60 
Fishery Bulletin 120(1) 
Table 1 
Summary of data on putative spawning of Greenland halibut (Reinhardtius hippoglossoides) tagged in 2003, 2005, 
2008, or 2011 and recaptured in the eastern Bering Sea and Aleutian Islands. Data collected include the tag num- 
ber, year of spawning observation, sex of fish, day of the year spawning initiated (D;), depth preceding minimum 
depth during spawning (Z;), shallowest depth during spawning (Z,,,,,), time at shallowest depth during spawning 
(Time,,in), depth following minimum depth during spawning (Z,), day of year spawning ended (D,), elapsed time 
spawning occurred (Dur.), maximum spawning ascent rate (Asc,,,,), and maximum spawning descent rate (Des,,,,)- 
Sex is presented for females (F), males (M), and those fish for which sex is undetermined (U), with a subscript indi- 
cating which sex it is likely to be on the basis of the archival tag data. Additional information on each tagged fish 
can be found in Supplementary Table (online only). 
m) 
WY 
o 
ta 
Z; (m) Z 
min ( 
Tag no. Year 
Time,in Zp (m) 
ASCmax 
(m/min) 
DeSmax 
Dur. (d) (m/min) 
5282 
5282 
5282 
4551 
4551 
383 
383 
383 
4122 
4126 
5319 
5364 
5385 
5385 
5385 
3883 
5334 
3880 
2004 
2005 
2006 
2006 
2007 
2012 
2013 
2014 
2004 
2004 
2004 
2004 
2004 
2005 
2006 
2010 
2004 
2009 
SSseseeeeSe0e yyy 
S 
Kd 
859 
972 
886 
716 
917 
619 
526 
527 
824 
1098 
1435 
1489+ 
689 
750 
664 
956 
347 
420 
343 
240 
254 
229 
240 
230 
234 
328 
239 
360 
221 
268 
508 
253 
266 
0100 
0800 
1115 
0132 
0452 
2220 
1435 
1125 
0345 
0430 
0300 
2130 
0445 
0245 
2300 
1716 
0000 
1608 
777 
895 
919 
716 
979 
617 
482 
591 
820 
1243 
1438+ 
1489+ 
665 
708 
670 
968 
0.08 
0.10 
0.07 
0.05 
0.08 
0.04 
0.02 
0.03 
41.43 
32.90 
27.48 
37.82 
16.75 
23.73 
0.18 
0.07 
13.6 
19.7 
17.0 
19.8 
18.9 
31.0 
29.5 
25.2 
25.6 
16.4 
23.3 
20.4 
24.5 
28.0 
26.5 
10.5 
20.6 
15.7 
17.9 
20.1 
11.9 
11.9 
14.3 
11.7 
20.3 
S 
ry 
8 January (Fig. 5). Another male, released and recaptured 
in the Aleutian Islands (tag no. 3883; Fig. 1), was at liberty 
for 2 winters, with tag data indicating that no spawning 
behavior occurred in the first winter and that a single 
spawning rise occurred in the second winter on 6 January 
(Table 1, Fig. 5). The shallowest recorded depths for males 
during spawning rises ranged from 221 to 508 m (Table 1). 
No effort was made to better estimate apexes when the 
sampling interval was greater than 1 min because males 
often had more staggered ascents and descents and lin- 
gered at shallow depths (<500 m), and as a result, the 
apexes of their ascents were not easily interpolated with 
linear methods. Temperature at the apexes ranged from 
3.6°C to 4.3°C. Time of day varied for spawning rises 
(Table 1), and individuals had varying patterns in fre- 
quency and duration of their ascents (Fig. 5). 
Fish of undetermined sex 
For 2 fish with usable data, sex could not be determined at 
recapture, but spawning behavior was identified for both. 
One of these fish (tag no. 3880) was released and recaptured 
in the Aleutian Islands and exhibited behavior consistent 
with a singular spawning rise of a female; this distinction 
is not definitive because males sometimes had only a single 
ascent evident in their tag data. The release and recapture 
sizes of this fish were recorded as 94 cm FL, and sexually 
dimorphic size differences indicate that this fish is likely a 
female because females typically reach greater sizes than 
males (Bryan et al., 2018). The singular spawning rise of 
this fish occurred on 11 January, beginning at a depth of 
1520 m and reaching a minimum depth of 310 m, before 
returning to a depth of 1361 m (Table 1, Fig. 6). The second 
fish (tag no. 5334) had a size of 69 cm FL recorded at release 
(no FL was recorded at recapture). This fish exhibited 
behavior with repetitive spawning rises between 2 January 
and 1 February (Table 1, Fig. 6), reaching a minimum depth 
of 266 m during this time. This spawning behavior was sim- 
ilar to that of known males in this study. 
Discussion 
Field-based tagging research on Greenland halibut can be 
used to infer previously unobserved reproductive behavior 
and is an important complement to lab-based research. 
The research of this study provides information for identi- 
fication of spawning rises of Greenland halibut. Further, 
results of this work indicate distinct spawning behaviors 
for each sex: females have a single spawning rise, and 
males often make repetitive ascents over a protracted 
period. Findings from analysis of archival tag data 
