-
本州中部の温帯河川に定着したフクドジョウBarbatulaoreasの繁殖特性
誌名誌名 水産増殖 = The aquiculture
ISSNISSN 03714217
著者著者畠山, 類北野, 忠
巻/号巻/号 66巻2号
掲載ページ掲載ページ p. 123-131
発行年月発行年月 2018年6月
農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia
Cooperation Support Center, Agriculture, Forestry and Fisheries
Research CouncilSecretariat
-
Aquacult. Sci. 66 (2), 123 -131 (2018)
Reproductive biology of a boreal N emacheilid loach
Bαrbαtula oreαs introduced into a temperate river
in central Honshu, Japan
Rui HATAKEYAMA1'* and Tadashi KlTAN02
Abs仕act:The reproductive traits of Bαrbαtula oreas were examined
in a population established in the Kaname River, Kanagawa
prefecture. Males exhibited unclear seasonal pa仕ernsin their
monthly mean gonadosomatic index (GSI), and discharged semina
from their genital ducts throughout the ye町.Females exhibited
obvious seasonal patterns in the monthly mean GSI, which
was higher in spring (March-April) and lower in summer
(July-August). Ovarian maturity was
divided into three developmental phases (resting, vitellogenic
and maturation), and the ovaries in the maturation phase, which had
the characteristics of ovaries in the spawning season, were
observed from March to July. Post-ovulatory follicles were found
even in the ovaries of small fish (く 100mm SL), indicating spawning
at age-1. Total fecundity was 1,049-10,671 per ovary,
increasing exponentially with the increasing SL. It was
considered that vitellogenesis occurred at a wide range of water
temperatures and day lengths (7.5-20.8°C, 9 h 47 min-14 h 33 min),
and spawn-ing season began when there was a transition to a
suitable spawning temperature (10.2-18.5℃).
This population, which matured at age-1, seemed to have a higher
intrinsic rate of natural increase compared to a native
population.
Key words: Barbαtula oreas; Acclimatization; Alien species;
Gonadal maturity
Fukudojo, Barbatulαoreas is a boreal loach
belonging to the family Nemacheilidae, and
is naturally distributed in Hokkaido, Japan
(Kottelat 2012).官官 distributionalareas of B.
oreas have expanded rapidly to lower latitudinal
rivers, such as the Abukuma River, Agano River,
Mogami River, and Kuji River in northeastern
Honshu, Japan, probably due to the release
of salmonid seed (Toujo and Hosoya 1998;
Ministry of Land, Infrastructure, Transport and
Tourism 2007). In recent years, B. oreas have
also established in the upstream Kaname River
in central Honshu (Yashima et al. 2011), which
is the lowest latitude river invaded by this
species.
There are many unclear aspects regarding
the ecological impact of B. oreas establishment.
Bαrbatula oreas may compete for food or habitat
Received 16 November 2017; Accepted 30 May 2018.
with native fish, including commercial species,
because it feeds on benthos such as aquatic
insects (Miyadi et al. 1963), hides under stones
during the daytime (National Institute for
Environmental Studies 2005), and tends to be
the dominant species in its natural and invasive
ranges (Nogami et al. 2001; Nagasawa et al.
2009; Hatakeyama et al. 2017).胞1owledgeof
reproduction in this species, in addition to feed-
ing and behavior, is essential for an appropriate
assessment of ecological impact.
百1eobjective of the present study was to clar-
ify first肱theenvironmental conditions in which the gonadal
maturity of B. oreas progresses, and
therefore in which river environments there
is the potential to reproduce, and secondly, to
identi命thereproductive traits of B. oreas estab-
lished in a temperate river.
1 Civil Engineering and Eco-Technology Consultants Co., Ltd.,
2-23-2 Higashiikebukuro, Tashima, Tokyo 170-0013, Japan. 2 School
of Humanities and Culture, Takai University, 4-1-1 Kitakaname,
Hiratsuka, Kanagawa 259-1292, Japan. *Corresponding author: Tel,
(+81)3-3988-2634; Fax, (+81)3-3988-3885; E-mail:
[email protected] (R. Hatakeyama).
-
124 R. Hatakeyama and T. Kitano
In the present study, the scientific name, B.
areas, was used according to Ko仕elat(2012), who reviewed the
confused taxonomy and nomen-
clature of loaches, a suborder of Cobitoidei,
although names such as B. toni toni (Miyadi et al. 1963), B.
toni (Nakamura 1984), Noemacheilus toni (Saito 1988), N barbatulus
toni (Masuda and Kobayashi 1994) and Nemacheil倒 的rbatulustoni
(Hosoya 2013) were used hitherto.
Materials and methods
Fish collectioれandenvi:γon制側taldαtα
Specimens were collected from a 1 km section
ups仕earnof血eKaname River in cen仕alHonshu,
Japan (35°23'24"N, 139°13'36官). Sampling was
conducted once a month, from April 2012 to
August 2015. Collection was by scooping with hand
nets from April 2012加 May2013, and in conjunc-
tion wi血 anelectric shocker (LR-20B: Smi出-Root,
USA)企omJune 2013 to August 2015. Du出1g出e
sampling period, a data logger (UA-002・64:Onset
Computer Co., USA) was placed in the water,
and temperature data recorded every hour to
be calculated as daily mean water temperature.
Day length data was obtained from Yokohama,
Kanagawa Prefecture, Japan, which was出enear-
est mo凶to巾 gsite初出eKaname River (National
Astronomical Observatory of Japan 1994).
Fish meαsurementsαnd dαtαα%α:lysis
The collected fish were anesthetized with
MS-222 in a laboratory and the standard length
(SL) and body weight (B"ワ measured.Sex was basically identified
from the pectoral fin-shape
according to Ikeda (1936). In fish in which the
secondary sex characteristics of the fin were
undeveloped, sex was identified by checking the
gonads under a stereomicroscope. Fish having
translucent and string-like gonads and no visi-
ble oocytes were treated as sexually unidenti-
fied. Fish having slightly clouded and enlarged
gonads with no visible oocytes, and fish having
visible oocytes, were treated as male and female,
respectively. In all fish,出egonads were removed
and the gonadal weight (G"乃 measured.As an index of gonadal
development, the gonadoso-
matic index (GSI) was calculated as follows:
GSI = 100×GW/BW.
Sexing fish, including the yearling, were
used for analyzing gonadal maturity and annual
reproductive cycle, because the gonads of year-
ling fish developed rapidly但atakeyamaet al.
2017), suggesting spawning at age-1. Males, col-
lected after April 2014, were examined with the
naked eye whether semen was discharged from
the genital duct upon pressing the abdomen.
Female fish gonads were monitored by record-
ing external features such as color, and oocyte
diameters; the gonads were photographed
using a digital camera, and then preserved in
70% ethanol after :fixation in 10% neutral forma-
lin or Bouin’s solution for 24 h. Some ovaries
fixed in Bouin’s solution were embedded in paraffin, sagittally
sectioned at 4 μm thickness,
and stained with Mayer’s hematoxylin-eosin.
The developmental stages of germ cells were
observed under an optical microscope.
Some ovaries fixed in 10% neutral formalin
were used to estimate the number of oocytes
and their diameters. Oocytes weighing approx-
imately 1 / 5th of the ovary weight were laid
out on a 1× 1 mm mesh on a petri dish and
photographed by a digital camera, and the
numbers and diameters were measured using
image analysis software (JCAM software:
]-SCOPE, Japan). Total fecundity (TF)但unter
et al. 1992), which was the standing stock of
advanced yolked oocytes in the ovary, was cal-
culated by gravimetric method as follows:
TF=GW×C,
where C is oocyte density (number of advanced
oocytes per gram of ovarian tissue). For compar・・
ison with the native population, TF of fish in the
Komaoi River, Hokkaido, was also calculated for
some ovaries, which were removed from sped-
mens collected by Hatakeyama et al. (2017).
Results
Conαdαl制 αtuγ#ヲα汎dα汎nualγepγoducti匂ecycle
A total of 462 fish had SLs ranging from 53.6-
149.4mm (Fig. l). The GSI was 0.1-1.2 in sex-
ually unidentified (53.6-91.1 mm SL, n = 25),
-
125 Reproductive biology of Barbatula oreαs
×
xusa’x
ooaR
omm滋実
xxxaa胃XX
oa冒翼×
xo
××調恒留。xxo
誕百偏X災UM突X
OV860辺倒x
-
xoaexE史XMM
ox。旬開ち《
X
OOM目MRvoλ
・・・・・
aeハ同開
xva契
X
O
×Xロ冨X
X
o
-xuRO
U穴×
00向
MOXX
O
Q
M
W
当然×
自
X
M
U
0
・0Axxooxoae×xx
98exx
nぬ問。
aexumx
。。調@《VA
oh油炉端
m
.
X
0
X
M×OXX0
68MO
×
××凶ROX
謡史
x
x
。
0
・8AO
X
0
0
6×
060
。oe《×
x
a
Q
R
a
x
o
由自主
x
・・
内】,.,λY0
・
。。a-RX
X
X
xxu《》
xx
・・
nvu品回関
内幽
gvoAo
o
x
x
。。。。
OOMxxxu
160
〔 140 6
5120 4コ-oJ) i3 100
’てコ.g 80 ,::
"' Vコ I .
40 AMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJA 2012 2013 2014
2015
Fig. 1. Standard length of Barbatula areas collected monthly in
the present study. o, male (n = 201); ×,female (n =
236);・,unidentified(n = 25).
60
developmental phase, histological characteris-
tics and frequency distribution of oocyte diame-
ters were investigated.
(1) Vitellogenic phase: GSI was 3.9-27.1 (n
= 108) (Fig. 3). The ovaries were enlarged and
light yellow in color, and large oocytes (290-
850 μm, n = 200) were visible and densely
distributed (Fig. 4a). Ovaries observed histolog-
ically had oocytes at the tertiary yolk stage or
lower (120.0-134.5 mm SL, GSI = 4.8-15.9, n =
4)σig. 4b). The ovaries in this phase had one
or two modes in oocyte diameter (Fig. 5a, b); an
ovary in November had one oocyte group con閉
sisting of oocytes at the tertiary yolk stage and
lower, but an ovary in February had another
advanced group (> 600 μm in oocyte diameter)
consisting of oocytes at the tertiary yolk stage,
even though two oocyte groups having each
mode were not completely separated in terms
of oocyte diameter (Fig. 5b). The ovaries in
the vitellogenic phase were defined as being in
a s句tein which oocyte development was pro同
gressing toward the next spawning season.
(2) Maturation phase: GSI was 4.3-24.0 (n =
61) (Fig. 3). The ovaries in the final maturation
or ovulation were enlarged, transparent and
light orange in color, and the oocytes were not
clearly visible (Fig. 4c). The ovaries that had
spawned at least once were more deflated than
those in the most enlarged state of the vitello-
genic phase, with large, clearly visible oocytes
σ50-970 μm, n = 172) (Fig. 4e) that were
light yellow in color and sporadically distrib-
uted. The ovaries in this phase had two modes
in oocyte diameter, even though two oocyte
groups having each mode were not completely
6 6 5 9 4 9 8 10 6 7 5 6 6 5 4 4 5 100
(
三豆、~
〉、u C Q)
;::;
:if 50 ... 匂~
Q)
〉世
"' Q) ~
Fig. 2. Monthly changes in relative frequency (%) of male
Barbatula areas discharging clouded semen企omthe gen-ital duct. .,
with semen;圏, withoutsemen.百1eArabic numerals indicate the number
of individuals.
0.2-2.8 in males σ6.5-148.8 mm SL, n = 201) and
0.4-27.1 in females (67.5-149.4 mm SL, n = 236).
The monthly mean GSI in males varied
between 0.8 and 2.1, with unclear seasonal paι
terns. Semina from genital ducts (84.4-139.3 mm
SL, n = 71) were observed throughout the yeaじ
but relative frequency was greater出an60% in
all months from autumn to spring (April-May
2014, November 2014-May 2015) (Fig. 2).
The monthly mean GSI in females varied
seasonally between 1.9 and 19.4. The mean GSI
was the highest in March (2013 and 2014) and
April (2015), and the lowest in July (2012) and
August (2013 and 2015) (Fig. 3). The mean GSI
in December 2012 and January 2015 reached
84.7% and 91.0% of the peak values in 2013 and
2015, respectively. The mean GSI decreased
rapidly to less than half the peak value in May
(2013 and 2015) and June (2014).
Ovarian maturity was divided into three
developmental phases as follows on the basis of
the exterior features. In some ovaries in each
-
126
30
マ~コ, 25 【 20にJ
r 10 。F宅でE X 。
R. Hatakeyama and T. Kitano
。
。 8 × ×
×
。
AMJ J ASONDJ FMAMJ J ASONDJ FMAMJ J ASONDJ FMAMJ J A 2012 2013
2014 2015
Fig. 3. Monthly changes in the gonadosomatic index in Barbatula
oreas. o, vitellogenic phase (n = 108);×,
maturation phase ( n = 61);・, restingphase ( n = 67). The
symbols with vertical bars indicate means ±
standard deviations.
Fig. 4. The ovaries in the three developmental phases of
Barbatula oreas. (a) exterior of the ovary in the vitellogenic
phase (120.0 mm SL, GSI 15.9, January 2013); (b) histological
features of the ovary of (a); (c) exterior of the ovary in the
maturation phase, during宣nalmaturation (111.3 mm SL, GSI 4.3,
April 2014); (d) histological features of the ovary in the
maturation phase, during final maturation, with oocytes in the
migratory nucleus stage (95.0 mm SL, GSI 5.9, June 2014);
(e) exterior of the ovary in the maturation phase (134.6 mm SL,
GSI 6.5, June 2013); (f) histological features of (e) with
post-ovulatory follicles; (g) exterior of the ovary in the
resting phase (128.3 mm SL, GSI 1.0, July 2014); (h)
histological
features of (g). Abbreviations: ar, atresia; runs, migratory
nucleus stage; pns, perinucleolus stage; pys, primary yolk
stage;
sys, secondary yolk stage; tys, tertiary yolk stage; yvs,
yolk-vesicle stage. Arrowheads indicate post-ovulatory
follicles.
-
(Fig. 3). The ovaries had the most shrink-
age among the three developmental phases
(Fig. 4g), and were transparent and orange.
The oocytes were not clearly visible but a few
atresias (230-650いm,n = 30) from the previ-ous spawning season
were scattered in some
ovaries. The oocytes in the perinucleolus stage
occupied a large portion of the ovary with a few
oocytes at the yolk-vesicle stage intermixed
(87.0-148.3 mm SL, GSI = 1.0-6.6, n = 10)
σig. 4h).官1eovaries in the resting phase were
defined as being in a state immediately following
the termination of the previous spawning season.
The developmental phases were observed
during summer-spring (August 2012-May 2013,
September 2013-May 2014, and September
2014-March 2015) for the vitellogenic phase,
spring-summer (April-June 2013, and March-
July 2014 or 2015) for the maturation phase,
and summer-winter (July-October 2012, June
2013-January 2014, and June-November 2014)
for the resting phase (Fig. 6).
127 Reproductive biology of Barbatula areas
separated (Fig. Sc); in ovaries observed histo-
logically (89.9-134.5 mm SL, GSI = 5.9-9.6, n
= 9), the advanced oocyte group consisted of
oocytes at the tertiary yolk stage and higher,
and the other group consisted of oocytes at the
secondary yolk stage and lower (Fig. 4d, f).
Post-ovulatory follicles (Fig. 4f) were found
in six ovaries, which included four ovaries in
fish ofく100mm SL (87.0-95.3 mm SL, GSI =
2.6-6.7), and were also found with advanced
oocytes, which was the migratory nucleus stage
in the most advanced oocytes. The ovaries in
the maturation phase were defined as being in a
state in which it was possible to spawn or very
close to spawning, or just after spawning.
(3) Resting phase: GSI was 0.4-6.6 (n = 67)
a n
u
p
、,n
v
ζ
J
今
4
・E’I
。匂αriα汎 mαtuγityαnde汎匂iγ0汎mentalconditions
Water temperature changed seasonally
between 5.0 and 22.8。C (Fig. 7). Day length
varied from 9 h 46 min to 14 h 34 min. The envi-
ronmental conditions were 7.5-20.8。Cand 9h 47 min-14 h 33 min
for the vitellogenic phase,
and 10.2-18.5℃and 11 h 55 min-14 h 33 min for
the maturation phase (Fig. 8).
Totαlfecunditヲ
TF was calculated using ovaries in出evitello・
genic phase, close to spawning, collected from
January to March (73.2-149.4 mm SL, n = 34).
b
:::;;- 0 ミ与 20 〉、にJ
5 15 コ]" 10 (l)
〉】
国
2 0 戸 20
5
C
qd
A
リ
ζJ
l
l
900
Fig. 5. Relative frequency(%) distribution of oocyte diame-ters
in Barbatula areas. (a) vitellogenic phase (121.0 mm SL, GSI 15.0,
November 2012, n = 424); (b) vitellogenic phase (114.8 mm SL, GSI
15.7, February 2015, n = 321); (c) matu-ration phase (125.8 mm SL,
GSI 7.4, June 2013, n = 405).
400 500 600 700 800 Oocyte diameter (μm)
300
4 4 2 3 4 5 6 5 5 7 3 5 5 5 6 I 7 4 6 7 5 11 3 7 6 5 8 11 6 5 6
9 10 5 10 8 6 5 5 5 5
00ーーー山田町田--園田園ーー_,.叶!河瞳圃臨圃阻酪.....|ぺ|圃園田園闘園・・・・・c
(
ヌ)
>, にみ戸
" “ 0-さ50" 〉}
依3
" 0::
0 AMJ J ASONDJ FMAMJ J ASONDJ FMAMJ J ASONDJ FMAMJ J A 2012 2013
2014 2015
Fig. 6. Monthly changes in relative frequencies(%) of
ovarian-developmental phases in Barbatula
areas.瞳,vitellogenicphase; •. maturation phase;囚,restingphase. The
Arabic numerals indicate the number of individuals.
-
128 R. Hatakeyarna and τ:Kitano
25 16
、「146、l 急
ロ
12-;_ "' 凸
10
。!.目 ・・・目目・..・・・目・・・ z 目白 ・・・・・目目’・・ ・・目・目目・・.. '8 AMJ J ASOND J
FMAMJ J ASOND J FMAMJ J ASOND J FMAMJ J A 2012 2013 2014 2015
Fig. 7. Seasonal changes in daily mean water temperature (solid
line) and day length (dashed line) in出eKaname River.
16
(ぷ14 益鴻コメ長 ・× 号〈以
@ 、
」f12 8 。 @ ⑨⑥ 凸国〉、10
6) ⑨ ⑥
きP0 I!) 0 ⑨
⑥
8 5 10 15 20 25
Temperature (℃)
Fig. 8. Relationship between water temperature and day length at
appearance of ovarian-developmental phases in Barbαtula
areas.×,maturation phase (n = 16);・,restingphase (n = 21); 0,
vitellogenic phase (n = 27). The dark and light-shaded areas
indicate the range of combinations of water temperature and day
length, when ovaries are in the maturation and vitellogenic phases,
respectively.
12000
10000 .c ;a 8000 ロロにJ
にお 6000 国
戸4000
2000
0
Kaname River: TF = 0.0007SL3・3263 r = 0.94
.. . . 、/・・.
・, . .
60 80 100 120 140 160 Standard length (mm)
Fig. 9. Relationship between standard length and total fecundity
in Barbatula areas. e, Kaname River (n = 34); 0, Komaoi River (n =
6).
Based on the frequency distribution of oocyte
diameter, oocytes of > 600 μm in diameter were
defined as advanced yolked oocytes.
TF numbered 1,049-10,671 per ovary (Fig. 9).
The relationship between the TF and SL was
regressed by power functions as follows:
TF = 0.0007SL3・3263 (n = 34, r = 0.94).
Meanwhile, the TF of fish in出eKomaoi
River numbered 1,564-2,685 per ovary (86.3-
105.3 mm SL, n = 6) (Fig. 9).
Discussion
It was estimated that B. oreas ofく 100mmSL in April were born in
the previous year in
the Kaname River (Hatakeyama et al. 2017). As
post-ovulatory follicles were detected in fish of
く100mm SL, it is apparent出atfemales spawn
at age-1. Semina, which likely include sperma-
tozoa, from genital ducts in fish ofく 100mmSL
suggest that males may also spawn at age-1.
Males produced semen throughout the year,
while females exhibited an obvious annual cycle in
GSI and ovarian maturity. The ovaries in由ematu-
ration phase, at a state of spawr血g,appe訂 ed企om
March to July.百1erefore,B. oreas is believed to spawn from March
to July, with the timing
regulated by female maturation. Spawning may
occur mainly in earlier months, as small fish of
く20mm SL were found only in the自rsthalf of
the spawning period (Hatakeyama et al. 2017).
In spring『earlys山田nerspaWIIing species, yolk
globules begin to accumulate from autumn;
October, e.g. in Misgurnus anguillicaudatus (Kinlura and Koya
2011), Pseudorasboraρugnax (Ohnaka et al. 2009), and age-1
Gnαthopogon
caerulescens (Okuzawa et al. 1986), and September,
e.g.加Micropterusdolomieu 01.ambe et al. 2004), and age-2 M.
salmoides 01.odo and Kinlura 2002). The earlier initiation in
accumulation of yolk glob-
ules in B. oreas, which was from August, suggests
that vitellogenesis progresses under a wider
-
Reproductive biology of Barbatula oreas 129
range of water temperatures (7.5-20.8℃) and/
or day lengths (9 h 47 min-14 h 33 min), com-
pared with other species.
Iρnger days and/ or increasing tempera加res
were mentioned as important environmental
factors determining the initiation of spawning
periods in spring-early summer spawning spe-
cies (Shimizu and Hanyu 1983; Asahina et al.
1985; Ota et al. 2015).百1emonthly mean GSI of
female B. oreαs was already high during winter,
but the ovaries in the maturation phase did not
appe訂 untilMarch (10.2℃, 11 h 55 min).官官
closely-related B. bαrbatulus in Siberia spawns not only from
April to May, but also from August
to October, iム undershort-day length, in a ye訂
in which water temperature is higher (Skryabin
1993). Although the influence of day length is
unclear, B. oreas spawning in the Kaname River seems to occur
when there is a transition to a suit-
able temperature, approximately l0°C in spring.
As at least two oocyte groups existed simul-
taneously in an ovary, the process of oocyte
development in B. oreas is categorized as being
group-synchronous oocyte development
(Wallace and Selman 1981; Takano 1989). In
most species with group-synchronous oocyte
development, total fecundity provides an indi-
cation of annual fecundity, the total number of
eggs spawned by a female per ye肌 becauseno
yolked oocytes are not regarded as developed
and are not added to the larger oocyte group after
initiation of vitellogenesis in the ov訂 y但unteret
al. 1992; Kurita 2010). To阻lfecundity in B. oreas may also be an
indication of annual fecundity.
The simultaneous appe訂 anceof post-ovulatory
follicles and advanced oocytes in an ovary implies
that this species spawns advanced oocytes
dividing into several clutches. However, the two
oocyte groups were not completely separated
and intermediate diameter oocytes were present
during the pre叩 awningto spawning season,
although they were few in number. More detailed
consideration is needed as to whether small
oocytes develop and are spawned.
According to the growth equation of B. oreas in 出eKaname
River但atakeyamaet al. 201η,body size is calculated to be
approximately 80 mm SL
in April at age-1, approximately 110 mm SL at
age-2, and approximately 125 mm SL at age-3.
Therefore, total fecundity of B. oreas in the Kaname River is
estimated to be approximately
1,497 eggs per spawning at age-1, approximately
4,319 eggs at age-2 and approximately 6,608 eggs
at age-3, and出etotal number of eggs produced
during the lifetime is estimated to be 12,424.
Mαtur,α:tio汎 αηdfeγtili;句切 αte慨zperiα:teγi悦 γ
The spawning period of B. oreas in the Kaname River was
regulated by the female maturation.
Vitellogenesis began from August (19.9℃, 13 h
24 min) and continued until the next spawning
season, occurring under a wide range of water
temperatures and day leng吐lSσ.5-20.8℃, 9h
47 min-14 h 33 min). The spawning season
appeared to begin from March (10.2℃, 11 h
55 min) and continue until July (18.5℃, 14 h
14 min). These environmental conditions, which
enable ovarian maturity, may exist widely in
lower latitudinal rivers in Japan than the Kaname
River.羽市enB. oreas is introduced into such rivers, gonadal
maturity is expected to progress.
For B. oreas naturally distributed in the subarctic regions,
high temperature seems to
influence establishment when introduced in
lower latitudinal regions. However, the upper
temperature limit for B. oreas survival is not clear, though it
is doubtless able to withstand up
to approximately 23°C, which was the maximum
temperature in the Kaname River habitat. It is
known that the lower limit of its distributional
range corresponds with that of Oncorhynchus mαsou, extending to
some lower reaches in the rivers of Hokkaido (Miyadi et al. 1963).
The
upper temperature limit at which feeding ceases
or dying-off begins is 26℃ in 0. masou (Takami and Sato
1998).百1erefore,the high-temperature
tolerance limit in B. oreas may be around 26°C. Bαrbαtu!αoreαs,
distributed naturally in the
Komaoi River, grow to approximately 55 mm SL
at age-1, approximately 95 mm SL at age-2 and
approximately 135 mm SL at age-3但atakeyama
et al. 2017), and is presumed to spawn for the
宣rsttime at age-2但atakeyamaet al. 2017).百1e
TF-SL relationship is unknown in B. oreas in the Komaoi River,
but TF was not greatly different
from出atin the宣shin the Kaname River. When
-
130 R. Hatakeyama and T. Kitano
the relationship was applied to B. oreas in the
KomaoiRive乙吐1etotal number of eggs produced
in a lifetime was estimated to be 11,187, in con-
trast to 12,424 in the fish in the Kaname River.
Taki and Kanou (2008) expressed the sim-
plest concept of alien fish invasiveness as
follows: Invasiveness = Invasive biological char-
acteristics (e.g., habitat characteristics, feeding
habit, fertili町)× Highintroductive opportuni-
ties. Fertility is an important parameter deter-
mining invasiveness. The potential fecundity
in a lifetime of B. oreas may not differ much
between the Kaname River and Komaoi River,
however, B. oreas in the Kaname River mature
in the short term; that is, they have a high
intrinsic rate of natural increase.
The life history仕aitsof B. oreas may differ
depending on the environmental characteristics
in each river (Villeneuve et al. 2005; Trippel and
Harvey 2011), but the spawning season may
also be initiated earlier in the lower latitudinal
rivers, because a thermal rise in spring occurs
earlier (Lam 1983; Conover 1992; Hatakeyama
et al. 201η.百ms, it is predicted 出at出e
grow吐1period after hatching will be prolonged.
Additionally, growth is possible during winter
due to higher temperatures但atakeyamaet al.
201η.τberefore, when this species is in仕oduced
in rivers further south than出eE匂nameRive乙
where the water tempera加redoes not rise above
a certain level during s山田ne乙itis expected出at
也eSL at first maturation will be larger and the
fertility of the population will increase fur仕1er.
Acknowledgemen臼
We血ankShinichi Murata, Ryosuke Tanamoto,
Sho Terachi, and Kazutaka Togashi, of the
School of Human Environmental Studies, Tokai
University, for their help with the field survey.
References
Asahina, K, T. Matsuoka, H. Fujimoto, H. Hirose and T. Hibiya
(1985) Effect of temperature and photo-period on gonadal activity
in a Japanese minnow Pseudorasbora ραrva. Bulletin of the College
of Agricultural and 防terinaryMedicine, Nihon Universi砂,42, 203-210
(in Japanese with English abstract).
Conover, D. 0. (1992) Seasonality and the scheduling of life
history at different latitudes. ]ournαl of Fish Biology, 41 suppl.
B, 161-178.
Hatakeyama, R., T. Kitano and Y. Machida (2017) Growth and early
gonadal development in boreal Barbatula oreas (Jordan & Fowler,
1903) introduced into a tern-perate river in central Honshu, Japan.
Biogeography, 19, 163-171.
Hosoya, K. (2013) Family Cobitidae. In “Fishes of Japan with
Pictorial Keys to the Species.防l.1. 3rd edition" (ed. byT. Nakabo),
Tokai University Press, Tokyo, pp. 328-334 (inJapanese).
Hunter, J. R., B. J. Macewicz, N. Chyan-huei Iρand C. A.
Kimbrell (1992) Fecundity, spawning, and maturity of female Dover
sole Microstomusρacificus, with an eval-uation of assumptions and
precision. Fishery Bulletin, US., 90,101目 128.
Ikeda, H. (1936) On the sexual dimorphism and the taxonomi-cal
s匂加sof some Japanese loaches. Zoological Magazine, 48, 983-994 (in
Japanese with English abstract).
Kimura, A. and Y. Koya (2011) Annual reproductive cycle of a
wild population of oriental weather loach Misgurnus
anguillicaudatus in Gifu Prefecture, central Japan. Japanese
Journal of Ichthyology, 58, 1-12 (in Japanese with English
abstract).
Kottelat, M. (2012) Conspectus cobitidum: an inventory of the
loaches of the world (Teleostei: Cypriniformes: Cobitoidei). The
Raffles Bulletin of Zoology, Suppl. 26, 1-199.
Kurita, Y. (2010) Influence of spatio-temporal changes in stock
reproductive potential on the recruitment levels of fish. Bulletin
of the Japanese Socie砂ofFisheries Oceanography, Suppl. 74, 4-18 (in
Japanese with English abstract) .
Lam, T. J. (1983) Environmental influences on gonadal activity
in fish. In “Fish Physiology,防l.IX'’(ed. by W. S. Hoar, D. J.
Randall and E. M. Donaldson), Academic Press, New York, pp.
65-116.
Masuda, H. and Y. Kobayashi (1994) Cobitidae. In “Grand Atlas of
Fish L俳 Modes”, TokaiUniversity Press,
To防o,pp.4(ト41(inJapanese).
Ministry of Land, Infrastructure, Transport and Tourism (2007)
River Environmental Database.
http://mizukoku.nilim.go.jp/ksnkankyo/index.html, accessed on 11
Oct. 2016 (in Japanese).
Miyadi, D., H. Kawanabe and N. Mizuno (1963) Barbatula toni toni
(DYBOWS阻).In “Coloured Illustrations of the Freshwαter Fishes of
Japan”, Hoikusha, Osaka, pp.139-140 (in Japanese).
Nagasawa, T., K. Morita and J. Tsuboi (2009) Iρngitudinal
distribution and changes in the fish fauna of a mid-scale river,
Shorn River system, eastern Hokkaido, wi仕1notes on signal
crayfish.Japanese Journal of Ichthyology, 56, 31-45 (in Japanese
with English abstract).
Nakamura, M. (1984) Cobitidae. In “Keys to the Freshwater Fishes
of Japan, Fully Illustrated in Colors”(ed. by M. Nakamura),
Hokuryukan, Tokyo, pp. 56-57 (in Japanese).
National Astronomical Observatory of Japan (1994) Local
Calendar. http://eco.mtk.nao.ac.jp/koyomi/ dni/index. html.en,
accessed on 11 Oct. 2016.
-
Reproductive biology of Barbatula oreas 131
National Institute for Environmental Studies (2005)
Invasive Species of Japan. https://www.nies.go必/biodiversity
/invasive/DB/ detail/50780.html, accessed on 11 Oct. 2016 (in
Japanese).
Nogami, T, Y. Watanabe and M. Nakatsugawa (2001)
Research on fish habitats in the Makomanai River. Proceedings of
Hydraulic Engineering, 45, 1123-1128 (in Japanese with English
abstract).
Ohnaka, T, T Maeda, T Kitano and Y. Koya (2009) Annual
reproductive cycle of the threatened cyprinid species,
Pseudorasbora pumila subsp. sensu Nakamura (1963). Japanese ]ournαl
of Ichthyology, 56, 47-58 (in Japanese with English abstract).
Okuzawa, K., K. Furukawa, K. Aida and I. Hanyu (1986) Annual
reproductive cycle of the honmoroko Gnαthopogon elongatus
caerulescens. Bulletin of the Japanese SocieかofScient♂c Fisheries,
52, 1957-1960 (in Japanese with English abstract).
Ota, Y., Y. Ishihara, H. Saitho, T Onuki and N. Akiyama (2015)
The environmental factors influencing the ini-tiation of spawning
period of bitteling Acheilognathus melanogaster. Aquαculture
Science, 63, 437-445 (in Japanese with English abstract).
Saito, Y. (1988) Homalopteridae. In“The Fゐhesof the Japanese
Arch争elago.防l.1. 2nd edition" (ed. by H. Masuda, K. Amaoka, C.
Araga, T Uyeno and T Yoshino), Tokai University Press, Tokyo, p. 59
(in Japanese).
Shimizu, A and I. Hanyu (1983) Environmental regulation of
annual reproductive cycle in a spring-spawning bit-terling
Acheilognathus tabira. Nippon Suisan Gakkαishi, 48, 1563-1568 (in
Japanese with English abstract).
Skryabin, A G. (1993) The biology of stone loach Barbatula
barbatulus in the River Goloustnaya and Olkha, East Siberia.Journal
of Fish Biology, 42, 361-374.
Takar凶, Tand H. Sato (1998) Influence of high water tem-perature
on feeding responses and thermal death of juvenile masu salmon
under aquarium settings. Scientific Reporおofthe Hokkαido Salmon
Hatchery, 52, 79-82.
Takano, K. (1989) Ranso no kozo to haigushikeisei (Ovarian
structure and gametogenesis). In “Reproductive Biology
of Fish and Shellfish'’(ed. by F. Takashima and I. Hanyu),
Midori-Shobo, To防o,pp. 3-34 (in Japanese).
Taki, Y. and M.Kanou (2008) Gairaigyo to do tsuki-auka但owshould
we associate with alien fish?). In “Gairai seibutsu no risuku kanri
to yuko riyo (Risk Management and Effective Utilization of Alien
Species)”(ed. by Association of Japanese Agricultural Scientific
Societies), Yokendo, Tokyo, pp. 147-170 (in
Japanese). To吋o,K. and K. Hosoya (1998) Fukushima-shi
surikami-
gawa de saishu sareta fukudojo Noemαcheilus barba-tulus toni
(Dybowsky) (Noemacheilus barbatulus toni (Dybowsky) from the
Surikami River in Fukushima City). Fukushima Seibutsu, 41, 33-36
(in Japanese).
Trippel, E. A. and H. H. Harvey (2011) Reproductive responses of
five white sucker (Catostomus commer-sonz) populations in relation
to lake acidity. Cαnαdian Journαl of Fisheries and Aquαtic
Sciences, 44, 1018-1023.
Villeneuve, F., G. H. Copp, M. G. Fox and S. Stak,とnas(2005)
Interpopulation variation in growth and life-history traits of
the introduced sunfish, pumpkinseed Lepomis gibbosus, in southern
England. Journal of Applied Ichthyology, 21, 275-281.
Wallace, R. and K. Selman (1981) Cellular and dynamic aspecお
ofoocyte growth in teleosts. American Zoologist, 21, 325-343.
Yambe, H., A. Munakata, K. Aida, N. Fusetani and S. Kitamura
(2004) Reproductive cycle of smallmouth bass in Lake Akimoto.
Nippon Suisan Gakkaishi, 70, 896-906 (in Japanese with English
abstract).
Yashima, N., T Tamino and T Kitano (2011) Notes of Pungtungia
herzi and Noemancheilus barbatulus toni as domestic alien species
collected from Kaname River. Nαtural History Report of Kanagawa,
32, 109-113 (in Japanese).
Yodo, T and S. Kimura (2002) Gonadal maturation of large-mouth
Bass Micropterus salmoides in Lakes Shorenji and Nishinoko, Central
Japan. Nip戸onSuisan Gakkaishi, 68, 151-156 (in Japanese with
English abstract).
本州中部の温帯河川に定着したフクドジョウ Barbatulaareasの繁殖特性
畠山類・北野忠
神奈川県・金目川に定着した北海道原産のフクドジョウ Barbatulaoreasについて繁殖特性を調べ
た。雄では GSIの季節変化が不明瞭で,精液の出る個体が周年認められた。雌では GSIが季節的に
変化し, 3~ 4月に高く, 7~ 8月に低かった。卵巣の成熟段階は 3相に分けられ(卵黄蓄積相,成
熟相,休止相),産卵期の特徴を示す成熟相の卵巣は 3~ 7月に認められた。排卵後j慮、胞は満 1歳と
推定される体長100mm以下の個体でも認められ,解化の翌年には成熟すると判断された。第一卵群
の卵母細胞数は1,049~ 10,671で,体長増加に伴い累乗関数的に増加した。卵巣への卵黄蓄積は幅広
い水温と日長の条件下(7.5~ 20.8°C, 9 h 47 min~ 14 h 33
min)で進み,産卵期の開始は産卵適水
温(10.2~ 18.5℃)への移行により起こると考えられた。満 1歳で成熟する本個体群は,自然分布域
の個体群に比較して高い内的自然増加率を持つと考えられた。