26 SALMON GEAR LIMITATION 



These data provide the basic statistics for two important parts 

 of the biostatistical analyses. One part is the number of .units fishing 

 in the United States fishery on any given date during the season. 

 As has been mentioned in the previous section, the number of licenses 

 gives only an upper bound for the maximum number of units that 

 could have fished in the fishery on a single day. The second part 

 is the detailed catch and effort statistics needed to provide basic data 

 for estimating relative gear efficiency. A mathematical model was 

 developed which gives a simultaneous estimate of the relative ef- 

 ficiency of the several types of gear fishing in a given small statistical 

 area on a given date. The method uses all daily records of two or 

 more types of gear operating at the same time in a particular area. 

 It was found that the relative efficiencies of the different types of 

 gear varied considerably from area to area and from season to season. 

 The size of the fish in the run and their schooling behavior are among 

 a number of factors that appear to affect the relative efficiencies of 

 the various types of gear. Standardized relative efficiency factors were 

 computed from the several years' analyses and were computed for 

 the large statistical Areas 1, 2, 3, and 4 (Fig. 1) by combining the 

 individual estimates of relative efficiency from the smaller statistical 

 subareas. The relative efficiencies for each species in each of the 

 statistical areas is shown in Table 1. It should be noted the relative 

 efficiencies are expressed in terms of gill net units which give a 

 convenient measure of the relative fishing powers of the purse seines, 

 reef nets, and gill nets. 



The maximum number of units of gear available during the 

 season does not provide a measure of the number of units that would 

 be available to fish on different days during the season. Analysis 

 of the catch and landing data revealed very definite seasonal patterns 

 in number of landings recorded per day. Daily patterns observed 

 for the years from 1956 through 1961 were combined to obtain 

 the average seasonal patterns shown in Fig. 14 for each of the dates 

 and areas. This figure is standardized in much the same way that 

 the entry patterns of the various species into the fisheries were 

 standardized. If the time scale is shifted so that the run is either 

 later or earlier than normal then the gear patterns are shifted in a 

 similar manner. The number of units available to produce the 

 seasonal availability patterns shown in Fig. 14 were computed from 

 the number of units that made landings on the peak day during the 



