618 
Fishery Bulletin 95(3), 1997 
Table 2 
Comparison of reproductive characteristics in some agonid fishes. 
Species name 
Spawning 
mode 
Embryonic 
period 
and egg 
diameter 
Spawning 
substrate 
Parental 
care 
Spawning 
system 
References 
Agonomalus mozinoi 
unknown 
unknown 
1 mm 
barnacle, tube worm 2 
without 
remarkable iteroparity 
of small clutches 
Marliave, 1978 
A. probosciadalis 
internal 
fertlization' 
110-114 days 
2.05-2.30 mm 
between rocks and 
sand on bottom 
without 
remarkable iteroparity 
of small clutches 
Iioka and Gunji, 1979 
Aoyama and Onodera, 1989 
Aigonus cataphractus 
unknown 
1 year 
1.76-2.23 mm 
on roots of kelp 
unknown 
remarkable iteroparity 
of small clutches 
Eherenbaum, 1936 in 
Breder and Rosen, 1966 
Bracdyopsis rostaratus 
internal gametic 
association' 
287-324 days 
2.1 mm 
on bottom 2 
without 
remarkable iteroparity 
of small clutches 
Sugimoto, 1987; this study 
Ocella iburia 
internal fertilization' 
unknown 
unknown 
unknown 
unknown 
unknown 
Sugimoto, 1987 
Podothecus sachi ' 
internal gametic 
association' 
92-104 days 
1.70-1.75 mm 
unknown 
unknown 
remarkable iteroparity 
of small clutches 
this study 
1 The studies had been reported before publication of internal gametic association (Munehara et al., 1989). 
2 The findings were observed in aquaria. 
host invertebrates, for aspiration and filtration, in- 
cidentally supply oxygen to eggs deposited inside or 
on the invertebrates (Munehara, 1991). The pro- 
tracted period of incubation may have promoted egg 
deposition in any safe cradle for embryos rather than 
parental care. 
Multiple clutches are produced by agonid species 
during a breeding season, as demonstrated by histo- 
logical observation of the ovary of P. sachi; moreover, 
observations of A. mozinoi, A. proboscidalis, and 
B. ostratus indicate that females spawn small 
clutches almost daily in aquaria (Marliave, 1978; 
Iioka and Gunji, 1979; Sugimoto, 1987; Aoyama and 
Onodera, 1989). The fifth characteristic is the 
remarkable iteroparity of small clutches, which may 
have evolved i n association with the laying of eggs, both 
into narrow spaces and without male involvement. 
In summary it is suggested that five common char- 
acteristics, i.e copulation, a protracted period of in- 
cubation, concealment of deposited eggs, lack of pa- 
rental care, and remarkable iteroparity of the repro- 
ductive ecology of agonids have been closely corre- 
lated with each other through evolutionary construc- 
tion of their distinctive reproductive style. Copula- 
tion enabling impregnated females to spawn eggs 
without subsequent involvement of male fish seems 
to be a principal element of these characteristics. 
Acknowledgments 
The authors wish to thank the crew of the Yuki-maru 
and the staff of Usujiri Fisheries Laboratory, 
Hokkaido University, for collecting specimens. This 
study was supported in part by Grant-in-Aid for sci- 
entific Research (05760145) from the Ministry of 
Education, Science and Culture, and The Special 
Grant-in-Aid for Promotion of Education and Science 
at Hokkaido University. 
Literature cited 
Aoyama, S., and H. Onodera. 
1989 . Breeding habits, larvae, and juveniles of the agonid 
fish, Agonomalus proboscidalis in captivity. J. Jpn. Assoc. 
ofZoological garden and Aquarium 31:14—20. [In Japanese.] 
Breder, C. M., and C. E. Rosen. 
1966 . Modes of reproduction in fishes. The American 
Museum of Natural History, New York, NY, 941 p. 
Gomelyuk, V. E., and A. I. Markevich. 
1986 . On the strength of the egg case of the sea raven, 
Hemitripterus villosus (Cottidae). J. Ichthyol. 26:148-150. 
Gruchy, C. G. 
1969 . Canadian records of the warty poacher Occa 
verrucosa, with notes on the standardization of plate ter- 
minology in Agonidae. J. Fish. Res. Board Can. 26:1467- 
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