LOSS OF SALMON FROM HIGH -SEAS GILLNETTING 

 WITH REFERENCE TO THE JAPANESE SALMON 



MOTHERSHIP FISHERY 



Robert R. French and J. Richard Dunn' 



ABSTRACT 



Studies by the National Marine Fisheries Service on the loss (i.e., dropouts, those salmon 

 that become unmeshed or otherwise escape from drifting gill nets; and fallouts, those salmon 

 observed falling from gill nets as the gear is hauled aboard the vessel) of salmon due to high- 

 seas gillnetting were conducted in the North Pacific Ocean and Bering Sea from 1964 to 

 1969. Losses attributed to dropouts and to predators and scavengers, as determined by indirect 

 methods, were estimated as 32% for immature salmon for fishing periods up to 12.5 h (1964) 

 and 21% for maturing salmon for a 3-h fishing period (1965). Loss estimates derived from 

 direct observations in 1966-69 were 6, 14, and 41% for fishing periods up to 1, IVi, and 11 h, 

 respectively. Estimates of losses of immature salmon were 46% up to 11 h and 20% for 

 maturing salmon for the same time period. No losses were recorded for fishing periods of 3 h 

 in an inshore commercial gill net fishery in Puget Sound, Wash., in August 1967. 



Losses attributed to fallouts from U.S. research vessels during 1965-70 amounted to about 

 1.4% of the total number of salmon landed, a figure similar to that reported for Japanese 

 research vessels. 



The estimated annual loss from dropouts (including predators and scavengers) by the 

 Japanese mothership fishery would range from 5.5 to 10.8 million fish in applying an 

 estimated average loss of 20% (for maturing salmon) to 33% (for maturing and immature 

 salmon combined) to the average annual catch of 22 million salmon by the mothership fleet. 

 It was estimated that an average of 0.6 to 1.8 million sockeye salmon, Oucorhynchus nerka. 

 of Bristol Bay, Alaska, origin would be lost annually from the Japanese mothership fishery 

 (depending on total catch). The estimated annual loss due to fallouts (1% of landings) would 

 average over 200,000 fish each year, of which 25,000 sockeye salmon of Bristol Bay origin 

 would be lost on the average. 



The estimated large numbers of salmon lost from gill nets (and probable high mortality 

 of those fish escaping) indicate a relatively large waste of resources due to a high-seas gill 

 net fishery. 



For many years, Pacific salmon, Oncorhynchus wounds and scars in 1946. Talbot (1950) 



spp., with gill net marks have been observed in showed that the percentage of net-marked 



coastal waters and in spawning streams, indicat- sockeye salmon in the daily catch below Hells 



ing they had escaped from gill nets. Percentages Gate on the Fraser River during 1943-47 



of net-marked salmon in some river systems ranged from to 75% . 



have been substantial. For example, from 1944 With the advent of the Japanese offshore gill 



to 1952, counts of gill net-marked salmon at a net fishery in 1952, Japan and the USSR have 



weir near Brooks Lake, Bristol Bay, Alaska, reported net injuries to salmon in coastal 



showed 6.3% of the annual escapement of sal- waters. Thus, Petrova (1964) reported that up 



mon were net-marked (Nelson and Abegglen, to 15% of the salmon ascending the Bolshaya 



1955). Hanson, Zimmer, and Donaldson River (USSR) in recent years had gill net 



(1950) reported about 4% of the sockeye, O. injuries. She observed that these net-marked 



nerka, and 6% of the chinook, 0. tshawytscha, fish were less effective as spawners; net-marked 



salmon on the Columbia River showed gill net chum salmon, O. keta, retained more than 



20% of their eggs and many died before spawn- 



— r- — r ^-^ r- . VI . . N.I  x:- u ing- Konda (1966) noted that as early as 1934, 



'Northwest Fisheries Center, National Marine Fisheries ° ^ , ^^ , xr i t i j 



Service, NOAA, Seattle, WA 981 12. drift net fishing off the Kuril Islands was caus- 



Manuscript accepted January 1973. 



FISHERY BULLETIN: VOL. 71, NO. 3, 1973. 



845 



