were made using a random stratification scheme 

 (Fig. 1). 



Both juvenile flatfish surveys used a No. 36 

 Yankee shrimp trawl, with a 38.1 mm mesh through- 

 out and a 12.7 mm cod end mesh liner. The Septem- 

 ber 1980 survey was in the northern Gulf of St. 

 Lawrence, NAFO Division 4R aboard the chartered 

 stern trawler Zagreb. The trawl was equipped with 

 a single tickler chain for approximately 53% of the 

 fishing sets (see Walsh 1984). A total of 53 30-min 

 fishing sets were made (Fig. 1). The October 1981 

 juvenile survey was in Hermitage Bay and Fortune 

 Bay aboard RV R. V. Shamook. A total of 28 fish- 

 ing sets in depths of 188-402 m were used in the 

 analysis. Most of these sets were of <30-min dura- 

 tion owing to otter doors being stuck in the heavy 

 mud of these bays and the catches were adjusted 

 upward based on the ratio of actual tow to the stan- 

 dard 30 min (Fig. lA). Both juvenile surveys were 

 based on line transects that ran perpendicular to 

 depth contours so that all depth zones would be 

 sampled. Stations in the Gulf of St. Lawrence were 

 about 10 mi apart on each line while the surveys in 

 the two bays were about 2 mi apart. The purpose 

 of these two surveys was to test the use of a small 

 mesh trawl and delineate depth distribution of all 

 flatfishes in the area sampled. 



Method of Analysis 



Total lengths of witch flounder were grouped into 

 2 cm intervals for the analysis. Catches of witch 

 flounder at each station were divided into two size 

 categories: juveniles (<30 cm) and adults (>30 cm). 

 Majority of witch flounder are sexually immature 

 at 30 cm (Powles and Kohler 1970; Beacham 1983). 

 Depths of catches were broken down at 20 m inter- 

 vals and a Kolmogorov-Smirnov two-sample test 

 was applied (Siegel 1956) to the cumulative distribu- 

 tion of both size categories for each data set. The 

 null hypothesis used states that there is no differ- 

 ence in depth distribution of juvenile and adult witch 

 flounder; i.e., the values of the population from 

 which the juvenile sample and the adult sample were 

 drawn have the same cumulative distribution. The 

 alternative hypothesis used stated that there was 

 a difference in depth distribution, i.e., the two- 

 sample cumulative distributions were far apart and 

 suggests the samples came from different popula- 

 tions. The level of significance used was «: = 0.05. 

 A catch frequency was calculated for each size group 

 over 20 m depth intervals. 



The analysis was used on five data sets: 1) otter 

 trawl catches for 1978-80 in both Division 4R and 



Division 4S were combined to increase sample size 

 and coverage of the Gulf of St. Lawrence; 2) otter 

 trawl catches in Division 4R, 1980 were used to com- 

 pare with 3) shrimp trawl catches in Division 4R, 

 1980; 4) shrimp trawl catches in Division 3Ps; and 

 5) combination of the catches of both gears from sets 

 north of lat. 50°N in Division 4R, 1980. The latter 

 combination of data was used for two reasons: 1) 

 There were no successful sets made by the shrimp 

 trawl in depths <180 m owing to rough bottom while 

 the otter trawl had sets in depths as shallow as 120 

 m, both vessels were in the same area at the same 

 time, and 2) given a bias in gear selectivity, com- 

 bination of catches of both gears should be repre- 

 sentative of the population located in this small area 

 of northern Esquiman Channel (Fig. 1). 



Results 



Trends in depth distribution of witch flounder 

 using different fishing gears showed no significant 

 difference in the cumulative distributions of juvenile 

 and adult witch flounder in all data sets (P > 0.05) 

 (Table 4). 



No. 41.5 Yankee Otter Trawl 



Divisions 4R and 45, 1978-80. Juveniles were 

 found in a depth range of 102-464 m with a median 

 located in the 241-260 m depth interval. Adults were 

 distributed in a depth range of 91-484 m with the 

 median located in the 181-200 m depth interval 

 (Table 1, Fig. 2 A). 



Division 4R, 1980. Both juveniles and adults were 

 distributed in a depth range of 122-464 m. Most of 

 the juveniles were located in the 241-260 m depth 

 interval while the median of the adult witch flounder 

 was located in the 160-180 m depth interval (Table 

 1, Fig. 2B). 



No. 36 Yankee Shrimp Trawl 



Division 4R, 1980. Juvenile and adult witch 

 flounder were widely distributed in a depth range 

 of 187-502 m. The median of juveniles was located 

 in the depth interval 241-260 m while for adults it 

 was the 261-280 m interval (Table 2, Fig. 2C). 



Division 3Ps, 1981. Juvenile and adult witch 

 flounder were widely distributed in a depth range 

 of 188-402 m. The median of juvenile distribution 

 was in the 281-300 m interval while that for adults 

 was in the 261-280 m interval (Table 2, Fig. 2D). 



149 



