178 
Fishery Bulletin 99(1 ) 
equate spawner biomass in the hot spots. Adult shortraker 
and rougheye rockfish are reported to live on habitats con- 
taining steep slopes (>20°) and numerous boulders (Krieg- 
er and Ito, 1999). If these habitats are degraded by fishing 
activity and if stocks in these areas become reduced, then 
Gulf-wide stock stability might be at risk. By establishing 
harvest refugia, essential fish habitat for adult shortraker 
and rougheye rockfish can be conserved. 
Harvest refugia can also be used to ensure an appro- 
priate proportion of shortraker and rougheye rockfish in 
catches. Because these two species are managed as one 
subgroup of the slope rockfish assemblage, the fishing sea- 
son is subject to the attainment of the combined level of 
two TACs. This management strategy has led to a discrep- 
ancy between the intended ABCs and the actual catches 
of the two species. Trawl survey estimates of exploitable 
biomass and recommended ABC show species proportions 
(shortraker to rougheye rockfish) of 3:7 and 4:6, respec- 
tively; whereas, commercial catches show a 6:4 ratio. Obvi- 
ously, this reversed proportion of exploitation between the 
two species will incur a faster decrease of the shortraker 
stock than is expected. 
Separate management of these two species may be ap- 
propriate but because of their overlapping habitat, there 
could still be excessive waste through discards. Out of all 
the trawl hauls with either shortraker or rougheye rock- 
fish sampled by domestic observers during 1987-97, about 
50% of the total hauls contained both species. By weight, 
such hauls containing both species accounted for about 
72% of the total catch of shortraker and 78% of the total 
catch of rougheye rockfish. This finding suggests consid- 
erable habitat overlap, even though survey data indicate 
that individual species have somewhat different bathy- 
metric and habitat preferences (Soh, 1998; Ito, 1999). Nev- 
ertheless, refuge networks can probably be designed to 
take advantage of differences in the habitat preference of 
shortraker and rougheye rockfish to achieve the desired 
proportions of these species in commercial catches. 
In summary, refuge management can potentially be 
used to solve a number of management problems. By se- 
lecting a moderate size, number, and spatial distribution 
for harvest refugia, the apparent short-term costs or risks 
can be reduced as much as possible. A solution to the prob- 
lems of bycatch waste, protection from stock depletion, 
preservation of essential fish habitat, preservation of the 
existing spatial distribution of substocks, and prevention 
of serial depletion of substocks can potentially be achieved 
through refuge management. 
Uncertainties in the results of our study resulted from 
the fact that populations may behave and adapt differ- 
ently under different environments with different fishing 
pressures. Furthermore, there is an uncertainty regarding 
the sustainability of recruitment owing to a lack of knowl- 
edge of larval and juvenile stages and the impact of an- 
nual or interdecadal variability in oceanic conditions. 
For practical application of a refuge system, additional 
research is still needed. Optimum shape, location, and 
size of refugia can best be achieved through adaptive 
management, by using monitoring and observations from 
existing refugia to redesign the network. Potential costs 
or risks, or both, are also expected. The fishing industry 
needs to be involved in gaining a full understanding of 
any loss incurred by the displacement of fishing effort 
from specified areas. Harvest refugia may prove to be un- 
successful if illegal fishing cannot be controlled. Investi- 
gation as to how to prevent such illegal behavior and to 
promote a practical and effective monitoring system still 
needs to be undertaken. 
Acknowledgments 
This paper is based on a dissertation by S. K. Soh, in 
partial fulfillment of the requirements of a Ph.D. at the 
University of Washington. The research was supported by 
grants from Washington Sea Grant and the Joint Institute 
for the Study of the Atmosphere and Ocean ( JISAO) under 
NOAA cooperative agreement no. NA67RJ0155, contribu- 
tion no. 668. 
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