Echave et al.: Interdecadal change in growth of Anoplopoma fimbria in the northeast Pacific Ocean 
373 
used in our study with the data updated through 2010 
and found results that were not significantly different 
from the results of our analysis with data collected 
through 2004. Therefore, our initial results were used: 
VB parameter estimates for females from 1996-2010, 
L m - 79.9, 6 = 0.22, t 0 ~- 2.23; VB parameter estimates for 
males from 1996—2010, L oo = 6 8, 6 = 0.273, t 0 =— 3.01. The 
updated growth estimates provide a better fit to the 
data, and they are the result of decades more age and 
growth collections with previous size biases corrected. 
We view these updated growth estimates as a needed 
and substantial increase in biological realism for the 
Alaskan sablefish stock assessment model. In the fu- 
ture, growth will be revisited periodically, but as data 
accumulate, the addition of the newest data should have 
only nominal effects on recommendations for harvest 
rates (Hanselman et ah, 2007). 
Conclusions 
In moving closer to estimating true underlying sablefish 
growth, we have revealed that, historically, the sizes 
of sablefish modeled in the Alaskan sablefish stock 
assessment were slightly too large. This study aids in 
describing the population of sablefish in Alaska more 
realistically as having a smaller maximum size. The 
use of these improved estimates will result in more 
conservative management in the short term but more 
harvest stability in the future. Although a specific cause 
and time for the changes in sablefish growth was not 
identified, these changes have occurred. To properly 
manage this important economic resource, the updated 
estimates for growth should continue to be used for the 
NMFS assessment of the Alaskan sablefish stock. 
This study provides an example of the importance 
of identifying and correcting for biases that may be 
produced from different data collection strategies and 
of scientists periodically revisiting life history param- 
eter estimates used in assessment of various stocks. 
The result of such efforts could mean the difference 
in overestimation or underestimation of abundance 
and, in turn, could have an effect on allotted harvest 
recommendations. 
Acknowledgments 
We thank N. Hillgruber for reviewing this manuscript 
and for providing much guidance and C. Lunsford for 
his contributions and suggestions. 
Literature cited 
Armstrong, M. J., H. D. Gerritsen, M. Allen, W. J. McCurdy, and 
J. A. D. Peel. 
2004. Variability in maturity and growth in a heavily 
exploited stock: cod ( Gadus morhua L.) in the Irish 
Sea. ICES J. Mar. Sci. 61:98-12. 
Beamish, R. J., and D. E. Chilton. 
1982. Preliminary evaluation of a method to determine 
the age of sablefish (Anoplopoma fimbria). Can. J. 
Fish. Aquat. Sci. 39:277-287. 
Betolli, P. W., and L. E. Miranda. 
2001. Cautionary note about estimating mean length at 
age with subsampled data. N. Am. J. Fish. Manage. 
21:425-428. 
Clark, W. G„ and S. R. Hare. 
2002. Effects of climate and stock size on recruitment 
and growth of Pacific halibut. N. Am. J. Fish. Manage. 
22:852-862. 
Clark, W. G., S. R. Hare, A. M. Parma, P. J. Sullivan, and R. J. 
Trumble. 
1999. Decadal changes in growth and recruitment of 
Pacific halibut ( Hippoglossus stenolepis). Can. J. Fish. 
Aquat. Sci. 56:242-252. 
Driggers III, W. B., J. K. Carlson, B. Cullum, J. M. Dean, D. Oak, 
and D. Ulrich 
2004. Age and growth of the blacknose shark, Carcharhi- 
nus acronotus, in the western North Atlantic Ocean with 
comments on regional variation in growth rates. Envi- 
ron. Biol. Fishes 71:171-178. 
Goodyear, C. P. 
1995. Mean size at age: an evaluation of sampling strat- 
egies with simulated red grouper data. Trans. Am. 
Fish. Soc. 124:746-755. 
Hanselman, D. H., C. R. Lunsford, J. T. Fujioka, and C. J. 
Rodgveller. 
2006. Alaska sablefish assessment for 2007. In Stock 
assessment and fishery evaluation report for the ground- 
fish resources of the Gulf of Alaska, p. 341-428. North 
Pacific Fishery Management Council, 605 W. 4th Ave., 
Anchorage, Alaska 99501. lAvailable from http://www. 
afsc.noaa.gov/REFM/docs/2006/sa blefish.pdf. I 
2007. Assessment for 2008. In Stock assessment and 
fishery evaluation report for the groundfish resources 
of the Gulf of Alaska, p. 195-312. North Pacific Fish- 
ery Management Council, 605 W. 4th Ave., Anchorage, 
Alaska 99501. (Available from http://www.afsc.noaa. 
gov/refm/Docs/2007/GOA Safe, pdf.] 
Hanselman, D. H., C. R. Lunsford, and C. J. Rodgeveller. 
2010. Assessment of the sablefish stock in Alaska. In Stock 
assessment and fishery evaluation report for the ground- 
fish resources of the Gulf of Alaska, p. 329-468. North 
Pacific Fishery Management Council. 605 W. 4th Ave., 
Anchorage, Alaska 99501. (Available from http:// 
w w w. a fsc.noaa.gov/REFM /Docs/20 10/G OASafe.pdf. 1 
Heifetz, J., and J. T. Fujioka. 
1991. Movement dynamics of tagged sablefish in the 
northeastern Pacific Ocean. Fish. Res. 11:355-374. 
Heifietz, J., D. Anderl, N. E. Maloney, and T. L. Rutecki. 
1999. Age validation and analysis of aging error from 
marked and recaptured sablefish, Anoplopoma fim- 
bria. Fish. Bull. 97:256-263. 
Imsland, A. K., A. Foss, and S. O. Stefansson. 
2001. Variation in food intake, food conversion efficiency, 
and growth of juvenile turbot from different geographic 
strains. J. Fish Biol. 59:449-454. 
Kaplan, A., M. A. Cane, Y. Kushnir, A. Clement, M. Blumenthal, 
and B. Rajagopalan. 
1998. Analyses of global sea surface temperature 1856- 
1991. J. Geophys. Res. 103(C9):18, 567-18, 589. 
Kimura, D. K. 
1980. Likelihood methods for the von Bertalanffy growth 
curve. Fish. Bull. 77:765-775. 
