National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
e established in 1881 «<= 
Spencer F. Baird & 43 
First U.S. Commissioner } 
of Fisheries and founder ate 
of Fishery Bulletin 
Abstract—A total of 69 specimens of 
Fedorov’s lumpsucker (Humicrotremus 
fedorovi) caught on the continental 
shelf and slope of Simushir Island in 
the northwest Pacific Ocean were dis- 
sected and studied for stomach con- 
tents. The Fedorov’s lumpsucker was 
found to feed mainly on the young of 
fish species, including the walleye pol- 
lock (Gadus chalcogrammus), northern 
lampfish (Stenobrachius leucopsarus), 
and northern smoothtongue (Leuro- 
glossus schmidti), crustaceans, such as 
Themisto pacifica, Primno macropa, 
calanoids, gammarids, mysids, and 
caprellids, and squid. Histological analy- 
ses of ovaries revealed iteroparity, deter- 
minate fecundity, group-synchronous 
ovarian development, and total spawn- 
ing. Testes were of an unrestricted lobu- 
lar type. Chorion and thick zona radiata 
of Fedorov’s lumpsucker correspond to 
the condition of eggs in specimens of 
other fish species that release demer- 
sal eggs. Absolute fecundity values 
of Fedorov’s lumpsucker in our study 
were significantly less than those that 
have been reported for other species 
of Cyclopteridae. The results of this 
study provide the first data on this little 
known species of this family. 
Manuscript submitted 12 August 2020. 
Manuscript accepted 11 March 2021. 
Fish. Bull. 119:33—40 (2021). 
Online publication date: 8 April 2021. 
doi: 10.7755/FB.119.1.5 
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. 
The first data on the diet and reproduction of 
Fedorov’s lumpsucker (Eumicrotremus fedorovi) 
llya Gordeev (contact author)" 
Kristina Zhukova' 
Svetlana Frenkel’ 
Email address for contact author: gordeev_ilya@bk.ru 
" Russian Federal Research Institute of Fisheries and Oceanography 
17 V. Kransnoselskaya Street 
Moscow 107140, Russia 
* Lomonosov Moscow State University 
GSP-1 Leninskije Gory 
Moscow 119991, Russia 
The genus Eumicrotremus, 1 of 6 gen- 
era of Cyclopteridae (Scorpaeniformes: 
Cottoidei), includes 18 valid species 
(Froese and Pauly, 2020). This genus 
is distributed mostly in the northern 
Pacific Ocean. Four species inhabit 
subarctic and Arctic areas: pimpled 
lumpsucker (E. andriashevi), leather- 
fin lumpsucker (E. derjugini), Atlantic 
spiny lumpsucker (E. spinosus), and 
Newfoundland spiny lumpsucker 
(E. terraenovae). The Fedorov’s lump- 
sucker (E. fedorovi) inhabits the waters 
of the northern Kuril Islands off the 
eastern coast of Russia (Mecklenburg 
and Sheiko, 2003) and has been rarely 
recorded as bycatch in the area of the 
Kuril Islands. Lumpsucker species 
spend most of their lives away from 
the shore. They can be found 100 km 
from shore in the open waters of the 
Pacific Ocean, before they return to 
shallow waters (200-300 m) to repro- 
duce (Orlov, 1994; Chuchukalo, 2006). 
No information on the diet of Fedor- 
ov’s lumpsucker was available prior to 
this study. According to existing records 
on the diet of other Eumicrotremus 
species (Tabunkov and Chernysheva, 
1985; Orlov, 1994; Melnikov, 1995; 
Kuznetsova, 1997; Chuchukalo et al., 
1999; Roshchin, 2006; Antonenko 
et al., 2009; Berge and Nahrgang, 
2013), lumpsucker species feed on var- 
ious crustaceans, juveniles of squid 
species, pteropods, juveniles of fish spe- 
cies, and polychaetes. Lumpsucker spe- 
cies feed intensively throughout most 
of the year and have been reported to 
make diurnal vertical migrations in 
the water column to follow their main 
food item (hyperiids), and this move- 
ment pattern explains their regular 
presence in open water (Chuchukalo, 
2006; Antonenko et al., 2009). 
The reproductive biology of Cyclopte- 
ridae has been previously examined in 
studies of the lumpfish (Cyclopterus 
lumpus) and smooth lumpsucker (Apto- 
cyclus ventricosus) (Cox and Anderson, 
1922; Davenport, 1985; Kennedy, 2018; 
Zhukova et al., 2018). Information on 
the reproductive processes of other 
members of Cyclopteridae is scarce and 
fragmented. Lumpsucker species pro- 
duce clusters of demersal adhesive 
eggs and spawn in coastal waters (at 
depths down to 300 m). After spawning, 
males guard the fertilized eggs 
(Mecklenburg and Sheiko, 2003; 
Panchenko and Balanov, 2020). Female 
Pacific spiny lumpsucker (E. orbis) and 
spinous lumpfish (E. soldatovi) have 
been reported to have died after a single 
