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Fishery Bulletin 115(2) 
10 
E 
8 - 
6 - 
O 
O) 
“cO 
E 4 4 
-Males 
- Females 
30 
40 
50 
60 
—T” 
70 
—I 
80 
Initial fork length (cm) 
Figure 8 
Estimated annual growth for male (dashed lines) and female 
(solid lines) sablefish [Anoplopoina fimbria) that resided in 3 
depth zones (Zl=141-302 m, Z2=327-649 m, Z3=1112-1225 
m) when they were initially captured off Newport, Oregon, 
during 1996-1998 (tagging set 1) or 2003-2004 (tagging set 
2). Growth estimates were derived from the full nonlinear re¬ 
gression model (Table 4) with time at large set at 365 days, 
depth at both tagging and recapture set at the mid-depth 
within each zone, and recapture gear set at fixed gear. For 
each depth zone, the range of fish sizes was restricted to that 
observed for recaptured fish with known sex. Fish from both 
tagging sets are combined. 
a refuge in which females can survive and reproduce 
over many years, capitalizing on periodic environmen¬ 
tal regimes favorable to larval survival and production 
of strong year classes. 
Implications of spatial movement patterns 
In contrast with the northern stock of sablefish, long 
distance movements were much less evident in Oregon 
fish and consistent with prior studies of the southern 
stock (Dark, 1983; Wespestad et ah, 1983; Fujioka et 
ah, 1988; Kimura et al., 1998). After 13 (2003-2004 
tagging) to 20 (1996-1998 tagging) possible years at 
large, only 9% of all recaptured fish were taken from 
locations >200 km from the tagging sites. Beamish and 
McFarlane (1988) found similar proportions of dispers¬ 
ers for fish tagged off Vancouver Island (fish that are 
likely to be part of the southern stock), but increas¬ 
ing dispersal for fish tagged off Haida Gwaii, Queen 
Charlotte Islands (fish that are likely to be part of the 
northern stock). The number of fish that dispersed from 
Oregon waters may have been underestimated if tag 
reporting differed by region. However, the nearly con¬ 
tinuous geographic occurrence of recaptured dispersers 
across Alaska slope habitats (Fig. 7) and the high esti¬ 
mated levels of reporting, particularly in more recent 
years (Hanselman et al., 2015), suggest that Alaska 
fishermen are very cooperative in returning tags. 
Lower fishing effort and lower reporting rates in 
California waters may have resulted in reduced 
recovery of fish that moved south. For the years 
of possible recaptures in this study (1997-2016), 
sablefish landings in the California commercial 
fishery were on average 78% of the annual land¬ 
ings in Oregon (Pacific Fisheries Information 
Network, website). Because emigration rates ap¬ 
peared to increase over time and tag loss rates 
are cumulative, it is possible that some dispersers 
were not recognized because of tag loss. Overall, 
however, there was a clear tendency of Oregon 
fish to remain in Oregon waters, particularly for 
larger fish and fish residing in deeper habitats. 
The fish that did disperse primarily traveled 
north and west, reaching almost to the farthest 
extent of U.S. waters in the western Aleutian Is¬ 
lands. Interestingly, dispersers from British Co¬ 
lumbia waters also traveled primarily north into 
Alaska waters (Beamish and McFarlane, 1988). 
Although McFarlane and Saunders (1997) report¬ 
ed a number of recaptured fish in the Bering Sea 
for fish tagged in British Columbia waters, they 
did not report whether those fish were initially 
tagged off Haida Gwaii or Vancouver Island. Of 
the fish captured in Oregon waters in this study, 
none were recaptured in the Bering Sea. 
There was an increased likelihood of migration 
with time at large, as with the results of Beamish 
and McFarlane (1988), but a few fish moved up to 
2000 km within the first year after tagging, sug¬ 
gesting a high capacity and motivation for migra¬ 
tion. The underlying reason for why some fish make ex¬ 
tensive migrations, whereas others remain in the same 
general location for many years, is elusive. Morita et 
al. (2012) concluded that fish dispersing away from 
Bering Sea and Gulf of Alaska locations were mostly 
females that gained a growth advantage by migrating. 
We did not find a difference in growth between dis¬ 
persing and resident females, but we did find a growth 
advantage for dispersing males. A propensity for dis¬ 
persal may be related to individual differences in be¬ 
havioral syndromes (Conrad et al., 2011). For example, 
intrapopulation differences in dispersal distances were 
found to be correlated with behavioral traits by Fraser 
et al. (2001) and Cote et al. (2010). Although dispersers 
are likely lost to their natal stocks, they maintain the 
metapopulation integrity of the species, and an exten¬ 
sive body of theory dating back to Hamilton and May 
(1977) argues for the fitness benefits of having some 
portion of a population disperse to different locations. 
This life history attribute of sablefish has clearly been 
successful considering their current geographic range. 
Growth 
Growth rates of recaptured fish generally matched pre¬ 
viously observed patterns, with females growing faster 
than males, small fish growing faster than large fish. 
