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Fishery Bulletin 113(3) 
of Pacific ocean perch directly (e.g., currents that ex- 
ceed swimming speeds) or indirectly by impacting bio- 
genic structures that would otherwise provide refugia 
from currents (e.g., physical removal of structures in 
high current areas or their morphological adaptation 
to differing local current or sedimentation regimes). 
We hope to use in situ observation of current speeds 
and fish behavior (e.g., optical sampling) over trawlable 
and untrawlable bottom in the future, along with direct 
measurements of water velocity into the net mouth, to 
try and elucidate some of the potential mechanisms of 
this phenomenon and to improve the predictive power 
of these models. 
We were not able to account for all of the variables 
that may influence the distribution and abundance of 
Pacific ocean perch in the Aleutian Islands. Among 
these variables were the availability of prey and the 
substrate type at each bottom trawl survey station. 
Both of these factors are known to influence the dis- 
tribution and abundance of rockfishes (Carlson and 
Straty, 1981; Pearcy et al, 1989; Matthews, 1990; Love 
et al., 1991; Stein et al., 1992; Krieger and Ito, 1999; 
Yoklavich et al., 2000; Boldt and Rooper, 2009). Pacific 
ocean perch feed primarily on copepods and euphasiids 
both as juveniles and adults (Carlson and Haight, 
1976; Brodeur, 1983; Boldt and Rooper 2009), and the 
success of these predator-prey interactions is concen- 
tration dependent and partly mediated by the avail- 
ability of light that enables a fish to locate its prey. 
Water column light (irradiance) profiles vary widely 
across the Aleutian Islands (senior author, unpubl. 
data). Fish species are known to change their behavior 
in response to changing ambient light levels (e.g., Ryer 
and Olla, 1999; Kotwicki et al., 2009). The amount and 
spectral range of the available light in the water col- 
umn may be another important component of EFH for 
fish with visually mediated behaviors (Sathyendranath 
and Platt, 1990). Incorporating irradiance and spectral 
quality of light as habitat parameters in future models 
will provide new insights into delineating fish habitats. 
Effective management of fish populations and fishing 
activities requires better knowledge of the functional 
relationships between fish species and their habitats. 
In the case of Pacific ocean perch, we have concluded 
from this study that the species occurs predictably 
within certain depth ranges, in certain areas, and that 
they can be associated with erect forms of sponges and 
corals. In the Aleutian Islands, fishing activities can af- 
fect benthic habitats by causing damage and mortality 
to sponges and corals. A number of studies have shown 
that recovery times for sponges and corals damaged 
by bottom trawling or natural phenomena could be on 
the order of decades to centuries (Freese et al., 1999; 
Andrews et al., 2002; Rooper et al., 2011). Diagnosing 
the relationships between commercially important fish 
species and biogenic structures vulnerable to damage 
from human activity will be useful for management 
decisions to balance habitat protection and commercial 
fishing opportunities. 
Acknowledgments 
The authors thank the captains, fishermen, and sci- 
entific staff who spent many hours at sea conducting 
these surveys. We thank D. Somerton, W. Palsson, K. 
Mier, J. Orr, and the anonymous reviewers for their 
time and effort that greatly improved this manuscript. 
In addition, we are indebted to M. Martin, L. Britt, and 
R. Harrison for their insightful and often lively discus- 
sions that helped us maintain our perspective. 
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