Figure 4. — Form for recording mark recoveries and biological data. 



marks. Marks selected were the excised right or left 

 ventral liii, with and without the adipose tin. In 

 addition, [)art of the left maxillary bone was re- 

 nio\-ed in the e\en nunihcred brood years and part 

 of the right maxillary in odd numbered brood 

 years. These marks, together with the hatcheries 

 involved and expected age of appearance in the 

 sampling area, are shown in table -I. 



Procethires for selecting tish, marking them, 

 and sampling them at release to estimate mark 

 ratios were the same as described earlier for the 

 connnon (adipose-maxillary) mark. 



Certain items of information concerning the 

 rearing history were collected at each hatchery 

 to explain some of the expected variations in con- 

 tribution Ijetween hatcheries and ln'tween vears. 

 This information included numbers of adults 

 spawned, incidence of disease in adults,, mortali- 

 ties during incubation of eggs and rearing of 

 young, incidence and treatment of disease in 

 progeny, diet, fish size at release, and water tem- 

 peratures during incubation, rearing, and at the 

 release site. 



For the same [)uri)Ose, groups of marked and 

 unmarked fish obtained at time of release from 

 each hatchery underwent numerous tests at Aber- 

 nathy Salmon Cultural Laboratory. Variables of 

 interest included physical capal)ilities, body com- 

 position, hematology, and pathology. Physical 

 capability of each group of fish was indexed by 

 use of a stamina tunnel; body composition of pro- 

 tein, lipid, ash, water and glycogen was determined 

 by proximate analyses; hematology consisted of 

 hematocrit determinations and chemical measure- 

 ments of blood plasma to determine levels of cal- 

 cium, phosphorus, chloride, glucose, protein, al- 

 bmnin, cholesterol, icteric index, creatinine, uric 

 acid, ammonia, and urea; and pathology included 

 examinations for disease organisms from which 

 a "disease index" was determined. 



ESTIMATING PROCEDURES 



The contribution (catch) of hatchery-reared fish 

 will be estimated, as noted earlier, from data on the 

 proportion of hatchery fish that were marked (or 

 expected marked to unmarked ratio), the chinook 



r S. FISH AND WILDLIFE SERVICE 



