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Relative abundance of sea lampreys,. „ 5l 



Some biological characteristics of spawning runs. ..„ 53 



(1) Sex ratio and differential migration of sexes.oo, 53 



(2) Length composition of spawning runs.,, . o . . « . , o o. . . 5U 



(3) Weight composition of spawning runs. . . . . » . „ . . „ » .. 57 

 (It) Relationship between length and vjeight in 



(5) Migratory habits and behavior . . . ..... <,.«,.. o .,.» . 59 



(6) Distance of migration. ... .,....„.,..,...,,.„...„ „ 65 



(7) Pathology, parasitism, and predation. ,...,„. o... . 66 



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(8) Reproductive potential of sea lampreys ..o ... .... . 70 



(a) Collection of materials.,. 70 



(b) Egg development and maturity in 



spawning migrants .,.o„o..,.oo..,o...,.<,o. 71 



(c) Egg production, „..o, .,o .,,,.. ... ...<.., o, » 78 



(d) Percentage of unspa;vned eggs,,.,,,..,,,.. 82 



V. Spa^-ming habits and spawning requirements of the sea lamprey. 83 



Physical characteristics of the Ocqueoc River watershed,. 83 



Duration of the spawning season, ..,.,,...,,.,..,,.....,.. 87 



Pattern and extent of spawning activity and its relation 



to certain stream characteristics, ....... ^ o. ..o ....... ,, 91 



Spavming habits and behavior, . , ....,.,,. ........... . 9U 



(1) Pre-spawning behavior ....,...,«.,.,.,„o,,, 9U 



(2) Spawning behavior; the spawning act, .,,......„, „. 96 



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(U) Summary of spawning requirements .,.,,,.,.,0...,., Ill 



(5) Post spawning behavior, ,,,,.,...,,..,,, ,0 ,„.,,,, , 113 



(6) Adults prevented from spawning. ,,, ..,,,,,..,.,,, , 111; 



VI. Physical degeneration of migrants and mortality of post= 



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(3) Degeneration of the digestive tract and changes 



in the color of the liver. ,..,,„,,•. ,,,,,,, «.,.,, . 120 

 (I4.) Discoloration of flesh. .,.,,.,„......„,.,,...,,,, 131 



VII, Some economic characteristics of spawning runs.. .,,.,.,,.,, .0 131 



VIIIo Investigations of the larval, non-parasitic phase of the 



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Age and size of larvae at time of departure from the 



nest, and production from the redds o.....,,.,..,.,.o,,,. 137 

 Distribution in the Ocqueoc River, larval habitats, and 



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Size of larvae and estimated length of larval life...,,.. IU8 

 Transformation of larvae into parasitic adults,... ...o, .0 l53 



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