140 
National Marine 
Fisheries Service 
NO AA 
Abstract— The reproductive potential 
of northern rockfish (Sebastes poly- 
spinis ) and light dusky rockfish {S. 
variabilis) in the Gulf of Alaska was 
examined by measuring the success of 
oocyte and embryo development. The 
potential annual fecundity, reproduc¬ 
tive failure rates, and relationships of 
these parameters to maternal size were 
examined. Both species have a season¬ 
ally synchronous reproductive cycle 
with parturition occurring in the late 
spring to early summer. Northern rock¬ 
fish had a mean relative fecundity of 
165.1 oocytes/g for specimens captured 
in December and 109.6 embryos/g for 
specimens captured in May. Light 
dusky rockfish had a mean relative 
fecundity of 152.1 oocytes/g for speci¬ 
mens collected in December and 108.1 
embryos/g for specimens captured in 
May. Reproductive failure was easiest 
to discern for the samples from fish 
collected in May, with partial and total 
failure primarily occurring because of 
lack of oocyte development or fertil¬ 
ization failure. Northern rockfish had 
a rate of total reproductive failure or 
skipped spawning of 16.3%, and light 
dusky rockfish had a total reproductive 
failure rate of 15.6%. As light dusky 
and northern rockfish grow larger 
throughout their lives, their relative 
fecundities increase and the likeli¬ 
hood of reproductive failure decreases. 
Fecundity values, failure rates, and 
maternal effects on the reproductive 
potential of these species can be used 
to inform future stock assessments. 
Manuscript submitted 5 July 2018. 
Manuscript accepted 27 June 2019. 
Fish. Bull. 117:140-150 (2019). 
Online publication date: 12 July 2019. 
doi: 10.7755/FB.117.3.2 
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. 
Fishery Bulletin 
&r established in 1881 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Reproductive potential of light dusky rockfish 
(Sebastes variabilis) and northern rockfish 
(5. polyspinis) in the Gulf of Alaska 
Christina L. Conrath 
Email address for contact author: christina.conrath@noaa.gov 
Kodiak Laboratory 
Resource Assessment and Conservation Engineering Division 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
301 Research Court 
Kodiak, Alaska 99615 
The northern rockfish (Sebastes 
polyspinis ) and light dusky rockfish 
( S. variabilis) are the second- and third- 
most commercially important rockfish 
species in Alaska waters, behind the 
Pacific ocean perch (S. alutus) (Hulson 
et al., 2015; Lunsford et al., 2016). Both 
species are captured predominately by 
bottom-trawl, catcher-processor fishing 
vessels or smaller shore-based trawlers 
operating out of Kodiak, Alaska (Clau¬ 
sen and Heifetz, 2002; Hulson et al., 
2015). The stock assessments of these 
species in the Gulf of Alaska use a sep¬ 
arable, age-structured model as the pri¬ 
mary assessment tool. Input parameters 
to the model include fishery-dependent 
data, such as catch, age, size, composi¬ 
tion, and maturity data, and fishery- 
independent data, including estimates 
of biomass and age and size composition 
based on biennial trawl surveys (Hulson 
et al., 2015; Lunsford et al., 2016). 
Northern rockfish range from waters 
of northern British Columbia and 
Alaska, across the North Pacific Ocean, 
to the eastern part of Kamchatka 
Peninsula and the northern Kuril 
Islands in Russia (Allen and Smith, 
1988). They are most abundant in 
Alaska waters from the central Gulf 
of Alaska to the western Aleutian 
Islands. Adult northern rockfish in the 
Gulf of Alaska are found in relatively 
shallow offshore banks of the outer 
continental shelf at depths of 75-150 m. 
They are the second-most abundant and 
commercially important rockfish in the 
Gulf of Alaska and the Aleutian Islands 
fisheries management areas (Clausen 
and Heifetz, 2002). Northern rockfish 
have supported a valuable domestic 
commercial fishery since 1990 in the 
Gulf of Alaska and were captured in for¬ 
eign and joint venture fisheries prior to 
this period (Hulson et al., 2015). 
Light dusky rockfish range from 
Hokkaido, Japan, through the Ber¬ 
ing Sea and the Aleutian Islands, to 
Johnstone Strait, British Columbia 
(Love et al., 2002). Light dusky rock¬ 
fish are commonly found at depths of 
100-200 m in the Gulf of Alaska, and 
the highest catch per unit of effort 
generally occurs at depths of 100-149 m. 
Light dusky rockfish are most com¬ 
monly associated with northern rock¬ 
fish, Pacific ocean perch, and harlequin 
rockfish (S. variegatus), and bycatch of 
light dusky rockfish is highest in hauls 
of vessels targeting northern rockfish 
and vice versa (Reuter, 1999). 
All species within the genus Sebastes 
mate using internal fertilization and 
give birth to planktonic larvae (Kendall 
and Lenarz, 1987). These species appear 
to be truly viviparous, meaning that 
the embryos receive sustenance from 
the mother in addition to yolk reserves 
during gestation (Boehlert et al., 1987). 
