FISHERY BULLETIN: VOL. 71, NO. 3 



Table 8. — Number of salmon marked and observed in gill nets over varying periods of time, 



April and May 1969. 



Nets 



and 



set Date 



no. hauled 



Set 



position 



No. fish 

 marked 

 during 

 patrols 



Number of fish observed after marking' 



Up to 1 h 

 later 



Up to 2 h 

 later 



Up to 5 h Up to to h 

 later later 



98,-1 14-, and I33-mm mesh nets (multifilament): 

 1 4/25 Lat.55°10'N 1 



Long. 155°00'W 



11 5/09 Lot. srOO'N 3 



Long. 165°00'W 



12 5/10 Lat.52°10'N 1 



Long. 165°00'W 



Total 

 Percentage loss 



1 14- and 133-mm mesh nets (monofilament): 



1 4/25 Lat.55°10'N I 



Long. 155°00'W 



9 5/07 Lot. 49°00'N 3 



Long. 165°00'W 1 



11 5/09 Lat.51°00'N 1 



Long. 165°00'W 



12 5/10 Lat.52°10'N 1 



Long. 165°00'W 



Totol 

 Percentage loss 



64- and 98-mm mesh nets (multifilament): 



9 5/07 Lot. 49°00'N 



Long. 165°00'W 



Total 



Percentage loss 



Grand total 13 



Percentage loss 



lA zero (0) indicates that the net was examined, but no marked fish were observed; a dash ( — ) indicates 

 that the net was not examined. Numbers in parentheses indicate number of possible observations for the 

 time period; difference from the number marked is because some observations were not mode in rough 

 weather. 



assume, however, that the overwhelming 

 majority of salmon caught in the small mesh 

 nets (64- and 83-mm) are immature fish. The 

 larger mesh nets (98-, 114-, and 133-mm), 

 however, capture both maturing and immature 

 salmon, depending on the season and avail- 

 ability of each group. The studies conducted in 

 the spring of 1968 and 1969 were primarily on 

 maturing salmon. By comparing the rate of 

 loss of salmon from small mesh nets in 1966 

 and 1967 (and in July 1969) with the loss rates 

 of salmon from large mesh nets in the spring 

 of 1968 and 1969, we may effectively compare 

 the loss rates of immature and maturing 

 salmon (Table 11). 



Overall loss rates for mature salmon were 0, 

 4% (±8.9), and for three periods (1, 21/2, 

 and 5 h) and about 20% (±7.5) for periods up 

 to 11 h (Table 11). Immature losses were 9% 

 (±4.3), 17% (±5.6), 58% (±18.0), and 46% 

 (±4.6) for the corresponding time periods. 

 Overall loss rates were similar for mature fish 

 in large mesh mono- and multifilament nets 

 (19 and 18%), as were the rates for immature 

 salmon in the same nets (48 and 42% , respec- 

 tively). Loss rates of immatures in small mesh 

 multifilament nets (45% ) were also similar to 

 the loss rates of immatures in the large mesh 

 mono- and multifilament nets (42 and 48%, 

 respectively). 



860 



