An investigation of the Greenback Flounder, Rhombosolea ...
Transcript of An investigation of the Greenback Flounder, Rhombosolea ...
AN INVESTIGATION OF THE GREENB.ADK FLOUNDER,
RHOMBOSOI& m>IRINA GUNTHER
by
A thesis pre sen ted for the degree of Doctor of Philosophy in the University of Tasma:nia.
I.
II.
III.,
IV.
v.
VII.
VIII ..
IX.
x. XI.
XII ..
XIII.,
xrv.
XV.
XVI.
XVII.
CONTENTS
Introduction .....
System.a.Uc Position ...
Distribution and Habi. ta. t
Fishmg Methods
The Commercial Catch
samplmg
Total Length-Stanllard Length
Weight-Length ... ., .......... ..
Growth Rate and Age Determination
Spawni.r1g and Gonad Ma.turi ty e ... ,. .........
Length and Age at ]1 irs t lila turi ty .. .. • • • .. .,
Handedness, Reversal and Ambicolou.ra ti.on ..
Parasites
Raciation
Acknowledgm.en ·ts
References • .. •
" ..
Page
1
2
4
8
12
21
23
2ll-
31+-
47
66
70
75
76
97
98
99
I.. INTRODUCTION
Apart from the work of Thomson and Anderton ( 1921 ) »
]1inlay ( 1928), and Rapson ( 1940), l:i.ttle is known of the
biology of sou them. hemisphere Heterosoma ta ..
As it is usual for fishery il:1.ves tiga tiona to be first
directed towards commercially important species the relative
minor importance of the flatfishes in most southern countries
accounts for the small contributions made to the knowledge of
this interesting group. The three papers referred to above,
describe work done in New Zealand where flatfish :form about
ten per cent. of the landed weight of trawled scale fish or
seven per cent. of the total ca.tcll of all species ..
Although the catCh of the commercial species of
flounders and soles is less than one per cent. of' the total
scale fish catCh of Australia, they are nevertheless economically
impor·tant in the areas where they are caught due to the high
:market price they command.
The greenback flounder is the predomil:um t fla tt'ish of
Victorian and Tasmanian waters and forms n1ore than ninety per
cent. of the whole A.us tralian flatfish catch . ., The en tire
flounder fishery is limited to the opera tiona of on.sh.ore
fishermen and the numbers taken by either trawl or Danish
seine are negligible.,
- 2 -
This represents the first attempt to coni;·rilmte to the
biological knowledge of the species in Australia and it
should be poin·ted out that its contents should be regarded
as an introa.uctory rather a oornprehensive account of
the problems investigated$ 'l'hroughout the work the ·writer
been conscious ·the need for a far more extensive
sampling prograr.om.e ·than funds and f'acili ties per.m:i.. tted but it
is hoped that is presented will a useful guide to
future investigation the greenback fl01.mder.,
II. SYS~Dl:NJA11J:C POSI'l'J:ON
of the order Heteroson~ta®
ill New :Zealand but ...=~:.::;;;;;;.;;;;;;
one of four species of
All four species are l"epresen ted
the only member occurring in
Australian waters.. 'l'he Rhombosoleinae were first described.
by Gunther (1862) who published descriptions of six species ..
This mm1ber was added to in subsequent years but it was not
until 1926 that attempt was made to elucidate the
accumulated synonymy. This was ably undertaken by J.. R. Norman
d:u:r.•ing his taxonomic of flatfishes collected during the
cruises of F .I • 11Endeavour11 • In his report (Norman 1926) he
stated that he had not at·tempted to oomplete the synonjlln;y :t'or
every species but had cu•J.."'i""'"Ju..L 01.1. to include all of the more
important "''"'of•· ........ ichthyologists .. The four
species of ~~~~~:.;!; <.iUJ·',l~J""""''~ .... by Norman, namely ~.;;.;;;,;;;.;;;;.;;;; 7
3 -
lmo'll\n members
~~~:::.~:!:: .!~:-~::!.~ (part) Gunther, 1 p&
1882, p .. 1
1 ' p,. 11 1882~
P• 1 II 1906, 197; Stead, 1908, 1 04.;
' 36; 1 p. XIII;
Vfai te, 1 P• 1 . p .. . 'I! J '
' 1 P~ 1 '
p ..
p. 1
1 401; 1 p .. 1
1
p. 1 p. 1 1 '
1921' 1 1 . '
' p .. Lord & 1
p .. 1
' p.
p. 1
be
which failed to
the vvide This be con-
sidered section on the
The
occu.xrence
its
a
The
' i.t
as it is
be to as
s.
1
are
in Vfestern
range of
is somewhat
Tasmania, and
extent of
I.)'
I
in
the
es t'l.:tari.es
is
5 -
bays although it he..s been taken down to a
It be nineteen
from the of the commercial
limit is
fish
in in
A us
vdthin
the
three
of occurrence there is not
known. ..
arot.md ....... .,,a=• ..... a.
were small, (Blackburn &
In New ""'"'<:U-"" ... ..,. (1 )
nets in two to five
abund.an t outside the
in
of floun.der
1
was
taken dovm.
in
but was
to Graham observed
during the autumn was more common in the
but most were the where go
after that ;;;.;;.:;;._,;;,;~;;;;;..;;;;= did not
t the very shallow
flounder .::;;.:;:::!!!~~~ -...;;;;;,_;;;..;;..;..;.;.;,
it is common
in its young
.Although
the l:imi ts of its range,
able
water
is
and these localities are well
Such an area is near Hobart, in sou them
e:xpanse water eleven miles
the
the
suit-
Fig .. 1)
in
142(1
VICTORIA
, ..
& A 5 S STRAIT
~INDERS I,
9
SOU-THE AN
0 C E AN
144 146 148 150
Fig .. 1 Map of Victoria Tasmania mentioned the
- 6 -
from one ~.,.,r.,..,.. of a I
to sea channel about a of a mile
which to
thirty feet i:n the
are
water
oi' total area. flats are are covered
vlith beds fine
to bottom as spend most the deyligh.t hours
by a of' bottom a
on
worms .. Two enter Pi ttwa ter
influence on the
winter to sunm1er values for
- 19.,50 %o); slightly
value of 00 due to
in
tlmt can
and '
as it is
year. in
eastern a of r..abitat
a It has same of
rnud or an area of about 1 square
has range of to and the
- 7 -
of water varies £rom five to sixty :!.'he
and
any
total
Corner Inlet areas
and
catch of
Arthur, in southern
more :flounders than
per cent® of the
is a good
a non-estuarine habitat, direct contact with the
sea~ 'rhe port itself about miles long and varies
width one to two miles@ Water of depth from twenty to
thirty fathoms occupies most of the area and shallow flats are
oonfined the of the mouths of a few small
The of Port Arthu:r can be described as oceanic a;nd
large beds of .;;.;..-.~-""---~=;;;;.;;;,;:::,;:;;;. __ ~~.:::.t...-=
in temperature is from 1 2 .. 1 - 17. 8° C e
The range
E~lounders are not
there in q.uetll ti ty they are :L"'l t:b.n.e es tllaries but a.:re
nevertheless numerous enough to fished for conmercially.
in J.<:l.<:>il!.i;li.u ... a which are
suitable
Helens) and
for
are
and in
a.nd
it is
can be
sizes of the adult
the ·the
smaller
with Corner
as an
are found in
doubtful. It will be sho'\11'11 later i.'!'l 'Llle
the number of fish
The
Port
fish
- 8-
as was the percentage of male fish. The largest
propor'l;ion of males in any one
the lowest nil ..
was 12.7 per cent. and
FISHING ME'IiiODS
(a) Amateur fishing
A considerable cauan ti ty of floumlers are talcen by
or sport fishermen largely by the light and. me1;hod..,
Although it is impossible ·to gauge fue ex:ten t of "t;his
type of fishing in Tasmania it is know.n it accounts for
a large pro:portion of flounders trucen a:nd gives rise to many a
on the of the prof'essional :tisherm.en,. This
so because amateurs generally not muC".h concerned the
observance of the minimum leng-th laws, usually taking
fish they see often speax· unders:i.ze fish for The
au thor has seen j.ns runa teur spearers filling an a:pple
case with young f'ish the course of a night's fishing, and
men emptying on the shore rJefore leavi:ng,. :Many areas
are "WOrked by both prof'essional and amateur fishermen and it
fairly cornmon for -the former to cover same ground closely
following
discarded.,
in 1'asmania
period occux·s
taking
There is a five
'IJ!it.Lich may
closed season for flounders
to
June to October which to
a~ike so that the
the warmer mo:n ths.
spearers who
gives every
·wade to
- 9 -
of
es to reduce
were
the
In is no season areas
ere
some
the summer but cioea not the
on
amateurs to
more
means
cannot be
the fish that
the
are
ve.ry scarce
and vrere
- 10 -
as
dozen to be
Beach ••••• ,.n "I
being two consec.'U.tive
1
were
in great l'lWnb~~rs
dozen. I
at Browa 1 s
dozen
the net
years Ta:mar., ] 1or some years past the
have been sca:r·oe, fact almost
the Trumr and
have
they are as numerous as
The used time was
3
and nets were
inch. mesh
ei~f:i.ciency
to
mesh nets was
9 inches had been to
the
Huwever, it was
II ce:rta:L'l seascn unf:i t
should be
close season
food
these
t',rto :m.on ths
- 11 -
as the answer to
the bulk of the comrnercial :is
taken seine nets ::in some clue to and.
tmsuitable
fathoms in
i..11.ches, knot to lmot ..
is
9-12 feet
The nets v-ary from
depth with mesh
As the technique of beach
is well lmow.n u:nnecesstu·y that
flounder are often worked. in
A catch of shallow water i:n.s tead of at right angles to
five dozen marketable in the one hfml would be
considered
to i'isher:m.en
and the
by
are
o±" the
tible to con-
~'he moon also is said
play an :ilrrportan t role in the movements of the
fishing are when
to flood, ·the wind is very light,
tide ha.s
there
no moon.,
v~ater
Under these the
the
tide
to
11Vith
is very poor.
with low
move a.cross
The author
of
pressures,
been fow1d that
no tice(l Vlhils t
to be
conditions
u:nl:i.ke the ar11a teur
and
in
considered
is
done
f'ashioned
smne gauge. The
reflector
'l'his
:ts
an
as would be
of
- 12 -
in
do not allow more
xootorcycle
to
up to
three
use three
or vr:ire of the
the fish on the
mom1ted on a lJ.Uu.u . .~..<::> about four
'When can
Mesh nets are very rarely due, no
with the to the
over the years reasons.
'I'he the State De1omrtn1en
are inaccurate
Two
quanti~ fish
.u:oi.~LL,_rc;u_ by to
are required. to
their
'l1o establish
not tru1y
to
amateur
returns and
returns
state cf a
mnount of'
A considerable
who are
not or
it is
to
to
- 13 -
the terms men
the time fishing, and ef'i'ect of'
on Tasmania.
was made, are scanty prior an wa.s
to tem
a to be
their month These
were not vvri·ter but totals of
oorn:piled Jrisheries
All
are
(a.)
The to of from to
due to the "'""''""""'·"-'''"'"" of
the
all fish, were
'"~•~•vu lb However,
years was 11 million lb and 1 ..
lb.. the
of' to
19lt.5 and 2 .. 11 In comparison of the
the State the
therefore be
'l'he
years 1
relative
- 14-
by weight of
varies from
of the total f'ish
one to two per cent~
1 (These data are
species for the t~o
shown in Figure 2
and sb.ark omitted for convenience) where the
of ·the catches can be more easily compared. )
The 'rasmania.n floun.der ca·tch from records
the 1931 956 is sho'Wl"l. gra:J?hioally 'I' he
fluctuating nature of the histogl~arn from 1931 to 1939 is no
doubt due to a certain exte11. t to the inadequacies of the
s ta tis tical records.
at
must be macle
years contribute to
1 91.;5 and in tJ:lis
But as it seems lilcely f'rom evidence
to earlier allowance
natural changes in abun(lance .. The war
lack of info:r.mation between 1939 and
i;t is noteworthy that from 19~j to
i9lt.5 (when lack of manpower manifested :ttself in most
fisheries) the flounder is maintainet1 l1.0,000 lb.
It be out that the war, blackout
fish
of
to
where
1
the use of lights which the
no doubt the
so that
from the services a.nd in
lb.
returns from fishermen
1 with th.e
3 the catch :rises
to the extent
gave a indication of
1
'rABLm 1
CA 'I'C:H B"Y
SHOWING IMP011 'l'.AJ:\fCJ.il
YEAHS 1
GHE1WJBACK FLOill'ifJ)I~H
1 1955
species
catch
15,048
1l,.,
8
7,
1'una
3,
10,
9,
7,
3
'1
0 "' 0
C::J e ~
WEIGHT OF CATCH
0 0
SALMON
"' 0
WHITEBAIT
coo FLATHEAD
lTRUMPETER
lFLOUNOER
MULLET
PERCH
MACKEREL
GARFISH
TREVAL.LY
PARROT FISH
BREAM
M lSCELLANEOUS
SALMON
FLATHEAD 1=====;----l
TRUMPETER
GARFISH
coo
PARROT FISH F----. '-----..JMlSCELL.ANEOUS
(THOUSAND POUND)
"' 0 0
II.> VI 0
"' "' 0 "' 0 0 ----,-~
I I
I l
I
0 ,...
I
I I l
I I
I
I
I I
I
I I
I I
I I
I I
t l i 0 0 0 0 0 0 .o on .., t'l N
0
( SONOOd ONVSOOHJ.) H:>J.V:> 1VONNV
1
1 lb in 1953
tl::tat
the
( 1) The
to an
(
(3) The
in
In
men fairly
I•1rom 1
lb e.nd 19
1
decline from
but s
lb in 1 to
appear
I ~~ ma;;r 'be
make such an
case of the
reasons:-
is
in
f:tsh
of
lb which
the
are
are
by a
to
and are
number of men
1
the 1938 a.nd 1 stated the frora
In view
due to and
trend from 1 cannot be
are a more
years ..
.As :individual
of The
2.
The closed season
second
some par·ts of' the
about 300
summer tha..11 it is
that
be
a
11vinds and
1
of the
catches
the years
From the
to over-
had some
years 1947-1
those of
the
and these are
September 14
October 11"
that
be
winter
more
smmner and autumn when
calm. occur ..
DAR
1
1
1
1
1
'l'fJE
6
2
FLOUND:lfu1.
AND Sl!~COND
JAN. 1 -
16
no recm:-d
7,
10' 1
11 , 1
1 lb
1 1
ltACH
months
1 -
8
no record
8,178
:per
2,1 1b
17
in
order to compare s:i .. ze composi tio:n.
area relatively JJ:l;a.cc~es
Bay.,
Pittwater,
hook-sh.a,ped Tasrnan
area
from
distribution of
of the same net
srutq?les were
same netting
are
show a
in to the 20 em or
per cent.
......... ,,...,. commercially
the
and the
cOJ:i'Jnen ces
to be
to spearers
some
at
is
areas and
:ts
was
difference
the
group 'but
number
P:i.ttwater
worthy
that juvenile
1 ern at wtci.ch
fishery.,
from an
of
hauls were
"'""·"'"""" by
of
of
oases .. The
In the
number taken
this group
both places
are abundant
·togram of
the is
l,. om below the .uu..u ..... m .... m
10
8 1.1 ME &AY MARCH 1954
6 N" 301
4
"' .., i'! z
2 w v tt. w a.
0 .--> 12 v z ,.........
w t-- PITTWATER :::> a
"' 10 tt. u.
N = 209
8 r-- f--r--
r--f-
6
- f- ' 4
1--
f- ..--.--
1- rt r- h ITl 2
0 25 30 10 15 20
TOTAl. l.ENGTH (em.)
- 18
length .. In advancing the above contention it is assumed
that p:t"'f'essional fishermen do not take any ty of
below the length ( 230 mm) ru1d. considering the
of disposal for 1-:Jrofi t the feels that this is a
assumption ..
It is realiz<:J('i, however, that san~les represented by
the two histograms are or duration
to be EUJ.yth:i.ng more than a on which to advance a hypothesis
regard.ing the effect amateur on the flounder
Hovrever, appears that if spearing has been detrimental to
the professional it throug)l the
nmnber of flounders attain:i.ng legal size rather
the fecundity of the population$
(b) 111he Catch -Ec::onomic Ir~portance
Of the forty-three main species of edible teleostean :f'ish
taken :in Victorian waters the flounder lies tenth in order
catch weight and commands the highes·t price.. The South
roost expensive fish on the market in Victoria varying six
to nine shillings per pound a.s from to six
per pound for ll'rom 1 to 1 the
fish catch of 1 2. 8 mill::ton lb
tha. t period the
between 1.3- 1.7 per 5 shows the 1 teleostean
catch order of
·- 1
In Victoria, unl:Uce Ta.srn,:mia, there a well
central fish market situated in llk~lbourne through which the
bu1k of the fish sold in the State :passese There :i .. s a
tend.ency for to be bour,h t diret}t from the
to a ext en by guest-houses, hotels, and the l:Uce but
it to assume thai; amount srnall to be
for the purposes of on
flounder catche shmvn in I<'igure 5 and ~:able 3 are taken
from market records and. have been checked. with
are not usually
included :in their
6 shows the ···~·~;;;~··- of the from
1 vd th a trend curve
mnoo the data with a moving average <Jf' three.
~f.'he drop in
depression
mirl showr::: the
toot time ancl the even lovrer in the
lack of manpower to the war ..
But ::tt is thc·Yt eve:r.t a:t'ter enjoying a dur:i.ng
the la:tter period the 110stwar d.oes not i.t~~
level as in 1'asma.rda, and 1 a slight downwa.rd trend is
and. the marlcet dern.and.
ou tUned for ~ras:man:i.a0
(i) 'rhe lack of
as regF.:~.rds numbers
flounder apply to as has been
(c) Conclusions
catch data to 1 9~5, lim:i. t
\:13dd'9'NS
\.0 It\ CT\
l:I30N001.:l ~
~ e OY3HJ.V,.:l >l::lO't:l w
!1} ·a q)
VW3'dll fir
Q'd'9'H::l11d 13 ~
g "' HSI.:ll:IV!l Ill
~ ~ •1"1 1M
Qlf3HJ.'t'1::1 QNifS q)
~ 11.1
N01"111fS
!~ ~ 0
J.311nl"' f>~ •1"1 t>g Qlf::IHJ.¥1::1 'ti3!>1J. ~ .~
VJ.nO::>If'tll;IVII t.r\ .,
bl) 0 0 0 0 ·n 0 0 0 1%1 ~ Q Ill
(sONOOd ONVSOOHJ.) H::lJ.Y::l ::10 J.H!li3M
The
LB
1934 1 1 ~ 81,.9 27' 1
1
1 196, 1 1 ,208
63
1 1
1 l,.2~
1
1 1 9760
1 1
1 1
1 1 62, 1 1
1 1 112
1950 1
1
1 1 1
1953 1 ,012 1.q., 1
1 150, 6 6,849 1 16l,j., 19' 1 11,7 1
350
,... 300 <I) 0 z :::> 0 Q.
250
:X: u .... 150 <( u
...1 <( ::;; z 100 z <(
so
r-
1-
1-
1-
r
01930
6
~
~ r-
/'
"' / 1--1---
1935
..--
~
h .--" ...... ,.,; ...._ ........ ,....-
~r --- ......__, 1--
\ L v - 1--
-
~ 1--
1940 1945 !950 !955
three,.
- 20 -
to the ensuing te:n years the period from which any conclusion
can be d:x:a-vvn as to the state of the flounder fishery Tasmania~
(ii) Although it cannot be established. that the decline
1n total catch since 19115 in part been due a decrease
abundance ·there is some evidence that the activity of
spearers may have the numbers of legal f'ish available,.
(iii) The present ~~u.J.L.w.~/M!!! legal length of inC'..hes does
not give maturing fish adequate protection.. (This question
will be covered a later section of this )
(iv) The
environmental factors are unrelated (a), (b), or (c)~
(d) Conclusions
(i) 'l'he statistics available m~e a reasonable indication
of the catches for this State but until more detailed information
such as the number of' shots of the net made throuf)lout the
the quantity of used, and the selectivity of the mesh it
will be to assess accu:l:'a tely the :t'ishing
(ii) The Victorian fishery is roore stable of
r.l'asmania, showing sma.ller fluctuations the catch from year
to year. However, the period from 1946-1956 can be regard.ed
as a more accurate indication of the state of i;he fishery because
during these recent been high and the demand
for flounders tunsatisfied.., Prior 1911-6 demand was affected
by the economic of the 1930-1938 period and
:production with manpmvt:r shortage during the war years.,
to
increase its and a:n,y subsequent be
expl~:dned as a depletion stock.,
After the vm.r han<lling fa.cili ties as transport,
qu.ali ty ~ and supply ice improved wh.i.ch ""u• •. ;;vLa .. !:e~.l~ovu. Hld..J'-I..Illl,.l.m
product;ion.,
Thus the slight d_mmvifa.r'd
light of available statistics the
population over-exploitation.,
VI,. SAMPLING
(a) Methods
It was not procedure of
observat-ions on market material
investigation as a ln.;."U'ke t to in
soon the world war., All f:tsh is direct ·to
several some of 'Whom ovrn retail shops ancl ·the
demand. flounders is they are sold consumers
iumed.ia tely., In it is the cu.s tom to
serve flounder complete save the v:i.scera whi<:".h are
,.,.,,,.,"{,..,.r~ by the f'ishe:rmen as soon ati possil)le
It is also impossible rernove the without
either the or
inves
commercial 'rhe
u:nders w:ll,Jc<u.C~.u..Lc fina:ncial
of Hence
all used in the
- 22-
were
were
of
(i)
'WaS used to
the net were:
on 'When
an eleven
·the the
on the
the
inch mesh was
to
were
were
J?or the
fish were
PBJ)er a
or least
U'-•"J'""' not or
of
were used
The net was
net
net was
to 'be for
as and from
the
(b)
were
order
the total
were
were wet
I'c is
terms
be
th
was measured with
other
was done on a
excess
to
'I'he
to e:xpress
to
standard a value purposes of
in the case o:t' flounder, wi·th
was
The a 1723
110 rum :nearest
and the mean. VJl\S
group!!> is 1!1 igure 7 ..
:from th£~ extre.1ne f.'evr
all about a
is
of'
two other
(G-irard),
( 1 ) , and the
( 1950) 0
per cent .. .. of'
the y:::: X ""
length one to
·the
X 812 y or
y ·- 1. X
VIII ..
The 'WaS
reasons:
Fig. 7
~ E u
v
J: .... ~ z IJJ ..J
..J <(
b
40
30
.... 20
10
STANDARD LENGTH (em.)
The total lengtq/standard length relationship in the greenback floundere Measurements are taken from representatives of 1:x>th sexes.,
]':i.rstly to measure the seasonal change in the relationshi,p
and to correlate it with :bwreasea. weight due to gonad development ..
Secondly to determine the leng·t;h which the weight incre&~e
is ~m.i table define an optimum size for fishing.,
ThirClly to compare the weight/length relation of
represen.ta:tive SWilJ?les of f'lounders from
possessing significantly di.f'f'erent meristic characte:t-i.stics.
That the weight/length index of a species varies co11sider-
ably with the year, state of gonads, and feeding con-
ditions been s:hovm by Clark ( 1928) and Ancona ( 19 37) ..
Thus to arrive at a mean value it wa.s necessa.:t"Y
treat data from a series of samples extending over a period
twelve months., Although the most obvious cause o:C cha.ng:ing
weight/lengt.h ancl decrease :i.n gonad
weight, the changes occurring throughout ·!:;he year are not due
to this alone"' It appears that l:i.nked vri th the development
of the gow:t.d to maturity is the building up of body fats and '
tissue .. This will be evident when the s ea.sonal variation
males shows co~para.ble fluctuations w:t th ·!:;he f'emaJ.e
aJ.. though the relative weight of' gonad per weight of fish is
very different for sexes .. A ripe ovro."Y usually fo:rms
about 17 .. .5 per cent,. of' the total weight of the fish and
s:pent about 1,.1 per cent .. In the male however the testis
exceeds 1 @ 3 per ce:n t.. anrl when per
of' the
(a) :Methocia
of'
1 the
range in
1
The
range 1 over
th,ere
In both ·the mean
This
8 which were are
1'able
of' in ·10 and ·11
and the are seen ·to e.1:;out the curves
were
Y1bere C
by L .. The
from the
of the fish is
FEMALES • •
MALES K---X
8 The
LOG. TOTAL LENGTH
... :1: ~ w ill:
..I < ... 0 ... z < w ::i
ci 0 ..I
9
FEMALES e e
MALES o---o
The
0
LOG. TOTAL LENGTH
vreight on flounders from
June 1954 to May 1
for for the
'l'HE MJJ:.!Uf WEIGHT OF JUV.ENIIlll AND ADULT PI TTWATER ]1L0UNDERS FOR EACH CENTIMETRE OF TO'l'AL lENGTH
urrr.li:RV AlS OF l'OTAL lENGTH
mm
1 14 19o5
11
12.5-1.3lr- 0
1 41+ 8
1 3
155-1 .1
165-17lj" .6
1 84. 8
1 94 7
1 3
1 0
1 7
275-284
1
22 • .5
.5 5
i,.5* 1
51.4
7
5 85.1
~1
117 .o 1 4
1 8
176~2
90.0
3
118~0
134.6
1 3
173.5
195.,0
.. o
83
.6
313.5
305-314 9
466.6
1
Fig. 10
180
160
140
120
n
FEMALES e •
MALES '"X----X
... viOO
IX ~ 1<.1
ll: 80 .J c 1-0 1-
60
40
oL-----~------~----~~----~------L------L----~ 100 120 180 200 220 240
TOTAL LENGTH (mm.)
The weight,/length relationship in juvenile male and f~e flounders from Pi ttwa ter, March 1954.
500
FEMALES •---•
MALES X-- -ll
400
,., ~ 300 / ... / :t / !2 / "' lO / .... / .. / s / ...
/ /
200 /x
100
160 260
TOTAL LENGTH (ftlm,)
Fig. 11 weight/length relationship adult male and flounders data over "the of twelve
, June 1 -May 1955.
another 'Z
Vt,triation, K = W/L:; will be discussed
If Y the weight expressed in g;m X the ·total length
in mrn equations for the cu:r"Ves are;
March 19511• sample (TI'ig., 10)
Males Y = Se5427 + 2~802 (Log X) or Y = .. 000031~~9 x2e802
]'em.ales Log Y = 08 + 3.040 (I,og X) or Y = x3
June 1951,. - May 1955 sample (]'ig., 11 )
Males Log Y :;;: 4.0165 + 1 (Log X) or Y = l''ema.les y:::: +
(b)
The values
1<he 11 0-240 rnm fish 823 for the larger 170-3l10 rnm
J?or the were 802 and 2.611. The
difference in values of 11nu samples (0~138 for
females and o. 2 for males) 1i'Vas due to the fish being
eollectec1 throughout twelve roonths ·whihtt the fish
constituted a single month's
It is evident that as they older the female fish
increase in weight for length at a sliglrtly greater than
the although this relationship does not hold young
fish.
1 nnn male fish have a weight/length factor
females. This is also in the intersection of tt~
length plots of the same
That this is not an due
met
1
is borne out cu!'V'es 1 70-.3l~<O mm
also mm .. The
for also show a meet.,
Hagerman (i Orcutt ( 1
sexes Dover sole and
which ·the male
other. weight/length CUX'Ves
Dover parallel but as are
mm standard were
a-ppear to meet at about 1 the
not
the
of
It livill be
fish
Unl:il~e a
'l'hus a
to
200 :mm may
season" I
:is; be tv'reen
number of o
do not lie
has been
occurs
the
is about
ova that
are
and
ripe
a:pproaches the
mnsidera.bly
'be
of an ovrary
not
the
up by
not exist
of
- 29 -
the ovary
a similar
of' th.e
In the
of the
the tef3tis is
t more than 0.06
a.nc1
to the same
:pass a
body wall
ul ti:m.a tely
such a
a:pplied to
differences
takes
thrul that
assume the found
In order to in ·this
be ·tween two fish were
.,.-a ... ,_ and ~rere used
less than 1 :mm or mm in
were
All fish 1.vere three
from
The data are shown in 'l'a.ble 5 and. the regression of
weight on log length for the8e two samples is presented in
IYigure 1 2. 'J:he two coefficie:n. ts
being ,3.052 ru1d Port Sorell
The equations for the cuMres are:
Log Y ~· 9675 + .3
or
Port Sorell Log y = 5. 1lf.81 +
or
size (~omposi tion
a value of
(Log X)
967 967
X)
967.
of the same
:Ln. the we:i.ght/length mu.s t be due to one or more
following causes.
( i)
( )
(iii)
:in mean gonad spawning
It w:tll be shmvn in a section of the paper there
are certain
flotmders the tviTO areas 'but it that ·the cause
of weigiJ.t/length rn.o:r·e jus tif:tably lies vr.i. th ( ii) than
(i)~ to consider the
of (
the curves and. the cx.mverge tov1a1"ds
their it seems highly that the vreight/
length of' inuna ture
The mean of the 1 mm group 'by
TABLE 5
7l:!E Vv'EI.GIEL'/LENG~L'H H:l~LATIONSlliP O:B' .ADUW~ :B'ENJ.ALB: ]'LOUNDF.JZS FRO!'vl: TWO LOCAI.i'J:'l'IES
INTE:HVALS 011' TOTAL LENGTH mm Ivllt1AN Vl!UGHT GM Port Sorell
185-19l!- f33 ~ 1 82.,8
195-201+ 96 .. ~. 96.9
205-21~. 106.8 115.8
121+. 7 131 .1
225-234 139.2 1~ .. 9.lj.
235-241+ 165.7 170.6
21.~-2511- 177.5 201.1
20l, ... 6 210.3
265-274. 236.0 2411-•2
275-284 249.5 261 e9
285-291.1- 279.2 299.8
295-301{. 330.1 351 ... 3
PITTWATER
PORT SORE~~
2>3500 2-1500
12 o:f :fe:n.al.e adult
mature f'ir3h
it was not
to
from i'h:'i..s :it is n10re
:i.n mature
In the tho of the
·the condition
c (
an index o:t'
:t•elati.vc to would be
body
the
to
to the of
It wa1.1 therefore c
of' the seasonal
in
Some
c
(1 ll
(1
In the
each
eluded
'J'IIill be
(1
..
It
the
as
of
32
shown. more
who
II
as the case
have
hold
net
use
are
trend
and
(1
' Kes·teven (1
' Le (1 ) '
dra1i1/rl
to
to
was
mean mean
the small number male
1
the sexes it
same
the
were
do net
as
to some
a.s
con-·
of'
as there
TABLE 6
Iv.lAH~ TO .u,,.,.,.._,,., HA:t'IO IN SAMPU~S WEIGH'l'/LENGTH
Jun. 1 1600
1 50.0 100
1 . 50 .. 5 1 . 1 .2 1
0
1 .2
Dec 0 : 1 ~0 103
0 98~0 9B
•1 . 7.8 92 ~
1 . 1 8 ~
8 .. J+
May 1 6.8
1 11; ... 1 99
1 19.6 98
1 28.6 86
1 37 .. 8 113
1 5h.5 1
Nov. 1 21.0 1
Dec. 1 35.6 107
- 33 -
is a higher proportion of male f'lounders :i.n the three monthly
Port Sorell samples than in corresponding Pi.ttwa.ter samples ..
The fo11J1er were all by beach seine and the latter by s:pear.,
ted below and presented graphMonthly values of C are
ically in li'igurt] 13$ l•'or coJnv<::m:l.e:rJLOC both male and
·values been ...... ~, .... .~.-..u. by 1 o3.
Whilst the condition of' greenbac.1lc flound.ers does
not
can be
during the ·what fluotua tiona do
correlated with the spa'lfllning cycle ..
has a winter spawning season that exter1ds over a of up
to eight months on }JUi table conditions,
and the .~.-<;;;!lli:;l,.wJ •• t.u.16 four mou th.s No·vE>.mber to ]'ebruary,
alth.ough f:i.sh be found in :roe the majority of'
them ar·e in the In 1 the
1)egins to fall in .l1.ugust 1 the male value more sharply than the
female, until it rE}aches its minimum in October,. However, in
NoVG.-'ffiber it ccn:unences to r:i.se again until January of the following
year when it
that year.
a point not short of maximum for
'rhe sudden ax-or~ in ]'e'bruary is sur:prising but
cid.es with the month at which the mean ova diarn.der J .. s at its
lowest (see li'igur~} 2.3).. ])ur:i.ng the remainder of 1 11C11
no time reaches the equivalent of value of 195lt..
vmich leads to assumption that environmental conditions
were not sui table as long a period in the latter year.
This effect shows up to the same degree in the male g.,ra;ph,
0·120~ • ,, , \ , \ / \
0•110. \ \
0 0 g. " v
1&. 0 0·038
"' w :;:) ...1 < >
13
\ \ \
\ ' \ I \ I
' I \ I
\ ,,/ •""
1954
MALE ------FEMALE
!955
~'he sudden 11 0 11 in October obviously due to a late
r~pawning run as a similar. peale oce-'Urs for that month
Figure 23$
It has been pointed out that there is a great dif'ference
in weight between the of the tv110 sexes.. Notwithstanding
the two G"llrves a:r:e of similar form trend which .t .. uu.J..v~:~.
the possibility that other such as the f'onnEtt:ion ancl
a:bsorption fat tissue and
food contribute to the
the year*
of
of adequate seasonal
of 110 11 throughout
IX~ GHOWTH RA'l'Jn AND AGFJ DET.ER1v1INATION
well-lmcwvn methods of approac:h to the problem
ar1d grovrl;h determination were the
(
Unlike somt:.: northern hemisphere the scales of the
greenback are 1J.seless age
from d.ifferent n<:~1C'oC!'< of body were
any
When
impression
they mig,ht be of use.,
(b) Otoliths
were studied the wr:i.ter was ·under
also were unsatisfactory for growth
inves tiga.tion an.d. collection of' ·them was not as as
other c:ri teria
care in the selection
it might
they were
of
been .. Hovrever, in the
to an.d
became to follow the
for the first three years of the fish
approached 300 rnm a high proportion of otoliths un-
readable due to ·thei.r opaqueness and no fish longer
1:han. 320 mm otoliths that could be read with certainty ..
In order to ascer·tain whether the older
facili:tated
advantage.,
in the
specimens were thus treated to no
The obsct.l:l.'i ty of the a.uuu. ........ was found to lie not
of the but in the tendency
the annuli to become opaque as age of the fish increased . .,
It ·wa.s that the o'l::oli ths coulo. be most satisfactorily
removed from the :f'lounder 'by with a.
knife bet"'<Yeen the eyes and the :tnsertion the right
otoliths can then be lifted ou·t
They we:re not immediately visible and had to be
for with fo:r.ceJ?S.. After o had been cleaned
by rubb:l.ng bet-ween the f:i.ngers they vre1~e in small
which was ·written the length of the i':tsh together
·with the place and date of collectiorJ® Where both
otoliths were collected' as nearly 10 per cent® exhibited
degrees of one or the other .. In some cases
both otoliths were affected. by this cond.ition~
J:l'or reading purposes the otoliths were placed m1der water
in a Petri d:i.sh, the bottom of which was covered by a
of blacl( wax, and viewed by means of a low power dissecting
was
v .... t::"'-'"''u.. about nine from
otolith l:>e read by
the flound.er almost f'la t
c:onvex
the
About
of ·was not:i.c:ed
zones but clove oil and
'l'he
coula. be
1vithout the
ur1d.er a lens.
Molander ( 1 on
the
o~.-u.·.u.Jl!L and summer
:rm:;:w.e:cL d.uring the
s 0
zone formation with first
and in
COII~1;>0Si tion Of
to the
of o
The
A
zones ancl their
season
a
such a manner tlla t
One
other
water a
tinction between
not
of
only be seen
has shown
zone
t:he opaque
in the
·width is
nuclei.
fish
A
It
thought that fish possessing such were spaw.nerl in late summer
and "l;l1eir early development took place what is a normally
slow g,rowing period., On the whole the otA>li ths 'Nere easy
to ovdng to ·the of superm.m1ery or false s..mmli ..
Before the use otolith measur(~ents
calculating :i.n termediat;e lengths the proporti.onal growth
anrl otolith must be es tablishecL. Although <Tensen ( 19.38)
discovered that f'or the and. growth was
agreemen:t was found between the two for the
as
1vell as the and posterior
ma:cgins were compared with the length and it wa13 found that
of ·these mea:::mrc':lmen ts ·the 'best with the length
was found ·the (lis tance the cen.tre the to
the 'l.'hi:::: measurement will l)e referred to as
the otolith 1"f.i.d th.,
l:i.ne otolith "<vicHh on fish length
:l!'igure 1l1• incl.i.eates that the growth and is
proportionate flmm.der~~ between 1.3 - 32 em total length.
As the regression li:ne the ·y (otolith vd.dth) axis a.t
1 ~m<l does not pass through the origin this ·was
from 'both the otolith wldth measurements and the
clis tance from the nucleus to each annulus :i.11 the determina. tion
of intermediate lengths. This ad,justs the proportionality end
so perrrd.ts the use of the formula LJ. = (r..J+>/W)l ·to ca.l<..'Ulate th<.~ .. ..~.· a
301
25~ :> 0
"' 20 ...J < v "' -:i 15 .... 0
i :z: .... 1or :::; 0 i 1-0
J
10 15 20 25 30 32 TOTAL LENGTH (em}
The width on f':ish
- 38-
intermedi.a te leng-ths0 The following notation is ur1ed the
above e::x:press:i.on.-
1 a
:lntermediate length
total fish leng·th
of otolith measured from
margin. to ventral or more
centre of nucleus to annulus
Suecess:i.ve an:nul:i e.re '
1 a2' and
It was
the
of
L.l. 1·
to use the
ana
the
·the o tc>li th
..
the
it was
' and
annulus
t;o age
it is necessary to seleet a birthclay month.Q month
represents the period which ·the pass from one age
e;roup t.o the and it is cxmvenien t to the
mont:h V'l.hich The long
the such a
birthday rnon th As the month of appro Yi·-
mB .. tely in the mj.ddle of' the spair<~ning season it was as
the month and the 31 s t day as the b:trthday ..
f'orma tion of' the mid of the annulus may also 1)e takoo
to o c<.m.r in the w.hole period. of the laying O.ov111 of the
annulu::; from May to
if the of' the age are
been
so that
the
the
than
To
the nucleus to the outside
each. be
three rnon ths 1
this the g,rOUJ?S
I+, II+, and r:~o on,
of all the
were drt.l11i-'ll occurs
the of As
out t;he a.n:nulus i~~
season ancl tJ.1r;) months
size values of
'l'able
the Y
:ln eaeh age g,roup
in
is show:n
with
It be
been
'l'he
oi~
age g;:roups is not :i.s r1ue to th.e
of' the
'l'he
means of the
(i)
OVt'lr
curve in
(
the of fish was
15 has been drawn
used
OF
13 A i
19 20 21
Mean Otolith ( )
TA.BLE 7
Q ./
4 )1.,6
9$ 6 4
9wr1
=
2 3
10.2
21!W{)
19 9
6
----1 5 4
NU:MBE;H ii.CrJ GROUP
I1iJNG'1H
(em. 0+
13 1
111- 3 1
15 1 7
16 11
17
1
19 9
20 10
,.,,.., •:•~ 2 1
1 3
2 7
25 1 2
'''" 2
7
~··
30 1 2
31 1 1
1
... -----
AGE GROUPS
____ ... ----
Fige 15 the flounder for the life as derived from
:L."ldicates fish..
were by and as soon as
to well the dinghy~ Wll."l
done 1:Je t•~reen 9 p.,m .. fish reserved
for were abou·t 9 a .. m~ so
any could be rej In
way the most f:i.sh \'vert.~
Pe·tersen disc vrere used.
:in the manner
hand in such the in the
or Side nn1"\A1"m<'\j;j.
awl
from the centre of the
loaded
the 'l'he was
turns vdth
onto tihe
and the
of'
then bent
dovvn close
1>rere
the pro gramme white
of
close
on the
out for
on
vv:tth the
as evidenced
a rr.onthlb
the
It was
the
sand
tencled
*I' he
the
was :in
wear the
of wont tags that been
used and ~~=v·~~ on
to
to
on
:eo observe the
flounders 13 15 em
in the
worms a week
(
two
of the
reeovered ·was
of the tags on the several
ina were
10 -
per
<..'Ornmen.ced
not grow
twelve weeks
aerator a
were
Cf!n and the U<~diH.l'w.!.
of the
this were returned
that were
8 or 1 ~ per
two
so as
The
six
mea.suremen t
of'
to
returns and this
in
of
the
It was ,. ,..,,.."'
one
to
1 em. between the
to measure to
or for a or
to nine
one hundred and ~dxty~
were
area.
ton to the
one hundred and
the southern
1;o
c1oes 11ot travel
vdthin a
but
area. It :might
l)e tbat
it,
movem.en ts the
of
the case of
M~:.mzer
over !'l o:f' a
other
In the
9 shows the nurnl1er
group of
e.ble th~::d; none of the ·1 0 - 15 em
the in the
did
should
account
It 1nc1.y v:ell
was from
the number
this are
It
were returned
size groups~
been
that
as ·111ras
per
that
A
of the small Bizes that
them and ama tetU'
'be lo·~h to d:i.sclose the
lENG~~H
(an groups ·:·;-;.:~
10 1 0 0
1'1 1h 0 0
12 0 0
13 0
14 14 0 0
15 0 0
16 1 17
1"7 24 0 0
18 20 2 1
19 2 1l ..
20 40 2
1 1~96
4
')"I: '-,.. 6 11,. 76
24 23 !J.. 17.
2 10.
1!t" 4
9 0 0
3 0 0
1 0 0
30 2 0 0
F:ig., 16 The and total
IO
7l
"' 0 l> "0 -i c , "' 0
for reasons .. On the other
the small could due
causes and of ·bhe Manzer (1
th9. t the size of the could not be
the munber of or ·the
but
v>'e:re in the
16 (
(1
returned fish
This
nurnbered to
smt:.tlles t fish
ern group~
1
ern.
11 where other
~rhe
were
his
When the tv<u
not
in
do the means
the
of
decreases viii th
the
was in the
season.,
1 7 • The t:i:n1E:
of' the
are
column of
be
the
measured both times by
li'!Sli
+ ± 2.
1
350r
17
• MEASURED BY AUTHOR ON RECAPTURE ' LENGTH WHEN TAGGED • LENGTH ON RECAPTURE
:L"l the 11 where more
T.t\.BLE 1
lk;sULTS Oil
2 3 3 3 4 8 5 tJ
v .. 15 7 '? 7t 8 .,1
<:> ? 9 • 99 z;:; 10 .,1
368 28 Q 0 _.,
? ? .j I
232 15 ? 220 ? 0 16
186 ? 1 17 57 4 18
4 19
220 22 23
be
beyon(l
has
shows
any
to wh:i.ch
been
s 2
to
on over a
be
with the
that of use, line 15,
as
not
which for over and a
half years was by the finder to have "tail
away11 was at
a length mm. However, the
growth this it seems that a
at fourth year have a length the
m:m ..
The
in
( cl) Frequency
the
upon fish a.t the same size
The ra:nge in
an
the
some extent
In
extended
There
'to measure
1)y ·the
was
to overcome the
season of
110 fish 1narket
numl)ers
were
con-
and
the same
brood. result ..
moctes :tn
this may "be overcome to
of
was
caused
it 'W"8.S not
areas f:i.shed a:nd ·tho gear used®
of and fish
vrere rr:here were also
o:t: IV+ ana. fish to clue g.rowth these two
However :is some of the presence of
groups over a some others
a moc1al
'J:he
be of
In the t.~.rves
em for
there is
The cc:l!mot be
occur at and
em moC:le :ls
e:;cis terwe of two
season.,
:ts 1ty the
1 em
1
is ·w:tth the
ure
were
used as the number
mon
months
slti.ft of 2
In
fish us
mo<les
22 em
nineteen
:i . .n
was
1
over the fom:- mo:r.1.
growth
0*6 em
tvm
:t-roveniber vvhere two
the 21 an
error or the
traci;ed
in
August ·J
in
an increase
andiH+ from
19
the
the broken lines dra:\Vl1 through mtrvesa '!.'he group
e,an be more than the both it
18
20
30
20
10
22. XII. 54
10
38~~------~~~--1--L--------~~~-}-L~--~~~--~~
20
10
3g~L-----~~~=?--~L_----~~~=---~~----_2~~~~--l
20
10
TOTAL LENGTH (em)
25 30 35
'I'ABLEl 12
STA~'ISTICS OF FEMALE FIA)UNDERS :E'ROM WHICH THE DATA PLOTTED IN FIGURE 18 WERE TAKEN (MEAStJl?EMENTS IN MM)
n ::: :NUMBER EXA.ti!INED A.M. = AHI 'IHMETIC lll[t!lN S.D .. :::: STANDi\.RD DEVIA'I~ON S.E .. :::: S1'ANDARD :E::RR.OR OF THE MEAN
MONTH MODE S.E.,.
1954 June 19-30 92 22 23 .. 4 .±. 2.64 .± o. July '17-.33 96 23 23 .. 6 : .±. 3- ± 0.33
August 1 ·102 2-4 24.$1 .±. 3.21 ± 0$32
Septembe:r 19-.33 105 ~ .• 5 .t 2.68 .:!;, 0.26
Oct-<Jber 20-33 96 24 24 ... 6 ± 2.82 ± o. November 20-32 104 & 24 .. 2 ± 3.09 .±. 0,.30
Deceniber & 24 ... 6 .:t 91 .± 0.29
1955 ,January 19-.33 88 23 .. 6 ±. 2.74 .± o.
~,ebruary 19-.31 100 22 1 ± 2.15 ± 0.21
:.March 19-3h 93 22 2h.1 ± 3 .. 11-0 ± 0.35
April 20-33 87 22 25.7 .± 3.38 ± 0.37
May 19-.33 86 22 23.2 ± 92 ± 0.31
June 19-29 93 23.0 ± 2.38 ± 0.25
July 19-.36 91 22 23.1 .t 3. 20 ± 0.34
August 18-.30 85 22 23.3 ·± 25 .± 0.24.
September 17-34. 113 23 23 .. !~o .± 2. 74 .:!:. 0.26
October 20-.34 43 23 23.5 .± 2.98 ± O.l~
November 18-32 102 22 22.3 ± 2.63 .:!;, 0.26
December 19-33 104 22 23.0 ± 2.41 ± 0.24
19
20 15 10
5
15 10
5
20 15 10
AUGUST 1954
5 20L_~~---+~~~~~~==~--
15 > 10 u 5 z
~ ,'~l .. 20 ~~~~~--r-~-r------~~~e=~~---j ... 1955
15 10
5
20 15 to
5
15 10
5 0~-L--L--------d~-=~--~~~--~~
'![~--~~------~~------~~
thftt tb.e fastest
The summed
of
]lrom the
yea.r of
male ancl
by loss than 0~5 ern ~:md the mean
thril
of
em
the
a mean
13.
rate dec:rc:)ases to
mm a month and
rate the mm and
the {'J:nc1 the year
The seconcl third rates are
clemons tra te a
it is est~nated to
The of'
from to
to fourth year
of 8 mm per
0 ern.
,,_,,.u>.JJ lVUl.'rrJRI ~lY
and
350
300
9oo 150
Fig. 20
~ 20 MONTHLY SAMPLES (Ill. 54 - Xii. SS) --
d' 20 (IIi. 54 - xli. ss) -··--·-----·
~ 12 (vi. 54 - v. ss) ------
, ... -....... ' ' ' ' ,l '\
I. \ I •,
I \ I ,, __ ..... -, I \
I \ I \
{' \ I \ I \
I \ : ', : ' .... __ .... I ''•....,.,
.:.:.f. ... --:·········--·······-···-·-. .... _ -··--····· '•'-'= ...
200 250 300
TOTAL LENGTH (mm.}
f'l.ou>"'lders examined of the
400
1955
1
1955
1.3
CID, LENGTH lP.BEQUENCY CURVES SHOWN IN
n = NmlBER EXAMINEID A .. M.. ARI ~!:EMETIC lirE!N S.D.. STANDARD DEVIATION S@E .. = STANDARD ERROR THE .MEAN
,QAL~\;.'&1 IN TOTAL Llfu'm'IH
(mm)
1
1
1
n
23
S.E ..
+ 07
± 19
Cl.evelopmen t of ova in ~;.-.;~;.;..'-·=·;;;;:;:;.;;;;; was made somewhat
by fottr :factors®
l~:Lrs tly, the spawning season was found to b1;; greatly
prolonged;
samples was lovr;
and
EIJ.ighi;ly the
, the proportion
third.ly, running
stages of'
male f':Lsh in the
femal.e~1 were
OV'l'JXY
As the length of the spawning season be dealt with
:i:n sect:lon it wlJ..l suff'icien t to state briefly
O'Ver a of months, al thoug.,h
some fish. wi ·l,h o:r ova b<::li encountered any
month of the ~'he :manner :i.n whi.ch a prolonged spa:vvn:i.ng
growth iie ·term:i.na t:Lon has 1:Jeen in the
section and the s tu.<l,y of adole::o;cence and age a.t maturity
s:irnilarly rendereii by this The rnore
the sea~;on the will be :Ln
size of d.evelopi:ng ova at any chosen t::bne of observation~ This
to Vl'he:n following g;rowth of ova
in frequency dir~ t:r.·ibu tions from month to mon tho
SeC'..ondly, bc1cause of the difficulty of captur:tng ms.tt~re ana.
ripe males d.u:rin.g the invest:tgat::i.on, and the absence adequate
observational s it was necessary to confine
study of rna tu.ri ty and spawning to female Although
the 10 - 17 em flounders the percentage of males
between • 0 and 56.7 per , as rna turi ty was reached the
the
to the
of
H3
:Ln
over the length
or
The
was 18 an
f::i.ah
so that
the of -the rurve
em :ln 21 would be mature.
curve ·the same
of
of the sexes
the
"£.1.'""""'''-'• Kav~asaki and.
1
shows
·- 0. 6 per eent.
tlu; alt'lo s t
sex
( 1 95'1 )
two groups the sex
the
age.
one h1.mclre(l
(1
:may
) showed.
or decr.ceas e
number of cisoos per
of to 1100 in
the
on the
the reverse
in age groups I+
Van
sexes was the
from one
which the not
II+~ older age
the sex ratio to the
in anct a
60
:I: fl) 40 "-
.....
...J <(
~ 30
..... 1!1 <( 1-z ..... 0 20 a: "' !1.
10
Fig., 21
LENGTH FREQUENCY -------
PERCENTAGE
20 25
TOTAL LENGTH (em:)
The numbers o~ male flounders :L'>l each an. of total length expressed as a percentage of tOtal number e:x.a..-rd.ned. The broken l:ine indicates the length composition of male fishe
0 30
z c s: "' "' lD
0 "T1
s: ]>
r
"' ., "' ::1:
them the
reason the :in sex the
ir~ not from the cla ta
Geiser ( 1923, 1 the
the sexes is clue to the
to survive
males, as tenCl. to move
That there is a
older fish seems
of tv..10 sexes
1 In 20
less thttn the
of 8 o:n be tween the
no
em
Because
were :few aui•hor
and
view of' several minor
of
there iti
female
YV:<:\s a maJ.e
measured
Meth.ods
appearance of
to pursue
ova use it
and the
com
to
than
have been used.
(1 'lhe
study but
'be L\S well outline
em
Ovaries 1 flounders over a
of a were at
and consis
of were nettt:ld
to t:hne f'or the of
of
t entire
Where the
:i. t :Ln a h11 :x. 1 11 tube
Where the
<'IetectablE} even eggs
OVa:J.'Y vvas
a ten per cent.
of the ova:cy
due ·to pressure was
ova was
they could be u"'""'·"""'""""" vv:i. thou t
:81 or a Sn1&,ll
ou·~ needles, on a slide,
so the
the
t1se of a
A was used
ments an
015 rom..
any al
of' 'lf<as
an.d covered a
eggs sub-
to be without the
up
to actual measure-
in one
to
.p 52 -
the
ova:ry a:nc1 the rne an
were
rnay have been dis~~~•~n
and the
When it was
of eggs of'
of' the
was then
to eggs :had been ~~'"'"''"'"""•
(b)
fish can.
ova, or the
ova were measured
the
errors causea.
was
the one ovary a
ova the
con tinuec1
in
the
of
in tenoo of
its
are to define state the f'ish
measurements
Because it is
fUl to draw
up a series o:t' terms that will
the of' ova as
and to the of the fish the
of are ' as
(c) Ova
(i) Ova .... It at the outset
th'3.t the be into
one or more of three size
Grotpi: this group
eggs destined to mature range
in ova to be mm and the ova
a
ha1:l:' the ova diru-neter in
r:ggs ·tended to in clusters had been
out on a whilst the ones were
"by
all of
II: in this group 1 mm
fmd to v<~hich
as the increased
eggs up o. mm
a thin
mm in
and ·were
vdth a very
and
:rhe nucleus was
and 'brown
oi1 were which in size from i to i the
•• 5l.f.
The in. the gr·ou:p were to be
th those
t
the f'ouncl in
(ii)
as
(
( 1 ) Imrna ture .,
'l'he
An ovru:-y which con~
ovar;y cculd be
one that haa.
the
'i'h.ere were two
but would
had never
:in the spa:w:n-
season,
and had
and
1
to
and
the
laol<::s
(
tion of ova
o:C the
The
ova:t'Y con'ta:ined
ma t·ure the ne~d season 1 ova.
were
As in the
ovt):l~ of the c1oes not revert
is
vessels v1hereas of
a.
blood vesaels.
ova were
To overcome in the
the
had never
but
~.:heoe terms
(
g:t'OUJ?
fi.sh were
to hundred ova
(13)
stock
In (il) roocles at
or III ova or may not
vr.Lth ·the
at random
mature and
from
1
of the
two lm.ndrea
of four adult
mm.
the took
in the
oornmenced. i~o in size as the
sho'Vi/.11
process :has
are:
·the
1'wo
t-vvo
al:)out to be
3 to
grou}.) ova
whether
season 1 eggs 1Je
0
IS
> u z Ill ::::. a ... a: ..... IS
s
A
ISO
small Stage
OVA DIAMETER (,Ill) 300 450 600 7SO
m
- 56 -
or whether they degenerate and are resorbed. It is common in
some species of flatfishes for all ma:ture eggs to be discharged
at spawning, only the immature stock remaining :in the ovarye
'I'his condition is met with in the dab (Wheeler 1924), the starry
flounder (Orcutt 1950), and the Dover sole (Hagerman 1952) all
of which, during the spawning season, contain no intermediate
groups of ova between ripe and immat11re stages.. Conversely
in the Ca.lifornia sand dab (Arora 1951) and plaice (]'ranz 1910)
a stock of u.nripe maturing eggs remains after spawning which are
ultimately reabsorbede Such is the case with the
f'lounder&
Observation of running ripe ovarier::1 showed that a large
number of ova were released during the spawning act which left
the ovary qui.te flaccid.. This indicates that the ova which
undergo maturation in preparation f'or spav11n:ing do so in a body
and not in small batches over a considerable interval of time ..
The ultimate fate of the secondary group of ova must now be
Two types of readily recognizable ova:ries vvere
found to be consistently present in spent f'ish, one containing
the group of maturing eggs in question and the other in which
it WM lacking. (See graphs (C) and (D)e I1'ig., 22). The
study of ovaries of type (B) showed that at ·the? time when the
mature ova were lying freely jn the lumen the seoondary group
of ova were firmly attached to the walls and in such quantity
that they were estimated to be potentially as numerous M those
- 57 -
already mature@ No instance of the breaking down and resorption
of' this group was noticed throughout the study.. Once it
been established that these eggs do become mature the question
of' the interval between spa:wning of the two groups presents
That the secondary group are the s took from which the
ova d.estined for the following year are dra:wn is discounted by
curve (D) in which the largest ova are seen to be in the 0. H30 -
0.315 :mm class. While no accurate assessment of the time lapse
between rna turing batches of ova could be made it is likely~ ·
amsidering the length of the spawning season» that it may be
a period of 'Weeks or even :months®
The second noticeable characteristic that not ova
that to mature are destined to achieve final maturity.,
Ex:am.ination of fully spent and maturing adolescent ovaries
showed the presence of two ova groups measuring 0$0~-5 - 0.135 :rom
The smaller group represents
the i:mma ture stock whilst the larger comprises the succeeding
season' s crop which has already en tex·ed the maturing
In some cases there occurred a further class from 0 .. 100 -
0 .. 330 mm which, if in spent adults showed signs of degeneration.,
It appears that these were ova in which, for some reason,
development did not continue and it rnay 'Well be that they formed
a ttreservoir" from which any losses due to mortality in later
stages were replenishede That they did ultimately degenerate
'WaS borne out by microscopical observation and confirmed by
- .58 -
their "'""' .... ,,_._.,.,__.._ absence in ovaries from November
the modal ova diameter wa.s 0.150 mm0
The monthly ova frequency data in Figure 23 show that the
growth of eggs from 0.150 to 0.450 mm in the ad:ult and adolescent
flounder is acoonq:>lished in four to five months., During this
:period growth is regular as is demonstrated by the occurrence
of all intermediate size the month to month samples.
However, once the ova reach a size ranging from 0.}30 - 0.1450 mm.,
development appears to be hal ted and a s took of ova awaiting
:rna tura·tion is formed. The exi.s tence of this pre:ma tura tion
group is clearly seen in the frequency histograms for the
spaming period., From June to October 1954 (Fig. 23), with
the excep·tion of two fish in August and one in September
October, the largest group of eggs have their mode at
0.450 mm. During the same period mature ova measure 0.675 -
00825 nn Which draws attention to the noticeable absence of
O.J.J50 - 0.675 mm eggs.
Light has been on the absence of in the in tar-
mediate stages of the final maturation process by ]'ul ton ( 1897)
working on haddock. He concluded that the relative scarcity
of such ova was due to sudden change from the densely opaque
oondi tion to the dis tended tranaparen t fo:rm added that the
actual extrusion of eggs took place as quickly. Hickling ( 19 30)
also a.ttribu.ted the low percentage of "running ripe" female
hake on the spawning grounds at the height of the spavm.ing
DlClMOlA 19541
JULY 19!5!5
OCTOHfl ttSS
40 50
DIAMETER OF OVA. SCALE DIVISIONS.
TABLE 14
MONTHLY VARIATION IN MEAN OVA DIAMETER (RIPE OVA EXCLUDED) OF PITTWATER FWDNDER FROM JUN]] 1954 TO DECEMBER 1955.
CLASS INTERVAL FIVE SCALE DIVISIONS WEERE 1 SCAlE DIVISION = 15 MICRA
MONTH
1954
June 18 .. 46 ±. 7 .. 365 ±. 0 .. 772 91 277
July 19 .. 44 ±. 7.066 .± 0.714 98 292
Augus-t 21 .. 92 .±. 7.572 ± o .. 742 104 329
September 20 .. 01 .± 7.772 .± 0.773 101 301
October 16 .. 68 ±. 6.514 .:t 0.668 95 250
November 13 .. 99 ± 6.179 .± 0.606 104 210
December 11 .. 82 ±. 4.628 + 0.465 99 177
1955 .January 10.28 ± 4.039 ± 0.426 90 15~-
February 12.88 .:t 4· 951 .± 0.531 87 193
March 18 .. 22 ± 7.161 .:t 0.755 90 273
April 20 .. 35 ± 6 .. 939 ± 0., 744 87 305
May 19 .. 63 . ±. 6 .. 998 ± 0.782 80 294
June 20 .. 70 ±. 6.705 .± 0 .. 695 93 310
July 19 .. 10 . ±. 8.092 ±. 0.858 89 287
August 22.44 ±. 7 .. 657 ± 0.835 84 337
September 20 .. 00 ±. 7.054 .± 0.670 111 300
October 19 .. 21 ;.± 7.211 .± 1.170 38 288
November 13 .. 00 ±. 5.477 .± 0 .. 548 195
Deceml:,er 12.40 .± 5.320 ±. 0 • .527 186
- 59 -
season the ova "" . .l..J:J<:it..L..I..I..&l!. in ba tclles
final rna tu:ra tion u:r1:>oe~s in the
follow this not only were no between o.
0. 630 mm enc:x>untler~:;d throughout s but the munoer
~.;w, .. ,u.~..~..~.g ripe
It is
flounder seeks
Female
.1."W:uu .. u.g ripe UVl.lU..J..
to
in extremely
's
were found
water.,
by the
However,
.. .~..~., ...... .~~..<:>...~.- occurrence
to estuarine
been taken
to time by .LJQ.&J\...I.I:l•u "''"' ..... A"' ...
1 ) As there are
that the greenback
and tidal
supported
which it was
of locality
evidence was
ova and
not
and
fathoms
, unpublished
from
in deep water 11.0 opinion can be given
fish two
is also no abundance
estuarine
sp~a.w.ramg migration
as no:rmal
spawning
that might
oonseq~en tly
months
occurrence of a
habita.t
including
:mm
- 60 -
(e) Spavming Times
The length of the spa:wn.ing season for flounder in Tasmania
has been. a subject for argument and speculation ever since the
first fishing regulations were drawn up during the middJ.e of
last centucy.. Opinions given before royal commissions and
enquiries into fisheries regulations varied between a short
spa:wning season of two months in the middle of con-
tinuously throughout the year .. The results of the present
investigation show that the spawning period, although prolonged,
can be defined and that a marked cycle exists,. It must be
emphasized, however, that it was not possible investigate the
effect of environmental factors on spawning from one locality to
another and the results presented are indicative of the condition
found in one estuary namely Pittwater.
The 1nonthly frequency distributions of ova diameters
(Table 14, :F'ig.. 23) show a decided seasonal periodici. ty over
nineteen successive 1nonthse The histograms were constructed
by grouping the raw data in class intervals of five scale
div.i.sions with values of 5,. 10, and 15 scale divisions as mid
points.. It was thought that as there was often a degree of
distortion in. preserved ova which exceeded two scale divisions
nothing was lost by grouping and the much tidier distribution
shown subsequent to grouping justified this trea "bnen t of the
raw data.
In. considering the curves it should be borne in. m:i.nd that
- 61 -
ova in the class measuring 30 divisions (0 .. 450 mm) are
'those awaiting maturat:ton., Beca:use of the suspected rapid
development from stage to full rna turi ty and also considering
'the few fish obtained containing fully ripe or spa:w:ning ova the
]resence of those 0~~?0 mm in diameter were taken be as
:indicative of inc~pient spawning as was the presence of ova
measuring 0 .. - 0.,800 mm ..
The ovaries contain a large proportion of well d.eveloped
eggs from March to September but during the remaining months
(October to February) the numbex· o±' ova is oons:i.derably
dimi.nished the:tr place taken by small ones which :f'orm a
dis tinct mode at 0. 150 rnm., This ra:lili.er short period when
grea·t majority of ova are much larger the
stoCk is brought to an abrupt end with their growth during
March and April.. As growth proceeds the proportion of 0. 150 mm
eggs naturally decreases and this condition holds, apart from
the suggestion of a recession in Jtlly, until September when a
shai'l> decline in frequency of' large ova col1m'l.enoes. The
seasonal fluctuation in egg maturity is more apparent in
]'igure 24 where the mean ova diruneter of each monthly sample
is plotted . ., Because ripe ova are a.lmos t t\vlce tb.e size of
those awaiting maturation and also the nu.mber of running ripe
fish in a sample is not truly indicative of the matu:dty of the
sample, Stage III eggs are excluded the calculation of the
means ..
- 62 -
The curve shov;s a occurs in
August of both but 1955
as
mean diameter
It
one
commence the .., .... .,,.,,.,,
the season
both 1954
in
it oen
have a mean
was
the 195.5 curve to be
ova found
ova .. 390 - .ll-95 mm.
an.d are
theory the
Ma:r;oh by a
in as
the light the
...... '"'"'~"· ... at a more rapid
of'
1954. As
OaJmc:r& be n"'"' • ...,'l:r~~rl
a
ot:
numerous
brE~ak:Lng do'Wn
takes place about
in extrusion
curve must
spaming
the
fishes
Now the
development
a rise
- 63 -
by a to spawn
tempera turee a number of
such, agents as
nature of'
in common
the winter
ova can be
men ths of 1954.-1
temperature was
above
presence of'
changing
However, as
most other
and consequently
with
which
tr.an 13°0 1
'WaS
with a mean ova the
the
of'
the two curves
is
1 1 is in
the curve.,
a
summer
would would a
slow or late on
season,.
autumt1 seasons
is 1
1 " 25) 1950 April
14 .. 6°0 wa.s than the same of' 1 '
and
not to a In 1955 an even
the was suoh it
ron:1mence April<~~ Thus 1955
apaming season long the oeeul."renoe
of ova April June of
0 u
0 '-' ... a: :I \( a: ... Q,
::f ... 1-
... ~ 0
...
.J <( u "' ri ... 1-... ::f ::!: 0
<(
i)
r--------o;;---~=======-----------------~--------~345 OVA
22
20
18
14
12
10 ... ', , ' I
'•' 0
J
I I
I I
I I
I
TEMPERATURE- ---
• I\ I \
I \ I \
I \
I '• I I I I
I I I I
I I I I
I I I I
I I J I I I I I
I
~ I
•
I I I I I 1 I 1 I I I 1 I I I I I I \ I \ ,•,, I
I \ /" ....... , / ~ \ . ,
I ' I \ I \ I \ I \ .... \ .........
1954 1955
Monthly variation in mean d.iameter of egg~~ from Pii:;twater flounders during 1954-55, with the corresponding mean water--temperature G"UX'Ve.
300
150
22
20
18 •
,.., . u ~
PITTWATER
PORT SORELL ST. HELENS
16~\ 0 •
'J \
11.1
g 14
~ 11.1 Q. 2 11.1 1- 12
10
8
.~'··· I I
/ I ' : ,• ' . ,
• • ............ ---•'!'*' -... ... ,........ ..·• .. , .. · ..•..
... ~ ;· I :
.. ~· /
/ . . . . • .. .. '
.~ ~\ \\ \\, . '
!
\ ', . ·······~"~, ., .. -g·--t .. •
I : I :
'~· I·''···./, ,,··~. I/
1: '·~··. /:
''4..1/ •
6L-L-_L __ L__L~L--L~--~~--~~--L-~--L-~--L-~~--~~ MA M A 5 N J F M AM J J AS 0 N
1950 1951
25 of seasonal
- 65-
and
ova. The drop in mean for July 1
of one degree 1:/!ay which bad
dOWll
is thrown on
commences, or this is ...... ,"' .... "'"'""'
maturation of
may be due to a
of hal, ting or
reason a shadow
or not there
the
made
a fall in ternnE,ra
only .. by laboratory exr:,er1.mEm
from
""J..I~~Vli,IJ,.u&.!', of' eggs
The implications
of possibilit,y
season.. For mean
was 13. and
the water "''""'""""""'~"'" below this
u.,;_,._._Lu.u. of seven October, a
1
during 1 950-1
for only
months.,
a variation of
seasons must be
the water was \o)ll;/ .... ~.~...:;,.~, ·
in
gonad
the curves
development
open up
over
extended
For a co:r~~St>on.tl1ng
the mean
of 1950
the
two "'.l:''~··J&.u.~.•·~
induced ur·::un~>.rJ
e.s seems highly P~::>bltbl.e
The present which 1-f.I..'\JJUJ!.,IJ.I. taking
from 1 to ,_ .. ,,... .. .,,~ 14j was u.o;;"'"-J>li.A'"',. to give
to fish LU . .I.L".LIU<
concerned only
1
did
curve
a seven :mon tl1s 1
a OOJ::Tesp,:-~nd~:1n;gl;'i
a
were ,.,.,,_.." ... , .. ., ... -~""m
of course not clear as ""'""'""'~""""''II!<.
the
year
water 'teJ'!IPE~re
be tween the
1
was
and
by
of
- 67 -
n~~...,~ 17 em in
the
at was
the
150-
season as
LU.LL\JW~~AM ~D<aml~~ iS
It
occurrence of ova ..
these was noticed
the
17 to 20 an
addition
of
to one
mmc
the
fish
number of' of
1
in
The curve
om
Qllt, That the nA1r<ll"'!<~'>.n
are
is
"'P':>!. .. A ..... u.115 season over a ~'A""·"'tk'"L-c:~.~.~ .. .,,.,
were
the curve could be
of
ova been
of one
was
were
of the ovary and on
an were
in
the
per
)
f'rom
TABLE 15
IEJ:iGTH FREQUENCY DISTRIBUTION OF l<IATURE FEMW!l FLOUNDERS.. iliE FIGURES IN i'HE RIGHT-Hl!ND COLUMN REPRESENT THE PERCENTAGE MATURE IN EACH CENTIMETRE
GROUP
NO., EXAMINED PER CENT MATURE
6
3
9
17
7
21 121 12
22 21
107
55
25 78 73
28 30
29
72
31 13 76
32 9 71
9 100
34 3 60
35
1
100
90
80
70
60
50 ,. u 2: .. " ~ 40 ...
30
ao
10
0 16 30 12 34 96
TOTAL LENGTH
The
size range .. group are so c'Urren t spawning season,
- 69 -
~:~. mean value of approximately 75 per cent~ of total mature fish
observed at any· one time possessing 0.350 - 0.800 rom eggs
indi.cates 1 per cent., maturity. This is to say at one
time during the spawning season about one quarter of the :rna ture
f'emale population are spent f'ish.,
Length at maturity may be converted to age by reference to
the growth curve Figure 1 The range :in total lengths of
fish at rna turi ty is seen to be from 20 - 27 an with
majority becoming ma:ture at appro:xi:mately 24 an., This falls
largely in the third year of life although as Table 8 indica tea
me.tt~ty be achieved by larger year whilst a
percentage p:t"'bably do not become
their :fourth year.. However, i.t be safely that 70 per
of flo'U!.l.del'S adulthood spamed at the
completion the year of life.,
The length of the greenback flounder 23 an
(9 ) which :f'rom ]1igure 26 protects appro:x:ilnately Jt) per cent.,
of the spaming population.. Should additional oonserva tional
measur·es be deemed necessary further protection of immature :fish
could be brought about by raising the minimum length 255 mm
( 1 0 ins. ) • .An increase of one inch would result in the
reduction in the percentage of' immature :fish likely to be
by more than 1 0 per oen t.,
It is
one of
other
same side
as
Some
been
The
HANOIIDNESS RI.!."VERSAL AND AMBICOLOURATION
known
vice versa is
or
or
be
es
head which the
right or left that
be
of
that the
IIH.I'"'""J~o;;;~ of Heteroso:mata 87 were .uv.~.-mc~.A..t • .y
tends to pr,ed.cDina
and warm teim>Elra
In and oold
155
Iiubbs ( 1945) ..
w.i th the
and.
These
of
o.>>;>.,!.W-",.,Y £:~;~~:!:!'_!:~~~ were UU.UUCLLL and occurrence
is so rare as to IEl."Pl)es,r
number an.cl in the
more
ins """'·'"'"''"" of ., . .,.1!r<~>'ll''"'"'
( 1876)
(1
to Norman ( 1926)
of
935) drew
by 1876) who
but not give
of'
the
one reversed
the which over
no
a
on the
tm~~~~:.E!!: were not
been made on
it appears ft~o:rn
uncommon
a
been but a
t.o the
v~.~~~;1£<) were nn•~p~~Y~irl
remembered seen
and
- 72 ~
A further abnormality common to flatfishes is the condition
known as ambioolouration. This phenomenon, characterized by
the fish pc>ssessing var.ving degrees ot' pigmentation on the
nonnally unpigmented blind side, is well known in the turbot
and European dab and is of'ten associated
appropriate eye t..o complete its :migration0
·the failure of
Usually correlated
wlth the
dorsal fin
migration of the eye is failure of
comple·te its devE!lopment with the result that the
stTucture terminates a fleshy hoo~-like pr~cess and is not
forward snout as in the nor~1al fish. The
incidence of ambiooloura tion is thought to be
rare although Haast in 1873, discussing =~=::.;;;.;;;;;;;; and ...._.,,~....._,..,.
quoted fishermen as saying that such """"""""'"'~·'""'"''"' were
uncommon., The
an ambicoloura te flounder. This f:i.sh was at
Coorong, South Aus traliall fol"'IVarded to the British Museum.
Where it VV;aS described by Nornum (1926)* In consideration of
the apparent rarity of ambicolourate greenbacl: flounders the
description of a specimen 221 1nm long by the
1953 is given,.
This specimen differs from the nomal the
formation of the head, the position of the left eye, the
possession of a left pelvic fin, and the extensive pigp1entation
of the blind side.. Certain peculiarities of' the lateral line
:in the region the head are also evident.
The fleshy
dorsal
same
are almost
i')Xtremi ts of
margin
the
side*
shown by
slightly
on between
the dorsal
by the
more pronounced
by
flounder
In
position
As can be
eye 'Which.
the "'.l''"''-'•""""'*
mouth.
are joined
with the
fish,.
operculum
eyes and the other
bends a.L'Uos t at right
both
development
of' the
(1935) and
cases,
may explain
seen in ]ligure
with the
on
a common
line
one fork
the
in
·(· .. ·.~· .. ·.· . . . . ·. ·.: . . . .
' . .
',
. . . \ . . I
0
.' .
. ·\ . \
• ' I ....... ·... . ,,. . ~ .. ' . \
' .. ', .
~-~·~,<<~~·~,-"' ' . . ... · ... .. .·.
.'
._ ... --~--
speciinen of
at an
16.
be commensurate
the
The
of the snout
it
w.i.th the
·to
- 74-
30° to
ambi-
the
are seen
of
:i.s course due to
..
the
the
mean number of uur-N>U
in
it is only
the
It
is
'l:ABIE 16
MORPHOMETRieS OF THE AMBICOLOURATE SPECIMEN OF R. TAPIRINA CO:MPA.RED WITH mE RANGE IN CHA.RAOTERB
OF NORMAL SPECIMENS., (s = d ::::
---·---------------~----AMBICOW'URATE
Body depth in length
Head. total
lower jaw
Eye
Orbital width
Number dorsal
tl II II 42
It It It 18
II It ( It 6
It It II (d)" 6
" " pect,. ( II 11
It II It (d)" 11
Total length 221 IIJn
181 IIJn
Depth of body 110 mm
Female
RANGE IN SPECIES
1 - 2.,1
,3.1 -
... 3.7
4..8 - 6 .. 0
4 .. 0 - 5 .. 0
40-
16 - 21
6
10 - 1.3
10 - 13
been
placed eye
with
I:n
fish and
The only
markedly
the
Heterosomata
well to
spear
by
PARASITES
"'"'"''"'u·"~"'... "WaS found to
A sma.ll nelt:"C€111
ne:mE;. todes
wa.s a
were on the one
there :no of
a
were of
'l'able 1
With one were
side of' the region of
patches and
forms with a
as is uvJ~lultlu..
free
un-
(1957) ..
in
fish is
to the
scars.,
TABLE 17
1'HE INFESTA~L"'ON OF GRJ!!lllNBADK FWUNDERS
Ag~~OBpE~ ~~~
8
1
1
0
1
2
3
7
position or1
were leecli.es fou.nd
that
of
It
and time
on the was thought to
way to the
In no
~.1s probably "'""""'""·ul'!,
or UPlPCJ:UlOiS
places as
in
in fishing
in
are taken
to
in
a view
or
th to
vd tla
and the s
The
In
of the mean
of mean
to
147 th tm::a~' .HJL~'-"'-''
v'Vill be
Port
in
the means may be
means ar.·e
SllOW that
areas
some but is
the
of
of
two groups
west the
<f)
!!:! 1Ll Cl.
lfl :::l <f)
z a: w 1-<f)
< ST. HELENS w
(PORT SORELL
!I) w u w
STANLEY 0..
"' "' :::l
"' z
PORT WELSHPOOL a: w 1-
"' Ul :;:
MACQUARIE H.B.R.
Fig.,
$125
$ 119
$121
$ 100
$''
$35
$ 2S
L .. L .... L_.L 57 60 63 66 69 39
NUMBER OF DORSAL RAYS
of dorsal vertebral The range the mean
$125 $125 ~ $119 $119 ----F
$ 121 $ 211 ¥0 D 1oo
' 100 ~ $11 ~I t" $35 r t32
$25
42 45 48 50 II 14 17 19 30 32 34 NUMBER OF ANAL RAYS
Fig ..
VICTORIA
42° ® WESTERN suasPECIES
(F) EASTERN SUBSPECIES
~DEPTH < SO FATHOM$ ~DEPTH > 30 < 40 FATHOMS c:::=:JD£PTH > 40 FATHOMS
SOUTHERN 0 C E A N
144 150
Sketch of Strait showing position the Pleistocene Bass Bridge as indicated by the 30 and ltD fathom. co:n tours from current Admiralty
Sampling localities and the geographical of the two subspecies are also shown.
the
(a)
of
use
the
error of di.f.'f'4~rEmc~e "''""'""'"""''"'
by d/ R:i.Ll:;!,~-£1 VJi'U~'Y"o<!.
means m1d g.~,~9uao_ is
of
in the mea.n some In ord.er
VYLY.u be d.rawn
process
be
the means
it is
one
t:h.e
caae evan
II
!I
the
2
M1
N1 and. N2
5
p
"
11 it was
+ N2 i;
2
were
N2.
test
Pt. Sorell (W)
Stanley (w)
St. Heler..s (E)
TABLE 18
T"rlE COMPARISON OF SAMPlES l!'RW EACH LCCA.LI TY WI W: THOSE FRW ALL OTHER A..~ M3 EXPRESSED BY THE d/d"d TEST OF SIGNIFICANCE .. (S.,::: signi:f':icant,N.S .. :::: not s:igni:f'icant)
E = ea.s tern subspecies
CP~T.ER PORT ARTHUR (E)
De 10 .. 920 A. 10 .. 950 (s)
G.,R .. 25. v .. 9.361
D, 6.081 A. 6.422 (s)
G.,R .. 8.407 v. 5.845
D .. 1.858 A .. 1 .. 980 (N.S .. )
G.R .. 6.144 v. 0,.8)2
D .. 7 .. 278
W = western subspecies D. = dorsal rays A. = a.'lal. rays
G .. R.. = gill rakers V. = vertebrae
PITTWATER (E)
13 .. 500 14.100 (s) 8.630 9.365
7.386 7.598 (s) 4.230 5.793
0 .. 387 0.,056 (N .. S .. ) 1 .. 650 0.994
8.750
PORT WEIBRPOOL (W)
0.401 0.609 (1feSe) 2.160 0.272
0.536 0.649 (N .. S.,) 1 .. 291 0.329
8 .. 510 5.890 (s) 5.357 6e7)8
ST .. EEIENS (E)
12 .. 640 13.400 (s) 10 .. 110
8.360
4 .. 64,5 7 e478 (s) 5.060 6.250
A., 8.330 (s) 10 .. 36o (s) G.R .. 10.250 4.16o
Pte Welshpool (w) v. 8 .. 340 6 .. 290
D. 2 .. 300 A .. 2,.630 (N .. S.)
G.R., 7.940 Pi ttwa ter (E)
v. 0.199
STANlEY (W)
0.306 0.651 (N .. SQ) o.ooo 0 .. 630
It is
lllBY be
The
w:ith the
on
of'
two
one
to
the 't'WO
for
in.
case
25
20
15 /
10 .r.r ,•
5 //
DORSAL RAYS
__ ,. ~~6--~~--~~--~--~-----~--~--~~.
30
25
20
15
10
,..., I '
I \ / \
I \ I '.
I ' / '
ANAL RAYS
w I '
~ 5 .-... ·/ •,,'·-- -~ ~~8~~4~0~--4~2~--4+4~--4~6~~~~~~~~52.
~ 40
:r 35
30
0 25 z ~ 20
8 19 0: Ll.. 10
5
010
60
50
40
30
20
10
029
WESTERN SUBSPECIES-
GILL RAKERS
VERTEBRAE
34 35 36
EASTERN SUBSPECIES-
31 Frequency distribution curves of four meristic characters f'lounders the eastern and western
The data :from Port Arthur, ttwater, and St.. ~ is S'I.Umlled in curve and from Port Welshpeol, Port Sorell, and Stanley, treated the western curve. Statistics are given Table 1~, the results of the ts of significance Table 20.
TABIE 19
TEE ""'"'~""""""...., ..,.....,...,. ........ ~....... DATA F.ROM WITHIN
n
Rays ± g Rays 0 .. 1193 1~ ::1
± Oo0886 c;j Gill Rakers 1-17 1 ..; ::J
5' p., 31 ± 0 .. 563 ± 1
Dorsal Rays .033 ± 2.017 .± 0.1055 365 s:::
0.0746 365 0 Anal 43 .. 1 ± 1 .,.-~
+' ~ ± Oe0640 3 Gill Rakers 12-19
e ~ 356 11) p., o. + +'
~ ~
the
Wes as is cl~:~ar 21., The
1 dorsal and ray·s
when the
been
On the with means
the of and
t.he same are
have been dravm a are
(b) s
Once it it
or more
be
the
TJ\BLE 20
REsULTS OF TES1'ING TEE SIGNIFICANT 'f'\-r,:ll'r.."i'f:'•nT.I,Ili"<'l:;l OF MERISTIC CHARAOTERS TWO SUBSP:OOIES.. significant)
Dorsals
Rakers
17 .. 510 s
1 265 s
1 s
13.132 s
TABLE 21
COMPARISON OF THE :MEAN DORSAL AND ANAL FIN-RAY COUNTS THE M.ADQUARIE HARBOUR WITH THE MF.ANS
THE EASTERN AND ·VlES'rERN Stl:BSPEOIES.
6. (s)
WESTERN SUB-SPIDIES
1.1 (N.S.)
1.007 (N.s.)
see:ma
is on
is the
as
measures
of
a race with
the
the
ed be a 'When the
more than 10 The measure of
the measure
ver~en.oe 'between races is
be·tw'een per
or more.
by
was
of one Ol'
not
1
and
area
is
In
on
mean
:rhe
cannot be
be due
:ins
between 62 and
call
the measure of'
it
It
(b)
Western
0.7
Eastern
THE FREQ'UEJ."'VY VERTEBRAE IN
58 61
GILL RAKERS WESTER.i'l SUBSP.ECIES
7 .. 8 1 1 2 3.6 0.8 )
4. 20.,0 7
9 .. 0 22 .. 2 8 11 .. 2 9 0 .. 3
6 25 .. 3 1 11.0
1 1
1 22.,2
8 42·0
) % 6.8 2 .. 1 2 .. 1)
0 .. 7 1
) 4
) '" No .. o:f )
) ) %No., )
) ) %No .. of )
:fish
Dorsal
or
the
be ma.:rked
area but
between the
of
al.so
is a
(1
the two is
(
a
as
of one
zones
)
939)
or more
or
out,
zones.,
or sub=
sub-
sense :i.t
in
- 85 -
was first recorded by G·ill ( 1863) found, amongst certain
labroi<l f'ishes of the western coast of North America,
tendency of a cold enviromnen t to about the laying
dovm of more vertebrae than occurred in fishes inhabi.ting Wa:tmer
·vvaters. However, Cox (1903) that three of
on the A tlBl'l tic seaboa:rd ru:~.a. reduced finra;y cmm ts
specimens from more habitats® In his pa:per Cox not
assume this to be nonnal for the species he cleal t Wi.th drew
to the range in New
Brunswick than xnuch south as a
of anomalous of' this effect was pro-
v:i.decl by ( 19.51 ) who subjected eggs
to 1;em:peratures ancl was able demonstrate
:highest num1-,er of raJrs were at inte:r.:mediat.e
tempe;ra tures whilst a i.; extremely or low a
fewer number of
idea that the
resulted., Cox r..ad forward
fish is plastic enough to
:modifi.ed by cheoo.ges of the envirorunent and T~.ing fou:nd
although the number of segments were
clete:r-m:tned sr10rtly before the 11 eyed egg11 stage is reached.,
A the varj.ation in fjnrays and. vertebrae of the
starry f'loundel" (Plat}£ht;t:;y:s ~) from three points on
'WaS tern North .Arnerican from Alaska to Puget Sound was
by Tow.nsend in 1937 who recorded in "the
means of these characters bet'Wee:n. the places.,
s i;udy of the same species
extended to Monterey
significant dif:f'erenc(:'l
out by Orcutt (1950) was
value
belongs to the
the same ntunber
where fish '"'"" '""'"'' no
However,
Alaska a
flounder
Souncl s:pec:i.xnense
were compared with
was noted., The
It interesting
and pm'lsesses a.ppro:x.:bnately
as the greenback:
oo:mpare i:;h.e meristic
of the species with ,~ .. ,",__,,. .. ,...-r:
range and corresponding sea teJ:npE~ra
winter months when
pres en ted in Table
any two sa:mples within
been used in the 1..)\.)J,u~n:u.-..~ • .,
Port Sorell. have selected as
This is
sub-species could
table, St.. Helens
of'
of temperature was for them i.n
environments be as sim:i.lar.,
In the absence of on the behaviour
of the developing embryo of R. ~JLir:i~l.a under extreme.s of
temperature and the suggestion that
in tic cha.racters are not the result phenotypical
influences cannot be fully substantiated. But assuming the
representative of
RAYS, STARRY d..1V'-'"'u ... Jw. .............. ..,, ....... , ..... GJi!lOGRAE .. .u.. ... ,JJ:l.iioJ SEPARATion INVOLVED
St .. Helens -Port Sorell
Hele."lS -
extent
s
The
been mentioned
of the
were
it a-p-peB.I'S
eastern and
to
the
an early tha:w
overlooked.
of
monthly
Port Sorell
and """''"""''-'L""'>""'
wb.ich was
on
if the
<.A,~;tt\A,U..',l,' c:u t vr.:t th
in
and the
result
the
and
the
e:.d.s
the case
:i.s
to north
bo~ra.e:r:ina Bass
But as
The
the
beoome~J
of
the <.:~.!.J'""<:>"Auc
the
be tween the
two 'Which
widely geographically
Port Welshpool
It :is now
1951;;
always orr!4cnrr's
( 1942)
the
a.
them
one
one
as
in
it ..
the
into these
the observed d.ea:r.·th of
corner of the
be used. in the
the
late
are knawn to hav·e
1 the
it is
was
In the
the
the
its
the
any
This was bo:rne out
it
to the
'I' he
the
the
genus
to Jordan and draw
of
the
ice
world
and one
nlalltle of
sea level
a
it
sea level
by the
the
western
the
of the
Pleistocene
on
91 -
the
of
, as David ( 1
of the
area.,
evi.dence
area
western
It has been
covered the
t if
lowered as sho\~
of a
both the
of ice ancl
a n.orthern
this the
the
the
end of the
to ~ the
on
have been
of
1 to
which
t
the sea
under the
sea of the
It
from the 1\osciusko
If
co as
ice on the
to
feet in
taken
been
:Into
Emd. salinity from that of the western
~roday of the Coral Sea currt1nt October
to Apr:H is thought to be the
of the t ~easman mass
with to
the coast of
con::munieat:i.on) oonsid.ers that a
sea level to the would st:nl
water
It would be
the living i.n
woulci Carter ( 195·1) is of the
is even to
now
be sho'Wl:1 that :i.n this case m in tc:'lrval e>f about
years betvreen the time md the
the
to
been with i;he end of' the Periocl and the
rise in se.9. followi.ng th~) mel tjng of
It was ·the of the Tasma.r:tian
wr1o n.o but before the coming of tJnte
Australians and the by the absence
fossil the latter in As the
of the the
and in depoaits is set between 20
·100 ,000 yea't's ago it may be taken Bass Strait assumed its
form about this
that
are
condi
'J:he of' in the
will always oecur between
ted. and. much of
'l'his :ts
a process of
pat:·t of w:h.ich ir:~ caused
to of microevolution pro blem .. "l
of the (1
that quant:l.:tative are
to
the
out
of environment of the
two tions in ·wh.ich the grottJ?
would. h.a.ve ·been and lower
than the eastern may have ca:nsed meris
to observed. natural
tiom.1 (;older waters of low
favour increased d.o warmer waters
If thi.r.; wa.s so and a
the .number of' in the tions becaJne
tht) corm.ts wb.ich
may be accounted.
That is cliff'erences evolved during the period of'
barrier no
lt
'them
the extent
that the
Uon ancl
the absence
returns, r.as
where
Du.e to the
that once has
of
are still :ir1
and the
awe.re t:b.e
to
U"'U.\VU~>trated by
es ln the
~~~~~~~becaL~e 'ted in'to
the Bass L'and
remained
sea level
The
The tvvo
800,000 years
was
to 100,000 years a.go
genot;ypic
could be thro'Wn. on
aware
more
in
New
not 'been
thus formed
which ti!ne
by a
due to the
of' Inicro-
the
much more
occurs where
~:'he ancl ha.bi ts of
ther) ace recorded
to the in
Some
to
growth and
" Age at
and seasonal is rneasuremen t
ova.,
in
is
Possible tence
two a
Bass Stra.i t area i8
The author wi::;hes to acknowledge the and ad.vice of
V. V. , Zoology University of
:rasmard.a, under whose the work was
th'3nks are also d:ue to Mr. A~ M. Olsen, C.S*I9H~O.
Di·.;ri.s::ton of
members of the
spe cirnens .<:U1d
thanked
and who vr.i.th
assisted wil;h the
The Chief of' the above D:tvision :i::.;
C.S.I.H.O. to cover cost
Also remembered are th<:: efforts of Clark,
Donalcl AlElxe,nd.er and. Ernest And:rew::.1 who mi:my a
the
of
field
a research
who also provided.
by the
spac;e and a la:unch
M .. U. ( 1
i terra.:nees.
H.,L. ( 1
dab.
~-
Blaokbu:rn., M .. ,
Boulenger,
the m1.nnow
G .. s. ( 1
- 99 -
.- La Croissance
).- An
.. -
) .. -
w.s. ( 1
by the :M.,V*
158.,
A stu~v
to the
02 ..
of its causes ..
R .. M. ( 1 ) • - Condition
Hauraki
(4):
telnau~ F .. de ( 1 .-
les Animaux Med-
jQ: 163-22,4..
the California
..
.- Report on
j.n
a s
Australia. 168.
Clark, F .N. ( 1925) .- The l:i.fe
a'l atherine with tide spawning
51p.
B
~·» .::::...::::;:;:.:;;;_=:::.:::;.¥
I!,.,N~
, ]1
• ,J@ , and
, E~ ( 1
the release
N.S.
s (1
.-
) .-
20p.
)
in the
the
On the
(7): 1
1
( 1921~). The death rate the
among
1 ( ):
th.e labroids the wes ·tern
North
nomen cla 'Lure$
) New
:in
I A
(1 almost
I'O the reoord.ed
( 1862) ) (3):
'£he the
02 "'
' J. ( 1 Bome of New
'l':ra:ns. :P:coc. .z.
Hart .• ,J (1 of Bri
season ancl concli
of
Hile,
i.n lakes of'
Hubbs, .-in
Hu1:ibs 9 (1 of
to
Notes on
His (1
the
1
s. ( 1
varie t:lez. 11 ( : 1
s® ( 1 Oxford
( 19l~).
and \ ) .
( 9.' ) .- :E'ossil
the
(1 ) ..
the Sen.cuti I.
(
( .- Studies :in
L. of the
the
i.n
of the
Aus
on
1
,T ~C. ( 1 ). length studies of
of' Columbj.a
J: ( 6): 1
E. ( 19J~).
)6.
A l:lst, the
of the
on the
N.S. ~ 11
New I~ q08·) _ \ '~·~ .
219~308.
I:I.G. (1950) The life his s
, W.,J. ( 1 ). Notes on 'the New
1
) . Hibliogrt:>..pby of New
and dis
the sole a
ancl
56p.
• ( 1
end
of 1951+) ~ 3.
Hoe, (1 ti"lte Zoology.
1 New York).
A.V. (1952),- of meristic
in
on
) . -
:in
Oosten, J. ( 1
, E.R. (1906).·~ Notes on Au.s and
fl: (.3): 1
Waite, H. ( 1 911 ) • ~ Scien t:tfic ts of New
Government trawling 1
1 ( 7;). ~ , .. .! ,
of' "the
sb.es South
(1
(1
(1 sole a:n.C.l
Eocene
t