Table 4-. — Statistical analysis of percentage infestation data 



the north-south distribution of rockfish 

 parasites. The solution of this problem 

 and the related problem of the life 

 cycle of Prosorhynchus would require 

 a detailed, biological investigation. 

 Such an investigation might well be 

 worthwhile if it yielded information 

 that could be used to eliminate or at 

 least to alleviate the parasitic infesta- 

 tion that presently is a decided limiting 

 factor in the utilization of rockfish. 



Distribution in fillet . --The distri- 

 bution of parasites according to the 

 area of the fillet (figure 2) is shown 

 in table 5. Most parasites occurred 

 either in the meaty shoulder portion 

 of the fillet or in the tail portion. A more 

 even distribution of the parasites was 

 noted in this year's survey than in last 

 year's. Only the D area was observed 

 to be consistently low in parasites. 



Blemishes 



Examination of sanaple lots of fillets 

 showed that over 90 percent of the 



blemishes occurred on the skin side 

 of the fillet. For this reason, only 

 results from skinned fillets were con- 

 sidered in evaluating the occurrence 

 of blennishes. Unfortunately, this re- 

 striction limited the source of our 

 data to two catches (45,000 pounds) 

 from the middle area and one catch 

 (44,000 pounds) from the southern area. 

 The incidence of blemishes is shown 

 in table 6. A comparison of the inci- 

 dence of blemishes in the middle and 

 southern areas is given in table 7. 

 Apparently there is little difference 

 in the number of blemishes in fish 

 from the middle area and from the 

 southern area. 



The distribution of blemishes in the 

 fillets is shown in table 8. The meaty 

 shoulder area appeared to contain the 

 least number of blemishes; the tail 

 area, the greatest number. 



Although blemishes were observed 

 in 52.3 percent of all of the skinned 

 fillets exannined, these bodies are 



Table 5. — Average niimber of parasites in designated area of parasitized Pacific 

 ocean perch fillet, according to fishing grounds 



Fishing gro\md 



Number of parasites per fillet area 



B 



D 



Northern. 

 Middle... 

 Southern. 



0.63 

 0.76 

 0.38 



0.43 

 0.34 

 0.22 



0.54 

 0.47 

 0.40 



0.09 



0.18 

 0.06 



0.60 

 0.38 

 0.26 



0.67 

 0.31 

 0.46 



