502 
Fishery Bulletin 95(3), 1997 
(Ricker, 1975). Obtaining representative samples 
from each age class becomes difficult when fish size 
and age vary with bottom depth. Considering also 
that during spring-summer, yellowfin sole abundance 
increases with decreasing bottom depth (Nichol, 
1995), population estimates of yellowfin sole growth 
and length or age at maturity should be weighted 
accordingly. Because groundfish assessment surveys 
in the eastern Bering Sea do not cover the shallow- 
est areas of yellowfin sole distribution during spring- 
summer, current estimates of yellowfin sole growth, 
as well as size and age at maturity, are inherently 
biased high. Given that most demersal fish distrib- 
ute themselves along a size-depth continuum 
(Macpherson and Duarte, 1991), the potential for 
similar depth-related sampling biases in other dem- 
ersal fish species appears probable. 
Acknowledgments 
I thank Steve Syrjala for his comprehensive statisti- 
cal advice, and the Age and Growth Unit of the Alaska 
Fisheries Science Center for the age determinations. 
Claire Armistead, Pam Goddard, Gary Walters, and 
Terry Sample helped tremendously with the data 
collection. Frank Morado, Nick Hodges, and Lisa 
Mooney performed much of the needed histology 
work. I thank Dave Somerton, Bob McConnaughey, 
David Sampson, Gary Walters, Dan Kimura, Jim 
Ianelli, Gary Duker, and James Lee for their con- 
structive reviews. Suggestions from three anonymous 
reviewers helped improve the final manuscript. 
Literature cited 
Armistead, C. E., and D. G. Nichol. 
1993. 1990 bottom trawl survey of the eastern Bering Sea 
continental shelf. U.S. Dep. Commer., NOAATech. Memo. 
NMFS-AFSC-7, 190 p. 
Bakkala, R. G. 
1981. Population characteristics and ecology of yellowfin 
sole. In D. W. Hood and J. A. Calder (eds.), The eastern 
Bering Sea shelf: oceanography and resources, Vol. 1, p. 
553-574. U.S. Dep. Commer., NOAA, Off. Mar. Pollut. 
Assess., U.S. Gov. Print Off., Wash., D.C. 
1993. Structure and historical changes in the groundfish 
complex of the eastern Bering Sea. U.S. Dep. Commer., 
NOAA Tech. Rep. NMFS 114, 91 p. 
Bevertom, R. J. H., and S. J. Holt. 
1957. On the dynamics of exploited fish populations. Fish. 
Invest. Ser. II Mar. Fish. G.B. Minist. Agric. Fish. Food 
19:1-533. 
Chilton, D. E., and R. J. Beamish. 
1982. Age determination methods for fishes studied by the 
Groundfish Program at the Pacific Biological Station. 
Can. Spec. Publ. Fish. Aquat. Sci. 60, 102 p. 
Cushing, D. H. 
1975. Marine ecology and fisheries. Cambridge Univ. 
Press, New York, NY., 278 p. 
Fadeev, N. W. 
1970. The fishery and biological characteristics of yellow- 
fin soles in the eastern part of the Bering Sea. Translated 
by Isr. Prog. Sci. Transl., 1972. In PA. Moiseev (ed.), So- 
viet fisheries investigations in the northeastern Pacific, 
part 5, p. 332-396. [Available from U.S. Dep. Commer., 
Natl. Tech. Inf. Serv., Springfield, VA, as TT 71-50127.] 
Grant, W. S., R. Bakkala, F. M. Utter, D. J. Teel, and 
T. Kobayashi. 
1983. Biochemical genetic population structure of yellow- 
fin sole, Limanda aspera, of the North Pacific Ocean and 
Bering Sea. Fish. Bull. 81(4):667-677. 
Jacobson, L. D., and J. R. Hunter. 
1993. Bathymetric demography and management of Dover 
sole. N. Am. J. Fish. Manage. 13(3):405-420. 
Hunter, J. R., J. L. Butler, C. Kimbrell, and E. A. Lynn. 
1990. Bathymetric patterns in size, age, sexual maturity, 
water content, and caloric density of Dover sole, Microsto- 
mus pacificus. Calif. Coop. Oceanic Fish. Invest. Rep. 
31:132-144. 
Kashkina, A. A. 
1965. Reproduction of yellowfin sole (Limanda aspera, 
Pallas) and changes in its spawning stocks in the eastern 
Bering Sea. Translated by Isr. Prog. Sci. Transl., 1968. In 
P. A. Moiseev (ed.), Soviet fisheries investigations in the 
northeastern Pacific, part 4, p. 182-190. [Available from 
U.S. Dep. Commer., Natl. Tech. Inf. Serv., Springfield, VA, 
as TT 67-51206.] 
Krivobok, M. N., and O. I. Tarkovskaya. 
1964. Chemical characteristics of yellowfin sole, cod and 
Alaska pollock of the southeastern part of the Bering Sea. 
Translated by Isr. Prog. Sci. Transl., 1968. In P. A. Moiseev 
(ed.), Soviet fisheries investigations in the northeastern Pa- 
cific, part 2, p 271-287. [Available from U.S. Dep. Commer., 
Natl. Tech. Inf. Serv., Springfield, VA, as TT 67-51204.] 
Macpherson, E., and C. M. Duarte. 
1991. Bathymetric trends in demersal fish size: Is there a 
general relationship? Mar. Ecol. Prog. Ser. 71(2): 103-112. 
Nichol, D. G. 
1995. Spawning and maturation of female yellowfin sole 
in the eastern Bering Sea. In Proceedings of the interna- 
tional flatfish symposium; October 1994, Anchorage, 
Alaska, p. 35-50. Univ. Alaska, Alaska Sea Grant Rep. 
95-04. 
Reish, R. L., R. B. Deriso, D. Ruppert, and R. J. Carol!. 
1985. An investigation of the population dynamics of At- 
lantic menhaden (Brevoortia tyrannus). Can. J. Fish. 
Aquat. Sci. 42(Suppl. 1):147-157. 
Ricker, W. E. 
1975. Computation and interpretation of biological statis- 
tics of fish populations. Bull. Fish. Res. Board Can. 191, 
382 p. 
Rijnsdorp, A. D. 
1994. Population-regulating processes during the adult 
phase in flatfish. Neth. J. Sea Res. 32(2):207-223. 
SAS Institute Inc. 
1989. SAS/STAT user’s guide, version 6, fourth ed., vol. 
2. SAS Institute, Cary, NC, 846 p. 
Trippel, E. A., and H. H. Harvey. 
1991. Comparison of methods used to estimate age and 
length of fishes at sexual maturity using populations of 
white sucker ( Catostomus commersoni ). Can. J. Fish. 
Aquat. Sci. 48:1446-1459. 
