170 
Fishery Bulletin 108(2) 
D q Cedar 
Trachurus japonicus 
: Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr 
1 2005 2006 2007 2008 
2004 2005 
onr\7 200ft 
Figure 5 
Monthly maximum (rectangles), minimum (triangles), and average (circles) body length of black 
rockfish ( Sebastes inermis) found associated with (A) cedar, (B) broadleaf, and (C) PVC artificial 
reefs, and those of jack mackerel (Trachurus japonicus) found associated with (D) cedar, (E) 
broadleaf, and (F) PVC artificial reefs. 
The cedar ARs hosted fish assemblages within the 
first two to three months of deployment. These recruits 
may have come from the adjacent coastal habitat or 
from offshore. Rapid colonization of ARs was also re- 
ported by Bohnsack et al. (1994) who observed that fish 
species, number of individuals, and biomass reached 
peak levels within two months of deploying concrete 
ARs in Florida. 
There was only one species, Acentrogobius pflaumii, 
that decreased in abundance in transect 1 after the de- 
ployment of ARs. This goby is the fifth most frequently 
observed fish in the adjacent natural reef (Masuda, 
2008), but relatively few were associated with ARs. 
Therefore it is unlikely that the attraction to ARs in- 
duced the decline in the population along transect 1. 
The relative stability of fish species and abundance 
observed among the three transects supports the con- 
cept of an inshore migration and is in agreement with 
data of Connell (1997) who found that the number of 
recruits did not differ between ARs located close to and 
far from a natural reef. Sanchez-Jerez and Ramos-Espla 
(2000) also confirmed that antitrawling reefs deployed 
in a seagrass habitat had little effect on seagrass fish 
assemblages in the surrounding area. We therefore 
conclude that the three types of ARs deployed in this 
study provided additional habitat for young fish without 
any significant depletion of numbers in the existing fish 
community. 
The average number of fish in the adjacent habitat 
was 171 individuals per 400 m 2 , or 0.43 individuals per 
m 2 . Fish density on the cedar reef was thus 10 times 
larger than that of the adjacent area. Bohnsack et al. 
(1991) reviewed experimental studies, where fish densi- 
ties at natural reefs were compared with those at arti- 
ficial reefs, and found that in some cases the latter can 
host densities of more than 10 times that of the former. 
Therefore, our results of fish density on cedar ARs are 
within the range of previously reported ARs. 
