234 
National Marine 
Fisheries Service 
NOAA 
Abstract— -Blackspotted rockfish 
(Sebastes melanostictus ) and rougheye 
rockfish (S. aleutianus ) are sympat- 
ric species found in the North Pacific 
Ocean. However, these species were not 
identified as separate taxa until the 
mid-2000s, and they remain difficult to 
differentiate in the field. These species 
are managed as a single mixed stock 
despite the fact that the North Pacific 
Fisheries Management Council rates 
them as Tier 3 species, meaning that 
an individual assessment including his¬ 
torical data is required for each. In this 
study, we developed a technique that 
distinguishes these species on the basis 
of otolith morphology and age, allow¬ 
ing both old and new collections to be 
identified to the correct species. Tissue 
samples and otoliths were collected 
from 1847 specimens during survey 
seasons in 2009 and 2013. Tissue sam¬ 
ples were identified genetically to spe¬ 
cies by using the Sma6 microsatellite 
locus. We used morphometries, weight, 
and age from 859 otoliths to develop a 
logistic regression model that identi¬ 
fied 97.3% of blackspotted rockfish and 
86.2% of rougheye rockfish. Otolith 
shape analysis distinguishes rougheye 
rockfish and blackspotted rockfish and 
can allow for more focused manage¬ 
ment of these species. 
Manuscript submitted 14 November 2018. 
Manuscript accepted 15 August 2019. 
Fish. Bull. 117:234-244 (2019). 
Online publication date: 30 August 2019. 
doi: 10.7755/FB.117.3.10 
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 
ft* established in 1881 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Using otolith morphometric analysis to improve 
species discrimination of blackspotted rockfish 
(Sebastes melanostictus ) and rougheye rockfish 
(£. aleutianus) 
Jeremy P. Harris (contact author) 1 
Charles Hutchinson 1 
Sharon Wildes 2 
Email address for contact author: jeremy.harris@noaa.gov 
1 Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
7600 Sand Point Way NE 
Seattle, Washington 98115-6349 
2 Auke Bay Laboratories 
Alaska Fisheries Science Center 
National Marine Fisheries Service, NOAA 
17109 Point Lena Loop Road 
Juneau, Alaska 99801 
The blackspotted rockfish (Sebastes 
melanostictus) and rougheye rockfish 
( S. aleutianus ) are 2 of the largest and 
longest-lived rockfish species found in 
the North Pacific Ocean.The distribution 
of blackspotted rockfish stretches along 
the western coasts of the United States 
and Canada from Northern California 
to the Gulf of Alaska and across the 
Aleutian Islands and North Pacific 
Ocean to as far as Japan. The rougheye 
rockfish ranges from California to the 
Aleutian Islands (Orr and Hawkins, 
2008). They are 2 of 72 rockfish species 
found in the North Pacific Ocean (Love 
et ah, 2002). Although not targeted, 
rougheye rockfish and blackspotted 
rockfish occur as incidental catches 
in several major fisheries in the Gulf 
of Alaska, Bering Sea, and Aleutian 
Islands. Their slow population growth 
and late maturation make them vul¬ 
nerable to overfishing (Ormseth and 
Spencer, 2011). These species are sym- 
patric throughout the waters of Alaska, 
the coasts of British Columbia, Canada, 
and the West Coast of the United States, 
and they have only subtle morpho¬ 
logical differences (Orr and Hawkins, 
2008). Difficulties in accurately iden¬ 
tifying these species have complicated 
research into their life history and 
ecology. Although both species are 
managed as a mixed stock at present, 
separation of the stock into individual 
species would be a major improvement 
in future assessments (Hicks et al., 
2014; Shotwell et al., 2017). 
Jordan and Evermann (1898) first 
described S. aleutianus, but it was 
not until 36 years later that Matsub- 
ara (1934) described a similar species, 
S. melanostictus. However, subsequent 
researchers reexamined the issue and 
found only 1 species with significant 
variation in body coloration (Barsukov, 
1970; Kanayama and Kitagawa, 1982). 
A series of recent projects has since 
noted a genetic split within the species 
S. aleutianus, first on the basis of pro¬ 
tein allozymes (Seeb, 1986; Hawkins 
et al., 2005) and subsequently by using 
mitochondrial DNA and microsatel¬ 
lites (Gharrett et al., 2005; Gharrett 
