Zimmermann Maturity and fecundity of Atheresthes stomias 
599 
Histology is used to determine maturity, and detailed 
descriptions of maturity stages (adapted from Rickey, 
1995) are provided for both males and females. 
Changes in condition factor, gonadosomatic index, 
and hepatosomatic index are reported for the differ- 
ent maturity stages. Another objective of this study 
is to assess methods for describing arrowtooth floun- 
der maturity (macroscopic vs. histologic) and for de- 
termining total fecundity. The accuracy of macro- 
scopic maturity staging is assessed by comparing 
histological staging with macroscopic staging for all 
fish sampled, since Rickey ( 1995) noted the possibil- 
ity of misassigning maturity stages by macroscopic 
means. Comparisons are made between this study 
and results from arrowtooth flounder maturity stud- 
ies conducted from the eastern Bering Sea to Oregon. 
Materials and methods 
Maturity 
Arrowtooth flounder were collected from bottom 
trawl hauls aboard the NOAA vessel Miller Freeman 
(cruise 93-10) on Portlock Bank near the eastern end 
of Kodiak Island, Alaska. The hauls were made dur- 
ing daylight hours from 6 to 16 September 1993 in 
depths ranging from 66 to 165 m. Fork lengths (cm) 
were recorded, and somatic fish weights (less stom- 
ach contents) were measured to ±2 g on an electronic 
scale. The gonadal tissues were removed from the 
fish within a few hours of capture and preserved in a 
10% formalin solution neutrally buffered with sodium 
acetate. Eyed-side and blind-side lobes of the ovary 
were dissected apart and stored separately. Livers 
were removed and weighed on the vessel (±2 gm). 
Specimens less than 20 cm in length were weighed 
on the vessel and preserved whole in a 10% formalin 
solution. Preserved fish were later dissected in the 
laboratory, and liver weights were measured to 
±0.001 gm. 
The author assigned a macroscopic maturity stage 
to males and females (Table 1) based on external 
appearance of gonads, according to descriptions 
adapted from Rickey (1995). (The author is an expe- 
rienced groundfish biologist and prior to this project 
had examined the appearance of arrowtooth floun- 
der gonadal tissue, through sex determination work, 
on thousands of arrowtooth flounders). Collections were 
initially limited to two fish per centimeter for each sex; 
additional females were collected over the length range 
where macroscopic maturity stages overlapped. 
The accuracy of macroscopic stages assigned to 
whole ovaries was assessed by histological analysis 
of the ovarian sections. After being preserved in for- 
malin, gonadal tissues were blotted dry and weighed 
on an electronic scale (±0.001 g) in the laboratory. 
Sections for histology were approximately 3 mm 
thick. For females, the sections were cut perpendicu- 
larly through the eyed-side ovarian lobe as near to 
the posterior end of the lobe in order for the section 
to fit on a slide. For males, the section was cut per- 
pendicularly through a distal lobe of the testis, or 
through the entire organ, if small. Histological 
samples were dehydrated, infiltrated with paraffin, 
and embedded in blocks of paraffin. Sections were 
cut from the frozen blocks on a microtome at a thick- 
ness of 5 p, heat-fixed to a glass slide, and stained 
with hematoxylin and eosin. Under a compound mi- 
croscope, the ovary samples were assigned one of 11 
maturity stages on the basis of the most advanced 
oocyte seen (Table 2). Atresia of large, yolked oocytes 
was noted, but not quantified. 
The gonadosomatic index (GSI) was calculated to 
show differences in development of the gonads with 
respect to body weight: 
GSI = (gonad weight x 100 (/somatic weight. 
Condition factor (CF) was calculated as an overall 
measure of robustness of the fish: 
CF = (somatic weight x 100 (/length' 1 ’. 
A hepatosomatic index (HSI) was also calculated 
to estimate the relative size of the liver to body 
weight: 
HSI = (liver weight x 100 )/(liver - free somatic weight). 
Although HSI is generally not included in maturity 
studies, the liver plays an important role in sexual 
maturity of both sexes. Oocyte yolk comes from the 
manufacture of vitellogenin in the liver (Wallace, 
1985), and HSI may be a good predictor of male go- 
nadal development, as was shown for Pacific cod 
(Gadus macrocephalus; Smith et al., 1990). 
Significant differences between mean values of 
length, weight, GSI, CF, and HSI at the different 
maturity stages were tested with a one-way analy- 
sis of variance (ANOVA, a=0.Q5). The mean values 
were further tested with a Tukey test to reveal which 
means were significantly different. For purposes of 
these tests, fish in the late perinucleus stage (stage 
4) were combined with those that had atresia of pre- 
viously vitellogenic oocytes but that did not yet have 
mature oocytes beyond the late perinucleus stage 
(stage 11) in the current season. 
Females were classified as mature if their oocytes 
had entered the cortical alveoli stage (stage 5; Rickey, 
