Preliminary Processing of Data 



The original tagging and recovery data discussed in 

 this report were found in logbooks, original return 

 forms, summary tables, manuscripts, and cor- 

 respondence. Inasmuch as a large part of the recovery 

 information was taken from summary tables, which 

 were sometimes incorrect or incomplete, considerable 

 effort was expended in comparing these summaries 

 with original records. There was no method by which 

 the date and place of recovery could be absolutely 

 verified, and it was assumed that the summary tables 

 were correct if no evidence to the contrary was found. 

 If information was lacking or if a discrepancy was 

 found which could not be resolved by a search of the 

 records, the recovery was classified as having an un- 

 known date or place of recovery. The changes made as 

 a result of comparison with original records were not 

 many and were usually corrections of obvious errors. 

 In analyses where the recoveries were pooled by 

 geographical areas, recovery reassignments had little 

 effect on the results because the recoveries were 

 usually reassigned to traps near the traps to which 

 they had originally been assigned in the summary 

 tables. 



The tag return information was transferred to 

 punch cards and processed through an IBM 650 

 digital computer to compute such additional informa- 

 tion as days out and distance from the tagging station 

 and to punch a final basic card for each return. 



There were omissions as well as inaccuracies in the 

 data relating to a number of important factors. 

 Distribution of the seine fleet in time and space, the 

 size of the seine catches and the spawning escape- 

 ment, and an accurate measure of recovery effort or 

 outline of the program used for recovery were all un- 

 known. Each of these factors will be discussed in more 

 detail in later sections where they are pertinent. 

 Because almost no information was available on the 

 size and distribution of the seine fleet and its catch, 

 this report is restricted to a consideration of trap 

 catch data and trap recoveries of tagged fish, except 

 in the section on mortality rates. Since about 80% of 

 the recoveries were made by traps, this limitation is 

 not severe. 



To validate trap catch data, which were submitted 

 by the canneries to the FWS, persons acquainted with 

 trap operations in the areas during the years con- 

 sidered in this report were consulted on methods used 

 to estimate the daily and weekly catches of a salmon 

 trap. No method was found to verify all of the catch 

 data; therefore, no corrections were made in the 

 original cannery records. The fact that catch records 

 kept independently by certain canneries showed ex- 

 cellent agreement with the data submitted to the 

 FWS increased our confidence in the data. 



Daily catch data for each trap were transferred from 

 the cannery forms to IBM cards identical to those 

 used by the FWS for recording daily trap catches. 



When more than one brailing in a day was recorded, 

 the sum of the recorded catches was entered on the 

 IBM card. Records from licensed traps that caught 

 few or no fish were omitted. 



The actual daily catch was not always recorded, 

 and the analysis was based on the weekly catch. Traps 

 were frequently fished more than 1 day without being 

 brailed; they were emptied daily only during the last 2 

 wk of the fishing season. During the latter part of the 

 season when the runs were heavy, some traps were 

 brailed on Saturday and also on Sunday, a closed day, 

 for the usual fishing period of 5'/2 days a week. 

 Because the operation of traps during the weekend 

 closure is unknown, there is some doubt as to what 

 day those fish recorded as taken on Sunday actually 

 entered the trap. All traps were assumed to have been 

 empty at the beginning of each fishing week and the 

 catches were summed from Monday through Sunday. 



Release and Recovery Information 



A statistical coding scheme was used to group the 

 waters of the northern part of southeastern Alaska 

 into statistical areas and subareas (Fig. 2) for com- 

 puter analysis of the tag-recapture and catch data. 

 The closing dates of the fishing season for the years 

 1938-42 in the major statistical subareas were es- 

 timated from data on the daily trap catches (Table 1). 

 A description of the statistical coding system is 

 available in Simpson (1960). 



The locations and code numbers of the principal 

 trap sites and the tagging stations are shown in Figure 

 3. The code numbers used throughout this report are 

 the same as those shown in Figure 3 except for a few 

 minor changes such as those employed in what is 

 known as the Vaughn system (for further information 

 on this system, see the publication cited in footnote 

 5). The number of traps operating in each major sta- 

 tistical subarea (Fig. 2) each year is given in Table 2. 



The numbers of tagging experiments conducted 

 during 1938-42 and 1945 are given in Table 3. Release 

 and recovery data are summarized by year in Table 4. 

 Total recoveries, omitting those from streams, during 

 the period from 1938 to 1945 varied from 28% to 38%. 

 The total, over all years, of 7,027 tags recovered from 

 all sources represents 34.3% of the total releases; 

 79.8% of the total recoveries were recovered in traps 

 and 16.1% in seines. Because only 30 tagged fish were 

 recovered in streams, stream recoveries were not used 

 in any of the analyses and will not be discussed. 



Basic release and recovery information for each ex- 

 periment is presented in Table 5. The timing of the 

 releases during the season varied considerably from 

 year to year. In only three experiments were less than 

 100 fish released. Many of the tagging experiments 

 appear to have had a goal of about 500 fish. In addi- 

 tion to recovery percentages by type of gear, Table 5 

 also contains the mean and variance of the days-out 



