 period April 25 to June 6, 1905, when, as young fish (smolts), they were migrating to 

 the sea. The first marked grilse of this e.xperiment was recaptured June 1, 1906, and 

 subsequently many other marked specimens were taken (Johnston, 1908 and 1910). 

 Mr. Johnston published photographs of scales taken from marked salmon that had 

 returned after a sojourn of 1, 2, 23^, 2%, and 3 years in the sea. In aU recaptured 

 fish the number of broad summer (sea) growth zones on the scales corresponded with 

 that of the summer seasons the fish were known to have spent in the sea. Johnston's 

 results were confirmed by the work of Hutton (1909 and 1910), Malloch (1910), 

 Milne (1913), Menzies (1913), and others who reported on scales taken from marked 

 Atlantic salmon. 



Gilbert (1913) refers to a marking experiment performed in the midwinter of 

 1910-11 in California on some yearlings of the Pacific coho salmon. "In the spawn- 

 ing run of the winter of 1911-12 several of these returned to the same stream as mature 

 male grilse, with scales clearly in agreement with their known age, having formed a 

 single summer band outside the close-ringed nuclear area and a marginal narrowing for 

 the fall growth [p. 17]." 



Winge (1915) found that the marked cod studied by him formed one or two mini- 

 mum growth zones on their scales, depending on the interval between marking and 

 recapture. The minimum zones formed in March. 



Fraser (1921) reports the capture of a Pacific coho salmon on October 11, 1917, 

 and of a Pacific spring salmon on January 9, 1918, both of which had been marked 

 as fry on March 24 or 25, 1915. The scales of both specimens corresponded perfectly 

 with the known age of the fish. 



The California Fish and Game Commission made several experimental plantings 

 of marked Pacific salmon. In 1919 one specimen was captured from a lot of 3,500 

 quinnat salmon hatched in the winter of 1914-15 and marked on February 15, 1916. 



