138 
Fishery Bulletin 1 10(1) 
nificant changes in some of the guilds within the fish 
community were observed over the last four decades in 
the Gulf of Maine and Georges Bank region. 
Conclusion 
These simplistic life-stage recruitment models with 
known life-stage abundance and mortality rates, have 
predicted age-1 recruitment of Georges Bank cod and 
haddock to be close to recruitment derived by VPA 
methods. However, starting with annual egg abundance 
derived from the VPA SSB and using proxies for the egg, 
larval, pelagic juvenile, and demersal juvenile-stage 
mortality, the models could at best predict trends in 
recruitment for both species. Survey abundance esti- 
mates of the larvae used in these models can be used 
to forecast recruitment reasonably close with VPA esti- 
mates for some years. The larval period is the most 
quantifiable pelagic stage in terms of estimating abun- 
dance and mortality; it eliminates the need to survey the 
egg stage, and is closer in time to the demersal juvenile 
stage. Without such survey data it is difficult to assess 
the magnitude of mortality for these stages. 
Acknowledgments 
This is contribution #710 of the US GLOBEC program, 
funded jointly by NOAA and the National Science Foun- 
dation. We thank J. Hare, D. Richardson, and the three 
anonymous reviewers for their constructive comments, 
and E. Broughton, M. Travel - and X. Wu for revised 
figures. 
Literature cited 
Alonso-Fernandez, A., A. C. Vallejo, F. Saborido-Rey, H. Murua, 
and E. A. Trippel. 
2009. Fecundity estimation of Atlantic cod (Gadus 
morhua) and haddock ( Melanogrammus aeglefinus) 
of Georges Bank: application of the autodiametric 
method. Fish. Res. 99:47-54. 
Auster, P. J., and J. S. Link. 
2009. Compensation and recovery of feeding guilds in a 
northwest Atlantic shelf fish community. Mar. Ecol. 
Prog. Ser. 382:163-172. 
Bailey, K. M., L. Ciannelli, N. A. Bond, A. Belgrano, and N. C. 
Stenseth. 
2005. Recruitment of walleye pollock in a physically and 
biologically complex ecosystem: a new perspective. Prog. 
Oceanogr. 667:24-42. 
Beaugrand, G., K. M. Brander, J. A. Lindley, S. Souissi, P. C. 
Reid. 
2003. Plankton effect on cod recruitment in the North 
Sea. Nature 426:661-664. 
Beaugrand, G., and R. R. Kirby. 
2010. Climate, plankton and cod. Global Change Biol. 
16:1268-1280. 
Bolz, G. R., and R. G. Lough. 
1988. Growth through the first six months of Atlan- 
tic cod Gadus morhua, and haddock, Melanogrammus 
aeglefinus, based on daily otolith increments. Fish. 
Bull. 86:223-235. 
Brander, K. 
2003. What kinds of fish stock predictions do we need 
and what kinds of information will help us to make 
better predictions? Sci. Mar. 67 (suppl. l):21-33. 
Buckley, L. J., E. M. Caldarone, R. G. Lough, and J. M. 
St. Onge-Burns. 
2006. Ontogenetic and seasonal trends in recent growth 
rates of Atlantic cod and haddock larvae on Georges 
Bank: effects of photoperiod and temperature. Mar. 
Ecol. Prog. Ser. 325:205-226. 
Buckley, L. F., and E. G. Durbin. 
2006. Seasonal and inter-annual trends in the zooplankton 
prey and growth rate of Atlantic cod (Gadus morhua) 
and haddock (Melanogrammus aelgefinus) larvae on 
Georges Bank. Deep-Sea Res., pt. II, 53:2758-2770. 
Buckley, L. J., R. G. Lough, and D. Mountain. 
2010. Seasonal trends in mortality and growth of cod 
and haddock larvae result in an optimal window for 
survival. Mar. Ecol. Prog. Ser. 405:57-69. 
Ciannelli, L., K. V. Bailey, K. -S. Chan, A. Belgrano, and N. C. 
Stenseth. 
2005. Climate change causing phase transitions of walleye 
Pollock (Theragra chalcogramma) recruitment dynam- 
ics. Proc. R. Soc. Lond. B Biol. Sci. 272:1735-1743. 
Conser, R. J., and J. E. Powers. 
1990. Extensions of the ADAPT VPA tuning method 
designed to facilitate assessment work on tuna and 
swordfish stocks. ICCAT Coll. Vol. Sci. Pap. 32: 
461-467. 
Coyle, K. O., L. B. Eisner, F. J. Mueter, A. I. Pinehuk, M. A. 
Janout, K. D. Cieciel, E. V. Farley, and A. G. Andrews. 
2011. Climate change in the southeastern Bering Sea: 
impacts on Pollock stocks and implications for the oscil- 
lating control hypothesis. Fish. Oceanogr. 20:139-156. 
Daewel, U., M. A. Peck, and C. Schrum. 
2011. Life history strategy and impacts of environ- 
mental variability on early life stages of two marine 
fishes in the North Sea: an individual-based modeling 
approach. Can. J. Fish. Aquat. Sci. 68:426-443. 
Fauchald, P. 
2010. Predator-prey reversal: A possible mechanism 
for ecosystem hysteresis in the North Sea? Ecology 
91:2191-2197. 
Fogarty, M. J., L. Incze, K. Hayhoe, D. Mountain, and J. 
Manning. 
2008. Potential climate impacts on Atlantic cod (Gadus 
morhua) off the northeastern USA. Mitig. Adapt. Strat. 
Glob. Change 13:453-466. 
Fogarty, M. J., R. A. Meyers, and K. G. Bowen. 
2001. Recruitment of cod and haddock in the North 
Atlantic: a comparative analysis. ICES J. Mar. Sci. 
58:952-961. 
Folkvord, A., G. Blom, O. Dragesund, A. Johannessen, O. Naken, 
G. Naevdal. 
1994. A conceptual framework for enhancing and study- 
ing recruitment of marine fish stocks. Aquacult. Fish. 
Manage. 25 (suppl. 11:245-258. 
Frank, K. T., B. Petrie, J. S. Choi, and W. C. Leggett. 
2005. Trophic cascades in a formerly cod-dominated 
ecosystem. Science 308:1621-1623. 
Frank, K. T., B. Petrie, and N. L. Shackell. 
2007. The ups and downs of trophic control in continen- 
tal shelf ecosystems. Trends Ecol. Evol. 22:236-242. 
