Yoneda et al.: Reproductive cycle, fecundity, and seasonal distributions of Lophius litulon 
363 
Figure 6 
Photomicrographs of ovaries at the six different stages of maturity in Lophius litulon. (A) Stage 1 (imma- 
ture), (B) Stage 2 (developing). (C) Stage 3 (mature). (D) Stage 4 (spawning). (E) Stage 5 (spent). (F) Stage 
6 (resting). Bar = 250 pm; ow = ovarian wall; gm = gelatinous material; n = nucleus; o = oil droplet; pof = 
postovulatory follicle; ao = atretic oocyte. 
postovulatory follicles were examined. The frequency of 
ovigerous lamellae with yolked oocytes present clearly dif- 
ferentiates two ovarian conditions (Table 3). The ovaries 
of females in which more than 75.0% of the ovigerous la- 
mellae have secondary yolk stage oocytes are in stage 4, 
regardless of the degenerative stage of the postovulatory 
follicles. The ovaries of females in which less than 36.4% 
of the ovigerous lamellae have primary yolk stage oocytes 
are in stage 5. Some yolked oocytes in the process of be- 
coming atretic are found in specimens with primary yolk 
oocytes. No females were found with ovaries containing 
both postovulatory follicles and tertiary yolk or a more ad- 
vanced stage of oocytes during our study. 
Length and age at sexua! maturity 
There were clear differences between males and females in 
the size and age at sexual maturity (Fig. 7). The minimum 
size and age at sexual maturity for males were 325 mm TL 
and age 4; for females, minimum size and age at sexual 
maturity were 546 mm TL and age 5. The size and age at 
50% sexual maturity for males and females were 362 mm 
TL and age 5.4, and 567 mm TL and age 6.2, respectively. 
All males >390 mm TL and age 7, and all females >630 mm 
TL and age 8, were mature. 
Annual reproductive cycle 
Mature males were found over a longer period of the year 
than mature females (Tables 4 and 5). Spermatogenesis 
occurs throughout most of the year; therefore males with 
mature testes are frequently collected. In females, early 
stages of oocyte development occur between November 
and March, and the later stages from February through 
April. Females in stages 3 and 4 were collected from Feb- 
ruary to May, which is therefore considered the spawning 
season. Between May and November, most females had 
stage 1, 5, or 6 ovaries. 
