Laman et al.: Correlating environmental and biogenic factors with abundance and distribution of Sebastes alutus in Alaska 
271 
(Spencer and Ianelli 1 ). In addition to the commercially 
harvested species that are one focus of our groundfish 
surveys, we collect a large amount of biological and 
physical data that characterize the habitat where these 
animals are found. 
Previous studies have related the distribution and 
abundance patterns of Pacific ocean perch to physi- 
cal and biological oceanographic processes in Alaska 
waters. Logerwell et al. (2005) examined geographic 
patterns of demersal ichthyofauna in the Aleutian Is- 
lands and found that smaller Pacific ocean perch (<25 
cm, Reuter 2 ) inhabited shallower water (<150 m) than 
that inhabited by larger individuals, and they further 
suggested that large catches (>100 kg/ha) could be af- 
filiated with zones of increased productivity and prey 
availability. Other researchers have confirmed that ju- 
venile and adult Pacific ocean perch occur over similar 
temperature ranges but present different depth distri- 
butions ( i.e. , adults inhabit >200 m waters) (Carlson 
and Haight, 1976; Rooper, 2008). 
Epibenthic invertebrates, such as sponges, corals, 
and bryozoans, are common in the Aleutian Islands 
(Malecha et al., 2005), where they are collected regu- 
larly as part of the AFSC RACE Division bottom trawl 
surveys (Heifetz et al., 2005). Their extent and diver- 
sity also have been noted from submersible and un- 
derwater camera studies of the region (Rooper et al., 
2007; Stone et al., 2011). Despite their apparent ubiq- 
uity in the Aleutian Islands, we presume that these 
attached sessile invertebrates are patchily distributed 
in the trawlable areas where RACE bottom trawl sur- 
veys are conducted. Mounting evidence indicates that 
the presence of sponges and corals enhances structural 
heterogeneity in otherwise low-relief environments and 
can lead to increases in biodiversity and abundance of 
associated animals (e.g., Tissot et al., 2006; Beazley et 
al., 2013; Knudby et al., 2013). The morphological fea- 
tures of these biogenic structures may also serve as re- 
fugia for different life stages of commercially harvest- 
ed species of Sebastes (Freese and Wing, 2003; Rooper 
and Boldt, 2005; Baillon et al., 2012) and Atka mack- 
erel ( Pleurogrammus monopterygius) (Rand and Lowe, 
2011) in Alaska waters. 
Previous studies have also shown putative asso- 
ciations of rockfishes with sponge, coral, and bryozo- 
an assemblages across a wide range of physical and 
oceanographic conditions (Love et al., 1991; Rooper and 
Martin, 2012). Other studies have shown that rock- 
fishes in low-relief, trawlable habitats (e.g., sand or 
gravel bottom with few boulders or obstructions) tend 
1 Spencer, P. D., and J. N. Ianelli. 2010. Assessment of Pacif- 
ic ocean perch in the Bering Sea/Aleutian Islands. In Stock 
Assessment and Fishery Evaluation Report for the Ground- 
fish Resources of the Bering Sea/Aleutian Islands Regions, p. 
1033-1083. [Available from North Pacific Fishery Manage- 
ment Council, 605 West 4th Ave., Suite 306, Anchorage, AK 
99510.] 
2 Reuter, R. 2015. Personal commun. Alaska Fish. Sci. 
Cent., Natl. Mar. Fish. Serv., 7600 Sand Point Way NE, 
Seattle, WA 98115. 
to concentrate near the few boulders or rocky outcrops 
with attached epibenthic invertebrate communities 
(e.g., Freese and Wing, 2003; Du Preez and Tunnicliffe, 
2011). The Pacific ocean perch has been the focus of 
several previous studies in Alaska, and there is strong 
evidence that postsettlement juveniles and adults of 
Pacific ocean perch are found associated with sponges 
and corals (Krieger, 1993; Brodeur, 2001; Rooper and 
Boldt, 2005; Rooper et al., 2007). These studies have 
not distinguished species of sponges, corals, or bryo- 
zoans because of the difficulty in providing consis- 
tent identifications. Our study attempts to determine 
whether the presence or absence of biogenic structures 
across the broad spectrum of environmental conditions 
under which they occur affects Pacific ocean perch dis- 
tribution and abundance. 
Consistent field identification of sponges to specific 
or even generic levels of classification is difficult with 
the macroscopic techniques available in the field. Add- 
ing to the confusion, sponge morphological features, 
even within a single species, can vary dramatically 
with environmental conditions, such as current flow 
and sedimentation rate (Dayton et al., 1974; Bell and 
Barnes, 2001; Stone et al., 2011), and sponges quickly 
adapt their morphology to their environment (Palum- 
bi, 1984). Given these challenges, categorizing sponges 
into groups based on their gross morphology is an at- 
tractive alternative. The approach of lumping sponges 
into groups based on body form has the advantage of 
eliminating confusion caused by changing and differen- 
tially applied systematics and gives us an intuitive link 
to EFH. In this study, we consider sponge morphology 
from a functional perspective (the “fish-eye view”) of 
the structure it provides in the habitat. An added ben- 
efit of grouping the sponges by this functional morphol- 
ogy is to foster comparability of sponge assemblages 
among survey years by downplaying the differences in 
identification attributable to differing levels of exper- 
tise among the field biologists. 
Sponges and corals are vulnerable to removal or 
damage by fishing gear (Engel and Kvitek, 1998; Freese 
et al., 1999; Freese, 2001; Wassenberg et al., 2002; 
Stone et al., 2011). In addition, these sessile inverte- 
brates are long lived and have limited larval dispersal 
and reproductive potential (Andrews et al., 2002). As 
a result, a disturbance resulting in 67% mortality of 
sponges or corals would require 20-34 years for these 
organisms to recover 80% of their predisturbance bio- 
mass (Rooper et al., 2011). Their ecological importance, 
their vulnerability to damage or removal due to human 
activities, and their prolonged postdisturbance recov- 
ery times have led to the designation of some areas 
of notable coral and sponge diversity in the Aleutian 
Islands as “habitat areas of particular concern” under 
the Magnuson-Stevens Act and to their subsequent clo- 
sure to fishing (Hourigan, 2009). Gaining greater un- 
derstanding of the role that biogenic structures play 
in the distribution and abundance patterns of Pacific 
ocean perch in the broader context of the oceanograph- 
ic habitats where they co-occur could prove valuable to 
