5334:2004 
3880:2009 
Day of year 
Fishery Bulletin 120(1) 
5334:2004 
[\ 
-200-100 0 100 200 
Time (min) 
Figure 6 
Putative spawning rises, meaning abrupt movements of fish to shallower depths, identified in archival tag data for 2 Greenland 
halibut (Reinhardtius hippoglossoides) of undetermined sex tagged in 2004 (tag no. 3880) in the eastern Bering Sea and in 2009 
(tag no. 5334) in the Aleutian Islands. (A) Tag-recorded depths of fish are provided for the first 50 d of the year (grey circles), 
with black circles indicating depths during spawning rises. Panel titles are the tag number and the year data were recorded 
(e.g., 5334:2004 means data recorded in 2004 for the fish implanted with tag no. 5334). (B) Close-ups of spawning rises that 
reached a depth <400 m are provided, with the time for the minimum depth recorded set to 0 min to align all the rises. In each 
B panel, horizontal dashed lines at depths of 200 and 350 m are shown as references. 
that males have a prolonged spawning state during which 
their vertical activity increases. The single spawning rise 
means that females spawn once in a year and do not 
hydrate multiple batches of eggs, and this finding supports 
the results of recent studies that indicate that 2 cohorts of 
vitellogenic oocytes are not spawned in the same season 
(Kennedy et al., 2011). In a study of gonad development of 
Greenland halibut in the Barents and Norwegian Seas, 
males spawned over an extended period and females had a 
bimodal split between prespawning and postspawning 
(Albert et al.”). The results of that study are consistent 
with our finding that males actively spawn for a protracted 
period and females actively spawn for a very narrow 
period. Sex-specific differences that have been identified 
for Pacific and Atlantic halibut are nearly identical to 
observations for Greenland halibut, with males having 
more sporadic and protracted spawning behavior relative 
to the abrupt rises of females (Loher and Seitz, 2008; 
Murphy et al., 2017). The increase in vertical movements 
of male Greenland halibut during this presumed spawning 
time identified in these studies and in our study contrasts 
with reported spawning activity of Atlantic cod (Gadus 
morhua): a tide is evident in depth profiles of males that 
sit in lekking arenas waiting for females to spawn (e.g., 
Meager et al., 2010). 
These differences could also be used to infer sex for 
tagged Greenland halibut that did not have their sex deter- 
mined but were at liberty through the winter. For exam- 
ple, one fish of undetermined sex had spawning activity 
with the expected prolonged, regular periodicity of typical 
? Albert, O. T., E. M. Nilssen, A. Stene, A. C. Gundersen, and 
K. H. Nedreaas. 1998. Spawning of the Barents Sea/Norwegian 
Sea Greenland halibut (Reinhardtius hippoglossoides). ICES 
CM Doc. 1998/0:22, 19 p. [Available from website.] 
male behavior, and another fish that did not have its sex 
determined had the isolated spawning rise of a female 
(Fig. 6). Previous research in which archival tags were used 
on Greenland halibut (e.g., Peklova et al., 2012) should 
be reexamined for evidence of these behaviors and their 
annual consistency, given that this study was focused on 
the BSAI region and that our results cannot be applied to 
all populations across the range of this species. Boje et al. 
(2014) made at least one reference to a Greenland halibut 
suddenly ascending from a depth of approximately 800 m 
up to a depth of 450 m within 1 h during November, a move- 
ment that appears similar to the presumed spawning rises 
we have described. Identification of the presence or absence 
of this singular annual spawning rise for female Greenland 
halibut in other regions would be informative. 
The likelihood of a female Greenland halibut exhibiting 
spawning behavior may be delineated by length. The 2 
females that did not have spawning rises were the smallest 
females recovered, at 68 and 71 cm FL, and the 3 females 
that did exhibit this spawning behavior were larger than 
83 cm FL. We hypothesize that these smaller fish did not 
have spawning rises because they were not yet mature. 
It is possible that they did spawn without an obvious 
ascent like the larger fish, and additional research, such as 
deployment of the SeaTag-SP (Desert Star Systems, LLC, 
Monterey Bay, CA), which transmits a location and archi- 
val data when spawning occurs, could help clarify whether 
such small females are spawning with or without rises. 
Alternatively, a lack of spawning rises detected in archival 
tag data for the small Greenland halibut may not be associ- 
ated with size and could be indicative of skipped spawning. 
Skipped spawning, when a mature fish does not spawn, 
occurs in many taxa, such as the Pacific halibut (Loher and 
Seitz, 2008), sablefish (Anoplopoma fimbria) (Rodgveller 
et al., 2016), and Sebastes species (Conrath, 2017). Skipped 
