LeClair et al.: Seasonal changes in abundance and migration of Sebastes auriculatus and 5. caurinus 
309 
Spring Summer Fall Winter 
Figure § 
Mean densities and standard errors (summed over 3 transects and all 
years) for small (< 20 cm in total length [TL]) and large (> 20 cm TL) 
brown and copper rockfish (Sebastes auriculatus and S. carinus, respec- 
tively) observed at Point Heyer Artificial Reef , Puget Sound, WA, from 
summer 2005 through summer 2012. 
age monthly air temperatures summed over a 12-year 
period beginning in 2000 and recorded at a weather ob- 
servation station located less than 10 km from PHAR. 
Our water temperature data were therefore deemed to 
be an acceptable proxy for trends in seasonal tempera- 
ture at PHAR during the study. 
is usually distinguished from emigra- 
tion (a form of dispersal), whereby re- 
turn to an area does not occur (Lidicker 
and Stenseth, 1992), or occurs only by 
chance. Adding confusion (or clarity, de- 
pending on one’s perspective) to charac- 
terizing fish movement is the concept 
of home range (Burt 1943). According 
to McLoughlin and Ferguson (2000), 
home range is established once the cu- 
mulative area that is used ceases to in- 
crease over time (i.e., an asymptote is 
reached). However, and consistent with 
Burt (1943), it is generally accepted 
that home ranges comprise only those 
areas within which routine activities oc- 
cur over finer temporal scales, and that 
they do not include infrequent spatially 
broad-scaled movements, migration cor- 
ridors, or the movements of planktonic 
life history phases for which the total 
area used may not reach an asymptote 
over time. 
We have shown that both brown and 
copper rockfish exhibited pronounced 
changes in abundance between summer 
and winter at PHAR, that the changes 
occurred with regularity over a broad 
time span, and that the observed pat- 
terns were similar for both species. 
Whether the seasonal changes in abundance reflect 
migratory behavior hinge on whether the same fishes 
return to repopulate the reef during the summer. If, 
for instance, fish populations disperse over broad geo- 
graphic areas while overwintering in deeper water and 
return to shallower water without predilection toward 
Discussion 
The different sensory inputs that 
motivate animals to move and the 
variety of spatiotemporal scales 
over which movements may occur 
has led to some blurring among 
specialists over what constitutes 
migration (Dingle and Alistair 
Drake, 2007). The most broadly ac- 
cepted definitions of fish migration 
include some element of to-and-fro 
movement during the life cycle of a 
fish, and some predictability of oc- 
currence. Heape (1931) described 
migration as, “...that class of move- 
ment which impels migrants to 
return to the region from which 
they have migrated.” Harden Jones 
(1984) defines fish migration as 
“...a coming and going with the sea- 
sons on a regular basis...” Migration 
Summer Winter Summer Winter 
W=1045 N=563 N=156 
Figure 6 
Relative proportions of large (>20 cm in total length [TL]) and small (<20 
cm TL) brown and copper rockfish (Sebastes auriculatus and S. carinus, re- 
spectively) to the total number (N) of fish observed for each species at Point 
Heyer Artificial Reef, Puget Sound, WA, during summer and winter from 
2005 through 2012. Whiskers denote the 95% confidence intervals for the 2 - 
test comparisons of the 2 proportions. 
