302 
NOAA 
National Marine 
Fisheries Service 
Fishery Bulletin 
<%• established 1881 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Seasonal changes in abundance and compelling 
evidence of migration for 2 rockfish species 
ISebmtes auriculatm and S. caurinm} inhabiting 
a nearshore^ temperate-miater artificial reef 
Abstract— We used scuba over fixed- 
width strip transects to monitor sea- 
sonal abundances of brown rockfish 
{Sebastes auriculatus) and copper 
rockfish (S. caurinus) on a nearshore 
artificial reef in Puget Sound, Wash- 
ington, over a 7-year period. Spring 
and fall abundances were intermedi- 
ate and marked transitional phases 
between seasons of highest (sum- 
mer) and lowest (winter) abundance 
for both species. Analyses of length 
classes indicated that the numbers 
of seasonal juvenile recruits were 
not sufficient to account for the 
marked differences in abundance 
between summer and winter. For 
both species, the proportion of large 
fish (>20 cm in total length) to the 
total number observed in summer 
and winter was significantly greater 
during the winter. Late-stage gravid 
brown rockfish occurred in greatest 
abundance during the spring and 
late-stage gravid copper rockfish 
were observed only in the summer. 
We examined auxiliary data from 
a genetics study of brown rockfish 
that was conducted concurrently at 
the reef and interpreted the results, 
along with our survey findings, as 
providing compelling evidence of 
seasonal migrations on and off the 
reef. 
Manuscript submitted 20 October 2015. 
Manuscript accepted 19 April 2016. 
Fish. Bull. 114:302-316 (2016). 
Online publication date: 6 May 2016. 
doi: 10.7755/FB.114.3.4 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Larry L. LeOair Ccantact author) 
Ocean Eveningsong 
Jesse M. Schulte 
Email for contact author: larry.ledair@dfw.wa.gov 
Washington Department of Fish and Wildlife 
600 Capitol Way North 
Olympia, Washington 98501 
Understanding fish movement is par- 
amount to the design and implemen- 
tation of effective resource conser- 
vation and management strategies. 
Movement influences the dynamics, 
demographics, and genetics of popu- 
lations; the structure and function 
of ecosystems; species interactions; 
modes of energy transfer; and bio- 
diversity (Rothschild, 1986; Frank, 
1992; Merz and Moyle, 2006; Clark et 
al., 2009; Condal et ah, 2012). Known 
patterns of movement are often key 
considerations in the development 
of harvest management plans es- 
tablished to protect fish populations 
from overexploitation. For example, 
in the northeast Pacific Ocean, ling- 
cod {Ophiodon elongatus) are widely 
believed to participate in seasonal 
nearshore-offshore spawning mi- 
grations (Jagielo, 1990, 1995), and 
in some regions (e.g., Puget Sound), 
recreational fisheries that target 
lingcod are managed to protect near- 
shore spawning fish (Palsson et al.^). 
Pacific halibut {Hippoglossus stenol- 
1 Palsson, W. A., T. J. Northup, and M. W. 
Barker. 1998. Puget Sound Ground- 
fish Management Plan, 48 p. Washington 
Dep. Fish Wildl., Olympia. [Available 
at website.] 
epis) also undergo seasonal migra- 
tions (St-Pierre^), and establishment 
of the commercial fishery season by 
the International Pacific Halibut 
Commission is designed in large part 
to protect offshore spawning popula- 
tions (Loher, 2011). 
Fish movement also has crucial 
implications for the design of scien- 
tific sampling strategies and stock 
assessments, and movement poses 
both operational and conceptual chal- 
lenges for the selection of appropriate 
temporal and spatial scales in ecolog- 
ical studies. Inferences about the eco- 
logical processes under investigation 
may be constrained or confounded 
when, as is often the case, scales of 
operational convenience, rather than 
ecological relevance, are incorporated 
into study designs. Failure to identi- 
fy and integrate fish movement into 
study designs can lead to the selec- 
tion of temporal or spatial scales of 
observation that are ill-fitted to the 
study objectives, particularly when 
movement occurs over multiple habi- 
tat types. Sampling strategies that 
2 St-Pierre, G. 1984. Spawning loca- 
tions and season for Pacific halibut. Int. 
Pac. Halibut Comm., Sci. Rep. 70, 46 
p. [Available at website.] 
