Table 14. — Yellowtail flounder length frequency 

 distributions and percent retained for the large-mesh 

 (133 mm overall average) covered tows — six vessels. 



Table 16. — Yellowtail flounder landings and discards. 



Length 



Numbers caught 





interval 





133 nun 



Percent 



(cm) 



133 mm 



plus covers 



retained 



10-12 











0.0 



13-15 



1 



25 



4.0 



16-18 



13 



221 



5.9 



19-21 



26 



460 



5.7 



22-24 



62 



460 



13.5 



25-27 



109 



316 



34.5 



28-30 



132 



243 



54.3 



31-33 



335 



392 



85.5 



34-36 



532 



550 



96.7 



37-39 



319 



323 



98.8 



4042 



199 



199 



100.0 



4345 



118 



118 



100.0 



46-48 



46 



46 



100.0 



49-51 



9 



9 



100.0 



52-54 











— 



Totals 



1,901 



3,362 





Table IS. 



— Yellowtail flounder 



length frequency 



distributions and percent re- 





tained from uncovered cod end tows 



— six vessels. 













to retained by 



Length 











133 mm 



interval 



Numbers 



caught 



B 



A 



0. 



B x 100 



(cm) 



(A) 102 mm 



(B) 133 mm 



82/1 



10-12 











0.00 





0.0 



13-15 







1 



0.00 





0.0 



16-18 



15 



3 



0.20 





24.4 



19-21 



118 



2 



0.02 





2.1 



22-24 



460 



27 



0.06 





7.2 



25-27 



430 



68 



0.16 





19.3 



28-30 



395 



94 



0.24 





29.0 



31-33 



567 



301 



0.53 





64.7 



34-36 



833 



551 



0.66 1 





81.0 



37-39 



513 



444 



0.87 



Avg. 

 [ 82 



105.5 



40-42 



295 



223 



0.76 



92.2 



4345 



146 



144 



0.99 





120.3 



46-48 



46 



38 



0.83 J 





100.7 



49-51 



20 



11 



0.55 





67.1 



52-54 



2 



2 



1.00 





121.6 



55-57 



2 







0.00 





— 



Totals 



3,842 



1,909 









mesh uncovered retention percentages with the small-mesh 

 covered retention percentages and was found to be small. Con- 

 tinuing in the same vein, if all four types of tows (small and 

 large, covered and uncovered) were compared with the same 

 base (covered cod ends plus covers) and adjusted on a 

 numbers-per-tow basis, a comparison could be made between 

 the two mesh sizes that might indicate some degree of relative 

 efficiency. A larger number of tows than performed during 

 this series of experiments is required to do this with any degree 

 of confidence. 



An analysis of combined landings and discards (Table 16) 

 indicates a smaller catch with the larger mesh. From observa- 

 tions made during the experiments, it was noted that the ma- 

 jority of fish 30 cm (1 1.8 in) and smaller were discarded. This 

 is a lower cull point than in the past. Hennemuth and Lux 



Length 













interval 





Small uncovered 



Large uncovered 



(cm) 



Kg/fish 



No. 



Kg 



No. 



Kg 



10-12 









0.0 







0.0 



13-15 



0.02 







0.0 



1 



0.02 



16-18 



0.04 



15 



0.6 



3 



0.1 



19-21 



0.07 



118 



8.3 



2 



0.1 



22-24 



0.09 



460 



41.4 



27 



2.4 



25-27 



0.13 



430 



55.9 



68 



8.8 



28-30 



0.22 



395 



86.9 



94 



20.7 



31-33 



0.31 



567 



175.8 



301 



93.3 



34-36 



0.41 



833 



341.5 



551 



225.9 



37-39 



0.59 



513 



302.7 



444 



262.0 



40-42 



0.68 



295 



200.6 



223 



151.6 



4345 



0.86 



146 



125.6 



144 



123.8 



4648 



1.04 



46 



47.8 



38 



39.5 



49-51 



1.17 



20 



23.4 



11 



12.9 



52-54 



1.44 



2 



2.9 



2 



2.9 



55-57 



1.67 



2 



3.3 







0.0 



58-60 



2.14 











Totals 3,842 



Landings (discard < 30 cm) 



Discards 



% discards 



1,416.7 





1,223.6 



1,418 



193.1 



36.9 



13.6 



1,909 



195 



10.2 



944.0 



911.9 



32.14 



3.4 



% reduction in discards between mesh sizes: 75% by weight. 



(1970) reported a cull midpoint for yellowtail by the com- 

 merical fleet of 34 cm (13.5 in). Using 30 cm as the cull point, 

 the data from this series of experiments indicates a 36.9% 

 discard rate (by number of fish) for a 4-in mesh. A 5.5-in mesh 

 reduces this discard by 75% when compared on a weight basis. 



Pollock 



These results are based on a catch of 1,118 pollock made 

 during Experiment Three. (It should be noted that at night in 

 the same area catches of 14,000 lb of pollock in 2 to 3 h tows 

 were common.) Both vessels fished the same basic population 

 distribution (Fig. 9). The covered-tow method could not be 





20 







/I 

 \ 



' \ 

 J 1 









X 



o 



r- 

 < 



15 







/ l \ 

 / * \ 

 / i \ 

 / l \ 



/ ' \ 









_l 

 < 



r- 



o 



r- 









/ l \ 

 1 \ 



\ \ 









Li. 



O 



10 



- 





\ \ 

 i \ 



\ 1 











5 





s/ 



i ) 



V 



\ \ 



\ 



i ^i-^N — 



-*^ L-S ! 



26 32 38 44 50 56 62 68 74 80 86 92 98 CM 



25 



LENGTH 



Figure 9. — Vessel comparisons — pollock. Cod ends + covers: solid line = 

 Joseph & Lucia II; dash rule = Joseph & Lucia III. 



13 



