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