THORNE: DIGITAL DATA-PROCESSING SYSTEM 



the laboratory from either digital or analog 

 magnetic tape. 



Survey Area and Methods 



Port Susan (Figure 3) is exceptionally well 

 suited to hydroacoustic assessment studies. It is 

 a long, narrow basin with steep sides and rela- 

 tively uniform depth (between 100 and 120 m). 

 Each winter large concentrations of Pacific 

 hake enter Port Susan to spawn. They occupy 

 depth strata below 50 m and make up over 90% 

 of the biomass in these depths. An industrial 

 fishery was initiated in Puget Sound in 1965. 

 Annual landings have ranged from 6.3 to 10.6 

 million lb, over 80% of which have come from 



Port Susan (Millikan, 1970). Acoustical cen- 

 susing of Pacific hake in Port Susan was under- 

 taken in 1969 and 1970 by the use of analog 

 echo integrators (Thorne et al., 1971). 



During 13 to 16 March 1971, 4 .surveys and 

 21 net hauls were made for evaluation of the 

 DDAPS. Each survey consisted of nine oblique 

 transects spaced evenly throughout Port Susan 

 (Figure 3). The net hauls and three of the sur- 

 veys were conducted aboard the research vessel 

 Jolui N. Cobb, operated by the Northwest Fish- 

 eries Center, National Marine Fisheries Ser- 

 vice (NMFS), NOAA. Seattle. The fourth sur- 

 vey was conducted with a 23-foot inboard- 

 outboard cruiser. Research 1, of the Washington 

 State Department of Fisheries. Both vessels 



Tulalip 



Scale 



Nautical miles 



 I  I I 



Figure 3. — Port Susan, Wash 

 showing a typical series of tran 

 sects. 



839 



