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Table 2 
Estimates of bocaccio ( Sebastes paucispinis ) biomass with the swept-area method and based on Department of Fisheries and 
Oceans (DFO) groundfish surveys in each region in the years 2003-07. Percentage of coast-wide biomass refers to the fraction 
of coast-wide swept-area biomass (in regions 1-4, 8) that is on average found inside each region and is used in computing survey 
catchability. “SE ln(6io)” is the standard error for the mean of the natural logarithm of swept-area estimates of stock biomass 
in each region, with the mean determined from swept-area estimates in different years. “%Trawlable” is the estimate of the 
percentage of the region that was found to be trawlable based on random sampling of locations in each region for trawling and 
large sample sizes (>300 sites in each region). GFish=groundfish; WCVI=west coast of Vancouver Island; QCS = Queen Char- 
lotte Sound; HS = Hecate Strait. WCHG=west coast of Haida Gwaii. The total is obtained only from the DFO groundfish survey 
because the other surveys are contained within it. 
Survey number 
and region 
Biomass 
(kg) 1 
Percentage of 
coast-wide biomass 
Years 
of data 
SE 
ln(bio) 
% 
Trawable 
1 WCVI Gfish 
375,207 
50 
2004, 2006 
0.0540 
71.6 
2 QCS Gfish 
247,966 
33 
2003-05, 2007 
0.2950 
76.5 
3 HS Gfish 
35,340 
5 
2005, 2007 
0.2670 
78.3 
4 WCHG Gfish 
11,255 
2 
2006, 2007 
0.0507 
87.2 
5 WCVI shrimp 
20,787 
3 
2004, 2006 
0.0262 
100.0 
6 QCS shrimp 
27,767 
4 
2003-05 
2.1010 
100.0 
7 U.S. triennial Gfish 
180,599 
24 
2004, 2006 
1.8590 
82.0 
8 Unsurveyed 
76,664 
10 
2003-07 
0.2020 
0.0 
Total 
746,432 
1 Computed from the product of the average density from the trawlable area and the total area of each survey area. 
erence survey data set. Note that the regions covered 
by both shrimp surveys and the U.S. triennial survey 
lay within areas covered by the reference groundfish 
survey. For example, the biomass available in the WCVI 
shrimp trawl survey was based on the density observed 
in the tows conducted during the WCVI groundfish sur- 
vey, within the area covered by the shrimp survey. 
The fraction of total stock biomass, S s in a given area 
s, can be obtained by 
g It ,s(fT’S +a ( 1 ~fT,s)) (g) 
s 11 area s 
^ Itj [ frj + a {l- f r,j )) 
7=1 
where n areas = number of regions for the reference survey 
plus 1 to account for the coastal habitat 
for the species that is outside of the sur- 
veyed area. 
For the each region in the survey q prior model, I Ts can 
be considered a lognormal random variable; 
I T s ~ lognormal (hi ( 7™^), S.E s 2 ). (7) 
The cross-year median for the lognormal density func- 
tion, I™? , in Equation 7 can be computed from the 
empirical mean swept-area biomass estimate (I^ W S A ) in 
each area s and the standard error (SE): 
I™* = * exp< -SE 2 / 2), ( 8a) 
where 
tSw.A. 
1 T,s 
n yr,s 
X rSw.A 
y 7\s,y 
y = 1 
(8b) 
se‘: = 
X(l"(7?V)-ln('S' 4 )) ;and 
(8c) 
y = i 
(8d) 
where n - number of years in which a swept area 
biomass estimate is available for a given 
survey in the reference year set. 
The reference swept-area estimate for unsurveyed 
regions was obtained from stratified estimates of species 
density from trawled areas and the estimated habitat 
area outside of surveyed areas. Because the average 
catch per tow is based on tows over trawlable bottom, 
the swept-area estimate was adjusted to account for the 
estimate of the fraction of trawlable area in the survey 
area and the average relative difference in bocaccio 
density between trawlable and untrawlable bocaccio 
habitat (see Eq. 3). 
