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Fishery Bulletin 96(3), 1998 
sablefish were observed to move over 500 n mi from 
tagging to recovery, and more than 10% moved over 
1,000 n mi. In contrast fewer than 10% of west coast 
sablefish moved over 500 n mi. 
For the Gulf of Alaska, there is a strong proclivity 
for fish tagged in the southeast (areas 16-18) to move 
north and west and for fish tagged in the west (ar- 
eas 3-14) to move east and south (Tables 4 and 6). It 
is convenient to define movement north or west as a 
recovery from an area number less than the area of 
tagging, and movement east or south as a recovery 
from an area number greater than the area of tag- 
ging (Fig. 1). Several authors (Fujioka et al., 1988; 
Heifetz and Fujioka, 1991) point out that these 
directional movements are most pronounced for 
fish tagged at less then 57 cm in southeast Alaska, and 
for fish tagged at greater than 57 cm in the western 
Gulf of Alaska. The greater intensity of these size-se- 
lective migrations are supported by our data (Table 4). 
The patterns of migration can be illustrated visu- 
ally by considering maps of average movement where 
tag recoveries are aggregated by the area of tagging 
or the area of recovery. Figure 5 shows the average 
position of tagging (tail of arrow) for each of the 27 
areas for which sablefish were tagged (i.e. 23 areas) 
and the average position where subsequent recoveries 
occurred. Similarly, Figure 6 shows the average posi- 
tion of recoveries (head of arrow) in each area (i.e. 24 
areas) where more than 2 recoveries occurred and the 
average position of tagging (tail of arrow) for each ag- 
gregation of tags. 
For the Alaska population, Fig- 
ures 5 and 6 seem to show an ex- 
pansion and return about the cen- 
ter of sablefish abundance in the 
central Gulf of Alaska. By this we 
mean that fish tagged away from 
the center of the Gulf of Alaska 
tend to be recovered toward the 
center of the Gulf, and fish recov- 
ered away from the center of the 
Gulf tend to have originated to- 
ward the center of the Gulf. Such 
a pattern could represent random 
movement throughout the Alaska 
range, with concentration of tag- 
ging and recovery effort (Tables 3 
and 6) occurring in the central Gulf 
of Alaska. For the west coast popu- 
lation, the movement is more of a 
slight but steady northward shift 
whether the aggregation is by area 
of tagging or area of recovery. Such 
movement may be the result of mi- 
grations or may represent a biolog- 
ically static situation, one in which 
recoveries are influenced by increas- 
ing fishing pressure towards the 
north. 
As pointed out in the introduc- 
tion, sablefish inhabit a very broad 
bathymetry. In order to try to learn 
something of sablefish depth mi- 
grations, we tabulated depth at 
release for all tagged sablefish and 
depth at release versus depth at 
recovery for sablefish that were 
tagged and recovered (Table 7). 
Fish that were tagged in Alaska 
and recovered off the west coast, 
Alaska 
West coast 
Nautical miles traveled 
Figure 4 
Histogram and cumulative distribution function (cdf) of the distance traveled (n 
mi) for sablefish that were tagged and recovered. Distances are straight line 
distances that are minimums; actual distance traveled must have been greater. 
Histograms are binned in 50 n mi intervals, with the 0-50 n mi bin not plotted so 
that more detail could be seen. For Alaska the 0-50 n mi bin count was 2744, for 
the west coast the 0-50 n mi bin count was 3075. 
