HARVARD UNIVERSITY.

LIBRARY

OF THE

MUSEUM OF COMPARATIVE ZOOLOGY
13.414
GIFT OF

ALEXANDER AGASSIZ.

( L Fo ae 13°
if ‘de Lee

VUL 38 1957. 1891.

QUEENSLAND.

i) 77. Smee, 0 EG

OYSTERS AND OYSTER FISHERIES OF QUEENSLAND.

Presented to both Houses of Parliament by Command.

Department of Fisheries,
Brisbane, 30th June, 1891.

Srr,—I have the honour to submit to you a Report embodying the results of my observations and
investigations concerning the Oysters and Oyster Fisheries of Queensland conducted within the past two
years. To this is appended a return indicating the status up to date of the output of this fishery,
and the number and extent of the areas leased, as supplied to me by the district inspectors. Trusting
that the data and suggestions contained in this report may conduce towards an extended and yet more
profitable development of the oyster industry of this Colony.

I have, &c.,
W. SAVILLE-KENT, E.L.S., F.Z.8., &e.,

Commissioner of Fisheries, Queensland.
To the Honourable the Treasurer.

INTRODUCTORY.

The Oyster Fisheries of Queerisland occupy the third position upon the list of the leading
fisheries industries of the Colony with relation to their annual export value. That of pearlshell takes
the lead with an average yearly export value of £70,000. The béche-de-mer yields in a like manner
an average of £23,000, while the oyster fisheries for the past ten years have not exceeded an average of
£8,000. The exceptionally high figure of £13,068 was, however, obtained in the year 1889, and when,
owing to disastrous floods which temporarily devastated extensive areas of the oyster grounds of New
South Wales, and in a less degree those of this Colony, the prices realised for the oysters exported was
enormously enhanced. To the figures above quoted as indicating the annual export value of the
Queensland Oyster Fisheries, almost one-half as much again may be added as representing the home
consumption of the bivalve, and which brings the value of the total annual average output of the
fishery to some £12,000.

Though occupying a considerably lower position in the scale of actual annual value as compared with
the fisheries of pearlshell and béche-de-mer, the revenue accruing to the Government from the oyster fisheries
and in association more particularly with the excellently organised system of leasing and licensing
sections, banks, and grounds as private fisheries, is very considerably in excess of that derived from the
two first-named industries, being represented during the past year by a net revenue of close upon £4,500.
So soon as the Bill now framed is passed, and which has been prepared with the object of providing
facilities for the establishment of corresponding private pearlshell and béche-de-mer fisheries, a more
proportionate approximation of the respective revenues may undoubtedly be anticipated.

VARIETIES OF COMMERCIAL AND EDIBLE OYSTERS OF QUEENSLAND.

There is but one specific form of Queensland oyster that receives serious consideration from a

urely commercial standpoint. This oyster is the species commonly sold in the adjacent colonies under

the title of the Queensland “rock oyster,” and the technical name of which is Ostrea glomerata. Apart

from this form, which, as hereafter shown, embraces a large number of modifications, there are several

specific types of oysters indigenous to Queensland waters which, while not sufficiently abundant or

possessing other disqualifications for the ordinary export trade, are wholesome eating, and are utilised
more or less extensively for food.

The largest edible form of oyster found in Queensland waters is distinguished by the title of the
coxcomb oyster—Ostrea cristi-galli—so-called from the regular zigzag undulations of the outer edge of its
interlocking valves having some resemblance to a coxcomb. An illustration of this species wili be found
at Plate I1I., Fig 2. A pair of the ponderous shells of the coxcomb oyster not unfrequently weigh as
much as from 5 to 7 Ib., and have a diameter of from 8 to 12 inches. ‘Uhe species is an essentially salt
water form, and limited in its distribution to the tropics. It grows plentifully among the coral
reefs of Torres Straits, and the Great Barrier system in either an entirely submerged condition, or, where
exposed to atmospheric influences, at ordinary spring tides. Under these last-named conditions I have

ane observed
C. A. 62—1891.

\
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2

observed it in especial abundance on the fringing coral reefs surrounding what are known as M and N
Islands, belonging to the Northumberland Group, eastward of Mackay. This oyster is also to be seen in
some quantities in situ, but no longer alive, on the dead and appatently raised coral reef on the west
side of Magnetic Island, facing Townsville. As an edible variety the coxcomb oyster is somewhat large
and coarse, and is consequently most appreciated in a cooked condition. A smaller variety of coxcomb
oyster is not unfrequently obtained from deeper water in Torres Straits attached to the branches of the
black coral, Antipathes, and other zoophytes. It is remarkable for its production of finger-like projections
from the back of the attached valve. With the aid of these projections it retains a secure grasp on its
chosen fulcrum, though at the same time this hold may be so loose that the shell may be slipped to and
fro on its supporting base. This variety of oyster would appear to be identical with the Ostrea folium of
Linneus originally reported from the Indian Ocean.

The second largest species of edible Queensland oyster is also an essentially marine type, and
limited in its distribution to the tropical districts. It varies considerably in form, and may be either simply
ovate, with/a broaklér distal margin or boat-shaped with pointed ends, as, shown in the several figures of
Plates JIJ..and,IYV., illustrative of this type. The larger individual shells of this species not unfrequently
meastire as much! as.6 ot 7 inches in their longest diameter. Its edges, in contradistinction to the
preceding spacies, aye usually perfectly even, or only slightly indented. A notable feature of this oyster
is the very hard vitreous texture of its shell. Its colour externally is usually a light slate-grey, and,
interiorily, a pure white with a very conspicuous broad black band throughout its marginal border.
In association with this last-named feature it has received the name of the black-edged oyster, Ostrea
nigro-marginata. While by no means an unpalatable oyster in the raw condition, it, like the preceding
species, finds greater favour in a stew or scallop. The black-edged oyster flourishes side by side with the
form next noticed, Ostrea mordax, throughout the reefs and islands of the Great Barrier system, and
is particularly large and abundant on the rocky foreshores of Adolphus and other islands in the vicinity
of the Albany Pass, Torres Straits, and from whence it is extensively obtained as a seasonable delicacy
for the settlement at Somerset. The hardness of the shells of this species, and the difficulty of detaching
it from the rocks without fracture, even with the aid of hammer and cold-chisel, preclude its utilisation for
commercial purposes in the ordinary manner, though from its size and abundance in many localities it
might, in common with the form next described, be profitably canned or otherwise preserved. In
illustration of the substantial dimensions to which this oyster attains, it may be mentioned that the
hollow shell, illustrated by Plate 1V., Fig. 1, was found to have a holding capacity of four fluid ounces
or one-quarter of a pound of oyster meat.

The third species of edible oyster, other than the ordinary commercial type, indigenous to Queens-
land is the so-called Ostrea mordax, of Gould. Its area of distribution is a much wider one than that of
the two preceding types, it being found abundantly throughout the whole length cf the Queensland
coast-line, from Cape York, in the extreme north, to the New South Wales boundary at the Tweed Heads.
It has also been recorded from Fiji, Samoa, and other island groups in the Pacific Ocean.

While enjoying so extensive an area of distribution, Ostrea mordax may be said to attain to its
finest or maximum development among the coral reefs and islets of the tropical coast-line of eastern
Australia, and from its remarkable abundance in this region it may be appropriately, and is hereafter
distinguished by the suggestive popular title of the Coral Rock Oyster. In contradistinetion to the
ordinary rock oyster of commerce, this Coral Rock species is an essentially marine type, attaining to its
most luxuriant growth among the reefs and islets of the Great Barrier system, far remote from fresh water
influences, and rarely overstepping the boundary limit of pure salt water in its area of distribution along the
rocky headlands on the mainland seaboard. In this latter situation it not unfrequently grows as abundantly
and under conditions closely simulating those represented in the typical illustration given at Plate VII.
Fig. 1, of the rock variety of growth of Ostrea glomerata. The zone of growth most affected by Ostrea
mordaz on either the natural rocks, upheaved reefs, or stranded coral boulders, is coincident with that of
half-tide mark, and I have not so far, by either practical investigation or inquiry, obtajned information
concerning any instance in which this oyster has been found growing beneath, or even at as low, a level
as ordinary low-tide mark. ?

The characteristic features of Ostrea mordaz, in its most typical form, are its normally elongate
triangular contour, the very evenly lobate edges of the interlocking shells, and the opaque purplish-pink
hue of their external surface. Another peculiarity of this species as compared with the ordinary
commercial oyster, O. glomerata, which it often closely resembles in size and shape, is the cireum-
stance that it is almost always affixed to its rocky support by its left valve, while the last-named form
is as invariably affixed by its right one The flattened, freely movable so-called opercular valve is in a
corresponding manner developed on the right side in Ostrea mordax, and on the left one in O
glomerata. An additional point of distinction between the shells of these two species is furnished by
the circumstance that the scar or impression of the attachment of the large adductor muscle in 0.
mordaz is set very much further back, or towards the distal or growing edges of the shells, than obtains
in O. glomerata; this scar, moreover, in the opercular valve is more usually of a deep-black hue
while in the last-named species, though occasionally of a darker tint than the surrounding nacre, it is
more often colourless. ; 2 :

While the shape as above described represents the most typical form of Ostrea mordaz, it is
subject to almost as considerable a latitude of variation as the ordinary commercial oyster, O. glomoraen
This variation is the effect of its efforts to adapt its shape to that of its environment, and the shells ma ;
vary in consequence from an almost cireular to an abnormally clongate contour. A yet more cons ieuaae
modification of the very variable species is one in which the hinge or butt-end of the attached vate i
produced into a long hollow beak, which is found, on opening the oyster, to contain a very conse
amount of meat. This beaked variety would appear to be identical with the form upon which thes scat
title of Ostrea cucullata was originally conferred. Illustrations of this beaked variety, and eae r e
normal form of Ostrea mordax, are given at Plate II., Figs. 1 to4. A characteristic Feat of the
species under notice, so far unreferred to, is the one which, notwithstanding its excellent edible qualiti ;
disqualifies it from occupying a place in the leading markets beside the more familiar commercial saeotee
This disqualifying feature is represented by the tenacity and extensiveness of its union to its rock su on
and which is almost invariably coincident with the entire external superficics of the adherent chelle oaiee
a necessary consequence much labour is requisite to separate them from their attachment, and in the

operation

3

operation they are so liable to injury that, if packed in bulk and transported to long distances, a large
percentage would die and engender a rapid mortality among the survivors. The species is nevertheless
brought into some of the coast towns, such as Rockhampton and Gladstone, and there realises a price
corresponding with that of the ordinary commercial form. It is a question whether this oyster, Ostrea
mordax, might not be turned to more profitable account, by tinning or otherwise, by its collection and
conservation at temporarily-established stations in the immediate vicinity of its most abundant development.

In dimensions the Coral Rock oyster rarely exceeds a length of 8 inches, and the lower or
concave shells in the finest examples examined were found to possess a holding capacity of one and a-half
fluid ounces. The reproductive phenomena of the species have been found by me to be essentially identical
with those hereafter described of the ordinary commercial species, Ostrea glomerata, there being no
incubation of the brood within the mantle cavity as obtains in the more southern mud oyster, Ostvea edulis.

A small species of oyster which is tolerably abundant in various parts of Moreton Bay, and which
has in some instances encroached upon and taken possession of banks formerly occupied by the ordinary
commercial species, is the Ostrea erenulifera, of Sowerby. This species is usually less than one-half of the
size of the commercial oyster, and, while somewhat resembling it in general shape, may be distinguished
from that form by the more numerous, acuminately pointed denticulations of the peripheral border, which
are continuous, as in O. cristi-galli, with raised ridges of the external surface of the shell, and radiate
from the hinge or umbone to the periphery. Like Ostrea mordaz last described, it is usually attached by
the left valve. The colour of the shells of this species are also very distinct, being of a uniform grayish-
white externally, and greenish within, the characteristic purple tints of O. glomerata being altogether
wanting. Being too small for commercial purposes, the increase of Ostrea erenulifera on the banks
should, as far as practicable, be kept down, as, if left undisturbed, it will spread over the most favourable
breeding and spatting grounds, in addition to appropriating food material that would otherwise contribute
to the a al of the more valuable species. Illustrations of this diminutive oyster are given at Plate

IL., Figs. 5 to 7.

My attention has recently been directed by Captain Sykes, the Harbour Master of Rockhampton,
to an exceedingly remarkable variety of oyster, in some respects resembling Ostrea mordaz, that occurs on
Rocky Island, off Keppel Bay, and which is illustrated by Figs. 2 to 4 of Plate TV. In this instance the
hollow beak-like prolongation or umbone of the attached shell, alluded to in connection with the variety
cucullata figured at Plare II., Fig. 2, is so abnormally developed that the movable or opercular valve
presents the aspect of a small hinged lid set upon the summit of an elongate corrugated tube. In the
upper of the two examples figured the relative dimensions of the two shells are so disproportionate that
while the right or opercular one measures just over an inch in its longest diameter, the left or attached shell
measures from its free edge to its base no less than six inches. This extraordinary modification is
apparently brought about through the oysters being crowded close together with no room for lateral
expansion, all growth being in consequence associated with the vertical elongation of the attached valve.
As shown in the diagrammatic sectional view of such an oyster given at Fig. 3 of the same Plate, the
cavity occupied by the living oyster extends through the anterior third only of the entire shell, the
remaining or basal two-thirds consisting of concentric cellular lamine that represent its successive
growth-lines.

With respect to the shape and proportions of its component shells, this tubular oyster bears
a remarkable resemblance to a fossil group of bivalve mollusca known as the Hippuritidee, and which are
peculiarly characteristic of the cretaceous epoch. In the account of that family contained in Woodward’s
“ Manual of the Mollusca,” the portion of a closely analogous oyster is figured under the title of Ostrea
cornucopi@, a species originally established by Lamarck. The original figures of Lamarck’s type,
however, given at Plate 181, Figs. 4 and 5, of the “ Encyclopedia Methodique,” published in the year 1827,
represent arostrate oyster more nearly resembling the form of O. mordaz, illustrated at Plate IL., Figs. 2
and 8 of this report, and which I identify with the Ostrea cucullata, of Born. In a foot-note to the latest
edition of Lamarck’s “ Animaux Sans Vertcbres,” Vol, VII, p. 280, 1836, the editors maintain, moreover,
that Ostrea cornucopie and O. cucullata, as represented by the Paris Museum types, are varieties only of
one and the same species. In the same manner that the beaked eucullata has been shown to represent
a modification only of the ordinary Ostrea mordax, the very elongated tubular form here figured and
described may possibly represent an exaggerated growth of the variety ewcullata. From an examination,
however, of a very considerable number of specimens of all ages, and in all of which the tubular develop-
ment of the attached shell is equally pronounced, I am inclined to regard it as a distinet species for
which the name of Ostrea cornucopie—assuming it to be identical with Woodward’s type of the same
name—may be most appropriately retained. Among other subsidiary characters, which may be cited as
indicative of the close relationship of this variety cornucopie with the ordinary Ostrea mordax stock, is
that of the same peculiar opaque purplish-pink of the external surface of the shells, with which is combined
a corresponding striate sculpturing of microscopic fineness The scar-like marking forming the attach-
ment of the adductor muscle on the opercular valve is also invariably of a dense black hue. The associated
clusters of this remarkable oyster, when viewed superficially, with little besides the opercular shells
visible, can in no way. be distinguished from the ordinary growth of Ostrea mordaxz, and it is only on
breaking them asunder and exposing the abnormally elongated lower valves that their distinctness becomes
apparent. The aspect and flavour of the meat of this oyster also corresponds with that of the ordinary
mordaxz, and of which from within the deeply excavated lower valve a much larger morsel is to be extracted
than outward appearances at first sight promise.

An oyster apparently agreeing in all essential respects with the Ostrea cornucopia, here figured
and described, has been reported to me by Captain Sykes as occurring on the Locust Rock, Sweer’s
Island, in the Gulf of Carpentaria. Further investigation will not improbably lead to its discovery in

some abundance on the Queensland coast-line, and in which case it is qualified, from a utilitarian stand-
point, to oecupy a position equal with that of its nearest allied congener, Ostrea mordaz.

Although an oyster identical with the so-called mud oyster, Ostrea edulis, of the more southern
colonies has not been obtained from Queensland waters, a species bearing some resemblance to it has
been sparingly procured by me with the aid of the dredge in Moreton Bay, and is not infrequently
washed up in a much eroded state on the outside beaches. A highly characteristic feature of this species
is the single large indentation of its free margin, and which gives to its otherwise sub-orbicular shells a
saddle-shaped contour. It has also a peculiarly thickened margin, the outer edge of which when fresh
from the sea is coloured a delicate rose pmk. A figure of a single valve of this oyster, and also a profile

view

4

view of the conjoined shells, showing their characteristic curvature, are given at Plate IV., Figs. 4 and 5.
It not having been found possible to identify this oyster with any of the species hitherto included in the
Australian list, 1t is here proposed to provisionally associate with it the title of the Saddle Oyster—
Ostrea sellaformis. The largest specimens so far observed measured as much as 4 or 5 inches in
diameter, or a size calculated to yield a substantial amount of meat. Although met with as isolated
individuals only in Moreton Bay, it may not improbably grow in some profusion and in an associated
condition in the outside waters.

Among the species of oysters occurring locally on the Queensland coast, but which are of too small
a sige for commercial purposes, 1 may make mention of the Ostrea spinosa of Quoy, which I have
observed in some abundance on the rocky shores of Curtis Island in Keppel Bay, and also in Wide Bay.
It adheres firmly to the rocks, and is covered with elongated spinous processes, somewhat resembling
those of the Thorny Clams, genus Spondylus. A small, corrugated, red-shelled oyster that grows sparingly
in deep water in various parts of Moreton Bay is known technically by the title of Ostrea circumsuta.

A species of bivalve classed among oysters in popular terminilogy, but which belongs to the
genus Spondylus, previously referred to, demands brief attention with reference to the fact that it is
very unwholesome eating, if not absolutely poisonous. The species, while occurring as far south as
Moreton Bay, is most abundant among the coral reefs of the tropical coast-line. It may be easily recognised
by the symmetrical ovate shape and convexity of its component shells, the lower or attached valve of the
two being particularly deep and cup-like, and by the peculiar formation of the hinge-joint, the shelly
teeth of which so interlock with one another that, while the valves open and close with the greatest
readiness, they cannot be separated from one another without force, even after the death of the animal
and disintegration of the connecting ligaments. The flesh of this false oyster when opened is of a pale
pinkish hue. If partaken of in any quantity, in mistake for some ordinary edible variety, severe purging
and nausea usually ensues. In order to further facilitate the recognition and avoidance of this unwhole-
some species, a characteristic figure of it is given at Plate II., Fig. 8.

THE ORDINARY COMMERCIAL OYSTER, OSTREA GLOMERATA—ITS INDIVIDUAL
MODIFICATIONS.

The ordinary commercial oyster of Queensland, with which the appellation of the “ Rock Oyster’ is
most popularly associated, is best known scientifically as the Ostrea glomerata, of Gould. This bivalve,
however, is subject to such an infinity of individual variations, dependent upon its special conditions of
growth and environment, that some concologists have been led to confer a separate specific name upon
each most prominent variety. Since, however, intermediate modifications abound that unite these at
first sight divergent types into one harmonious series, the latest scientific opinion is in favour of
including the whole within the single specific title above cited.

The diagnostic characters of this typical rock oyster, Ostrea glomerata, as embodied in Reeves’s
original deseription, are as follows :—‘ Shell thick, irregular, sharp-ribbed, with the margin dentated or
lobed, very inequivalve; upper valve opercular, compressed, wrinkled, with thick concentric lamine ;
lower valve cucullated, purple externally, white within, edged with purple or black; lateral margins
denticulated ; hinge generally attenuated, produced, pointed.”

That modification of the species that is popularly known as the dredge or drift oyster, with
reference to the circumstance that it inhabits deeper water, from which it is collected with the dredge,
has had conferred upon it by Sowerly the technical title of Ostrea subtrigona. Its distinctive features
as compared with those of O. g/omerata are thus enumerated by the authority quoted :—

“Shell subtrigonal, oblong, or subquadrate, ponderous, rather narrowed towards the umbenes, broad
at the ventral margin, quadrate; margin strongly plicated, lower valve deep, greenish white, edged
slightly with purple; without, radiately plicated, concentrically banded with fawn and purple; hinge
acuminated, sides crenulated near the hinge. The sculpture of the shell is bold and large, and the square
character of the ventral margin is striking.”’

Oyster shells possessing the characteristic features incorporated in the two foregoing diagnoses
may be found growing side by side in the same cluster, collected from a bank exposed at ordinary low
tide, or if dredged from a depth of three or four fathoms. A tendency, nevertheless, prevails with the
shallow water, tide-exposed racial stock to develop the more luxuriantly frilled and convoluted marginal
border and brighter colours associated with the typical Ostrea glomerata, while with those growing in
deeper water a smoother and more ponderous form, with often an abnormally elongated contour, and
a more or less complete absence of the conspicuous colouration characteristic of the shells exposed to
light and air, is found to predominate. The several specimens figured in Plate 1 have been selected for
the purpose of illustrating some of the most characteristic modifications of this exceedingly variable
species. At Fig. 1 is represented a cluster of the most esteemed marketable form, or typical
glomerata, taken off a cultivated bank; Figs. 2 and 3 depict the concave adherent or so-called lower
valye, and the flat, movable, or opercular valve of a similar oyster separated in order to show the internal
structure and position of the muscular scar.

Fig. 4 has been chosen to illustrate a form very prevalent among the oysters taken from deep
water or dredge sections, and in which the prolongation and smoothness of the component shells are more
conspicuously pronounced than in the typical dredge or drift variety associated in the foregoing diagnosis
with the title of Ostrea subtrigona. This abnormal elongation, it would seem reasonable to anticipate,
exhibits a disposition on the part of the molluse to grow upwards towards the light, much after
the manner of a light-starved plant. That this tendency to elongate may be manifested at an early period
in the oyster’s life is well shown by the brood-cluster represented at Fig. 5 of the same Plate, and in
which a number of slender elongated shells are attached vertically to the dead valve of a Parallelopipidon.
These young oysters were dredged from a depth of fourfathoms in Moreton Bay. The same dredge haul
that yielded these specimens brought up, however, a much more considerable number of brood agreeing
strictly in contour with the typical form of Osfrea glomerata. Adult clusters obtained from a similar
depth, moreover, containing the normal and the elongated modification in the same group.

A third notable variety of the ordinary rock oyster, Ostrea glomerata, is most typical of the northern
area of its distribution. It is remarkable for its almost cireular or sub-orbieular contour, with prominent
radiating frillings and, most frequently, deep cup-like excavation of the attached shell. This type of
oyster is abundantly represented in the extensive banks and reefs in the neighbourhood of Keppel Bay,

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5

and is also dominant among those growing on the mangroves in the Endeavour River, near Cooktown.
It never attains to the large size of its southern congener, a shell having the capacity of a single fluid
ounce being of abnormal dimensions. This modified form would appear to be indentical with the type
upon which, on insufficient evidence, the so-called Ostrea mytiloides, of Lamarck, has been established. That
it is a variety only, however, of the common species, and not a distinct form, is abundantly shown by the faet
that oysters approaching the normal triangular outline occur among them, while the orbicular variation,
on the other hand, may not unfrequently be detected growing among the typical triangular southern race.
Representative illustrations of this characteristic orbicular variety will be found at Plate I., Figs. 6 and
7. Within the circle covered by the ordinary triangular, the orbicular, and the abnormally elongate
modifications of Ostrea glomerata that have now been enumerated, the inclusion of any of the numerous
intermediate local variations that occur will be an easy task.

COLLECTIVE CONDITIONS OF GROWTH.

Among the several natural phases of growth under which the commercial oysters of Queensland
occur in marketable quantity and condition, that in which the bivalve spreads itself over extensive level
banks that are more or less uncovered at low water represents the most important. These “ bank oysters”
may be attached to stones or dead oyster shells known as cultch, or, as still more frequently happens, to
the living shells of a peculiar species of whelk, Potamides ebeninus, Bruc., whose name, with the
aborigines of Moreton Bay, is that of “Toondah.”’ This whelk, which grows to a length of three or four
inches, is essentially herbivorous, feeding on the Conferve, lower algce, and other vegetable organisms
that abound on the mud flats so favourable to the growth of the oyster. The free-swimming oyster
embryos, or “ spat’’ become attached in large numbers to the exposed dorsal surfaces of the whelk’s shell,
and are carried about with it among the most luxuriant pasture grounds. Within a few months’ time the
oysters have increased to such a size and weight that the whelk is no longer able to travel with its burden,
and where the ground is soft sinks into the mud and perishes, leaving the living crown of oysters to mark
the position of its interment. Of the number of oysters originally adhering to the whelk, some four or
five, representing the survival of the fittest, usually grow to maturity and marketable size. Included
among some very fine examples of whelk-oyster growth placed at my disposal by Dr. Bancroft, I found that
the load of oysters carried by the living whelk frequently weighed as much or more than haltf-a-pound,
while the whelk itself barely weighed an ounce.

A typical illustration of an oyster bank, representing one of the rich oyster grounds of the Bribie
Passage, Moreton Bay, is given at Plate V., Fig. 1. It is noteworthy that the banks in this district are
formed more exclusively of oysters attached to ironstone pebbles lying upon a substratum of gravel and
tenacious mud. They enjoy a high reputation for their shape, size, and flavour. Oyster banks of the
character described exist in the most luxuriant natural conditions throughout Moreton and Wide Bays, the
northernmost point of their occurrence being Rodd Harbour and “Seyen-Mile Creek,” a little south of
Gladstone and Port Curtis. The oysters on these northern beds grow under conditions, on whelks or on
separate shell or stone bases, precisely parallel with those of their southern congeners, but do not in that
higher latitude attain to so large a size. The experiment of transporting these smaller northern oysters
to southern banks is now under trial, with every promise of a successful issue, though the considerable
interval of, approximately, twelve months has apparently to elapse before the new growth commences
that is required to convert them to marketable dimensions.

Concerning bank oysters generally. it may be mentioned here that this form of growth represents
the most important from a commercial standpoint. Not only are the largest numbers of oysters sent to
market taken from the banks, but it at the same time furnishes employment and a livelihood to a very
extensive section of the community. In this connection it may be affirmed that probably in no other
country in the world is so healthy, congenial, and unlaborious a means of earning a substantial competency
open to, and turned to practical account by, all classes as that of bank oyster culture in the Queensland
oyster-producing districts of Moreton or Wide Bays. With anominal rental payable for the ground
cultivated and occupied for a homestead, a climate that permits of dispensing with all but the most
necessary form of raiment, and fish procurable in such abundance as to substantially minimise the
butcher’s bill, no more perfect terrestrial elysium is probably at the disposal of small capitalists having
sufficient means for the supply of their most immediate necessities during that first year or two that must
elapse before their oyster crops have increased to a remunerative extent.

The description of growth ranking next in importance to the bank series constitute what are
known as oyster reefs. These in their most typical form consist of solid masses of oysters that may be
several feet in thickness, raised to a higher level than the banks—the tops being exposed at about one-
quarter ebb. As a rule, the upper crust, representing some five or six to twelve inches in thickness alone
of these reefs, consists of living oysters, the substratum being composed of the dead shells of their
ancestors. These reefs in their most characteristic state rest simply on a clay or gravel basis, but are not

-unfrequently associated with a rocky outcrop as their starting point. Oyster reefs, while formerly
abounding in Moreton and Wide Bavs, are now represented in greatly diminished numbers. Their
constituent oysters, in consequence of their crowded growth, are of small dimensions, but on being broken
apart and distributed on the banks soon increase to a marketable size. Such reefs haye consequently
formed one of the main sources for the collection of stock for cultivation on the banks, and this to such
an extent that few if any reefs are to be fourd in their pristine massive condition throughout the oyster
grounds of the Southern district. A highly characteristic illustration of a typical virgin oyster reef
selected from those which oceur in the neighbourhood of ‘‘The Narrows,” between Port Curtis and
Keppel Bay, is given at Plate V., Fig. 2. The oysters in this reef are accumulated in a solid mass four
or five feet thick, their density being well shown by the portion which has been undermined by the
eurrent and broken away from the parent mass. The originally horizontal superficial area thereby
exposed serves also to illustrate the rounded or sub-orbicular shape previously alluded to, that usually
characterise the growth of oysters where massed together in this more northern district. The basis of this
Inxuriant oyster reef and of otbers in the same locality consists chiefly of gravel and coarse sand
overlaying a tenacious clay, larger pebbles or small drift boulders transported through the agency of
flood currents being here and there interspersed among the general mass.

Typical rock oysters, wherein the bivalve occurs in masses attached to rocks, are well represented
in the illustration Plate VII. Fig. 1, reproducing the rocky outcrop with attached oysters at Burleigh
Head, near the mouth of Tullebuggera Creek, a little to the south of Southport. The oysters growing
under these conditions, though smaller in size than the bankers, are often of a deep cuppy pao at

Oxcellent

6

excellent in quality. Like those growing on the reefs they are well adapted for separation and cultiva-
tion on the banks, though the tenacity with which they adhere to their rocky basis involves considerable
more care and labour in their detachment.

What are known as “Mangrove” oysters represent an important item in the Queensland growth
conditions of Ostrea glomerata. These are the oysters with which originated the supposed travellers’
tales of earlier days concerning oysters growing upon trees. The most typical and commercially important
phase of mangrove oyster growth is represented by those instances in which the oysters start to grow on
the exposed roots and respiratory shoots or so-called “ cobblers’-pegs”’ of the white mangrove, Avicennia
officinalis, and by the process of accumulation may increase to such an extent as to constitute under the most
favourable circumstances massive banks scarcely less prolific than the typical reefs previously described.
The initial form of such a mangrove oyster bank, together with the perfected luxuriance to which it is
capable of attaining, is illustrated by Plate VI., Fig. 1, and Plate VII., Fig 2, representing reproductions
of selected photographic views taken respectively in Moreton and Keppel Bays. Where growing in the
prolific manner represented on Plate VII., they constitute, as in the case of the typical reefs previously
described, valuable material for segregation and artificial cultivation on the banks.

A second and somewhat less prolific variety of mangrove oyster growth is that in which the species
is found attached to the luxuriantly ramifying aerial roots of the red or orange mangrove, Rhizophora
mucronata, as illustrated in Plate VI., Fig. 2. Oysters on this description of mangrove more commonly
occur in the northern area of distribution of the species, and in such localities as the mouth of the
Endeavour River, near Cooktown, and at Bowen, Port Denison, constitute the almost exclusive representa-
tive variety of the species. This mangrove oyster occurs also in some abundance in certain parts of
Wide Bay such as the vicinity of the South Head. In consequence of its adaptation of contour to the
shape of its supporting fulchra, this oyster is apt to develope a very irregular form of growth; if, how-
ever, moved at an early stage of its existence and spread out under favourable conditions for culture on
the banks, it has been found by systematic oyster growers to well repay such attention. This being the
experience gamed on the Wide Bay oyster grounds, it may be anticipated that successful results would
also accompany a like treatment of the variety in its natural habitat further North. This anticipation is
supported by the circumstances that oysters of larger and edible dimensions and quality are to be
gathered from among the fallen débris lying around the mangrove trees, and where living more or less
separated from one another, they have room to expand. Giving due weight to this fact I am of the
opinion that remunerative banks, productive of oysters in at least sufficient quantities for local consump-
tion, might be established, with stock derived from the mangroves, in these more Northern districts. In
the establishment of such experimental banks attention should be given to imitating as nearly as possible
Nature’s own pattern, the banks being formed, not on the open sun-exposed flats but within that
umbrageous shelter of the mangrove trees where the species attains to its finest development in these
higher latitudes. The conditions indicated obtain on a sufficiently extensive scale for the practical
application of the above suggestions in both the estuary of the Endeavour River and at the mouths of
the several creeks debouching into Port Denison, in the neighbourhood of Bowen.

I have been recently informed by Mr. Yeo, the manager of the Moreton Bay Oyster Company,
that the above described variety of mangrove oyster grows so luxuriantly in favourable localities in the
neighbourhood of Rodd Harbour that as many as twenty or thirty bags ot oysters suitable for cultivation
on the banks have been gathered by their agents from a single tree.

The collective growth forms of Ostrea glomerata, known as dredge and drift oysters, remain to be
noticed. The first-named title is applied generally to all oysters growing below the level of usual ebb
tide, that of drift oysters being more exclusively associated with those lying loose and separately at the
bottom of the water, and which are supposed to have been washed from off the banks or beds, and to
drift here and there at the mercy of the prevailing currents. The tendency of the dredge, or deep water
oyster, to develop a more elongate shape with a much smoother and less crenulated marginal border has
been referred to on a previous page. With the typical “ drift’’ variety the tendency, through continued
erosion, to develop an abnormally massive shell is especially noteworthy, instances occasionally oécurring in
which the lower or right valve weighs as much as half a pound avoirdupois. The concavity of such a shell is
rarely of sufficient size as to contain more than a single fluid ounce, while the corresponding shell
of a large cultivated “bank” oyster, having an internal capacity of two fluid ounces, yields an
average weight of scarcely three ounces. Dredge and drift, as compared with bank, oysters con-
tribute to a less extent to the oyster trade of Queensland, the relative proportions so far as it
can be ascertained, while formerly considerably larger, beng now about 20 per cent. In
this respect the Queensland oyster fisheries present a marked contrast to those of the neighbouring
colony of New South Wales, and in which the dredge and drift varieties have until within recent times
represented the most important commercial factor. Among the arguments that have been advanced in
favour of the specific distinctness of the deep-water oyster, or Osétrea subtrigona, as it is designated by
those who advocate its distinction, is the one that this deep-water form will not live if transported to
the tidally-exposed banks, nor the bank variety if consigned to deep water. If the transition is made
unseasonably, unfavourable results are likely toensue. Where, however, the change is judiciously effected,
no difficulty is experienced in cultivating dredge or drift oysters on the ordinary banks, or vice versd. In
various localities in Moreton Bay, and notably at the Breakwater in Nerang Oreck, oysters grow in a
continuous sloping series from a depth in which they are covered by a fathom or more of water to the
tops of rocks that are dry with every ebb. Oysters taken from these exposed rocks are, moreover,
systematically and successfully laid down as ‘cultivation’? on a neighbouring dredge section, where
they are covered by at least two fathoms of water. No more practical evidence, probably, could be
furnished in demonstration of the specific identity of the deepwater and tidally-exposed series. Parallel
illustrations of a species of oyster adapting itself to the varied conditions of either total or partial
submersion are afforded by the typical European oyster, Ostrea edulis, or its Australian variety, O. angasi,
as it occurs in the more southern colonies. In the former instances it may be dredged in the open sea
at a depth of as much as twenty fathoms, being then represented by the large rough form commercially
known as Channel oysters, or it may be gathered somewhat rarely in England, but more abundantly in the
warmer waters of the Channel Islands, or on the neighbouring coast of France, adhering to the rocks
after the manner ot Ostrea glomerata. It is this same species, moreover, in its coarser natural form,
ordinarily taken with the dredge, that is cultivated on so extensive a scale on the tidally exposed foreshores
of France, or that is transformed, through a long and tedious course of manipulation, into the costly world-

renowned

7

renowned Colchester or Whitstable “ Native.’ The fact that the drift or deep-water form of Ostrea glom-
erata, as it occurs in Australian waters,is most commonly found separated by a considerable interval of space
from its congener of the rocks or banks, is probably explained by the circumstance that the strong current
or scour which is essential for its healthy existence is wanting in the intermediate barren areas. A deep
well-scoured central channel in which the mollusc flourishes is commonly separated from the equally clean
tidally-exposed, and current-swept litoral margin by an intervening area of stiller water, within which
mud and sedimentary matters accumulate to an extent rendering it unsuited for oyster growth.

In connection with the subject of “ dredge’’ oysters, it is worthy of mention that the theory has
been advanced that profitable beds of the ordinary commercial variety, Ostrea glomerata, probably exist
in deep water on the open coast-line of Queensland and New South Wales. The evidence adduced in
support of this theory is founded on the circumstance that oysters have been recently dredged under such
conditions off the Victorian coast-line in connection with the prospecting cruise of the Victorian Govern-
ment steamer “Lady Loch.” The successful results there obtained were the outcome of a report I made
on the Victorian Oyster Fisheries, and in which, in consequence of the traces of the existence of
oysters observed by me along the Ninety-mile Beach and other portions of the coast, I foretold their
presence in extensive beds, and recommended to the Government that experimental dredging operations
should be undertaken with the view of their discovery. The species of oyster in this instance, however,
was the so-called mud oyster, Ostrea edulis, var. Angasi, of which the largest natural beds are found in
the open sea. The Queensland and New South Wales commercial form, Ostrea glomerata, is an essen-
tially estuarine or brackish water type, and which, so faras my investigations and inquiries have extended,
is never met with in water that is permanently salt. There is consequently, I consider, little or no chance
of success attending any attempt that might be instituted to dredge for this oyster on the open sea-board.
Withrelation to the salinity of the water most favourable for the growth of the Queensland commercial oyster,
Thave found, in association witha prolonged series of investigations, that a mixture of one portion of fresh
water to four of standard salt water represents the most normal conditions under which it flourishes. In
times of drought it frequently happens that the oysters in many localities are immersed for considerable
periods in water that is entirely salt, and conversely during floods in purely fresh water. Should this latter
condition, however, obtain for over a week, disastrous results usually ensue, more especially with relation
to the immature stock.

Experiments were also undertaken by me with the view of ascertaining the action of water of
varying density upon the newly born oyster embryos or spat. Of ova and milt commingled with one
another in purely salt water it was found that but a very small portion of the ova were fructified, and the
subsequent development of these few proceeded very slowly. Another series placed in water consisting
of an equal proportion of salt and fresh exhibited the most active vitality, all the ova being fertilised and
speeding quickly on their developmental career. In a third series experimented with, the proportions of
water used were one part of salt water to three of fresh. In this instance the ova were entirely deprived
of life, and soon commenced to disintegrate. This last experiment assists mueh towards demonstrating
the deleterious action exerted by floods on the embryonic brood, and where the proportion of fresh water,
as in the example tested, is greatly in excess of the salt. It is at the same time worthy of remark that
the access of flood water appears to give a pronounced stimulus to the oyster’s reproductive faculties, an
abundant fall of spat commonly following after the advent of a flood, and thus compensating for its
ill-effects upon the previously developed brood.

ARTIFICIAL CULTIVATION.

The artificial culture of oysters, as understood and practised in connection with the Queensland
Oyster Fisheries, and as applied to the single species, Ostrea glomerata, consists essentially of collecting the
immature brood, locally known as “cultivation,” and separating and spreading it out on banks and
beds where the conditions are more favourable for its development to marketable dimensions. One
of the most important sources from which this ware or “ cultivation”? is derived, is represented by the
tidally-exposed reefs described on a preceding page, and from whence, with the least expenditure of
labour, vast quantities can be speedily collected. Not only have the oyster reefs and banks throughout
Moreton and Wide Bays been laid heavily under contribution for the supply of this “cultivation,” but
supplies for the same purpose are now being imported from as far north as Rodd Harbour and Keppel Bay.

Such is the enormous fecundity of the Queensland commercial oyster, and the extent of the areas
available for the adherence and development of the spat, that little or no occasion has hitherto arisen for
resort to the more elaborate methods of oyster cultivation practised in European waters, and which com-
prises as its most fundamental principle the provision of special apparatus for the catchment of the
embryo brood. Sufficient, however, as the supply may be to meet the existing demand, it may be
predicted that, with the increased home consumption and greatly extended export trade that may be
reasonably anticipated within the next decade, some more scientific method than that hitherto in force
will be in request for saving some portion of the vast amount of oyster spat annually produced, which,
under present conditions, is literally lost at sea. By the lowest estimate arrived at by trustworthy
investigators it would appear that each mature female oyster produces at least from 2,000,000 to
3,000,000 embryos at the annual breeding season. Of the vast number thus produced it has been further
estimated by Mobius concerning the European species, Ostrea edulis, that less than one individual oyster
in each of these million embryos runs the gauntlet of the innumerable perils that beset its career, and
arrives at maturity. The greatest amount of mortality that decimates this embryo host is undoubtedly
associated with its failure, after the maturation of its shell, to fall upon ground or materials to which it
is able to secure an effective anchorage. Unless the surface on which it falls is clean and entirely free
from slime or sediment, adhesion is not accomplished, and the embryo drifts away or sinks
into the mud or sand to perish. The aim and end of the systematic methods of oyster
culture in operation in European, and most notably French, waters is to encompass the salvage
of the vast shoals of embryonic waifs that would naturally run to waste. The accomplishment
of this highly desirable result is effected mainly through the provision of apparatus styled
“eollectors” that form attractive media for the adhesion of the spat. These collectors are
constructed of varying form and material. From the earliest days of oyster culture the old shells or
“cultch” of the oysters originally raised for the market have been systematically saved and placed
upon the beds with gratifying results ; such materials constituting, in fact, one of the most natural media
for the attachment of the embryo brood. Faggots of wood, best known by their ere title of

“fascines,”’

8

“«fascines,”’ have been and are still extensively used in French waters, and at the ancient oyster breeding
establishment of Lake Fusaro in Italy for a similar purpose. The most efficient description of artificial
spat collectors that have been invented are, however, probably those first introduced into the French
oyster grounds by M. Coste, and which consist of a cheap form of earthen tile, the under surfaces of which
are coated with Portland cement. The calcareous constituents of the cement, when set and seasoned, are
so analogous tothose of the parent oyster shells that the embryo brood adheres to it with equal readiness. A
second form of collector, successfully employed in France, consisted of cemented boards united by their
long edges in ridge-tile fashion, and being strung one above another in sets, and anchored by a stone, are
allowed to float freely in the current. This “ ridge-tile” form of collector was first employed by myself
with fair results in connection with the Government Oyster Reserves of Tasmania, established under my
supervision in the year 1885, with the object of resuscitating the at that time exhausted oyster fisheries of
that colony. Figures with a description of this form of collector were published in my report to the
Tasmanian Government for that year, and, acting on the information therein contained, Iam informed that
similar collectors were experimentally placed on one of the cultivated banks in Moreton Bay. These
collectors, as a result, were soon covered with spat, but, being set in shaliow water, they, as each tide receded,
fell to the ground, and the young oysters became a ready prey to crabs and whelks. The same form of
collector has also the drawback of getting water-logged and sinking to the bottom by its own weight after
prolonged immersion, and when the attached brood runs the same risk of premature destruction by
its natural enemies or by the accumulation of sand or mnd.

As an improvement upon and simplification of this ridge-tile collector, I subsequently made use of
the rough form of boards, known throughout the Australian Colonies as “split palings.” Such palings—
4 feet long, 8 inches wide, and 1 inch thick—were readily procurable at the low price of from eight to
ten shillings per thousand. Witha brick or stone attached by wire to each end on the under side,
the surface between the two bricks coated with cement, and a loop of wire fixed to the upper surface to
serve as a handle whereby they could be carried easily or lifted from or lowered to the bottom of the
water with the aid of a boat-hook, they were found to constitute the most convenient and economic form
of collector that could be desired. The bricks or stones on the under surface served the double purpose
of anchoring the collectors securely to the bottom of the water, and at the same time raised the cemented
surface above the reach of predatory crabs and whelks. In practical application these paling collectors
were found to possess all the efficiency of the French tiles, with the advantage of a far greater economy
of cost. The tiles, with individually smaller superficial areas for the attachment of the spat, cost in France
about £2 per thousand, and could scarcely be produced in Australia for double that price. In order to
test the efficacy of this description of spat collector in connection with the Queensland oyster, Ostrea
glomerata, a few samples were constructed and experimentally placed on ground at a spot where a few
mangrove oysters already existed, near the mouth of Nerang Creek. These collectors were deposited in
the month of July, 1890, and within from three to four months from that date were literally encrusted
with oyster brood having shells which averaged one inch in diameter. Two months later a large portion
of these oysters measured individually as much as two inches in their longest diameter, and being loosely
attached by the butt-end were ripe for detachment and distribution on the ordinary cultivation banks. As
many as 2,000 young oysters were thus found attached to a single collector, being the equivalent of what,
in the ordinary course of development, would, by the end of another eighteen months, represent a standard
two bushel-bag of marketable oysters. Photographs of these sample collectors in their newly-made
condition, and with attached oyster brood, are represented in the illustrations of Plate VIII.

Although the general employment of artificially prepared spat collectors upon the Queensland
oyster banks as here described is not recommended, and would be scarcely profitable in association with
the existing abundant supplies and the extensive natural spawniug grounds at the disposal of the leading
lessees of the oyster fisheries, there are undoubtedly circumstances and conditions under which their
introduction would prove of value. With the aid of these and kindred collectors, miles of what now repre-
sent barren unremunerative mud flats in both the Moreton and Wide Bay districts might be made to
produce an abundant harvest; while to small selectors having foreshore allotments at present yielding
them no return below high water-mark, they have at hand the ready means of substantially augmenting
their incomes. That in the no very distant future the employment of artificial spat collectors will be
desirable, if not obligatory, as a means of supplementing the natural supplies and meeting the increased
demand for both home consumption and export purposes that is likely to arise, is a conclusion, indeed,
that can scarcely be avoided. The more immediate necessity of resorting to artificial methods for collecting
oyster spat has, | may further observe, been strongly advocated by the Moreton Bay Inspector, Mr. C. 8.
Hison. At page 4 of his report for the year 1886, among a list of amendments recommended for the
better regulation of the oyster fisheries, a prominent position is allotted to that of the compulsory
employment by oyster bank lessees of artificial methods of spat catchment.

It would appear desirable under the present heading to make a brief allusion to the section on
oyster cultivation included in the same District Inspector’s Report for the year 1890. At pages 3 to 5
of the report referred to, extensive quotations are made from leiters treating on the subject, contributed
by a Sydney oyster merchant to the Sydney Press. The general tenor of these letters is to depreciate the
results that have been accomplished by methods of artificial cultivation in France. These results are, in
point of fact, so grossly misrepresented as to make it appear that the system is itself a failure, and that
no success could attend its introduction into Australian waters. The acceptance and re-publication of
these letters, in all good faith, in an official report, as embodying the latest and most accurate information
on the subject of oyster culture, is necessarily calculated to mislead the public and to discourage any
efforts being undertaken to profit by the highly successful results actually accomplished on the French
sea-board. It is with the object only of counteracting so undesirable an influence that a brief statement
of the actual facts, with accompanying statistical figures, are herewith submitted. Jn the first place, it
would appear that the data upon which the letters above referred to are based were derived from the
Government report on the oyster fisheries, Ireland, dating so far back as the year 1870, and at about
which time, as testified to by witnesses engaged to collect evidence, the French Oyster Fisheries were
undoubtedly in a very declining state. The cause of that decadence, which is fully explained in the
report, but is in a most unaccountable manner totally ignored in the documents cited, was the
ayariciousness of the oyster growers, who stripped their beds to such an extent to supply the markets as to
leave an insufficient quantity for the purposes of propagation. This error, however, was corrected as
s00n as recognised, aod with the result that within a very few years the French Oyster Fisheries had not

only

9

only regained their former position, but eclipsed previous years in productiveness. The accompanying
figures, derived from the French statistical returns, abundantly substantiate this statement. In the year
1873 the official value of the oyster produce of France was estimated at 2,447,565 franes, or roughly
ee For the three succeeding years the produee and value of the same fisheries are given as
ollows :—

Oysters taken off beds. Value in francs. English equivalent.
1874 402 104,731,350 sue 7,727,000 080 £309,080
1875 =& 227,640,212 200 11,247,416 BS £449,896
1876 a0 335,774,070 ses 13,226,296 set £529,051.

In the year 1887, representing the latest statistics immediately available, the total number of oysters
taken from the French fisheries is quoted at 375,000,000, showing that the magnificent record of the year
1876 has been beaten.

Among the evidence brought forward in the Sydney letters, with the view of depreciating the efficacy
of the French system, and republished in Mr. Fison’s report, much stress is laid upon the cireum-
stance that some twenty yearsago the Hon. Thomas Holt, recognising the value and capabilities of that
system, undertook, at an expense of some £10,000, though unfortunately without success, the construction
of extensive culture ponds, or “claires,” at George’s River, New South Wales, for the cultivation of
oysters on the same principle. The causes that led to the failure reported, however, were not attributable
to the system, but to the fact that a species of oyster differing essentially in form, habits, and methods
of propagation from the European type was experimented with. Having recently availed myself of the
opportunity of inspecting these extensive “claires”” constructed by Mr. Holt, Iam of the opinion that
they are altogether unsuited for the culture of the Queensland and New South Wales commercial oyster,
Ostrea glomerata, that was the subject of experiment. On the other hand, they would in all probability
prove highly suitable for that special fattening process of Ostrea edulis, for which alone these
claires are utilised in France. Properly constructed, these claires take the form of shallow ponds of from
twelve to eighteen inches in depth, and are so connected by means of sluices with the sea that fresh
streams of salt water obtain access to them only at spring tides; the water throughout the intervening
periods remains completely stagnant. It is through the culture of the French oyster under these special
conditions that that green colouration of the oyster’s tissues is acquired that command for it so high a
price in the Paris market, such colour being due to the character of its food, which consists almost
exclusively of the microscopic plants known as diatoms and the spores of the confervoid alge. This special
claire system of oyster culture is in no way suited to the Queensland oyster.

Oyster culture on the French system, on the other hand, in so far asit consists of providing supple-
mentary material or apparatus for the catchment of the redundant supplies of spat is undoubted]
worthy the attention of all oyster growers. Whether this material takes the simplest form of the returned
parent shells or eultch, or of tree-branches or fascines, or cemented tiles or boards, the result to be accom-
plished is identical, and it resolves itself to a question simply as to which of these can be most economically
or profitably employed on the areas under cultivation. In this direction it will be found that different
descriptions of oyster ground yield the best results in association with diverse descriptions of collectors.
On those beds and banks which are more or less completely submerged, and over which there is a sufficient
scour to prevent the accumulation of sediment, old oyster shells or cultch constitute the most convenient
and efficient form of spat collector to employ. This material, however, if laid on muddy banks, or where
there is an insufficient circulating stream, becomes speedily covered with slime and sediment, and is, in such
condition, useless as a spat-trap. The sine gud non of successful oyster spat deposit is the existence of
a perfectly clean surface for the embryo oysters to adhere to. On the oyster grounds in English waters,
such as Whitstable and Herne Bay, where the natural beds consist mainly of such old shells or cultch,
its surface is continually worked over with the dredge with the express object of exposing new and clean
shell surfaces for the attachment of the embryo brood.

The form of collector next demanding attention is that of fascines or faggots, composed of boughs
and branches of various sorts of timber trees. This description of collector is essentially fitted for employ-
ment on oyster grounds where they can be kept continually floating or submerged below the surface of the
water. The drawback to the use of fascines, or tree branches in any form, is their liability, on exposure
to light, to become speedily coated with slimy growths that leave no foothold for the young oysters.
Considerable differences are, however, manifested by distinct kinds of trees with reference to their
attraction for oysterspat. The commoner Australian gums, Eucalypti, and wattles, Acacias, are apparently
distasteful on account of the pungency of the essential oils and essences they continue to exude even after
prolonged submersion, and are but rarely encrusted with oyster brood. The Coniferce, including the cedars
and cypress-pines and also the shea-oaks, Caswarinas, have, on the other hand, been found in practice to
yield more favourable results than any other timber, and more especially in experiments conducted by me
relating to the artificial propagation of the Tasmanian oyster. The readiness with which the Queensland
species naturally adheres to the large branching aerial ruots of the orange mangrove, Rhizophora mucronata,
would seem to indicate that this material would form an excellent one for the systematic construction
of fascines.

To render fascines more efficacious as spat collectors, the boughs of which they are composed are, *
as used in Europe, not unfrequently washed over with cement. This modified form of fascines
leads to those descriptions of collectors in which cemented surfaces are exclusively employed. The
most prominent of these are the cemented tiles first employed by M. Coste, and with the aid of which
miles of barren mud flats on the coast of France have been converted into mines of wealth giving
employment to thousands of individuals. This description of collectors is eminently adapted, and was
originally constructed, for employment on banks or flats that are left uncovered at ebb tides, and is
unsuited for manipulation beneath the water.

The peculiar advantages of cemented tiles and of all forms of collectors constructed on the same
principle, consist in the fact that the relatively large cemented superficies, being on the under surface of
the collector, when placed in position, it remains almost permanently clean and ready for the adhesion
of the spat. They are consequently well adapted for employment on mud flats, where there is much sedi-
mentary deposit and under conditions in which other forms of collectors would be useless.

The “ split-paling”’ collectors, first introduced by myself in the Colony of Tasmania, as the nearest
approximate substitute for tiles, which were unprocurable, except at prohibitory prices, proved in all
ways equal to tiles as spat collectors, and in various directions possessed distinct advantages, Their price

of

10

of 10s. per 1000 rendered them cheaper for the purpose than any article previously employed. With
attached wire handles they were more convenient for handling on the exposed banks, and could, in addi-
tion, be easily deposited in or raised from water of a fathom’s depth. Their individually larger superficial
area entailed a considerable saving of labour in their manipulation, while, as indicated on a preceding
page, the circumstance of the cemented surface being raised by the attached bricks or stones some few
inches off the ground secured to the young oysters an immunity from the attacks of crabs, whelks, star
fishes, and other enemies to which they are exposed when the cemented surface, as is the case of tiles, is
in immediate contact with the ground.

The “split paling” type of spat collection, as figured in Plate VIIL., is, in my opinion, after an
experience of its successful employment under a variety of conditions, the most convenient and economic
form to employ in Anstralian waters, and may be characterised as an essentially Australian product.
Sawn boards may, as a matter of course, be fashioned into collectors of identical form and efficiency,
but at many times their cost, the relative price of the respective materials averaging 20 feet for 1d.
for the split palings, and 13d. per foot for the sawn wood. In practical use the split palings are further
found to possess an advantage over the sawn material, through the roughly parted natural grain of the
wood furnishing a more favourable key for the attachment of the cement. When split to order for this
purpose they should average at least an inch in thickness, and have as rough a surface as it is possible to
obtain. Where split palings are not procurable the rough discarded rails or boarding of any description
that is usually abundant around every settlement, may be pressed into service and be made to do good duty
before final condemnation for firewood. In the preparation of these collectors the palings or boards
should be soaked for a day or so in the water in order that the grain may swell to its full extent before
the application of the cement. Should this precaution be neglected the cement will not adhere to the
wood. Salt water is as good as fresh for mixing the ecment, and, as the process may be most con-
veniently performed at the water’s edge in the immediate neighbourhood of the beds under cultivation, °
this proves a distinct advantage. From experience gained by the use of these collectors in Queensland
waters it may be observed that about half-tide mark represents the zone within which the most abundant
harvest of spat can be gathered, and that at all times of the year, though the months of February and
August are more especially propitious for its collection.

On their first attachment to the cemented collectors it will be found that the young oysters adhere
to the cement by the entire surface of the attached shell, a condition of growth which obtains for the
most part in the central figure of the lower group of collectors figured at Plate VIII. After attaining to
about one-half of an inch in diameter, the free edges of the shells commence to grow outwards, and this
direction of their growth is continued until at an age of about six months they project an inch and
a-half or 2 inches from the collector. At this stage the young oysters may be easily detached with or
without the cement, and be jaid on the banks as ordinary “cultivation.” ‘lhe collectors may then be re-
cemented and re-laid for the catchment of a second crop. Cemented slates have also been found by me
to prove very efficacious spat collectors, and most nearly approach the French tiles. Slates procured as
an ordinary market article are too expensive for general employment. It sometimes happens, however,
as occurred with the supply experimented with, that condemned lots may be obtained at but a little over
the cost of carriage direct from the quarries. In utilising slates for this purpose I have found it most
convenient for manipulation to use them in combined series, wiring sets of half a dozen or so to each
side of a ridge-shaped frame constructed of light saplings cut to 4 or 5 feet lengths.

DESTRUCTIVE AGENCIES AND DISEASES.

Among the enemies from whose attacks the Queensland oyster-grower suffers serious loss of
stock, the small boring whelk, Urosalping paive of Crosse, must be awarded a prominent position. The
destructive iufluences exerted by this molluse are parallel to those of Murex tarentinus and Nassa
reticulata on the European oyster beds. The shell of the Queensland borer is much like that of the
last-named European species, but is more slender, and it has a distinct violet-coloured lining to the mouth
aperture. A figure of the species is given at Plate I., Figs. 10 and 11. The young oyster brood, from its
earliest attached condition up to about one-half of its adult growth, is much subject to the ravages of this
foe. Not unfrequently, it is so abundant and predaceous that almost the entire brood stock on a bank
or from dredgings I have investigated was found to be destroyed by this borer. Mature oysters, even, are
not exempt from the attacks of this enemy, one of the shells in the typical cluster illustrated by Plate I.,
Fig. 1, exhibiting at “a” the symmetrically cireular hole by which the Urosalpinx has gained access to its
prey. The drilling operation is performed by these boring molluscs with the aid of a toothed ribbon,
technically known as the “Odontophore”’, which is enclosed within, but can be partly protruded from,
the buccal cavity. It has been ascertained by direct experiment in connection with the European species,
Murex tarentinus, that the molluse takes about half an hour to pierce the shell of a young oyster
one month old, and eight hours to perforate a matured one of three years’ growth. The only
pec remedy for this destructive pest so far employed is hand-picking, a tedious process which,

owever, can be carried into practice with considerable success on the banks, especially with the aid of
children, who soon become great adepts in detecting and collecting the unwelcome intruder. By these
means the borer has already been fairly exterminated in certain of the most carefully-cultivated banks.
This same species of boring whelk has been observed by me in abundance on the oyster banks as far
north as Rodd Harbour and Seven-mile Creek, and where also it takes a heavy toll on the growing brood.
The interesting discovery was recently made and communicated to me by Mr. BE. Kelk, of Brisbane, that
another gasteropodous molluse, Natica plumbea, preys upon the Urosalpinx. This species, figured at
Plate IIL, Figs. 3 and 4, is of larger size than the borer, with a smooth snail-like shell. In the living
state a large fold of flesh, technically termed the mantle, is protruded from the shell and forms a con-
tinuous border of about an inch in breadth around the creature as it crawls. With this mantle it was
observed by Mr. Kelk to seize and envelop the living borers and to retain them within its folds until by
muscular force it had dragged from its shell and devoured its victim’s body. Should this recorded habit
of Natica plumbea prove on further investigation to be its customary one, a valuable remedy for the
ravages of the borer will have been discovered, and to be effected through the collection and placement
on the beds of quantities of Watice to devour and keep them in check. Before the application of this
specific it is, however, desirable to ascertain whether or not under certain conditions, such as the scarce-
ness of Urosalpinx, the Natice may not develop a latent taste for young oysters. This precaution is the
more necessary since in various standard natural history works small bivalve molluscs are enumerated as
constituting the ordinary food of the many species of the genus Natica. Starfishes

Lt

Starfishes of all descriptions, but more especially the ordinary five-fingered varieties, Asterida, are
universally held up for condemnation as representing the most insatiable foes of the oyster tribe. Whether
this wholesale condemnation is a just one there are some reasons for doubting. In many instances it has
been observed that the starfishes were merely acting as scavengers, and preying on dead or dying bivalves.
The direct experiment was carried out by myself some years since in one of the large English public
aquaria of keeping oysters and starfish, including the accredited most aggressive species, Uraster rubens, in
the same tank, These two pre-supposed antipathetic types were thus maintained side by side in perfect
health for many months without a single instance occurring of molestation of the oysters on the part of
the starfish ; these latter, however, fed freely on portions of the cut-up fish occasionally placed in the
tanks. How far this vindication of the starfish’s character would hold good in association with the
common shore species of South Queensland has yet to be demonstrated, and in the interimit is desirablein the
interests of the oyster-grower to recommend the clearance of this intruder as far as possible from off his beds
or banks. In this connection a suggestion concerning the destruction of starfish may prove acceptable.
It is by no means an uncommon practice among oyster cultivators on bringing up starfish in the dredge, or
finding them on the banks, to rip them in pieces and cast them aside or into the water again under the
impression that their life is destroyed. As amatter of fact each of the five finger-like processes
separated from the starfishes’ body is capable of growing into a fresh starfish, so that by the process of
dismemberment the further multiplication of the species is accomplished. To encompass the certain
destruction of these animals it is desirable that they should be carried to land and be deposited above the
reach of the tide.

The different species of Sea Urchins, or Sea-Hggs, Echini, have been occasionally associated with
oyster-eating proclivities. Their habits, however, are essentially herbivorous, and the only injury they
might possibly, but very improbably, do to oysters is that of piereing the very young and fragile shells
with their spines in passing over them.

Many varieties of fish prey more or less extensively, though not exclusively, on oysters. Among
these may be mentioned the family of the toad-fishes, Tetradons, porcupine fish, Diodons, leather-jackets,
Monacanthi, and the several varieties of breams, Pagride. The most destructive fishes on the oyster
banks are, however, undoubtedly the Sting-rays or “ Stingarees,’ as they are popularly denominated,
belonging to the shark tribe and referable to the genus Zrygon. The common dark brown species, Tygon
pastinaca, is probably the greatest delinquent in this direction. It avounds on the low-lying banks
throughout the oyster-growing districts, and commits serious havoc among the young stock with the
assistance of its pavement-like crushing teeth. A more typical oyster-eating member of the shark tribe
that abounds in the southern colonies and is occasionally taken in Moreton Bay is the so-called Port
Jackson shark, Heterodontus Philippi. It is of a tawny brown colour with an abnormally large head and
projecting brow ridges, and has a strong sharp spine developed in front of each of the two dorsal fins. It
rarely exceeds a length of 5 feet, but is provided with powerful crushing jaws, of greater strength
even than those of the Rays, and with which it easily breaks up the largest oyster shells. On
certain of the Tasmanian oyster reserves and private beds it wrought such havoe that the oysters were only
saved from entire destruction by fencing them round with wire netting. With reference to its oyster-
eating proclivities, the species is known in Tasmanian waters by the name of the “oyster crusher,” while in
some parts of Victoria it is called the “ pig-fish.” By way of illustrating the peculiar hardness of its
palate it may be mentioned that in the neighbourhood of Port Jackson, New South Wales, it feeds very
extensively on the spine-covered Sea Urchins, Echini, its teeth being frequently stained a bright violet
hue through its predilection for this diet.

A species of boring sponge, Hymeniacidon celata, has here, as in European waters, to be included
among the enemies of the oyster. Its attacks are, however, confined almost exclusively to old shells in
deep water,and which it honeycombs in every direction. The parasite is soon got rid of by the exposure
of the affected oysters to light and sunshine on the banks.

Several species of birds, including notably the so-called oyster-catcher, Hematopus longirostris, and
the numerous members of the crane tribe that frequent the oyster banks at ebb-tide, prey to some extent
on the young oyster brood. Next to the borer, however, the greatest amount of injury to the oyster
gu enene growing crops is probably committed by the innumerable species of crabs that infest the beds
and banks.

A destructive agency that has caused great losses to the oyster-growers of New South Wales, and
of which there was some suspicion of its having made its appearance among the oysters in Wide Bay, is
what has been styled the ‘“‘ Worm Disease.” This disease is characterised by the presence within the oyster
shells of patches of mud, which are more or less completely covered in by a a shelly or membranous redeposit.
One or more small worms, Leucodore ciliata, are almost invariably found enclosed within these mud-
cavities, and from which, through a tubular channel, they maintain a communication with the outer water.
This worm is usually credited with being the primary origin of the so-called disease, but on the
strength of a slight passing acquaintance made with it in New South Wales, and all the facts relating to
it that have been published, I am inclined to believe that the organism is only an accompaniment, and not the
cause of the disease. Mr. Whitelegge, of the Sydney Museum, who has approached the subject from the
standpoint of the worm being the originator of the disease, has made the following remarks, after
making investigations concerning its occurrence at the Hawkesbury River :—“The principal home of the
worm appears to be on the mud-flats about low water-mark. The oyster from this region, the Hawkesbury,
were invariably infected with the worm, particularly those which lay loose on the surface or were partially
buried in the mud. Those oysters which were fixed to some solid substance, and elevated ever so little
above the surface of the mud, were comparatively free from the pest.’’ The foregoing testimony goes
far to show that this so-called worm disease is essentially a “dirt disease.’’ It is only in a muddy environ-
ment, unsuitable for the healthy growth of the oyster, that it spreads, and that it is the mud, and not the
oyster per se, that attracts the worm, is demonstrated by the fact attested—that the oysters elevated
but a few inches above the muddy stratum are relatively free from the affection.

The inference that I am inclined to arrive at concerning the occurrence and manifestations of this
disease, is that the oyster through the foulness of its surroundings absorbs within its shell cavity, by
the ciliary action of its gills, a greater amount of mud than it can get rid of, and that the worm in its
free-swimming embryonic state being drawn within this cavity by the same cilliary currents of the oyster,
settles down with alacrity within so congenial a mud-lined cradle. The worm, Leucodore ciliata, under

discussion,

12

discussion, enjoys an almost cosmopolitan distribution. Its habitat, as described in Dr. Johnson’s
catalogue of non-parasitical worms in the year 1865, is as follows :—“ Found living between seams of slaty
rock near low-water mark, and burrowing in the fine soft mud which lines the fissures.” By a well-
known Queensland oyster cultivator, I have been informed that the same species of worm was noticed
by him many years ago burrowing in the mud-filled crevices of timber work in Sydney Harbour. The
species, like most members of its class, is an essential mud lover, and its natural instincts guide it in its
earliest larva] condition to seek out and establish itself within any appropriate mud-lined crevice.

So extensive have been the depredations of this mud disease with its associated worms in New
South Wales, that many of the formerly most productive oyster grounds of that Colony have been
practically depleted, and it is owing to this disease, mainly, that instead of exporting, that Colony is now
so largely dependent on Queensland and New Zealand for its supplies. Much anxiety is naturally
manifested to exclude this destructive agency from taking up its abode in Queensland waters, and having
that circumstance in view, the fullest information concerning its probable cause and possible prevention
will doubtless prove acceptable. In this direction | herewith reproduce the views on this subject
expressed in a lecture upon “ Oysters and Oyster Culture in Australia,’ I contributed to the meeting
of the Australian Association for the Advancement of Science held at Christchurch, New Zealand, in
January last. After enumerating the more salient features of the disease as already described, I thus
continue :—

“The rock oyster, Ostrea glomerata, affected by the disease is, as previously remarked, a species
that attains to its maximum development in brackish water, and indeed survives exposure to fresh water
immersions in times of floods that would prove fatal to the so-called mud oyster, Ostrea edulis. As a
corollary to these brackish water proclivities of Ostrea glomerata, its most luxurious development in New
South Wales has been high up the riverine estuaries that so abundantly intersect the coast line. The
Hunter, the Hawkesbury, and the Clarence rivers may be mentioned, not only as the most important of
the oyster-growing areas, but aso as those in which the worm disease, or, as it may be more correctly
termed, the ‘mud disease,’ has been most prevalent. In my opinion it is the altered conditions of these
rivers, brought about mainly through human agency, that has induced the diseased condition of the
oysters, their waters, in fact, being rendered more or less incapable of supporting the mollusc in a healthy
state.

“Through the clearance of the land and the establishment of townships and settlements through-
out the watersheds of these rivers, the rainfall which in former days fell upon and was more completely
absorbed by the primeval forests is now carried quickly away, and emptied by drains and culverts into
the watercourses communicating with the rivers. Simultaneously with this augmented discharge of
water into the rivers a vastly larger quantity of sediment is brought down, accompanied by a considerable
percentage of organic and chemical pollution that had no place in the composition of the water under
those conditions in which the oysters originally grew and flourished. This greatly augmented accession
of flood water, with its accompaniment of sediment and chemical pollution, cannot exert other than a
very deleterious influence upon the riverine oyster fisheries.

“A case in point in which the oysters, formerly growing abundantly many miles up a river’s course,
have been gradually pushed further and further down towards the sea through the agencies just described
fell under my personal observation in Tasmania. In the river Tamar, debouching on the northern coast-
line of that colony, the mud oyster, Ostrea edulis, was originally abundant from the Heads half-way to the
town of Launceston, some forty miles distant. By degrees, as borne testimony to by residents of the
district, the oysters have gradually disappeared from the formerly prolific higher portions of that river
known as Whirlpool Reach and the Middle and Eastern Arms. On my first visit to the Tamar estuary a
few oysters were still left in the lowest bay known as the West Arm, but these, both young and old, were
in a dead or dying state, owing chiefly to prolonged immersion in water containing an insufficient amount
of saline ingredients, but organic pollution from the town of Launceston probably also playing an im-
portant part in their destruction. Within a few years after this first visit oysters were practically extinct
in the Western Arm, and no success attended the efforts made to resuscitate the fishery in that district
by artificial culture. The last lingering remnant gathered there were in a decidedly unhealthy state, the
shells being discoloured and wanting in solidity, and the contained oysters being in the poorest possible
condition.

“Should the interpretation here suggested be correct with relation to the diseased condition of the
New South Wales Oyster Fisheries, it is evident that the prospects are but small of recovering the ground
lost to oyster culture in the several districts affected. It will consequently be incumbent on the oyster
growers of that colony to make the most of the water area left to them where the water is pure and not
liable to be invaded by the disease, and, if they are ambitious to regain that position formerly held in
which the colony was independent of supplies from external sources, they will require to turn their
attention to the culture of the mollusc on a far more scientific basis than has been hitherto attempted in
New South Wales waters.”

Respecting the existing or prospective invasion of the Queensland oyster-beds by this mud disease,
with its accompanying parasitic worms, I am pleased to be in a position to report that there is, at all events,
no evidence to hand of its presence at the present time. A little while since there was some suspicion of
its having made its appearance in Wide Bay, and a few specimens of oysters which, on being opened, were
found to contain a parasitic worm, were submitted for my examination. The worm, however, in these
solitary instances, was a nereid representing a different geuus than that associated with the New South
Wales disease, and had apparently gained access to the shell through a perforation originally made by a
boring whelk. There are circumstances, in my opinion, which will operate fora long while, and. it is to be
trusted, permanently, against the introduction of the disease under notice into Queensland waters. In
New South Wales, as previously stated, the oyster fisheries devastated belong entirely to riverine systems
that have become much altered in character, and polluted by sedimentary deposits through the clearance
of their inJand watersheds. The oyster grounds of Moreton and Wide Bays, on the other hand, have
such near and free communication with the open ocean that they are not influenced to anything approach-
ing the same extent by floods from the tributary rivers,and from the effects of which they specie
recover, t

13

It appears desirable for me to mention here that the fears that have been expressed in some
quarters lest the disease under notice should be introduced with the worm from New South Wales are,
in my opinion, altogether groundless. As a matter of fact Leucodoreis already here; it is of cosmopolitan
distribution, and has been obtained by me among the coral reefs as far north as Torres Straits. So long
as the oyster banks of Queensland are maintained in a clean and healthy state, the worm is not likely to
invade them. So soon, however, as these become choked with foul mud and sedimentary deposits, the
conditions will be made favourable for the advent of the worm, and it may most assuredly be expected.
While thus enjoying present immunity from the worm disease, which has wrought so much havoe to the
oyster fisheries of a neighbouring colony, there are circumstances, subject to the control of human agency,
which might arise and exert a very serious if not quite as disastrous an influence as those of Moreton
Bay. Reference is here made to the effects that would probably ensue through the establishment on the
Brisbane or other tributary rivers, on an extensive scale, of chemical works or factories without restrictions
being placed on the discharge into their waters of noxious fluids or other deleterious matters. At
present but a few of such factories exist, and comparatively little harm is caused, though already the
destruction of fish through such polluting agencies is now and again reported With a multiplication of
such pollution-creating factories, there can be no doubt that the effects would be serious to both the
oyster and the general fisheries of Moreton Bay, and so many and valuable interests being bound up in
these industries, it is highly desirable that measures should be taken in time to safeguard them from all
risk of deterioration through such an easily preventable cause.

There is one other agency at work which, if allowed to continue unchecked, threatens
to exert an unfavourable influence on the oyster fisheries of Queensland. Under existing regulations
what are known as the Government or public oyster reserves are supposed to be retained as breeding
centres for the express benefit of the general public, who are permitted to help themselves without restric-
tion to such oysters as they can consume on the ground, but are prohibited from carrying them away.
This privilege, however, has been abused to such an extent, that on many of the most extensive of these
reserves the oysters have been completely stripped and carried off in a wholesale manner. It is, in my
opinion, essential for the continued prosperity of the Oyster Fisheries of this Colony that judiciously
selected areas should be strictly and permanently reserved as nursery or breeding centres for keeping up
the supply of spat. Having regard also to the extent that many of the leased grounds and banks are
denuded of their oyster crops without compunction or consideration for future cultivators, it is, I consider,
highly desirable that a clause should be included in the leases granted requiring the continual reservation
on the ground or bank of a certain proportion of breeding oysters or, at all events, prohibiting their
entire removal. With such suggested breeding reserves, efficiently maintained, the Queensland Oyster
Fisheries would be well insured against all risk of the injury through over-depletion that has befallen those
of certain of the more Southern colonies. At the same time, the foundation would be laid for the develop-
ment of this important industry on a more extensive scale than has hitherto been attempted, and for
which there is a wide field open, more particularly in the direction of canning and other preservative
processes for the export market.

THE EMBRYOLOGICAL PHENOMENA OF THE QUENSLAND COMMERCIAL OYSTER.
(Ostrea glomerata).

Considerable uncertainty having up to a recent date prevailed concerning the embryological
phenomena of the ordinary rock oyster of Queensland and New South Wales, I devoted some time last
year to the investigation of this subject. The results of these investigations were embodied in a paper
communicated by me to the Royal Society of Queensland in February of that year, and from which the
following account has been epitomised :—

“The researches that have been already conducted by European and American naturalists, with
relation to the commercial oysters of the Northern hemisphere, have elicited the fact that the fertilisation
and development of the oyster brood or spat is formulated on two essentially distinct plans. In the
case of the most familiar Huropean type, Ostrea edulis, represented by the far-famed British native and the
variety so extensively cultivated on the coast of France, the propagation of the species is accompanied by
a condition in which the oyster is unfit for consumption, and is prohibited to be sold. This is occasioned
through the circumstance that the parent oyster nurses or incubates its brood within the pallial or mantle
cavity, throughout the early stages of its development, and does not liberate it until the shells of the
young oysters are fully formed. An oyster eaten during the later phases of the breeding season
appears to be full of sand or grit, this being due to the presence of the many millions of minute
embryonic shells. By oyster dealers at home, two distinct spawning conditions of the oyster are recog-
nised: the one, when the embryos contained within the mantle chambers of the parent are white and
colourless, being devoid of shells, is designated the ‘white sickness.’ The later stage, when, the
shells being formed, a grey or blackish tint is imparted to the entire mass, is known as the ‘ black sick-
ness.’ The close or spawning season of the ordinary European oyster, Ostrea edulis, extends through-
out the summer, from May to September, and is popularly defined as represented by those months
in which the letter ‘r’ is absent.

“The fecundation of the ova of the European oyster necessarily takes places within the mantle-
cavity or brood-chambers of the female, the fertilising fluid or milt of the male being discharged into the
water, and from thence it is absorbed and brought into contact with the mature ova by the ciliary
currents that exercise the ordinary respiratory and food-purveying functions in the female mollusc. This
plan of propagation was until within recent years supposed to apply to all descriptions of oysters.
Investigations associated with the reproductive phenomena of the American commercial oyster, Ostrea
virgineana, failed, however, to discover any trace of the brood or spat within the mantle cavities of the
breeding oyster, and it was ultimately demonstrated by Dr. Brooks (1880) that both the ova and milt
were simultaneously discharged into the water in their mature condition, and fertilisation being there
effected, the entire development of the embryo took place independently of the parent. Such being the
ease, the artificial propagation of the species by the commingling in sea water of the matured sexual
elements was considered feasible, and was successfully accomplished by the above-named authority. In
the case of the typical European oyster, Ostrea edulis, such a method of artificial propagation not

possible,

14

possible, chiefly on account of the fact that the embryos are matured within the brood-chambers of the
parent in a fluid medium, containing a large proportion of albuminous matter that cannot be artificially
produced. Following upon the discovery of Dr. Brooks in connection with the American oyster, it was
demonstrated by M. Bouchon-Brandeley, in the year 1882, that the small Portuguese oyster, Ostrea
angulata, exhibited developmental phenomena which coincided essentially with those of the American
species, the ova being similarly discharged into the water, where they are fertilised and developed
independently of the parent. The artificial fertilisation of the ova of this species, and the investigation
of the more important embryological phases of this Portuguese type, were also successfully carried out by
the authority cited.

“The oysters of Australia, like those of the Northern hemisphere, exhibit two distinct plans of
propagation. The commercial form indigenous to Tasmania and Victoria, but now so reduced in numbers
by exhaustive fishing as to be scarcely known in the market, cannot be distinguished from the Ostrea edulis
of European waters, and is usually associated by naturalists with the same specific title, but is sometimes
denominated the variety Angas? of the same type. The reproductive phenomena of this oyster have been
personally investigated by myself, and were found to coincide precisely with those of its European congener,
the embryos in like manner being fertilised and developed within the mantle or pallial cavities of the
parent. Similar phenomena have also been found by me to obtain in association with the closely allied
New Zealand mud oyster, and which is also apparently a local variety only of the same species.

“The most important commercial oyster of Australia is undoubtedly the familiar rock oyster, Ostrea
glomerata, of which Queensland enjoys the enviable position of producing the largest supplies; Moreton
Bay and Wide Bay alone growing sufficient quantities not only for home consumption but also for
exportation to the neighbouring colonies. The method of propagation of this oyster, to which I have
paid some attention within the past few weeks, is, I find, in all respects, identical with that of the American
commercial species, Ostrea virgineana. The fertilisation of the ova is brought about by their coming in
contact with the milt or sperm cells in the open water, the young embryos being thus cast adrift and
thrown upon their own resources from the earliest period of their existence. The artificial propagation
of this species by the abstraction of the matured sexual elements, the ova and spermatozoa, and their
admixture in a little sea water, may in consequence be eas‘ly effected, and yields a most interesting and
instructive embryological study. The method of procedure successfully adopted in accomplishing such
artificial propagation, and the more conspicuous metamorphoses through which the embryo passes before
assuming the parent form, may be described as follows :—

“The aid of a microscope with a magnifying power of about 200 diameters is, in the first instance,
indispensable for securing the most satisfactory results. On opening a number of oysters, the cream-
coloured fat-like mass near the hinge or joint of the bivalve shell represents the seat of the reproductive
elements. Inserting a fine spatula in the midst of this mass a small portion may be abstracted, and
spread out in a drop of sea water, or the natural juices of the mollusc, on an ordinary glass slip. Placed
under the microscope, the ova or germs of the female oyster will be at once recognised by their ovate or
pyriform contour, the separate ova having an average diameter of the ;3,;th part of an inch. The male
elements or spermatozoa, when abstracted and similarly treated, present a widely different aspect. Its
separate elements are so diminutive as to appear as minute granules only under the same magnification,
and a considerably higher amplification is requisite to illustrate their individual structure. This is then
shown to consist of a minute bulbous head and an exceedingly slender flexible hair-like tail, the pro-
portions between the two being much the same as that of the head and shank of an ordinary pin. After
a little experience it will be found easy to distinguish the comparatively coarse granular ova from the
cloudy masses of spermatozoa, when placed on the glass slip, with the aid only of an ordinary pocket
lens or even the unassisted vision. The assistance of the microscope is, however, desirable to insure the
most favourable results, and is altogether indispensable for tracing the further development of the
embroyos. In many instances it will be found, what can be recognized only with the microsope, that the
ova or spermatozoa, are not sufficiently matured, or, in the case of oysters purchased in the market, haye
become deteriorated by isolation from their native element for too long a period to permit of perfect
fertilisation. All conditions being satisfactory, the ova under the microscope should present a clean and
evenly rounded outline, while the vitality of the spermatozoa should be manifested by their active
oscillating and vibratory movements. Should the sperm cells fail to exhibit this vitality, their admixture
with the ova will prove of no avail.

In practice it will be found that the number of oysters containing the female elements or ova is
greatly in excess of those producing the milt or sperm cells, the average proportion associated with many
hundred examples recently examined being one male to six or seven females. The small quantity of milt
that is required to fertilise a very large number of ova satisfactorily explains Nature’s economy in this
direction. No peculiarities of external structure exist, so far as I have been able to ascertain, that
permit of distinguishing between the male and female oyster before it is opened. Healthily matured
milt and ova having been successfully obtained, portions of each, the ova predominating, may be mixed
in a watch-glass half full of sea water, and well stirred together. The ova, being heavier, will soon sink
to the bottom, leaving the spermatozoa diffused as a cloud through the water. After an interval of ten
minutes the top water may be poured off or withdrawn with a pipette and fresh supplied, and any
fragments of lacerated tissue or tufts of immature milt be removed with a needle; these, if left, will
decay and pollute the water. The pouring-off process should be repeated until the top water is quite
clear and the bottom consists entirely of fertilised ova. Ifa small drop of water containing the mingled
milt and ova is examined under the microscope at short intervals, some remarkable changes in the form
and structure of the ova will soon be observed.

Almost immediately following upon the admixture of the two elements it will be found that the
sperm cells are adhering in numbers by their dilated heads to the delicate capsular investments or vitelline
membranes of the ova, and communicating to many of them, through the vigrous vibrations of their
tail-hke prolongations, a distinct oscillatory motion. It may also be observed that through the
aperture of the narrower end of the capsule, known as the micropyle, several of the sperm cells have
effected an entrance, and have been brought into direct contact with the body of the ovum. The fusion
between the two elements that then takes place is not easy to trace, but the results arising from the
union are speedily manifested. The ovum prior to fertilisation was distinguished by the presence of
a central clear area with a contained nodular structure, the two representing what are distinguished

technically

15

technically by the titles of the “germinal vesicle” and ‘‘germinal spot” or the ‘‘nucleus” and “nucleolus.”
Shortly after fertilisation the substance of the ovum becomes opaquely granular throughout, and the
germinal vesicle is no longer visible. Within the second hour a small globular protuberance will have
made its appearance at the broader end of the ovum, and opposite to the micropyle. This is the so-called
directive or polar cell. Quickly following upon this, the entire body-mass of the ovum becomes furrowed
or constricted across the centre, anil each half is seen to contain a central nucleus. The upper half,
associated with the polar cell, now divides itself into two equal parts. These again split into four and
next into eight, the aspect of the ovum or embryo, as it may now be correctly termed, at about the end
of the third hour being that of a number of small coherent cells, superimposed symmetrically on the top
of a large basal cell.

This condition of development represents an important phase in the life history of the embryo
oyster. There are now present all the essential elements out of which the perfect animal will be built
up. Out of the smaller superincumbent cells all the investing membranes, tactile organs, and essential
animal structures will be fashioned, and they are consequently distinguished as the formative cells. The
larger basal cell, on the other hand, represents the nutritive or vegetable element, out of which will be
constructed the stomach, alimentary track, and all the appended viscera. Within from four to six hours
the smaller or formative cells have so increased and spread as to completely enclose the large nutritive
cell, and which in its turn now divides up and lays the foundation of the alimentary track. Tine hair-
like cilia are at this stage developed upon the external surface of the embryo, and by means of which it
progresses through the water in an irregular rotatory manner. The polar cell, which up to this stage
had occupied a conspicuous position, now breaks loose and disappears. The metamorphoses from this
point progress more slowly. From the tenth to about the fifteenth hour the general shape of the embryo
is somewhat kidney or turban shaped, it having a slight depression on one side. This represents what is
known to biologists as the gastrula stage, a structural phase which has been found to be common to some
period in the development history of almost every known form of animal life higher than the unicellular
protozoa. In its most typical condition this gastrula embryo consists of a cup-shaped body composed
of two single cell layers, the outer being built up of the animal or formative cells, and the inner one out
of the nutritive or vegetable cells. The distinctive appellations of the “epiblast” and “hypoblast’’ are
more commonly applied by biologists to these respective outer and inner cell layers.

After passing the “ gastrula”’ stage, development towards the typical organisation of the parent
oyster proceeds apace. The central cavity representing the stomach opens out by an anterior and a
posterior passage and apertures, which correspond respectively with the throat and mouth, and the
intestine and vent. The shells make their appearance at a depressionin the dorsal surface, and gradually
increase in size until they enclose the entire body. Simultaneously with these metamorphoses a disc
covered with powerful vibratile cilia has developed at the anterior extremity, and with the assistance of
which the embryo oyster can propel itself vigorously through the water. As the shells grow larger and
heavier the little oyster becomes less capable of sustaining itself in the water, and finally sinks to the
bottom. This is a crucial peoch in the molluse’s existence. Should it settle upon a rock, shell, or other
clean, hard substance, it attaches itself to it, and its life is assured; but should it, on the contrary, light
upon soft mud, sand, or other material to which it cannot adhere, it inevitably perishes. The proportion
of young oysters that find a secure anchorage in comparison with the vast numbers that are devoured, or
become literally lost at sea, is necessarily infinitesimal.

The time taken by the embryo of the Australian oyster to pass through the series of metamorphoses
enumerated, and to arrive at the attached or sedentary state, has been found by me, under favourable
conditions, to average four days, two out of these elapsing before the shells become conspicuously
apparent.

ag Within from eighteen months to three years from the date of its birth the embryo becomes a
marketable oyster measuring the standard two inches in its longest diameter. Such, however, is the
precocity of the species that, oyster brood not more than three months old, and but half an inch in
diameter was found, in association with the foregoing embryological investigations, to be laden with
fully-matured ova and milt.

Drawings made with the aid of the microscope of all the leading developmental phases of Ostrea
glomerata, as described in the foregoing communication, are reproduced in Plate IX. of this report.
Some further experiments that were conducted in association with these embryological investigations with
the object of ascertaining the influence of water of varying density, as in time of floods, upon this
embryonic oyster brood have been referred to at page 7. Among the practical results suggested
in connection with the foregoing embryological data here recorded, is the feasibility of fertilising and
artificially propagating the embryos of Ostrea glomerata in numbers largely in excess of what is accomplished
in a state of nature. In Europe, where the demand is so much in excess of the supply, and the market
prices consequently higher, and also in America, much attention is being given to the problem of thus
successtully cultivating oysters from their earliest embryonic state. By such time as this supply and
demand shall be equivalently balanced iu t!:e Australian market, a resort to this supplementary method of
artificial fertilisation and propagation may be found profitable.

Deratts oF AREAS Reservep on Leasep For OystER CULTURE IN QUEENSLAND WATERS, WITH
RetURN OF QUANTITIES AND VALUE or OysTERS EXxPoRTED.

The areas devoted to the industry of oyster culture in Queensland waters fall under the three
separate categories of dredge sections, oyster banks, and oyster grounds. Under the first-named title are
included extensive water areas producing dredge oysters only, and not extending shorewards above the
limit of low-water mark. These areas are leased by auction for terms of fourteen years to the highest bidder.
The waters of Moreton Bay were originally subdivided into forty-two such sections. The value of certain
of the more productive of these sections may be gauged by the fact that the rental realised for one of the
more important ones when recently put up to public auction was no less than £1,000 per annum.
Within the term of “ oyster banks” are included all oyster-bearing banks, reefs, or other areas comprised
within the limits of high water-mark and two feet below the lowest ebb. For these areas licenses are
issued at the uniform rate of £5 for any such bank not exceeding 30 acres in extent. The total number
of banks marked off, according to the latest returns, included in Moreton Bay, is 347, and in Wide Bay
167. In the Rockhampton district, including Rodd Harbour, Port Curtis, and Keppel Bay, ——

)

16

forty and fifty similar banks have been licensed or are under survey. The subdivisions termed “ oyster
grounds ’”’ have been recently defined to take the place of “dredge sections,” and for the purpose of
including areas producing oysters in collectively deep or shallow water, or from high-water mark on one
side to the same limit on the opposite side of any given area, These oyster grounds are, as in the case of
the dredge sections, let by auction on leases of fourteen years’ duration to the highest bidder.

The license-fees payable upon the boats occupied in the oyster trade, as affixed by the Oyster
Act of the year 1886, is as follows :—£1 annually for every boat so employed that does not exceed three
tons, and a further sum of 10s. for every ton or part of a ton above the measurement. The license-fee
charged for every person engaged as master, servant, or assistant in dredging, collecting, or carrying away
oysters for sale, is 10s. per annum.

Rervrn relative to the Quantity and Vatue of Oysters ExportEp from BrispanE and Marysoroueu.

BRISBANE.
Year. No. of Bags. Value. Year. No. of Bags. Value.
“a8 £
1870 200 eats aoe aoe 4,523 1,644 1881 aa 500 coe ces 7,559 6,153
1871 a6 20 ah “36 5,127 1,625 1882 oon act 200 ote 9,953 9,074
1872 nce ne Aon nee 4,060 1,427 1883 cao nat noo ace 7,878 7,342
1873 ot os ace sen 3,036 768 | 1884 mae wee ony ae 8,256 8,475
1874 at p00 soe ot6 3,912 1,704 1885 aoe on vine oc 8,076 8,094
1875 An 201 Nee sea 5,349 2,622 1886 o65 co 540 ase 7,512 8,533
1876 B00 ann Rae een 6,648 2,792 1887 oO) tee vee «se 7,167 8,240
1877 nos ner AC) den 2,736 1,639 1888 wae noe “a0 wae 6,191 7,616
1878 ean eee ave er 1,790 1,227 1889 en Od ond ood 9,791 13,368
1879 nce vee Sas 500 3,793 2,729 1890 (six months) fe ee 4,890 5,696
1880 of af in ee 5,293 3,475 J)
MARYBOROUGH.

Year. No. of Bags. Value. H Year. No. of Bags. Value.
1887 OEE oe RM en. 608 BiG 7° =| Giggg ee A SRS re £3,677
1888 “6 =a oe Sct 1,990 £3,326 1890 (six months) aa ned 1,300 £3,174

The foregoing return showing the quantities and value of the oysters exported from Moreton and
Wide Bays, has been reproduced from the Inspector of Oyster Fisheries, Moreton Bay district (Mr. C. L.
Fison), report for the year 1890. The figures relating to the Brisbane exports, extending over a period
of twenty years, furnish a practical illustration of the steadily increasing value and extent of this highly
important fishery.

It affords me much pleasure, in conclusion, to testify to the valuable facilities and assistance
afforded me, whenever needed, by the harbour masters and fisheries inspectors of the various districts visited,
towards the acquisition of the materials and information utilised in the compilation of this report.

I have, &e.,

W. SAVILLE-KENT, F.L.S., F.Z.8., &c.
Commissioner of Fisheries, Queensland.

EXPLANATION OF PLATES I. TO IX., ILLUSTRATING QUEENSLAND OYSTERS
AND OYSTER CULTURE.

Prate I.

Figure 1.—Typical cluster of the ordinary commercial oyster, Ostrea glomerata, the largest shell
exposed to view, showing at the point a, a circular hole made by the boring whelk, Urosalpinx paive.

Figures 2 and 3.—Right and left, or attached and opercular valves, of the ordinary growth of Ostrea

lomerata.

= Figures 4 and 5.—Adult shells and young brood of the elongate variety of Ostrea glomerata, of
common occurrence in deep water.

Figues 6 and 7.—Vertical and lateral views of the orbicular variety of Ostrea glomerata, most
abundant in the Northern districts.

Figure 8.—Oyster whelk, Potamides ebeninus, with attached oyster brood.

Figure 9.—Oyster spat and brood from one to three or four weeks old, in its earliest condition of
attachment to the cemented collectors figured at Plate VIII.

Figures 10 and 11.—Dorsal and ventral aspects of the oyster-boring whelk, Urosalpinx paive.

Figure 12.—Spinous oyster, Ostrea spinosa. A small non-commercial species from Keppel Bay.
Grows to about twice the size of the illustration.

Prate II.

Figure 1.—Lateral aspect of typical example of the coral rock oyster, Ostrea mordaz, attached to
fragment of coral from the Capricorn Islands, Great Barrier system, Lat. 233 deg.

Figure 2.—Vertical view of common modification of Ostrea mordaw, in which the anterior or butt
end of the left or attached valve is produced into a hollow beak ; a variety apparently identical with the
Ostrea cucullata, of Born.

Figures 3 and 4.—Attached and opercular valves of the beaked variety of Ostrea mordaz, the black
scar of attachment of the adductor muscle being conspicuously developed on the opercular valve.

Figure 5.—A cluster of the non-commercial oyster, Ostrea crenulifera.

Figures 6 and 7.—Dextral and ventral aspects of a detached example of the same species.

Figure 8.—Lower or attached valve of the poisonous oyster, Spondylus sp. a at

; LATE ITI.

17

Puare III.
Figure 1.—Lateral view of complete specimen overlying interior face of single-attached valve of

the black-bordered oyster, Ostrea nigro-marginata, from Adolphus Island, Torres Straits.
Figure 2.—Marginal view of complete example overlying interior face of attached valve of the
coxcomb oyster, Ostrea cristi-galli. From M Island, off Mackay.

Figures 3 and 4.—Ventral and dorsal views of the “ borer”-destroying whelk, Natica plumbea.

Prats IV.

Figure 1.—Boat-shaped example of black-bordered Oyster, Ostrea nigro-marginata.

Figure 2.—Tubular oyster, Ostrea cornucopiw, showing at h the hinge,and at h* the path of
growth up which the hinge has gradually travelled with the increasing size of the shell.

Figure 3.—Example of Ostrea cornucopia, showing the hinge path h* more conspicuously.

Figure 4.—Diagrammatie view of Ostrea cornucopia, showing at a the points of attachment of the
adductor muscle, and by the clear space the dimensions of the internal cavity.

Figure 5.—The saddle oyster, Ostrea sellaformis, internal view of a single valve.

Figure 6.—Lateral aspect of the component valves of Ostrea sellaformis, showing their charac-
teristic indentation.

PuatE V.

Figure 1.—A typical cultivated oyster bank, in Bribie Passage, Moreton Bay. Froma photograph.

Figure 2.—An undisturbed or virgin oyster reef, in the “ Narrows,” between Port Curtis and
Keppel Bay. A portion towards the centre of this reef having been undermined by the action of the
water, has partly fallen away, exhibiting the density of the oyster stratum. From a photograph.

Prate VI.

Figure 1.—A mangrove oyster bank in its initial condition, with oysters, Ostrea glomerata, attached
to the exposed roots and ventilating shoots or “cobbler’s pegs” of the white mangrove, Avicennia
officinalis. Reproduced from a photograph from Moreton Island, Moreton Bay.

Figure 2.—Mangrove oysters, Ostrea glomerata, attached to the elevated branching roots of the
Orange Mangrove, Rhizophora mucronata. Reproduced from a photograph taken in the estuary of the
Endeavour river, near Cooktown.

Prate VII.

Figure 1.—Typical rock oysters, Ostrea glomerata, growing on rocky boulders at the mouth of
Tullebudgera Creek, Burleigh Heads, near Southport. From a photograph.

Figure 2—A remarkably luxuriant mangrove oyster bank, consisting of solid masses of oysters,
that originated from individuals attached to the roots and ‘‘ cobbler’s pegs” of the White Mangrove, as
illustrated in Plate V., Fig. 1. From a photograph taken at Mangrove Island, Keppel Bay.

Prate VIII.

Oyster spat collectors constructed of “ split palings’’ weighted with bricks and coated on the under
surface with cement. The top figure gives a lateral view of a simply cemented collector, and the four
lower figures the upturned surfaces of four collectors encrusted with oyster brood aiter remaining in the
water about four months.

Prats IX.

Illustrating the Embrology of the Queensland Commercial Oyster, Ostrea glomerata— Gould.

Figures 1 and 2.—Unfertilised ova, with investing vitelline membrane and micropyle (a) magnified
about 500 diameters.

Figare 3.—Milt or sperm cells.

Figure 4.—Ovum with attached sperm cells immediately preceding amalgamation and fertilisation.

Figure 5.—Fertilised ovum from first to second hour after fertilisation.

Figuress 6 to 10.—Consecutive metamorphoses observable within the second and third hours after
fertilisation.

Figures 11 to 18.—Changes progressing within the fourth to eighth hours after fertilisation.
terminating in the ejection of the polar cell, and the complete investment of the larger nutritive cells
or hypoblast, by the formative cells or epiblast.

Figures 14 to 16.— Phases of the embryo known as the “Gastrula” type, observed between the
tenth and fifteenth hours of development. :

Figures 17 and 18.—Phases arrived at from within twenty-four to forty hours, and in which the
shells (sh.), mouth (m.), and vent, (v.), of the perfect oyster have made their appearance. :

Figures 19 and 20.—Lateral and dorsal aspects of embryo three to four days old, and in which the
shells have grown to such dimensions that they entirely enclose the body when contracted; magnified
about 200 diameters.

Figure 21.—Earliest observed attached condition of the oyster embryos or “‘psat.” Attained to
within the fourth or fifth day succeeding primary fertilisation of the ovum; magnified about fifty
diameters.

Price 3s. 8d.]

By Authority : Jamss C. BEAL, Government Printer, William street, Brisbane.

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SPLIT-PALING OYSTER SPAT COLLECTORS
WITH ATTACHED OYSTER BROOD.

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