National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
é established in 1881 =< 
Spencer F. Baird & : 
First U.S. Commissioner oy 
of Fisheries and founder ve ¥ 
of Fishery Bulletin 
Abstract—Understanding spawning 
behavior of commercial fish populations 
provides a basis for making manage- 
ment decisions related to these stocks. 
Archival tags can be used to define 
spawning behavior when depth-specific 
movements are involved. Spawning 
behavior of Greenland halibut (Rein- 
hardtius hippoglossoides) in the eastern 
Bering Sea and the Aleutian Islands 
was inferred from archival tag data. The 
predominant period of identified spawn- 
ing activity, based on abrupt vertical 
rises of females, occurred in January 
and February, and females reached 
apexes in their upward movement 
(spawning rises) at depths of approxi- 
mately 200-350 m below the surface, 
indicating that the release of eggs 
could occur at depths shallower than 
previously assumed. Females had a 
single spawning rise annually, a result 
supporting the notion that this species 
is a total (single-batch) spawner. Male 
Greenland halibut exhibited spawning 
behavior, rises to shallower depths one 
or more times, for an average of 20 d. 
For large female Greenland halibut 
(>80 cm in fork length), spawning rises 
occurred in consecutive years, indicat- 
ing that, despite oocyte development 
taking more than 1 year, spawning 
occurs annually. Inferring spawning 
behavior by using data collected with 
archival tags can aid in understanding 
the maturity of Greenland halibut. 
Manuscript submitted 6 July 2021. 
Manuscript accepted 7 February 2022. 
Fish. Bull. 120:55-67 (2022). 
Online publication date: 16 February 2022. 
doi: 10.7755/FB.120.1.5 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Characterizing spawning behavior of Greenland 
halibut (Reinhardtius hippoglossoides) in the 
eastern Bering Sea and Aleutian Islands 
Kevin A. Siwicke (contact author)! 
Andrew C. Seitz” 
Cara J. Rodgveller' 
Katy B. Echave' 
Email address for contact author: kevin.siwicke@noaa.gov 
" Auke Bay Laboratories 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
17109 Point Lena Loop Road 
Juneau, Alaska 99801 
? Department of Fisheries 
College of Fisheries and Ocean Sciences 
University of Alaska Fairbanks 
P.O. Box 757220 
Fairbanks, Alaska 99775 
Archival tags can be attached to fish 
to collect environmental data, usually 
temperature and pressure (converted 
to depth) at a minimum, and individ- 
ual events characterized by changes 
in such environmental conditions can 
be identified with data from recovered 
tags (Wilmers et al., 2015). The battery 
life of archival tags (also known as data 
storage tags) allows data to be recorded 
for up to several years, and the data 
therefore can be used to assess depth- 
or temperature-specific behavior, such 
as spawning, that occurs over annual 
cycles. Knowledge about reproductive 
traits (fecundity, maturity, and timing 
or location of spawning) of a fish stock 
is important for estimating the stock’s 
reproductive potential (Murawski 
et al., 2001; Wright and Trippel, 2009; 
Cooper et al., 2013). Population esti- 
mates, mean weights by age, and 
maturity ogives (often derived from 
histological, macroscopic, or laboratory- 
based studies) are used for estimating 
stock reproductive potential in the form 
of spawning stock biomass (Marshall, 
2009), although this measure is suscep- 
tible to size- and age-dependent effects 
(Trippel, 1999; Cooper et al., 20183). 
Misinterpretation of a reproductive 
trait can therefore lead to incorrect or 
biased estimation of stock reproductive 
potential. 
Data from archival tags have been 
used to determine spawning behavior, 
allowing the unobservable to be “seen” 
(Seitz et al., 2005; Loher and Seitz, 
2008; Murphy et al., 2017; Le Bris 
et al., 2018); therefore, this method can 
provide deductions of spawning behavy- 
ior. In archival tag records, abrupt 
movements of fish to shallower depths 
are identified as spawning rises. These 
ascents are thought to be analogous to 
spawning behavior of shallow-water 
flatfish species that has been directly 
observed when they swim off the bottom 
to spawn (e.g., Manabe and Shinomiya, 
2001). The rhythmic behavior of batch 
spawning, which refers to the behavior 
of species that spawn a batch of eggs 
