PROORESS IN BIOLOOTCAl. INQUIRIES. 7 



TIIK \\ iniT.FISHES AND THEIR RELATIVES. 



For a long time the Bureau, the several State fishery authorities 

 ooiu-erned, and the trade have felt the serious need of knowledge re- 

 ganling the habits of the Avhitehshes, ciscoes, and so-called lake her- 

 rings of the (ireat Lakes. Yet up to the present time we have not 

 had even that positive determination of the species "which is an essen- 

 tial basis of an inquiry into migrations, propagation, and other habits. 

 During the past two or three years Dr. AValter Koelz, general assist- 

 ant, has been detailed.to a comprehensive study of the whitefishes and 

 their relatives in the Great Lakes, beginning in Lake Huron. During 

 the past year he completed the field work and report based upon that 

 lake. 



His report, which represents a substantial advance in knowledge of 

 these fishes, is based upon a collection of 3,000 specimens of Lake 

 Huron Coregonines and on field data as to their breeding times and 

 breeding places, geographic and depth distribution, and migrations, 

 tie has definitely distinguished and defined 10 forms — 8 species and 

 2 subspecies — all of which are referred to the Linnaean genus Core- 

 goims. Two new species are described and three subgenera are recog- 

 nized {Leuc'ichthr/s^ Coregonus^ Proso pium) . The forms of one sub- 

 genus (Leucichthys) fall into two ecological groups: (1) the lake 

 herrings {artedl, manitonluiun) ^ and (2) the chubs (alpenae, reig- 

 /lardi, johannae, nigripinnis) and bloaters {hoyi and its variant pro- 

 fundus). 



The lake herrings are taken in shallow water to a depth of 16 

 fathoms, rarely deeper. One of them {arfedi) is known also to range 

 the surface Avaters to a considerable distance from shore. They 

 spawn in Xovember in shalloAv Avater on sand and graA'el. The chubs 

 and bloaters are taken near the bottom in Avater 30 to 80 fathoms or 

 deeper. They occur on mud or clay bottom and feed chiefly on species 

 of Crustacea and mollusca. The spaAvning season for the fiA^e species 

 extends from late August to March. 



The species of chubs and bloaters liaA'e definable but overlapping 

 ranges as regards depth. Each form has its greatest density of popu- 

 lation at the center of its bathymetric range, and this density dimin- 

 ishes toAvaid the borders of its range. 



The pilot, Caregonus {Proso pium) qiuidrUateralift^ occurs usually 

 along the shores to a depth of 20 fathoms. It breeds in November in 

 shallow water on rock or gravel bottom. The whitefish, Caregonus 

 clupeiformh., is also shore-loAnng. seldom occurring deeper than 20 

 fathoms. It spawns in XoA^ember in shalloAv Avater on rock or graA^el. 

 It is not expected that the report Avill be offered for publication before 

 the investigations in other lakes are completed. 



largpr (fewer) scales than tho rainlww, and there appear to bo other though incon- 

 spicuous and concealed structural differences. 



There is probalily more than one species or race of rainbow trout, and possibly also 

 of steelhead. However, the rainbow trout of fish T;ulture is largely from McCloud River 

 (Calif.) stock and should bear the name, not Hnlmo irideiix, l)ut l^aliiio shnstn. Tlie fish- 

 cultural rainbow stocl< has been more or less affected l)y admixture of another form 

 principally from Klamath River, which may be anotlier form or species of rainbow or 

 perhaps a steelhead. This admixture is clearly perceived in the api)earance iind structure 

 of many specimens of the rainbow stocl< of some of tlie hatcheries. Tlie steelhead stocic 

 has always, so far as itnown, been unadulterated S<nhno gnirdnrrii, although in the dis- 

 tribution from hatcheries it is Itnown that in some instances the two forms have been 

 regarded as identical and distributed as rainbow trout. Pure (ialmo Khasta is distin- 

 guished from pure Salmo gairdnerii by the smaller scales of the former. 



