348 Pari III. — Twentieth Annual Report 



On 31st October and 1st November 1900, two hauls in Aberdeen Bay, 

 in from eight to fifteen fathoms, yielded 432 plaice, the smallest of which 

 was 165 mm., or Qk inches, and the largest 593 mm., or about 22| inches. 

 The sexes were not separately measured. The curve shows they form 

 five or six annual groups, the first and last of wh^ch were not well 

 represented ; while the younger series inhabiting the beaches and 

 shallows were of course absent. The first group of forty-six ranged from 

 165 to 247 mm., and had an average of 226*5 mm. (8|-f inches). This 

 is greater than the true mean size owing to the paucity of the smaller 

 and medium members of this series; it ought to lie between 20 and 21 cm. 

 The second group Avas composed of 302 plaice, forming thus the bulk of 

 the catch, the smallest measuring 250 mm. (9i inches) and the largest 

 369 mm. (14^ inches), while the mean size was 309'7 mm., or 12^^ inches. 

 The third group comprised 71 plaice from 370 mm. to 438 mm., the 

 average size being 397'4 mm., or 1 5 ]-i inches. The curve shows that 

 this average is too low (the maximum oi'dinate being at 38 cm.), i.e. the 

 larger fishes were not present in due abundance. A fourth group 

 contained eleven fishes from 447 to 495 mm., with a mean size of 471-2 

 mm., or 18| inches. There were other two, one measuring 555 mm. 

 and the other 593 mm., each of which probably represented an older 

 group. 



On 30th May 1901, in 8 to 15 fathoms of water, 214 plaice were 

 obtained belonging to five groups, unequally represented, the measure- 

 ments furnishing somewhat irregular curves. 



The first series contained three females and two males, the former 

 measuring from 127 to 194 mm., with an average of 166"3 mm., the 

 latter 182 and 198 mm., with an average of 190 mm. The second group 

 comprised 31 females, from 212 to 299 mm., with a mean size of 260*4 

 nmi. (10:f inches), and 34 males, from 201 to 300 mm., with an average 

 size of 263*3 mm., the mean size of the group being 261 "4 mm. The 

 third sei'ies contained seventy-two females from 304 to 408 mm., with 

 a mean size of 351*8 mm. (13|- inches), and fifty-two males ranging from 

 304 to 376 mm., the average being 341*3 mm. (13y''3- inches). A fourth 

 series was represented by two females, 454 and 472 nmi., with an 

 average of 463, and fourteen males from 379 to 409 nun., with a mean 

 size of 390*4 mm. (15| inches). There were other four females 

 measuring from 521 to 584 mm., and averaging 552*0 mm., or 20| 

 inches. 



On 6th and 7th June the plaice in several hauls with the ordinary 

 otter trawl in eight to twenty fathoms were measured. A first series, 

 not well represented, comprised twenty-eight fish ranging from 123 to 

 196 mm., and having an average size of 176*2 mm. The second series 

 contained 247 females, ranging from 203 to 307 mm., the average size 

 being 262*1 mm., or 1 0^ inches, and 276 males from 201 to 302 mm., with 

 a mean size of 252*5 mm., or 9]-^ inches. The average size of this group, 

 according to the curve for the sexes mixed, was 256*1 mm., or 10-j'^ 

 inches. The next series contained 469 females from 308 to 413 mm., with 

 a mean size of 357*9 mm., or 14l inches, and 333 males from 303 to 385 

 mm., with an average length of 346*6 mm., or 13|^ inches. The mean 

 size of the plaice included in the curve with the sexes mixed (850 fishes) 

 was 355*3 mm., or 14 inches. There was a fourth series of 84 females, 

 ranging Irom 414 to 491 mm., and having an average length of 445*4 

 mm., or 17| inches, and forty-three males measm*ing from 386 to 455 

 mm., the average being 400*9 mm., or 15]~ inches. The mean size of 

 the eighty -seven mixed fishes included in this curve was 441*1 mm., or 

 17f inches. 



On 13th June a haul in nine to twelve and a half fathoms yielded 161 



