LeClair et al.: Seasonal changes in abundance and migration of Sebastes auriculatus and S. caurinus 
313 
their environment and not to any single environmen- 
tal factor in isolation (e.g., temperature), we consider 
it unlikely that either species moved on and off the 
reef in direct response to temperature alone, especially 
given that they would be leaving the relatively stable 
thermal environment of deeper water for the more 
broadly fluctuating temperatures encountered over the 
reef during the spring and summer. 
We hypothesize on the basis of our survey flndings 
and the evidence gleaned from Hess et al. (2012) that 
the observed changes in abundance of brown and cop- 
per rockflsh at PHAR are the result of seasonal reloca- 
tions of these species to different migratory destina- 
tions beyond their home ranges; most likely in response 
to reduced refuge space and prey density (e.g., due to 
reduced macroalgal cover and associated prey) during 
the winter months. Behaviors associated with spawning 
and mating may also play a crucial role in determin- 
ing the seasonal movements and spatial distributions 
for these 2 rockflsh species. The statistically signiflcant 
greater proportion of large brown and copper rockflsh 
present on the reef during the winter could be attrib- 
uted to an overall suboptimal year-round habitat that 
is interspersed with enclaves of microhabitats suitable 
for year-round occupancy and that are held more suc- 
cessfully by larger territorial fishes. 
The applicability of our hypothesis to brown and 
copper rockflsh populations elsewhere in Puget Sound 
is unclear. If habitat quality is correlated with rockflsh 
movement, behavioral variability among local popula- 
tions is likely to be high and our observed seasonal 
changes in abundance would not be conserved across 
sites. If, as proposed by Matthews et al. (1987), there 
is a relationship between habitat quality and rockflsh 
movement on and off reefs, determining the timing and 
magnitude of seasonal variability in rockflsh abundance 
at different sites could prove to be a useful means for 
ranking the relative importance of those sites for rock- 
fish conservation efforts. This research could be critical 
for establishing MPAs and for determining the spatial 
scales over which protection should be afforded. 
Exploitation of aggregating behavior by fisheries, 
such as often occurs with cods, forage fish, and other 
species, may be detrimental to the recovery of declin- 
ing rockflsh stocks if the aggregations are composed 
of migrant adults. Fishery managers may wish to con- 
sider the potential for, and management implications 
of, local rockflsh migratory behavior. Concentrating 
fisheries in the nearshore environment during times of 
year when migratory rockflsh are present could result 
in the depletion of local populations, particularly if ag- 
gregations are linked to spawning, courtship, or mating 
behavior. 
Generalized linear mixed-effects models, parameter- 
ized with spatially and temporally explicit habitat, prey 
availability, and movement data could aid researchers 
in identifying the key habitat attributes and environ- 
mental indicators that characterize essential habitat 
for these and other fish species. 
Acknowledgments 
We thank R. Buckley and T. Parra for assisting with 
data collection during the transect survey dives. Diver 
surface support was provided by P. Campbell, W. Dezan, 
R. Heikkila, L. Hiller, J. Hoback, W. Morris, B. Power, 
S. Reszczynski, J. Rohr, M. Ulrich, and T. Wilson. We 
are grateful to M. Hess for generously providing the 
genetic recapture data. Expert assistance with the sta- 
tistical analyses and interpretation was provided by K. 
Fenske. We thank L. Hillier, D. Lowry, R. Pacunski, and 
3 anonymous reviewers for providing helpful comments 
on an earlier draft. 
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