in Table 26 and Figure 14. There was near equal retention 

 above the 100% retention point, thus the distributions were 

 considered equivalent. From this method, a 50% retention 

 length of 31.6 cm (12.4 in) is obtained for the 131 mm cod end 

 which gives a selection factor of 2.41. The 25-75% selection 

 range is approximately 7 cm (2.8 in). From this data a choice 

 of 2.3 for the American plaice selection factor seems 

 reasonable and is in agreement with past studies (Holden 

 1971). The catch distribution of the two cod end sizes com- 

 pared with the overall available population (Fig. 15) along with 



Table 25. — American plaice length frequency 

 distributions and percent retained for 131 mm cod 

 end covered tows — Linda B and Metacomet. 



Length 



Numbers caught 





interval 





131 mm 



Percent 



(cm) 



131 mm 



plus covers 



retained 



10-12 







27 



0.0 



13-15 



16 



487 



3.3 



16-18 



16 



563 



2.8 



19-21 



18 



349 



5.2 



22-24 



32 



263 



12.2 



25-27 



34 



134 



25.4 



28-30 



36 



75 



48.0 



31-33 



20 



31 



64.5 



34-36 



19 



19 



100.0 



37-39 



29 



29 



100.0 



40-42 



12 



12 



100.0 



43-45 



19 



19 



100.0 



4648 



14 



14 



100.0 



49-51 



9 



9 



100.0 



52-54 



8 



8 



100.0 



55-57 



4 



4 



100.0 



58-60 



2 



2 



100.0 



Totals 



288 



2,045 





Table 26. — American plaice length frequency distributions and percent retained 

 for the 131 mm uncovered cod end compared with the 99 mm uncovered cod end 

 — Linda B and Metacomet. 



Length 









interval 



Numbers 



caught 



B x 100 = % retained 



(cm) 



(A) 99 mm 



(B) 131 mm 



A by 131 mm 



10-12 











0.0 



13-15 



4 



1 



25.0 



16-18 



11 



1 



9.1 



19-21 



26 



4 



16.7 



22-24 



74 



6 



8.1 



25-27 



109 



24 



22.0 



28-30 



79 



28 



35.4 



31-33 



44 



23 



52.3 



34-36 



35 



40 



114.3 



37-39 



25 



19 



76.0 



4042 



12 



15 



125.0 



43-45 



27 



17 



63.0 



46-48 



15 



17 



113.3 



49-51 



10 



9 



90.0 



52-54 



9 



9 



100.0 



55-57 



2 



4 



200.0 



58-60 



1 







— 



61-63 



1 







_ 



64-66 







1 



_ 



Totals 



484 



218 



66 





66 





IA = 



137 



J£ = 



131 



34 





34 





catch data (Table 27) do not indicate anything in regard to effi- 

 ciency but show discards can be reduced by 50% using the 

 larger mesh. 





25 



A 

















5 



20 



















c 



15 



/ ^ 

















° 



10 





•" r 



. — "" 



— -\ 





A 









5 



/ J 













\ / \ 





17 20 23 26 29 32 35 38 41 44 47 50 53 56 59 62 CM 



Figure 15. — Catch distribution — American plaice. Solid line = total cod ends 

 + covers; dash line = total 131 mm cod ends; dot line = total 99 mm cod ends. 



Table 27. — American plaice landed weight and discard summary — Linda B 

 and Metacomet, with an assumed discard at 30 cm (11.8 in). 



Small cod ends 



Large cod ends 





Weight (kg) 



% discards 



Weight (kg) 



% discards 



Day 1 



28.4 



29.4 



32.7 



15.6 



Day 2 



149.4 



25.1 



44.2 



15.6 



Day 3 



12.0 



41.2 



7.5 



20.2 



Day 4 



34.8 



30.0 



133.7 



11.4 



Overall discard average: 31.4 15.7 



Reduction in discards: 50.0% 



Catch, summary by numbers of fish 



No. discarded Small uncovered - 303 Large uncovered - 64 



No. landed - 181 - 154 



Total - 484 - 218 



discard 



■62.6 



29.4 



MANAGEMENT IMPLICATIONS 



Discards 



In New England the term "discard" can mean anything in 

 the catch that is thrown back overboard. This can include 

 desirable species too small to market, unmarketable species, 

 and bottom trash such as rocks and shell. A marketable fish 

 can become discard by management decisions such as quotas 

 or size limits. The captain also makes the economic decision of 

 retaining certain species and sizes based on price and markets 

 available. Probably ever since commercial fishing with nets 

 began, fishermen have been discarding fish too small to 

 market and hook-and-line fisherman have been complaining 

 about it. In England in 1558 these complaints caused Queen 

 Elizabeth I to issue a royal decree setting a minimum mesh size 

 of 2.5 in (Jensen 1972). 



17 



