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— Report
" The Danish Biological Station
to
The Board of Agriculture.
EVE and, VIE
"1908.
By
C. G. Joh. Petersen,
Ph. D.
Translated from ,,Fiskeri-Beretning for 1907”.
Copenhagen. "
Centraltrykkeriet. HØ 4
1908.
SA
From
The Danish Biological Station.
PRW Ariel PS VET:
Copenhagen.
jentraltrykkeriet
1908.
Contents.
First Report on the Oysters and Oyster Fisheries in the Lim Fjord, XV.
C. G. Joh. Petersen.
Second Report on the Oysters and Oyster Fisheries in the Lim Fjord. XVII.
Ci G: Joh.-Petersen.
FErrstReport
on the
Oysters and Oyster Fisheries in the Lim Fjord
> with one Chart, temperature-curves, 3 tables and 2 figures in the text.
by
C. G. Joh. Petersen.
Technical Adviser to the Department of Agriculture in matters concerning
the oyster fisheries.
Preface.
After I had been appointed, in 1905, Adviser to the Department of Agri-
culture in matters concerning the oyster fisheries, I endeavoured, partly through
investigations in the Lim Fjord, partly through communicaiions with those interested
in the oyster fisheries and partly through the study of the available publications
and official documents, to gain some knowledge of what had really happened to
the oyster fisheries in the Lim Fjord since their beginning in the year 1852. No
connected account namely was available regarding this matter, and a good deal of
confusion reigned. I considered it 'advisable therefore to bring together what I
had collected before the present contract ran out. The summary of the earlier
history has been prepared with the help partly of the Office for Crown Lands and
partly of the Office of Public Records. Two men have helped me greatly, namely,
Permanent Secretary, Mr. P. L. Holm Jørgensen and Justitsraad, Ritmester Paulsen,
the latter of whom has had a good deal to do personally with the oyster fisheries
for many years; to both I would tender here my thanks for their assistance.
The reason why I have not at the same time drawn up an account of the
conditions prevailing on the other oyster banks within the sea-territory of Denmark,
namely, at the Skaw (the »Fladstrand« oysters) and on the west coast of Schleswig
on the North Sea (the so-called Flensborg oysters), is that they are without impor-
tance for the practical fisheries and quite without interest in comparison with the
banks in the Lim Fjord. The rich production on the latter is clearly sufficient to
provide Denmark with oysters, even if the consumption became much greater than
it is now.
Copenhagen, April 1907.
The Author.
Contents.
Page
A. Historical summary: Danish investigations on the oyster fisheries and biology of
the oyster. The various contracts, their terms, results, etc. Undertakings with a
view to preserving and -increas ing the stock of oysters..........s000reueneene 3—19
AD DEN TIE e SEE VU SIRENE RE En EST RÅDNE SEES al ry FORE ENE ars 20
B. Investigations of the author in 1895, 1896, 1905 and 1906 etc.
Situation of the oyster banks in the Lim Fjord and the salinity. Duration of the
Spam esperodeENUum ber OS Paw Dine Sys ES Eee 21—22
The spat in relation to the temperature and salinity in aquaria. Duration of the
spat stage and occurrence in nature. The occurrence of the fixed spat on
colleetorskan denn diget SE ES Se ere ye RE ENE Te tee e re Fare ENE ERE 22—27
Harmful infduences and enemies both for the spat and adult oysters ............... 27—30
koodsolsthetorstert enlkaonketes rets tere SIRENE en sg Ra NRGeREl EEN SD NED 30—31
Estimate of the age of oysters. Measurements of the oysters on the banks. Tables
I—II. Growth of the spat; their occurrence in shallow and deep water.
Growth-stages. Oysters of ca. 3 inches usually 3—4 years old. Growth
varies under different conditions. The present standard for oysters is rec-
tangular. Many oysters do not reach the standard yet die of old age. How
large do the oysters become in the Lim Fjord? Smaller oysters should
also be fished. The present principle is wrong. The 4 years rest of doubtful
value. Biological knowledge has advanced since then. Å more intensive
J fishery might be carried on along with new experiments in antificial me-
thods of increasing the stock; the older experiments failed in principle ..... ” 31—39
ne ar SE EN ER NS en blee sd ere SEE DEERE ENS 39—41
A. Historical Summary.
Of the Danish publications on the oyster and the biology of the oyster
may be mentioned the following:
H. Krøyer: De danske Østersbanker 1837.
D. F. Eschricht: Om den kunstige Østersavl i Frankrig og om Anlæg af
kunstige Østersbanker i Limfjorden. Two reports to the Minister of Finance. Printed
by order of the Minister of Finance 1860.
Eschricht reports here on the endeavour of Professor Coste to form new
oyster banks on the open coasts of France at places where these had not been
present earlier. Coste's experiments had just begun at that time and seemed to
7) Appendices II—VII are omitted in the English translation, as they are of interest to
restricted Danish circles only; they contain partly the terms of contract hetween the Government
and the contracting Oyster Companies, partly also the conditions of sale.
+
show prospect of success; it proved later however that in certain ways they were
based on erroneous principles. Coste's ideas had great influence on Eschricht and
on his proposals to the Danish Government. He proposed namely to improve the
whole breed in the Lim Fjord by the introduction of new oysters, and suggested
likewise that the experiment should specially be made of forming new banks by
transplanting full-grown oysters. To induce private people to form such banks, he
further proposed that the fjord should be let in small parcels (as in France), with
exclusive rights to the lesssees to form such banks. They should further have
some recompense if successful. This was the beginning of the whole matter.
IJ. Collim: Om Østersfiskeriet i Limfjorden. Two lectures. (Tidsskrift for
populære Fremst. af Naturvidenskaben. 4 R. 3. B. 1871).
J. Collin: Kort Udsigt over Limfjordens Østersbanker (Tidsskrift for
Fiskeri 1871).
G. Winther: Aarhusbugten undersøgt med Hensyn til Anlæg af kunstige
Østersbanker.
G. Winther: Om vore Haves Naturforhold med Hensyn til kunstig Østers-
avl og om de i den Henseende anstillede Forsøg. (Af Nordisk Tidsskrift for
Fiskeri (Ny Række af Tidsskrift for Fiskeri). Anden og tredje Aargang. 1875
og 1876).
The author explains that he himself had never visited the oyster banks in
the Lim Fjord and complains, loc. cit. p. 193: »how great a need there is of a
systematic rational investigation, according to most recent methods and with con-
stant regard for the hydrographical and faunistic questions of the present day, of
these waters so extremely important for the oyster fishery«.
» Aktstykker« (Documents) concerning the representation of the earlier con-
tractors for the oyster fisheries in the Lim Fjord to the »Folketing« and relerred
by the latter to the Minister of Finance, with regard to compensation from the
treasury. 1879.
J. Collin: Om Limfjordens tidligere og nuværende marine Fauna. 1884.
In this general information is given on the fauna of the Lim Fjord.
C. G. Joh. Petersen: Om de skalbærende Molluskers Udbredningsforhold
i de danske Have indenfor Skagen. 1888.
It is explained in this why the oysters can no longer live in our fjords
and sounds round Funen, Zealand and in East Jutland. The hydrographical
conditions have namely changed since the period of the »kitchen middens«, and
several other shell-fish have also died out since then.
H. Tonning: VWOstreæiculture. Copenhague. 1893.
The author states in the preface: »Cet opuscule n'a pas la prétention
d'étre un ouvrage scientifique. J'ai cependant l'espoir, qu'il contienne ca et lå
quelques renseignements d'un intérét sérieux pour les progræs de Vostréiculture«.
Good information concerning the distribution of the oyster when discovered
in the Lim Fjord about 1350 is given in H. Krøyer's three reports to the Direc-
tor of Crown Lands; his reports are of considerable general interest and may there-
fore be reprinted here.
H. Krøyer's Report. 1851.
Ås soon as the Royal Commission, to whom the task was delegated of
draughting improved legislation for the Lim Fjord fisheries, had completed its
labours at Nibe, I betook myself without delay to Lemvig, in order to make
investigation of the oyster bank said to be there according to a report to the
Ministry from the Amtmand of the district Ringkjøbing, Greve Schulm. Ås the
result of this investigation I beg to submit the following report.
The small and narrow bay of the Lim Fjord running from north to south
at the end of which Lemvig is situated, has a depth of three to four, even five
fathoms at some places, but as a rule the depth is much less. The bottom is
partly sand, sand and gravel mixed, large stones and partly also soft alluvial clay.
Vegetation, of Zostera etc., appears here and there hut it seems to me not very
richly. The water is of considerable salinity, so much so that a salt factory has
been set up within recent years in Lemvig. On account of the sheltered position
of the bay there can be no strong currents or collecting of the broken ice there
in the spring.
Under such conditions, so favourable to the preservation and production
of oysters, I found if not an actual bank yet a by no means small number of
oysters scattered or distributed here and there, not quite equally but in varying
quantities, and it seemed to me that most were collected together on the west side
of the bay (the side most sheltered from the currents), especially on gravelly bot-
tom at a depth of four to six feet, with none on pure sand bottom. The size of
the oysters observed here was considerable; I even believe that they were larger
than any I have seen elsewhere in Denmark or in Norway. Very few of the spec-
imens showed in their shells signs of old age, on the contrary, the majority
were thin-shelled or might be considered from the nature of the shell
as about three to four years old. The quality of these oysters will prove to
be very good at the right time of year. On not a few I observe young oysters
growing; on the other hand I never found empty shells; although the fauna in
this part of the Lim Fjord has almost the same character as in the open sea
or in other words, although almost the same small forms of animal life live
in company with the oysters at Lemvig as for example on the Schleswig banks,
yet I never met with many of the forms which are harmful to the oyster, namely,
of star-fish very few and of crabs not any.
In carrying out these investigations I was supported in the most friendly
manner by Kancelliraad Voigt, Sheriff of the town and district, and it was due to
his instructions and help that the investigation was both relatively easy and quickly
brought to an end.
The apparatus used consisted partly of an oyster dredge brought by myself,
which however was found to be too small and light to be used with success on
the hard gravelly bottom, partly an instrument something like an iron rake but
(er)
with the teeth somewhat crooked, by means of which the oysters were taken up
in the shallower parts, partly also finally a diving apparatus broght from Harboøre
for the greater depths with stony hottom. The rake mentioned is perhaps the
most serviceable apparatus for collecting the oysters under the conditions at that
place, as it is just suited for use in shallower water where most oysters seem to
occur. In using it however, one must be able to see the oysters on the bottom,
and it can also only be used when there is no great movement in the water; which
should not however be any considerable hindrance in the way of the fishery, as
the fishermen should be able to collect in good weather the quantity of oysters
they need and put them in hoxes or other suitable places where they are easily
got at when wanted. This is the method used in Norway where the oyster fishery
proceeds everywhere, so far as I have had the opportunity to investigate, in shal-
low water and with apparatus more or less similar to the rake mentioned.
There can be no doubt that the occurrence of the oysters in the
Lim Fjord is certainly connected with the breaking through of the
North Sea, and that like the lugworm (Arenicola piscatorum Lam) and several
other marine forms they only entered after this natural phenomenon into the wes-
tern part of the Lim Fjord, where the conditions at several places seem also to
be very favourable to their reproduction and growth.
It was due quite to chance that the presence of oysters was observed at
Lemvig. It happened that a stone-layer of that town, by name Kristian Hede,
was taking up stones from the hed of the fjord for a pavement and observed the
oysters; he then constructed the above-mentioned rake and collected a few by its
means and sold them in the town. In this way the officials of the town became
acquainted with the matter, closed the bank and sent in a report to the Govern-
ment. But it is at the least very probable that oysters must exist in several other
bays and creeks of the western Lim Fjord, where no one as yet has had the
opportunity to observe them or where the ignorance of the inhabitants with oysters
has perhaps made observations unfruitful. As regards Sallingsund, I have
on this journey heard it stated with assurance by a sailor, (mate of the steamboat
Odin) from his own experience, that oysters occur in the neighbourhood of
Nykjøbing on Mors. And the same person states, though only from the reports
of others, that oysters are likewise said to be found on two reefs north of Livø.
In any case I consider it certain that several of the Lim Fjord bays, even though
oysters may not as yet have found their way in there, are well suited to oyster
culture, and thus that a by no means despicable source of income could be opened
up for a portion of the inhabitants along the fjord.
The question immediately arises therefore, how can the exploitation of
these oyster banks at Lemvig and of all the oyster banks, which will
certainly yet be found or laid down in the Lim Fjord, be arranged in
the most advantageous manner. Should they be declared crown property
(even where so-called cooperative fishery occurs) or made free? And in the first
case, should the Lemvig banks be at once contracted out, or should a more exact
knowledge of the distribution of the oysters in the Lim Fjord be sought for first
of all? In whatever direction the question may be settled in general, I venture
to suggest with regard to the Lemvig Bank, that since this bank is as yet
not very rich, it might perhaps be considered an advantage to preserve it for a
couple of years and keep a constant watch as to whether the protection causes any
appreciable increase. I do not believe however, that if at once contracted out it
would run any risk of heing quite destroyed, as the oysters living in the deeper
water and on stony ground could neither be taken with the dredge or rake, and
are thus fairly safe from the fishermen. On the other hand, the oyster belt wbich
extends from four to six feet of water would soon probably be cleaned out, as it
is so casily got at, and the fishermen would have in the high prices for oysters a
strong stimulus to carrying on an advantageous and but little difficult mode of
livelihood.
If the bank mentioned were to be considered as crown property and con-
tracted out, its discoverer, Kristian Hede, might perhaps be reasonably recommended
for a small reward; especially as it would be an inducement to others to make
the neighhouring stretches of the Lim Fjord the object of close investigation.
Kjøbenhavn, 23rd July 1851.
Most respectfully
Henrik Krøyer.
H. Krøyer's Report. 1852,
Having concluded the investigation of the Lim Fjord oyster banks entrus-
ted to me, as far that is as the shortness of the time permitted it, I hasten to
respectfully submit the results obtained.
1) According to the statements of both the fishermen and others acquain-
ted with the matter, no oysters have ever been detected in that part of the
Lim Fjord which extends between Hals and Løgstør grounds. The result
of experiments with the oyster dredge gave further confirmation of this. In Løg-
stør Bredning, Feggesund and Thisted Bredning as also the arm of
the Lim Fjord which separates Mors from Thyland, oysters are still ab-
sent, or if found they occur but rarely and singly and thus could not be the
object of a fishery. Aithough experiments induced by the catch of oysters
elsewhere in the Lim Fjord have been made at several places in the neighbour-
hood of Thisted, these have hitherto given no result and the people have been
restricted to the oysters obtainable over Nykøbing... Sallingsund right from Glyng-
øre down to Kaas has been fairly well provided with oysters, especially
however on the Salling side, and it is here that the greatest part of the Lim
Fjord oysters met with in trade are taken; for this reason also I have made a
special point of investigating as far as possible the present condition on this stretch.
The result I have arrived at is not very pleasant; with exception of a small strip
right in at the head of Harrevig and a point running out from Mors just at
the mouth of this bay — Sillerslev Øre — the whole stretch seems to be quite
devoid of any oysters of commercial value, on account of the harmful fishery.
And it will therefore be necessary to deal carefully and cautiously with
this part for some years, so as to give the oysters an opportunity to increase.
In the south beyond Jegindø and Kaas we come to the broads round about Wenø.
In this I have observed oysters at the following places: near Struer, though
2
only in small quantity; more abundant about 1 mile north of Struer at the neck
which extends out east of Strandbjærggaard (Adskjer Odde), also 4 miles east of
Struer opposite the fishing place Snøden about halfway between Volstrupgaard
and Handbjærggaard; lastly and in greatest quantity off Eising Sogn at Ny-
gaards Hage 3 miles or somewhat more to the north of Snøden. Although some
oysters are fished here and sent to Holstebro, yet the fishery has not been over-
done as at Sallingsund, and the banks therefore are relatively in a better
condition. Leaving these broads and passing through Ottesund into Nissum
Bredning, we find, so far as I have experienced, not a trace of oysters on its
nothern and eastern coasts or at Thyland, whereas the whole of the south
coast or the coast of the Skodborg and Vandfuld districts contains oysters,
though at most places only in small numbers. The principal places, so far
as known, are Lemvig Bay, especially at Kabbel-Odde and Helleris-Odde as
also outside this bay 2 miles west on the coast off Hygom-Sogn. This stretch
is almost never fished. Although the weather was favourable to my investigations
in high degree and enabled me to visit a not inconsiderable part of the Lim Fjord,
yet on the other hand the shortness of the time prevented me from taking into
regard various places which otherwise I should have liked to include in the inves-
tigation. Concerning the conditions I can therefore only state what was
told me at Nykjøbing, namely, that oysters were said to have been found in
these parts (in the south and east) yet only in small quantities, and that they
were already removed or the banks emptied. I believe I may consider it
of little importance that I was unable to visit the large branch of the Lim Fjord
which extends in a southerly direction from Løgstør down towards Skive and
Viborg, as I have never once heard that any trace of oysters has
hitherto been met with there.
2) After giving a general account of the occurrence of the oysters in the
Lim Fjord, I may touch upon the special local conditions under which they
are found, and which seem here not only favourable but almost absolutely neces-
sary for them. They are found near the land in small depths of about
2—4—6 feet and on bottom consisting of gravel and small stones resting
on clay.
On pure and fine sand on the other hand they are but seldom seem, pro-
bably because the spat are not able to fix themselves there. They are met with
in greater depths, thus 7 to 9 feet or perhaps somewhat more, wherever there
is stony ground, but in depths of 3 to 4 fathoms and more they never seem to
occur, even though the hottom måy he the same as on the shallow banks, namely
mud. Ås I had brought a capable oyster fisherman with me from Fre-
derikshavn, just for the purpose of having the deep water investigated by means
of the dredge, and as repeated trials with this apparatus have been quite without
result, not even bringing up empty shells, I belive we may consider it as fairly
certain, that no oysters live as a rule in deep water in the Lim Fjord,
which may probably be ascribed to the strong current, as the hottom cannot he
regarded as unsuitable.
An unexpected feature in the occurrence of the oysters is further the cir-
co
cumstance, that they were found in quantities at places where streams flow out
into the fjord, and where the water has thus a less salinity than usual. The
oysters are on the whole widely scattered and single, more rarely two or
three fixed together. On account of the general situation of the banks, the
fishery here must be light, simple and inexpensive, which is of no small
importance in respect to the farming out of the beds. In Sallingsund a so-called
»brile« is used for the fishery; it is a small iron harrel-hoop fixed on the end of
a 10 to 12 feet long pole and provided with a bag of wide-meshed netting. At
Lemvig a kind of rake was used with 4 or 5 teeth of 4 inch nails. Wherever the
oysters occur in quantity the fishermen according to my experience should be
able to take up about half a hundred in half an hour; and this agrees fairly
well with what experienced fishermen have told me, that they have fished
1200—1500 oysters per day. The fishing cannot be carried on in all kinds of
weather, but requires calm and sunshine, when the oysters are most readily
and most distinetly seen on the bottom. The oyster dredge is here not only
unnecessary but even useless. This apparatus is namely adapted to soft bottom;
it does not penetrate into the hard gravelly bottom and is thus dragged over the
oysters without taking them. When it is stated in the report that the oysters are
right on the shore, so that the water does not rise above the wooden shoes of the
collector, this may apply perhaps to one or another single oyster, but is to be
regarded as an exaggeration in any question of the oyster fishery.
3) Ås regards the nature of the oysters in the Lim Fjord, they possess
certain peculiarities which make them easily recognizable to the traimed eye, and
separate them from the »fladstrand« oysters. They are large, but very flat and
thin, almost leaf-like, and the shell has an obvious green colour. The ani-
mals themselves I have as a rule found to be bluishwhite, fairly lean and
inferior in taste to the »fladstrand« oysters. The consumers all say also
that the Lim Fjord oysters are too insipid and sweet to the taste. and cannot
be eaten without salt etc. In the trade they will therefore probably have a less
value than the »fladstrand« oysters, though they bave almost the same size, a
circumstance which will come into consideration in any farming out of the beds,
and which may be said to neutralise to a great extent the advantage arising
from the easy method of fishing in comparison with the »fladstrand« oysters.
What seems to me to characterize the Lim Fjord banks in contrast both to the
»fladstrand« and Schleswig banks, so far as these are known to me, is the large
quantity of the growth-stages or spat one finds on them; the small oysters,
sometimes so small that they can scarcely be seen with the naked eye, are fre-
quently found on both adult oysters and empty shells of mussels etc. This means
that the banks should thrive well and even where they are now spoilt,
should recover fairly quickly if protected for a couple of years. There
seems also to be an excellent opportunity for the eventual contractors or others
to establish oysters ponds with advantage. On the other hand, it would
be desirable if the too great production of the animals harmful to the oysters,
star-fish etc. could be restricted. These are found already in somewhat considerable
quantities on the banks.
10
4) I come now the questition, wheteher the oyster banks of the Lim
Fjord as a consequence of their situation are so shut off that the authorities
concerned, as has been stated, are unable to protect them from unlawful
fishing. I feel obliged to contradict this statement absolutely, and to
maintain the opposite, that if a bank is plundered the fault lies not at all with
the situation but in the indifference of the police, and as sufficient proof
of this I may point out that the banks round Lemvig have been almost perfectly
protected against attacks, although their situation is the same as the other banks,
only because the authorities have shown from the beginning that they were serious
in their endeavours to save the hbanks. The information given by Justitsraad
Rummelhof in his report to the Government, that 16,000 oysters (or perhaps a
much larger number, as I have reason to believe) were taken at Harrevig on the
two days preceding the prohibition, receives its explanation from statements collec-
ted on the spot, that the severe fishing was a result of most friendly infor-
mation to the fishermen that the prohibiton was near at hand and that
they must make the most of their time. The oyster fishermen therefore streamed
together from all quarters, and as one of the men fishing informed me, there were
over thirty hoats there beside one another in Harrevig fishing up the oysters from
the fjord. Another who also took part informed me that he had been fishing
on the very day of prohibition, but so early, that he was able to land and
sell his catch before the prohibition was proclaimed.
The prohibition however by no means prevented the oyster fishery from
going on, as I have been assured; a small changein direction was the only result.
The people in Nykjøbing, who had fished there gave up, hut the peasants
round about Harrevig etc, continued the fishery, and brought their catch in
sacks for sale to Nykjøbing; as the trade there had however to be carried on
with a certain amount of care and secrecy, the prices were low, and the sellers
had often to be content with 2—3 marks per hundred, wh;ch led to speculation
on a fairly large scale, as the merchants sent by no means small quantities to
Aalborg and other places. |
These reports seem to find confirmation in the large number of oysters
offered for sale and consumed in Copenhagen after the prohibition. I was told
also in Thisted that oysters could be obtained after the prohibition over Nykjøbing.
If any attention was paid to the trade, it was a sufficient answer to hluster out
thatthe oysters had been taken before the prohibition and kept in boxes.
5) Just as the varying views of the different persons in authority —accor-
ding to some the Crown has become seriously involved in prescriptive rights, whilst
in the opinion of others nothing more has been done in this direction than just
what could not be avoided — have had a harmful influence on the oysters banks,
as shown in the foregoing, they have also contributed in several ways to raise
discontent amongst the people round the Lim Fjord who consider themselves more
particularly interested in the oyster fisheries. Under the prevailing conditions it
will perhaps scarcely be possible to do away with at least the worst
existing irregularities in a quicker and better manner, than by at once giving
over the banks to lessees, a method which seems to find support in the com-
11
mon wish on the Lim Fjord and which is rendered easy in certain ways by the
fact that several have expressed themselves willing to take out contracts to farm
the beds.
The Office of Crown Lands will thus be able probably without great ditf-
culty to let out the Lim Fjord banks on conditions which would secure their
being maintained in good condition, as the whole care for their preservation,
development etc. would rest upon the lessee or lessees.
As the Office of Crown Lands must determine as to the letting out of the
Lim Fjords banks, several alternatives offer themselves, all of which could per-
haps be supported by plausible reasons: the banks might be let out in parcels or
in one lot; they could be put up to auction, or without auction the representation
already made, according to what has been reported to me, by Messrs. Claudi,
Lykke and Steenberg might be agreed to. If the beds are parcelled out,
a method so far as I could gather most in favour amongst the inhabitants on the
"Lim Fjord, and which perhaps, if regard is only taken to the momentary ad-
vantage, would give the highest return — then the part of the fjord which
has to be let out could be naturally divided into four basins: Nissum-Bred-
ning hbounded at Ottesund, Venø-Bredning bounded in the north by Jegindø
and Kaas, Sallingsund from Kaas to Nykjøbing and lastly the Bredning be-
tween Løgstør and Mors to Feggesund. By letting out the banks without auc-
tion to the persons mentioned, the risk is run of rousing great discontent
among those who might possibly wish to undertake the contract, but would find
themselves by this procedure prevented from competing. For the rest, I should
imagine, after the opinions expressed by these gentlemen to me, that this proce-
dure would be the one which gave the greatest guarantee, not only for
the maintenance but also for a further development of the oyster fisheries in the
Lim Ford.
As I have acted in the belief that, in case of letting out the banks, it
would interest the Office of the Crown Lands to have an approximate estimate
of what might fairly be considered the yearly income from the banks,
I have endeavoured as far as possible to arrive at a definite impression on this
point, and have constantly had it in mind throughout my investigations. Ås result
I venture to express the opinion that the lesses could scarcely at present
be able to pay a higher yearly sum than 400 Rd.”, if the banks are to be
not only maintained but also worked up and increased. But just as I must ev-
erywhere concede the incompleteness of my hasty investigations, I must also in
this extremely difficult point not lay any great weight on my estimate.
Even though I believe, judging from the present conditions in the Lim
Fjord, that I would advise the contracting out of the banks, yet on the
other hand I consider it right that the contracts should be for short periods,
to begin with not longer than 3 or at most 4 years. Not merely because the
value of the banks as just shown is problematic, but also because on the one hand
oyster production and culture might make great advances, and on the other con-
flicts could easily arise between the oysters fisheries and the older lawful fisheries
SEERE KT:
12
in the Lim Fjord, which would make it desirable to get the hands free as soon
as possible in order to make the necessary provisions. It might also be considered
to the purpose, to oblige the eventual lessees to give yearly reports on the banks
and on the progress and extent of the fishery, by means of which important con-
tributions towards a more complete and more trustworthy knowledge of the condi-
tions could be obtained.
My lack of training in the preparation of charts does not permit me to
follow out the wish of the Office to have a chart of the oyster banks in the Lim
Fjord. But if the Office would kindly have a chart prepared of the western
part of the Lim Fjord, on whatever scale might be considered suitable, I am
very willing to mark off on it the oyster banks know to me.
6) Å report on my two resultless journeys to Frederikshavn in order to
take part in an inspection of the »fladstrand« banks, will be sent in later.
I enclose herewith the papers entrusted to me hy the Office, concerning
both the »fladstrand« and the Lim Fjord. There is likewise included a detailed
statement with appendices so far as was convenient and possible of the travelling
expenses: 136 Rd. 1 Mk. 7 Sk., in which the surplus of the 150 Kd. namely 13
xd. 4 Mk. 9 Sk. is also entered.
Lastly, I beg respectfully to suggest that the allowance voted for my
investigation, 50 Rd., might be forwarded to me.
Kjøbenhavn, 6th September 1852.
Most respecttully
Henrik Krøyer.
H. Krøyer's Report 1853.
Alter inspecting the »fladstrand« oyster hanks in company with Kammer-
assessor, Herredsfoged Saxild, and drawn up a report as to their condition —-
which report makes it unnecessary to discuss the subject here — I travelled from
Frederikshavn to Sundby in order to continue the journey with the S. S. »Lim-
fjorden« to the parts of the fjord which possess oysters banks. The weather with
continuous storm and rain proved however to be extremely unfavourable for their
investigation. After waiting a day at Nykjøbing without being able to get at the
nearest banks, I resolved for the reason mentioned to go on to Struer and Lem-
vig, and to put off the imvestigation of Harrevig until the return journey.
Although the weather continued to be on the whole unfavourable, I suc-
ceeded during a short break in the storms in investigating the Lemvig banks as
sufficiently almost as was wanted. But as the weather on my return to Nykjøbing
had not become any milder, I was obliged to travel by carriage to Sallingsund
and from there to Harrevig, and then endeavour with a boat to make a survey
of the banks.
The results which seem to me to have been obtained, in spite of the
unfavourable weather, are as follows:
15
a) The Lim Fjords banks, and especially those at Lemvig, have suffered
not a little by the past severe winter, as all the oysters in less depths than about
four feet have been killed by the frost. This appears clearly from the fact that
I could not obtain a single living oyster from the depths mentioned, hut on the
other hand a number of empty, still partly connected shells (the animals in which
had thus died but a short time previously). At greater depths than four feet
living oysters were found but no empty connected shells.
This damage, to which the Lim Fjord banks are always exposed owing to
the natural conditions, will on the other hand be again made good by nature
itself, as often as a series of milder winters occur. It is naturally the business of
the contractors to see to the preservation of the oysters exposed to frost by remov-
ing them in time,
by The banks could not in general be considered as having been too
severely fished during the past winter, less so because the weather was to a
considerable degree a hindrance to the prosecution of the fishery. Some banks
were fished very little (at Lemvig for example), others so far as known not at all.
c) The banks in and beyond Harrevig seem however to be an exception
and to a great extent to have heen fished out, if I am able to rely upon the
experiments made, though it has to be remembered here that the unfavourable
weather as mentioned already was in high degree a hindrance to exact investiga-
tion. It will probably be to the interest of the contractors to let these banks alone
in the coming winter or to fish them to but a small extent.
dy That the oysters at some places, as reported by the lessees, were
covered by sand, I have not as yet been able to convince myself. The damage
cannot however have been of great importance. I believe also that the over-
sanding in the nature of things must proceed so slowly and gradually that the
exposed oysters might in one way or another be saved or protected, if attention
is paid to the matter.
e) The lessees do not seem up to the present, so far as I have been
able to detect, to have undertaken any work of importance either in the way of
exact investigation of the Lim Fjord oyster banks or for their increase or develop-
ment. The short time however, the weather and other excusable circumstances
should not be forgotten in this connection. The lessees have obtained oyster
dredges from Frederikshavn and are disposed to experiment with these in deeper
water. How far this will be successful however seems to me somewhat doubtful.
Just as I had unfavourable weather during the investigation of the banks,
other unfavourable conditions appeared on my return which made the journey
somewhat longer and more costly than it would otherwise have been. I may just
mention here the non-arrival of thé S. S. »Cimbria« and the stoppage of the S. S.
»Iri« at Aalborg in consequence of the epidemic, which circumstances obliged me
to journey round by Aarhus.
Included herewith is a statement of the expenses connected with the journey.
Kjøbenhavn, 9th August 18535.
Most respectfully
Henrik Krøyer.
14
In the »Jutland Post«, No. 155, year 1873, some information of importance
is found regarding the oyster fishery in the Lim Fjord in earlier years, in the
time of the lessees Steenberg, J. C. Jørgensen, M. N. Schibbye and Kløvborg. I
may cite a portion of this article though it contains several inaccuracies.
»We recognise the difficulty of giving a picture of the conditions, of which
only a small portion of the public, who it may be considered will read this, can
have sufficient local knowledge, as knowledge is necessary here of the earlier
conditions in the Lim Fjord, especially as regards the fishery, and we therefore believe
that it will not be out of the way if we first of all recall what these conditions
were about a generation ago. Until 1825 the water in the western basin of the
Lim Fjord was fresh, and the fishes were then the usual freshwater species which
occur in our freshwater lakes; but after the break through of the North Sea at
Agger in 1825, by which the fjord water became completely salt, all the earlier
fish im the fjord died out, so that the banks of the fjord were covered hy hundreds
of loads of dead freshwater fish. Other species now gradually made their appea-
rance, chiefly plaice and a smaller kind of cod. Oysters were detected in the
forties, when some fishermen in the western part of the fjord let it be known, that
they now and then took a kind of shell-fish, as they called them, in their fishing
apparatus; but they did not bring them forward or laid themselves out to fish for
them, as they did not know their value at that time. It was only in 1850 that
the father of the present writer Steenberg, late Agent Steenberg in Nykjøbing, got
notice of the matter through a fishermen bringing some oysters to Nykjøbing,
and after obtaining information as to where they had been taken caused the place
to be more closely investigated. He then obtained a small barrelful, which he
sent to a personal acquaintance of his in Copenhagen, who stood in close con-
nection with the Government of that time, together with information as to where
they had been found. These oysters were found on the north side of Salling in
Salling Sund so close to the shore, that with the water clear they could be seen
from a boat and taken up with a rake. They were scattered ahout singiy, not in
beds, and as the opportunity arose he got the fjord better investigated and thus
found oysters at other places, especially in Harrevig somewhat further to the
west, also single scattered oysters but nowhere in beds.
»The Government now took up the matter, prohibited the oyster fishery
in the fjord and in 1851 privately let out this fishery over the whole tjord for 3
years to Agent Steenberg in Nykjøbing, Kammeraad Lykke in Thisted and Justits-
raad Claudi in Lemvig at a rent of 300 Rd. yearly. This contract was on run-
ning out again renewed for 3 years to the same men, and then Agent Steenberg
took it over alone for 4 years until 1861, Then the contracts were auctioned for
a period of 10 years and the fjord on this occasion was cut up into 5 divisions,
namely: from the east as far as Løgstør (1st division), the large Livø Bredning
(nd division), the stretch through Salling Sund down to Struer (3rd division),
Thisted Bredning including the stretch west of Mors to Ottesund (4th division)
and Nissum Bredning from Ottesund west to Agger Canal (dth division). Of these
the writer's father Steenberg rented the 2nd and 3rd divisions and the under-
signed Kløvborg, Jørgensen and Schibbye the 4th and 5th divisions.
»During the first 10 years, from 1851 to 1861, when Steenherg in part
1H3)
alone had the fishery, the fjord was so well investigated that where the oysters
were and were not found became very well known, and the latter at the end of
the period was chiefly the case in the 3rd and Sth divisions and at various places
here and there. At the very end of the time oysters appeared in the neighbour-
hood of Fuur, whilst in the northern part of Livø Bredning and in practically the
whole of the 4th division no oysters were found. Although the oyster fisheries,
when the contracts were made in 1861, were known and had been carried on in
the fjord for the 10 years previously, and although the contracts were then no
longer made privately but by public auction, yet the importance of the fisheries
was so little regarded by the people around that the whole fisheries in the 4
-divisions named were let out for a sum of ca. 900 Rd. yearly, which was con-
sidered sufficient as matters stood, when no one would give anything for the fu-
ture uncertainty. The results of the first years showed also, that the thing was
of no great pecuniary importance, as the amount earned was then only so large
that we could carry on the business without being the object of envy. The Govern-
ment also recognised that the fisheries had at that time no very great importance;
but it had a right perception that they might possibly be helped forward in a
quicker manner and on a larger scale, if the lessees could be interested in the
matter, and this was reached by the Government, in the conditions, not imposing
as a duty on the lessees the making of certain arrangements but offering them a
distinct advantage on the expiry of the contract if they did so of their own accord.
As examples of. arrangements considered expedient by the Government were named,
the laying down of. oyster parks and artificial oyster banks, but it was added in
general »or other arrangements advantageous to the advancement of the fisheries«.
It was imposed upon the lessees however, that if they should make any such
measures, they should make an annual report to the Government regarding what
had been done and lastly the following promise was made to them in the condi-
tions: »In so far as the lessee at the end of his contract can show that he has
laid down oyster parks, artificial oyster banks or made other arrangements of ad-
vantage to the fishery, which might be considered as contributing towards the
receipt of a higher rent during the next contract, he is entitled to a half portion
of what the rent amounts to over what he himself has given, either paid out as
one sum or in a reduction of the rent if he himself should remain the lessee.«
»Where the oysters originally came from cannot possibly be determined
with certainty, but it is clear that they only arrived there after 1825; and if no
weight is laid upon the fact, that a private person was induced by the then
Amtmand Faye to introduce a lot of oysters in the thirties, which were laid down
in Nissum Bredning in the neighbourhood of his house, then there is hardly any
other probable cause for their occurrence than that the spat were carried in from
the North Sea through Agger Channel into the fjord. That the oysters have no
movement of their own need not be mentioned; but every one can gather there-
from that their occurrence and distribution must be due to currents in the water,
which carry on the young until they can find a place where they can fix them-
selves and which contains the conditions for their further development. That the
oysters do not require many years to grow up seems to be a fact; but it seems
also true that they require many years to spread themselves over a large extent
”
[3]
16
of water, through which the current is mainly in a fixed direction. In the year
1851 fully developed oysters were found on the Salling side of Sallingsund, and
some years previously, as already remarked above, it was learnt from the fisher-
men that there were oysters in Nissum Bredning, where in 1851 also, in the time
of the first contracts, they were found to be of so unusual a size that, if one
judge as to the age from the size, they must certainly have been older than those
usually brought to market. We helieve therefore that there is good reason to
consider, that the oyster spat entered the fjord and began to spread there at least
10—15 years before the first contract began, thus 20—25 years before our contract.«
The views of the lessees that the oysters must necessarily take some years
to spread themselves over the Lim Fjord from west to east, I do not share; if
the oysters as spat once enter the Nissum Bredning, they will certainly spread
themselves very quickly over the whole of the fjord as far as the oyster can live
at all, namely somewhat to the east of Løgstør. i mention this remarkable belief
in the slow spreading of the oyster as it has played an important part in the
history of the Lim Fjord fisheries. On the other hand, I must naturally agree
with the lessees that it was ouly after the breaking through of the Thyborøn
Channel in 1825, that it became possible for the oysters to live in the Lim Fjord;
as the Lim Fjord then became at one stroke the saltest fjord in Denmark — the
only one still sufficiently salt that the oysters can live and reproduce in it.
Collin writes: »As is well known, the part of the Lim Fjord which lies
west of Løgstør might be said to have been up to 1825 a complex of larger and
smaller, connected freshwater lakes, which had their common outlet into the
Kattegat.«
We learn from Krøyer's reports that the oysters almost as soon as they
were observed occurred from the western parts of the fjord and over the whole
of the area which is now fished (see Chart). Whether the few now found to the
east of Løgstør had anything corresponding in those days is not known and is of
no importance. It is of interest to note Krøyer's statement, that the young oysters
were so numerous in the Lim Fjord, much more numerous than on the banks in
the Kattegat; this agrees perfectly with my own much later observations on the
present conditions.
In 1853 the lessees Steenberg, Lykke and Claudi reported, that oysters
were to be found right down in Hvalpsund, at Rottholmene, Livø Tap etc., thus
over great parts of Livø Bredning. It seems to have been long before the banks
were found and long before it was learnt to fish them well; since even in 1856
the contractors report, that as the ice prevented the fishery in winter and »it can
only be carried on in calm and clear weather« they had but few fishing days in
the year. They only pole-dredged the ground and believed that the ordinary oyster
dredge could not be used in the Lim Fjord on account of the many stones on
the bottom. They stated that »no other oysters naturally can be fished than those
lying on the bottom, or so near the shore that they can be seen in clear weather. «
The fishery in the Lim Fjord was therefore not very extensive, although
there must certainly håve been a rich stock of oysters in the fjord.
The Government seems to have done nothing more in the matter after
getting Krøyer to investigate the banks: and it was certainly from foreign parts,
ild
after Professor Coste had made his well-known experiments in artificial oyster cul-
ture in France, that the impulse came to take up the matter. From available
documents for Nov. 23rd 1859 it appears, that on account of Krøyer's feeble health
the Government could not employ him again, and as the Professor in Zoology
Japetus Steenstrup was absent just at that time, the Professor of Physiology
Eschricht was called upon. Eschricht readily took up the matter, journeyed to
France in 1860, later to the Lim Fjord and sent in his above-cited, interesting
printed reports. It was in consequence of these that the Lim Fjord in the period
from 1861—71 was let out in 5 divisions, with the right to lay down oyster parks
in them, and that the standard for oysters was reduced by the Government to
21/, inches, as it was for the Schleswig and »fladstrand« banks. The lessees did
not however carry this standard into effect, but fished only the 3 or even 3!/,
inches and they took no advantage of their rights to lay down parks.
It has not been possible for me to ascertain whether Eschricht had any-
thing more to do with the matter later than 1862. The fishery evidently went on
as best it could during the 10 following years. The large numbers of oysters
fished at the end of this period show clearly that the fishermen had now learnt
how to dredge.
The next time the fishery was to be let out, ca. 1870, the Government
called upon a new man to be their expert, namely, Jonas Collin: he remained
the expert until 1905. In 1870 he proposed »that the standard under the new
contracts should be 3” or 31”«; Kontrollør Andersen proposed 3” in diameter
and it remained at that until 1893.
Appendix I gives a brief summary over the statistics concerning the
contracts and the oyster fisheries in the Lim Fjord, so far as I have been able
to obtain them.
Ås will be seen the fisheries were let out for the first time, 1852—53, for
ca. 400 Rd. (App. I). After 1861—62 and till 1870—71 the rent was somewhat
higher, 885 Rd. How many oysters were fished during the first period I do not
know; the number can scarcely have been great. In 1860 the lessees informed
Eschricht that they fished that year 150,000 specimeus, but in 1867—65—65—179
respectively 1,7 mill., 3,9 mill,, 4,6 mill. and 5,3 mill. were fished. After +
v the
rent rose from 375 Rd. to 42,000 Rd. The »Dansk Fiskehandelsselskab«
now obtained the management (business director Kuhnert, manager Paulsen).
Ås the rent of the contracts had risen so greatly the question was much discussed
of recompense to the earlier lessees, who claimed that they had improved the
fisheries in various ways and therefore according to the contract held themselves
enlitled to the half portion of the increased rent. I need not enter here any
further on this subject, but merely refer to the official documents (see List of the
Literature »Aktstykker«).
The conditions for the »Fiskehandelsselskab« are printed in Appendix IV.
The company fished during the 5 years of its contract respectively 75—75—71—57
and 6 million oysters, and obviously did good business. In 1876—77 the »Han-
delsbank« obtained the contract, again with Kuhnert and Paulsen as direc-
tors, but the rent was now raised to 240,000 Kr. per annum to begin with. The
quantities sank however from 54 to 314 to 24, 2% to 14, 2 to 1% to 11 to less than
18
one million in the last two years, and the rent to ca. 70,000 Kr. A glance at
Appendix I shows the gradua) decline from 1873—74 to 1885—86, a decline which
clearly shows that the old, rich stock had been so severely fished that it had be-
come noticeable"). This means that the stock of large oysters had become thin-
ned out, though not to the extent that the Table seems to indicate, as in the
Handelsbank's conditions (Appendix V) a paragraph (S$ 3) is found which reads:
»that the banks which are not able to give 1000 oysters full measure daily for a
boat well provided with 4 dredges under favourable conditions, have to be rested
during. the whole of that season«. This regulation, which seems to have been
very strictly enforced, gradually excluded the lessees from fishing over very large
areas, so that they finally were unable to take the number for which payment
was obligatory, namely 150,000. The Government then endeavoured to counteract
this decline by a provisional closing of the oyster fisheries in the Lim Fjord from
May 1885 to September 1890. This close period was only maintained however for
the first four of these five years, as appears from App. I. In 1890—91 the
fisheries were again let out to Tonning and Teilman-Friis for 5 years, and
later to Toning alone for another 5 years (see App. VI for the conditions). In
1900—1901 the fishery was let to Brinck, Jørgen E. Mar. Jensen, Halse and G.
H. Spellerberg (see App. VIN), who still have it. In the years after the close
period ended in 1890, the fishery never brought in more than about 1 million
oysters per annum; most in 1905—06, namely 1,200,000. It cannot be said there-
fore that the close period had good results; since before the closure about a mil-
lion were taken, and after its withdrawal about a half, though rising now evenly
to 1,200,000.
What we learn from the past years regarding the artificial methods
of increasing the stock of oysters in the Lim Fjord is not much. The
transplantations of standard oysters in earlier years for the purpose of propagation
is denied all positive value by the Government Adviser J. Collin, and certainly
with right. It was Eschricht who proposed this in 1860, and it was also through
his proposal that the fjord was let out in divisions with sole rights to the lessees
to undertake the laying down of oyster parks. That the result was so bad and
gave occasion to a law-suit for compensation was not Eschricht's fault; there is
a sound principle at the bottom of the division of the fjord into many small sub-
divisions; on this see later.
Since 1890 various experiments were made by Tonning, most probably
under the direction of Collin, at least under his inspection, at Oddesund and
Nykjøbing on Mors to rear young oysters in closed basins; but these have been
without result. In my opinion they were wrong in principle.
In spite of the apparently small results of the close period in the four
years mentioned above, better fortune has followed the endeavour to maintain the
stock than to increase it; only no profit has been made. In later years the idea
has on the whole been more to preserve than to increase, and people were obvi-
ously very much afraid that the stock might be wholly destroyed. The sorrowful
fate of the Schleswig banks in the North Sea perhaps contributed to this feeling.
7) Perhaps also the natural conditions, e. g. the hard frost in 1876—77, contributed to
the decline.
19
There can be no doubt either that severe fishing could remove almost the
whole stock in certain waters: this has happened, for example, according to infor-
mation I have received from Holland, in the Zuidersee, though the latter with its
smooth sandy bottom is almost everywhere adapted to dredging; the conditions in
the Lim Fjord are something quite different; its at many places very uneven
stony and rocky bottom (cement rock) sufficiently prevent a complete dredging out
of the oysters. Å combined dredging and diving system must at any rate be
used here to produce the total ruin of the fishery. A diver namely might take
up the oysters from the uneven places where the dredge cannot work.
Amongst the regulations from earlier times which have been of the grea-
test influence in preserving the stock must certainly be mentioned the standard
for oysters, 3 to 3!/, inches in diameter, in combination with the regulation that
a boat with 4 dredges at work must under favourable conditions be able to fish
at least 1000 standard oysters per day, to permit of dredging being carried on at
all on the banks in question.
The close time im the summer months, when the oysters are spawning
and not of good flavour has certainiy also had some importance in this regard.
The regulations that all star-fishes dredged up should be killed before casting them
overboard has scarcely had any importance. In later years the principle of pay-
ment for each single oyster fished has certainly contributed to a too careful treat-
ment of the stock. It was the raising of this rent from ca. 3 to over 6 øre per
oyster, which has brought up the income from the contracts after 1890 to about
the double of what it was in 1900; as the number of oysters taken has been
almost the same hefore and after 1900 (see App. I). Whether the diving for
oysters introduced since 1900 actually damages the stock less than careful dred-
ging I must leave undecided; by dredging the banks may be cleaned, but not
by diving.
Appendix 1. 20
Product of the Oyster Fisheries in the Lim Fjord, 1852—1906
Year. Lessees. Rent. | Number of oysters
| fished.
1852—53 | Steenberg, Claudi and Lykke. | 400 Rd. ca. 30,000
1853—54
1854 —55
1855—56 The same. By lol: ca. 86,000
1856—57
1857—58
1858—59 Steenberg alone. 322 Rd.
1859—60
1860—61 ca. 150,000 spec.
1861—62 DryNkRBree 885. Rd.
1862—63 Div. 2 and 3: Steenberg (lat-
1863—64 er his widow and sons).
1864—65 Dyveke andeoE CSE ansen '
1865—66 Mathrar Møller, Jørgensen, 1,147,350 spec.
1866 — 67 Kløvborg and Schibby (the 1,207,150. —
1867—68 first 2 however soon left 1,727,100 —
1868—69 the company). 3,868,500 —
1869—70 4620;967 -
1870—71 5,343,248 —
SEE 42: Dansk Fiskehandelsselskab. 42,000 Rd. 7,519,030 —
1872—73 (Paulsen, Kuhnert). 7,911,8258 —
1873—74 i 7,364,765. —
1874—75 5,551,155 —
1875—76 5,933,130 —
ISNOE TT Handelsbanken, (Paulsen, 240,000 Kr. BD OLDEEEE
1877——78 Kuhnert). 240,000 — 3,555,735 —
1878—79 240,000 — 2,628,025 —
1879—80 110,000 — 2875,130 —
1880—81 70,000 — 1,479,295 —
188] —82 111,747 — 2,075,990 —
1882 - 83 96,470 — 1,759,810 —
1883—84 84,000 — 1319465"
1884—85 946,865. —
1885—86 (921,825) —
1886—87 Close period.
1887——88
1888—89
1889—90
1890— 91 Tonning and Teilman-Friis. | 17,599 Kr. 44 Øre 586,648 —
1891—92 34,855 — 67 — 774570. —
1892—93 DODOS RE REDE 871,944 —
1893—94 26,632 — 48 — 765,299 —
1894—95 PAP, gl Es Yo REE 890,572 —
1895—96 Tonning. 32,679 — 45 —!| 1,007,178 —
1896—97 33,845 — 70 —! 1,053,828 —
1897—98 SONG DS TT GARS Go ES
1898—99 34709 — 78 —)| 1,088,391 —
1399—1900 32,349 — 2 — 993,968 —
1900—01 Brinck, Jørgen E. Mar. Jen-' 62,591 — 91 —! 1,009,547 —
1901—02 sen, Halse and G. H. Spel-! 70,256 — 60 —| 1,133,171 —
1902-—03 lerberg. 63,540 — 33 —| 1,024844 —
1903-—04 (STOD Sr] OS IKDGS) ==
1904—05 66,257 — 74 —| 1,068,673 —
1905—06 72,504 — 22 —| 1,238,846 ——
21
B. Investigations of the author in 1895, 1896, Ig0o5 and 1906 etc.
For a rapid glance over the hydrographical conditions in the Lim Fjord I
may give here some measurements of the specific gravity of the water, made
duringa vovage of »Havørnen« from September 4th—1lth 1890:
Temperature Salinity in "/,
At Gjøl was found a specific gravity of 1,0200 15, "C. eg
»… Løgstør » SUEE> » » EKO ZOND 2 69
»… Fuur » » » » » » 1,0215 5 » TE
In Launs Bredning » So » ”» See ON Br OS LSE ne
Virk-Sund » SEN » » SEE OTA GEDE ls
» Skive Fjord » » » » » 110173 14, » FAE:
West of Fuur » BØN ES ” » SODE Ds 2
At Ør Odde » » » » » » 1,0230 185% > 2705
In Kaas Bredning » SEES » ”» SEK OPDBE REED FEE 30E
North of Jegindø » BE » se BO22Æ AB 5 re
At Kaas Head » ”» 53 » » SME 023 6 ENS E 5 BIM
East of Venø » SEES » » SEMKOPS SETS 305
At Struer » EAR2) » SE 02565 330
In Nissum Bredning » sd ng » » SIF ODÆS EET SEES Br
At Krik » BD ” » SEN ONS GELSE 239
» Lemvig » » » » » » 1,0246 Il TE 3448
E. of Skibsted Fjord » »” » » » » 1,0200 TD » Eg
In Visby Bredning ” ,» 0» » » SE 0200 MAE NG
E. of Thisted Br. , , » » » SEE OZOS TESTE PER
At Nibe » BE% » » 1,0180 14, 208
The salinities given above are marked on the Chart accompanying this
paper with exception of the last at Nibe, which falls outside the chart. It will be
noticed that wherever the salinity is over 2,,,"/, oysters are found, and none on
the other hand where it is under 2,,,/,. Thus there are none at Krik, in Launs
Bredning and Skive Fjord or east of Troldholmene. The salinity was however
high at Gjøl, but it must be remembered that in the narrow, eastern part of the
Lim Fjord the salinity is so extremely variable, that a momentary picture cannot
be considered as giving any useful guide to the conditions there. This variation
can also be seen from the above figures, as at Nibe (at the outlet) only 2,5. "/,
was found 7 days after the observation of 2,;,"/, at Gjøl. On both days the
salinity was most probably the same at both places.
The salinity has thus undoubtedly a very distinct influence on the distri-
bution of the oysters in the Lim Fjord, but it is impossible for me to state the
22
precise percentage required; as it is not known at all these places how the salinity
varies at other periods of the year. The measurements of the salinity were made
in September 1890, but in spring the water is perhaps a little fresher, and during
great storms also the salinity may obviously vary somewhat at many places; I
am inclined to believe however that oysters with us can scarcely live and repro-
duce to any considerable extent, unless the salinity as a rule and especially during
the spawning time is up towards 3,. This is indicated by the hydrographical
conditions at the places where the oysters are constantly found, namely, in the
northern and eastern parts of the Kattegat, as well as in the Lim Fjord.
To obtain information as to the degree of salinity the spat require in the
free stage, a stage when we should expect that the salinity of the water or rather
the specific gravity would have great influence, the spat were taken from as far
as possible ripe oysters (thus very dark-coloured spat) and placed in several glas-
ses containing water of a specific gravity of 1,0150,' 1,0162, 1,0173, 1,0233 all at
a temperature of 15—189 C. After standing for a couple of days, it appeared
that almost all the fry had sunk down to the bottom in the glass with the smallest
specific gravity; several were obviously dead and hut very few ventured to swim
freely around in the water. In the glasses with water of greater specific gravity,
on the other hand, the fry continued to swim about freely for many days. We
might therefore believe that a salinity of ca. 1,016 was sufficient for the spat in
the free stage; but this is not definitely settled by the experiment, as I succeeded
in none of the many cases where such fry were placed in glasses in getting them
to fix themselves; they always died after a shorter or longer time; sometimes the
fry lived for 14 days under these experiments. I may further state here that the
fry can live in the free-swimming stage at a temperature of only 13? C.; this
observation was made on board ship. In the open I have found the free-swimming
oyster spat in water of only 15? C. At a temperature of ca. 19? C. or less they
can thrive and fix themselves; thus in the first days of August 1895 the quite
small spat (2— 13 mm.) were found on the collectors set out by me and on other
objects present in the water. The temperature was taken each morning about 7
a. m., and during the whole of the month of July 1895 the highest temperature
observed was 19,4" C. the lowest 15? C. During the same period the specific
gravity in Nykjøbing Harbour, where the oyster spat was also found in July,
varied between 1,02000 and 1,0239.
Temperature curves for Oddesund 1893—95 and for Nykjøbing 1895 are
appended in order to give some notion of the temperature in the summer half-year.
Ripe spermatozoa with distinct tail were found for the first time in an
oyster at Nykjøbing on May 24th 1895; but few were investigated. On June 14th
20 oysters from Ørodde were examined; 3 of them had white spat inside their
shells, one had blue spat.
On June 1åth 13 oysters over 2 inches were examined from Sallingsund,
b of which had blue and 2 white spat. The spat was now obtained daily in our
plankton net both in the harbour and in Sallingsund; it was present however in
much smaller numbers than the larvæ of other molluscs. Both night and day,
in bright, sunny and in dull weather the spat was found on the surface, but
constantly also in deeper wuter; it seems (lo be present everywhere and at all
23
times, but just like.all plankton in much smaller quantity where the water was
shallow or filled with Zostera, and where therefore there was but little current
and flow of water.
28th July: Of 39 oysters from Sallingsund and neighbourhood 2 had
white and 2 blue spat.
3rd July: Very few oyster spat in the plankton at Sallingsund, but many
in Nykjøbing Harbour. The currents are obviously carrying the spat some distance
round the fjord. The water from the North Sea certainly contains very few of
the spat. A few days later there was no oyster spat even in Sallingsund.
On the 8th—1lth July oysters from various places in Sallingsund and
neigbourhood were examined. Of 5 from Skælholmen 1 had blue and 1 white
spat; of 16 south of Glyngøre 1 had blue spat. Of 144 pole-dredged in Faarup
Vig (see Table I No. 6) only 4 had spat, none of which were quite blue; of 18
from 3—4 fathoms at Sallingsund only 1 had blue spat; of 61 pole-dredged at
Studeholmene at Højriis none had spat, but small oysters down to 2!/, inches
had spermatozoa with tail. Of 86 standard oysters and 150 under-sized from
Trehuse at Salling (see Table I No. 8) 16 had spat, a »dwarf« of 2'/, inches had
white spat; otherwise the oysters here seem but seldom to have spat before they
are 23/, inches long.
12th July: some oyster spat still in the water, even in days of windy and
rainy weather, but still more of the other molluse larvæ.
16th July: the temperature of the water has now sunk to 15? C. during
a long period of westerly storms and rain, and the oyster spat is very scarce in
the Sound; none at all are present in the harhour and few gastropod and mussel larvæ.
18th—19th July: warm weather again, and oyster spat appeared
at once.
25th July: at Bjørndrup 74 standard oysters and 302 under-sized and
young were dredged (see Table I No. 9), but only 6 had spat.
On the 26th and 27th July oysters were examined in large numbers from
Brevig and Snaven at Salling (see Table I No. 2), but only 7 and 9 respectively
were found to have spat.
On the 3ist of July and I1st of August oysters were brought up by diving
in Livø Bredning (see Table I No. 11, 12 and 13), but only 3 im all had spat.
On the 3rd of August the oyster spat were observed on the collectors:
some were even 13 mm. The fixing of further spat on the collectors has not been
observed later.
In August the stock of oysters on the banks in Venø Bugt, at Oddesund,
in Nissum-Bredning and in Sallingsund was examined (see Table Nos. 17, 15, 14,
19, 20, 16), but spat was found in hut very few. In agreement with this the
number of oyster spat taken in the plankton fell off in the course of the month.
The last oysters I found with spat were observed on 24th August (1895);
but oyster dealers in Nykjøbing informed me that they had found a few even in
September; and the spat was found in the plankton even on September Sth.
Whether these stragglers are able to develop must certainly be considered as
doubtful: the temperature in the water was only 13—17? and fell very quickly
in the following days. I had thought beforehand that July or August would be
i
24
the main spawning time of the oyster, and the investigation of this point was
therefore neglected somewhat in the beginning; hut from the data we may believe
that it begins a little earlier. It was also some time before I found out that we
could fish the small spat in the open with sufficiently fine pelagic net of miller's
gauze. Unless the period during which the spat remain wlthin the cavity of the
mother-animal is very short, it seems as if a relatively small number of oysters
take part yearly in reproduction; to determine the duration of this period is obvi-
ously an exceedingly difficult matter owing to the complete closure and lack of
transparency of the animal and nothing appreciable is known regarding it.
Although the weather in 1895 was scarcely favourable to the well-being
of the oysters in the Lim Fjord, there was nevertheless as shown a considerable
quantity of spat in the fjord, and the fixed spat was also observed both on my
collectors and on other objects in the fjord: posts, boats etc.; but what surprised
me most in these investigations of 1895 was, that I could not with certainty find
the young of the year in quantity on the banks after the spawning time, e.g. in
October. In Thisted Harbour I saw boats quite densely covered with the spat of
the year; but on the Lysen (Brevig) banks (see Table I No. 3) I found no spat
in October.
On Table II No. 13 the size of the spat on August 8th 1895 is represented
from measurements of 24 specimens taken on the collectors; No. 14 shows the
size of the same spat on September 24th 1895; a few are even already over 1
inch in length. If we remember that growth continues even somewhat late into
the autumn but stops in winter, we should clearly find each spring a group of
c
Do
5
oysters of about or under an inch in length, and in 1895 and 96 such a group
was found at many places where a large number of oysters were fished on a bank
(see Table II. No. 1, 2, 3 etc). å
It is possible that I have missed seeing the small spat on the banks in
1895, as in later years I found them in the autumn (see e.g, Table II No. 12,
September 1896 at Bjørndrup); but the specimens were then only //,—Y, inch
long, and it surprised me that they were so small as they were much larger on
artificial objects; see e.g. Table II No. 18 for September 19th 1896, i.e. the same
year in which a welled-box belonging to the Station, which had remained in the
water from the spring of 1896 till then, was found to be covered by ca. 25,000
young oysters of up to 1!/, inches in length (see figures on pp. 24—25), on an
average they were /, inch in length. On the tile collectors at Ørodde the 1895
26
spat were on September 24th on an average !/, inch in length (see Table II No.
14). I can remember distinctly, and have remarked upon it, that I was surprised
to find the spat much smaller on the natural banks than on the collectors and
artificial objects; but this seems to he the rule. In 1905 and 1906, when I was
again investigating the spat at Volstrup in the Lim Fjord in August (see Table
II No. 4 and 5), I found them to be only ca. Imm. or less. On August 1895
the spat on the collectors had already reached up to !/, an inch in diameter (see
Table II No. 13).
At Volstrup which was investigated very carefully in 1905 and 06 it was
found that many more oysters of the 0-group occurred in the shallow water (3—6
feet), where we pole-dredged tor the oysters, than in deeper water of 12—18 feet
where we dredged. A glance at Table III will further show that the »one-year
old« oysters were also more abundant in the shallow than in the deeper water.
In 1895, as mentioned, the spat were found fixed to various artificial
objects, thus: on limed tiles, on spars of fir, on a wooden barrel hung overboard
at the Biological Station, on pieces of granite hanging in and on the barrel, on
the bottom of the boat, on the wooden piles of the harbour. The barrel, in which
there was no bottom, was used to provide the aquaria on board with air; it had
a small hole at the top, from which a piece of guttapercha tubing carried the air
pressed out by the weight of the stones into the aquaria; when the barrel filled
with water (2 times in the day), it was hoisted up a moment and new air allowed
to enter below, whilst the water ran out. On August 3rd the oyster spat was
observed both on the barrel itself and on the stones hanging outside and inside.
Quantities of other organisms were also found here, e.g. Ciona canina, Phallusia
sp., Pomatoceros, Balanus, diatoms and algæ; but it was obvious that the plants
dominated on the sunny side of the barrel and stones; the green algæ were only
situated on the upper parts; on the other hand the animals kept more to the
shaded sides; and inside the barrel where there must have been extremely little
light (only from below), many Phallusia were still fonnd and a few oysters but no
plants. There is no doubt that light plays a great part during the fixing of the
oyster spat; but whether the reason is that the plants quickly fix themselves on
the light side and thus hinder any later fixing of the oysters, I must leave undecided.
We may compare with this the experiments made at Roscoff by Lacaze-Duthiers
during a number of years to get the oysters to spawn in a closed basin. The
experiment seems to have been successful beyond all expectation (Archives de
Zoologie experimental (3) T. 1. 18941). My experiments with collectors have only
been made on a very small scale; the material which gave the hest result was
tiles coated with lime, which seems to be the only method now usually employed
im France and Holland. In Thisted Harbour in the autumn of 1895 I observed
5 pleasure yachts, which had lain the best part of the summer in the harbour; 3
had been tarred in the spring, and the other two coated with a patent paint; on
July l1st they were all cleaned and again put out, and perhaps most of the patent
paint had thus been cleaned off. The bottom of these boats was much covered
with various animals and plants, but some almost exclusively with oyster spat.
N. et revue pg. XXV.
27
We notice again here that the spat had fixed itself on places where there was
some shade. Just as on tbe barrel so here, it is on objects which are near the
surface of the water and often moved by the help of man, that the spat are pre-
sent in quantity; the collectors were also in shallow water and the anchoring stones
especially were so hung that the waves could move them. These circumstances
may be accidental, of that I know nothing with certainty.
The spat can thus fix themselves on old tarred hoats; this i have observed
several times; but the tar must obviously be quite dry. On patent paint on the
other hand, if it is good, as it should be, the spat can scarcely fix themselves;
I have not found it so in spite of good opportunities. The patent paint is indeed
used everywhere just to prevent all organisms from fixing themselves to ships and
thus reduce the ease with which they move through the water, and it serves what
is wanted better than other stuffs; nevertheless, the algæ begin to make themselves
at home in the course of some months especially where the sunlight is strong,
near the surface. ;
As already mentioned, in 1895 I did not find the spat of the year at other
places than on »artificial objects«: but I often found the spat of the previous year
under »natural« conditions, e.g. in the spring (see Table I No. 4 and 5). They
were found both in shallow and deep water. All the oysters of under 1 inch in
length in spring could be reckoned partly to this group. If it is asked, where the
oysters were fixed the answer is, that they were most frequently on oyster shells
both living and dead, hut also frequently on stones and other dead mollusc
shells, as e.g. Tapes pullastra and decussatus, Cardium edule, Mytilus
edulis, Pecten varius, further on both living and dead shells of Balanus,
Pomatoceros, Buccinum undatum, Littorina littorea etc.
It is stated by certain authors that our common crab (Carcinus mænas)
is one of the worst enemies of the young oysters; this however does not prevent
the spat from fixing itself to the under-carapace of the crab, where the crab might
easily reach it with its claws and yet does not destroy it. On the lobster we
very often find a quantity of small oysters; but I have never seen an adult oyster
either on living lobsters or on dead lobster shells. The skeletons do not keep
long apparently after the lobster casts them off, perhaps even the lobster eats its
own shell as a rule. We do not find dead lobster skeletons in the fjord; at least
I have never seen any. The oyster spat can also fix itself on the hard parts of
sea-weed (Fucus vesiculosus) and sometimes does so on no small scale. Oyster
shells and stones are apparently the most common materials on which the oyster
spat fix themselves. Of stones all sizes are used from the largest to the quite small.
The oyster does not seem very critical therefore as to the choice of its
future resting place, a fact that in high degree tells upon the separate individuals
later; it only seems to seek for hard objects with somewhat clean surface.
With the fixing a very dangerous period in the life of the oyster is obvi-
ously completed; but even then it is far from being safe. A number of the spat
in shallow water for example will certainly be killed by the ice; a quantity will
be washed on land, for example many of those fixed on the Fucus; often the spat
are so crowded together that a portion must die from lack of room. Thus in the
spring of 1895 I found a quantity of dead spat in shallow water and among living
28
oysters, the shells still hanging together, probably the young of 1894; many spe-
cimens even were still living. I am unable to say definitely whether it was the
case hut I believe that the frost had killed them. Many authors state in the
literature on the oyster that the enemies of the oyster thin out the stock so much
and it is certain that the boring snails and worms as also the boring sponges
are very destructive; but of these we have only the last-named in the Lim Fjord,
and they had not been the cause of death,as where they have been they leave
some easily recognisable sign. I have found it very difficult on the whole, in
spite of careful search, to detect the animals or plants which directly attack the
oysters when fixed; in fact, apart from the boring sponges, worms (Polydora) and
man, I have been quite unable to find any with certainty; on the other hand I
have seen a Gammarid building its tubes of mud-particles over the shells of the
young oysters and the whole of the stone on which they had fixed themselves in
the well on board, and almost completely covered the oyster shells with these
tubes. As every storm in the Lim Fjord stirs up the loose layers of the hottom
a great deal, so that the water becomes hrown with the deposited mud-particles,
these Gammarids will always be able to find sufficient materials even if the oysters
are fixed high above the bottom; and if the tubes are only a little advanced the
mud-particles will be able to adhere of themselves, and the oysters will therefore
soon be covered by quite a layer of mud. This must be a great hindrance to
" their growth and may at length indeed smother them completely. That the
starfishes (Asterias rubens) eat oysters I have never been able to determine, in
spite of eager search on the banks where there were both oysters and starfishes;
it would require a large starfish in any case to eat an ordinary well-developed
oyster; that they feed upon other molluses on the other hand I have often seen,
but always only those which they could quite surround and smother. It is also
undoubtedly right that starfishes may be able to feed upon smaller oysters; we
have direct observations on this point from Schiemenz.
There are a few species of animals in the Lim Fjord, some gastropods
(Acmæa testudinalis and Chitons), which are very fond of gnawing at the upturned
shell of the oyster; they do not penetrate very deep as a rule, so that they can
scarcely cause any real damage to the oyster; they might even be considered as
doing some good, as they therewith keep the upper shell clean from plant growths.
These gastropods appear especially on hard ground; without them such plants as
Fucus, violin-strings (Chorda) and the like, would certainly overgrow the oysters
completely and possibly move them away from their place. These small gastropods
thus play an important part in the Lim Fjord, which must be more closely inves-
tigated in the future. I have only wished to draw attention to the matter here.
Possibly they destroy the very small, fixed spat.
The greatest dangers to the development of the oysters certainly do not
come from the animal life in the Lim Fjord, but much more from the surroun-
ding natural conditions and vegetation. The cold and especially the ice
have already been mentioned; the latter are certainly to blame that the oysters
are not found in quite shallow water in the fjord, but what obviously destroys
most oysters is the mud or sand, as also at places the disturbance caused by
the waves during storms. Ås regards the first two I have personally not seen
29
their effects but they are known for example to divers; these state that masses of
mud will very quickly (in a few days) cover the oyster banks on which they are
working, so that they are obliged to give up diving operations for a time; a storm
with a different current will however soon clean the bank again, and the oysters
are not necessarily dead, at least not all; the death-rate will obviously depend
partly upon the thickness of the layer of mud, partly on the length of time it
covers the oyster bank. Every one who has seen a storm disturb the water in
the fjord, and that unfortunately there is frequent opportunity to see, will have
noticed how after the storm everything under the water is covered with a layer
of mud, unless the current as in the narrow courses or the action of the waves
on the open coasts in shallow water again carries the layer away, from which we
know that this mud may also cover the more sheltered oyster banks. Masses of
sand might also cover the banks in this manner, hut the fine mud is certainly
the most dangerous. One circumstance comes into consideration here, however,
namely that wherever a dense growth of Zostera covers the bottom, the mud
accumulates there the most readily, as it comes to rest there most quickly; this
circumstance along with the fact that the weed itself contributes greatly to the
formation of mud on rotting away and through giving support whilst living to a
quantity of small organisms whose excrement and other remains likewise turn to
mud, makes the Zostera indirectly one of the greatest enemies of the oyster. The
Zostera may also be destructive directly, as before it has quite rotted away it
may lie in the rotting condition over the banks and thus smother the oysters. It
might also be thought that other sea-weeds as well as the Zostera would be harmful
to the oysters, and certain algæ may perhaps be so at places. There is unfor-
tunately much that indicates that the above-mentioned heaping up of the mud in
the Lim Fjord is increasing; certain parts of the fjord, e.g. Harrevig, are spoken
of, where oysters lived earlier but where the mud and Zostera now make it diffi-
cult for the oyster to live; yet I have no fixed opinion on this matter for the
time being, though it seems difficult to believe that the conditions are not as
described. Heaping up of mud seems to occur also in most of our other fjords.
It may be understood from this how it is possible that dredging can remove both
the mud and the Zostera and again make the ground suitable for laying out
oysters. That, on the other hand, dredging on an oyster bank where the condi-
tions are good is harmful to the stock of oysters as well as to the animal life on
the whole is likewise certain.
Wherever the bottom is stony without much mud and without vegetation,
we should there expect to find the most favourable conditions for the success of
the oysters, and this is certainly in general also the case, hut there are exceptions.
Dredging was carried on in August 1895 (see Table I No. 15 and 16) at" Hilligsø
and at Oddesund on hard ground, which consisted chiefly of stones on an average
from ca. 10 to !/, inch, but nothing else came up in the dredge. As the Table
shows, extremely little spat occurred on these banks in comparison with what is
found on many other banks, for example at Bjørndrup and Hanbjerg (Table I No.
9 and 14). This small quantity of spat is not characteristie of these waters as a
whole, as the oyster boats hbelonging to Lemvig took up later a considerable
quantity of spat there in the dredge, and Handbjerg with its small stock of spat
30
is indeed not far from Oddesund; the poverty is in fact only characteristic of
strictly limited localities just with this stony ground. On closer examination of
the oysters dredged up I noticed that they had been much rolled about, so that
all the small cross ,lamellæ and sharp corners usually seen on oyster shells had
been rubbed away; the whole oyster had been rounded off like a pebble; the same
applies to the stones in these localities. It might happen however that an oyster
had taken up a position in a hole in a stone or in the hollow of an oyster shell,
which was especially the case with the few younger oysters found, and these did
not have the rounded appearance but had preserved their thin corners undamaged.
There is only one explanation of the phenomenon, it seems to me, namely, that
it is the motion of the waves at these places exposed to the west, which is able
to move and roll the stones and oysters against each other during the frequent
storms in these localities. The shells in the living oysters are thus ground down
not only at the edges but everywhere on the outer surfaces, and although the
øysters at these places grow very thick shells (the so-called »etage-oyster« because
the thickness of the shells is caused by the formation of one layer of shells after
the other), in order to counteract the grinding process, they are by no means
comfortable here; this is noticed especially in their soft parts; these »etage oysters«
are shunned by all oyster-eaters. The results of the gnawing of the gastropods
above mentioned also perhaps help to make the shells rounded.
That the strong movements of the currents on the bottom affect the young
oysters first and chiefly is clear, as they have the weakest shells and are certainly
very often broken in pieces during the storms, which accounts for the small
quantities of young oysters at these places. Naturally the other animals living at
these places which have heavy shells also bear signs of the grinding process, and
the difference is very obvious which can be seen in a collection of oysters and
other shellfish dredged at such localities from another dredged at a quieter spot.
Concerning the food of the oyster, many erroneous opinions have
held sway for long in the literature as well as with us. It was known certainly
that the oysters must feed on quite small, almost microscopic organisms and it was
concluded from this that they lived on the plankton, which is indeed exceedingly
rich in the Lim Fjord. I was however much struck by the fact that I could never
find the plankton forms in their stomachs, either of the plant or animal kingdom,
which are so abundant in the Lim Fjord; hut only quite small, green algæ or
diatoms which do not belong to the plankton and usually only in small quautities;
further some sand and mud particles were often found in the alimentary tract of
the oysters. In a »Rapport over de oorzaken van den achteruitgang in hoedanig-
heid van de Zeeuwsche oester. ”s-Gravenhage, 1902«, new light has been thrown
on this matter. At the instigation of the Dutch Government an enquiry was
made into the reasons for the decrease in the oyster fisheries at several places in
Holland; extensive observations were therefore made at various places by Dr.
Hoek with amongst others Dr. H. C. Redeke on the biology of the oyster.
Redeke specially studied the food of the oyster and came to the surprising but
most probably in the main correct result, that the oyster in Holland lived almost
31
exclusively on bottom-diatoms, not on planktom-diatoms; further, he sometimes
found remains of copepods, larval worms, Noctiluca, Tintinnidæ and Radiolaria in
the stomachs of the oysters, but the chief food was absolutely the bottom-diatoms.
He found also that it was especially in the autumn and winter months that the
vyster had much food in its stomach as a rule, whereas in summer during the
spawning time its stomach was usually empty. I may add to this that the plankton
is very scarce in the winter months, and most plentiful in the light season of the
year, which agrees well with the described features of the oyster's mode of life.
We can thus understand why the oyster only has a fat appearance and good
flavour in autumn and winter, because it is then feeding greatly and collecting
into its tissues a quantity of glycogen as a kind of reserve food. Thus, in the
"warm season of the year only 6—8/, of glycogen was found in the substance of
the oyster, but in winter 15—20'/,. The oyster spat must in any case however
be said to form an exception to the rule, that the oysters feed specially in the
cold season of the year, since the spat fix themselves in July—August and have
already grown considerably under favourable conditions by September and October.
The rules applies more especially perhaps to the oysters taking part in reproduction.
Concerning the age and growth of the oyster in the Lim Fjord
various opinions have been expressed; but actual investigation of the matter seems
never to have been made. Eschricht estimates the oysters of 3—4 inches to be
»at least 4 years old«, probably in agreement with Agent Steenberg. These deter-
minations of the age rest merely on guess work, as we cannot see with certainty
on the older shells how old they are, and this is difficult enough on the 2—3
year old; certainly the zones of growth on the shells have something to do with
growth-periods (years), but it is often not easy to determine them with certainty.
I endeavoured therefore, already in 1895 and 1896 as well as in later years, partly
by direct observation of the growth of the young on the collectors, partly
by measuring all sizes of oysters on a bank, to determine the year-groups, as
can be done often for other animals (measurement-method). The result of these
observations is shown on Tables I—IIL On the two first (of older oysters) the
measurements are given in inches, on the third im cm.; for the sake of accuracy
I have retained the original measurements partly in inches partly in cm.
The growth of the spat on the collectors can be seen from Table II, No.
13—18. In August 1895 the young oysters were on an average !/, inch in dia-
meter, in Sept. a little over ”/, inch; on Oet. 29th 1896 they had reached sizes
between Z/, and 1%/, inches. The spat which fixed itself in the summer of 1896
on a large welled-box used for the carriage of plaice (see pp. 25 and 26), reached
in Sept. the same large size between 7/, and 1!/, inches, being on an average ca.
1 inch in diameter. The young oysters on the collectors thus reached up to a
little under one inch in the first year and up to ca. 1!/, the next year; but I am
certain that this does not represent the normal growth of the young oysters in
the fjord under ordinary conditions. The young oysters found on the banks in
Sept. and Oct. 1896 (Bjørndrup and Langehage, see Table HM No. 12 and 10),
were namely considerably smaller, only ca. ”/, inch. These two localities last-
named lie in deep water (2—3 fathoms), whilst the young oysters from all the
»
collectors had lived in shallow water, 1—2 feet. I must conclude that the shallow
water is much better suited for the fixing and thriving of the young oysters than
the deeper; and I believe we may consider it as a general rule that under other-
wise favourable conditions many more of the spat åre met with in shallow water
than in deep in the autumn in nature. See for example Tab. III, Volstrup, where
in August 1906 we obtained by pole-dredging in. 3—4 feet of water a quantity of
just fixed spat; dredging in 2—3 fathoms gave far fewer. Even the one-year old
oysters here at Volstrup were much more numerous in shallow than in deep water
(see also the other Nos. in Table). So few were the one-year old oysters in the
deeper water, that I find it very difficult to consider them as sufficient for a rapid
renewal of the stock. Å
The young of the year thus seem both more numerous and more
favourably placed in the shallow water, at least till far on in the autumn,
but a danger then approaches in the shape of the cold in winter, with drifting
ice and ground frost, especially in the severe winters. The artificial oyster-culture
in Holland is as is well-known based on these conditions. During the spawning
time in summer collectors, as a rule tiles covered with lime or the like, are laid
out in so shallow water that they lie dry at ebb-tide; on these the spat from the
natural banks fix themselves; but hefore the winter comes all the collectors are
taken up; the lime with the spat (ca. 1 inch or less) is scraped off, and the small
oysters åre placed either on banks in so deep water that they cannot be damaged
by the cold, or they are kept through the winter in special ponds (hospitals) out
of danger from the frost and laid out next year at suitable places where they can
grow sufficiently well. The Dutch oysters are eaten when small (natives), only 3
usually 4 years old.
The question is whether a similar method would be possible in the Lim
Fjord; of this see later; but one thing may at once be mentioned, namely, that
there is no appreciable ebb and flood in the Lim Fjord; without further consider-
ation it is not possible to make use of the Dutch method under our conditions.
Where the work in Holland can be done by wading we must go about in boats;
yet this is certainly not an insurmountable difficulty.
To obtain a view over what the measurement-method can show regarding
the further growth of the oyster, Tables I—III must be more closely studied.
On these Tables is represented the size of the oysters on the different banks in
4 different years. The oysters were taken partly with the dredge, partly with a
pole-dredge (a kind of hand-net on a pole) by means of which the oysters can be
fished on ground where the water is so clear that they can be seen. We may
certainly suppose that both methods give a representation of all the sizes of oysters
occurring on the banks, as the dredge especially brings up everything with it:
stones, mussels large and small, and further, the small oysters which one might
be afraid would fall through the iron meshes of the dredge, are fixed to larger
objects so that they are also brought up. We might rather imagine that the
pole-dredge selected the large oysters, as they are the easiest to see, and this is
perhaps also the case; but nevertheless, as a matter of fact, the pole-dredge as a
rule brings up the smaller oysters in greatest number, which must he considered
33
as complete proof that the small oysters are more numerous on the shallow grounds
than in the deep water.
Å glance at the Tables I—III shows at once, that most of the oysters
taken wereeither large ca. 2"/,—4 inches (ca. 6—10 cm.) in diameter, or quite
small under or about 1 inch. We exclude here the young of the year (0-group),
which in the autumn are often so extremely numerous and can then as a rule
be easily separated from the older by their small size, 1/, inch or less.
In the spring we usually meet with a group of small oysters of !/,—1
inch on an average, hut it is far from being so numerous as the 0-group was in
the autumn, and I believe that this group consists of the young oysters of both
the preceding years; these small oysters namely grow so differently that I have
been unable to separate them hy exact measurements. Their reduction in number
is due to the death-rate caused both by the winter cold and the attacks of enemies.
If we can thus not even separate the 0 and I groups longer than for a few months
in the autumn, it is obviously hopeless to search after the subsequent groups 2
and 3 etc. The remarkable minimum at ca. 2 inches (or ca. 4—5 cm.), found in
almost all the measurements, may probably have its explanation in that many
small oysters die, and those at ca. 2 inches grow so quickly that they soon join
on to the adult group (6—10 cm.). This minimum does not move either in the
course of the year (see Tab. IIM), but may be different on different banks, accor-
ding as the oysters are larger or smaller on an average. Thus, it is higher in
the large oysters dredged at Volstrup (see Table III) than in those pole-dredged
there in the neighbourhood (Table III). Concerning the age and growth of the oyster
the measurement method can therefore only show, that an oyster of ca. 6—7 cm.
is as a rule 3 summers old, and that the oyster begins to grow more slowly
in length at 6—7 cm. This is of the greatest importance in the determination
of the minimum standard size, concerning which more mention will be made later.
By marking oysters, if we could only find a practical method, we might
be able to follow the growth at the different places and under different conditions
with great exactness; this must be tested in the future. If it should be done, it
would .certainly prove that the oysters grow very variously under different con-
ditions, thus for example in the youngest group (0-group) according as it is fixed
on collectors in shallow water or on the deeper banks.
That the oysters when older do not become very large in shallow water,
is shown distinctly in Table III, where all the oysters pole-dredged from April 1906
to August of the same year have apparently not grown in the least: most of the
adult group are at 7—8 cm. the whole time, and in the previous year 1905 (see
the Table No. 4) they had quite the same size; but unfortunately there was but
little fishing m 1905. These pole-dredged oysters are almost all under-sized accor-
ding to the present conditions of the contracts, as the rectangular standard now
used of 8 cm. in breadth and. 3 cm. in height permits all flat oysters of
8 cm., to pass through as undersized and even many at 9 cm.; only 2å of
all the pole-dredged oysters (those at 10 cm.) are therefore certain to he
considered as standard oysters. It appears as if these oysters in the shallow water
(8—4—5 feet) never become standards, and they are so situated that a severe
winter, it is to be feared, will kill them, if they do not die earlier from old age or
34
other cause. There are many thousands of these small, exceedingly well-flavoured
oysters at just as dangerous places in the Lim Fjord; on this see Krøyer's report.!
Table Ill likewise shows a number of measurements of oysters dredged at
Volstrup, just beyond where the others were taken with the pole-dredge, in 2—3
fathoms but at a distance of about a hundred yards. These also do not seem to
have grown appreciably from the spring to autumn 1906 nor from 1905 to 1906;
but many of them are however over 9 cm. in length and a large number are up
to the present standard; whether all could grow so large is a question I do not
venture to answer. The largest I have dredged and represented in the Tables
were ca. 5!/, inches (14 cm.). Although the oysters may be much larger In the
Lim Fjord, "it is not normal; many oysters certainly never grow larger than
3—4—5 inches, - even if allowed to live as long as they can; this is well-known
among the experts of the Lim Fjord, and was just the reason why the rectangu-
lar standard was introduced; as it prevents the old and thick oysters from passing
through, even though not 3 inches broad. In so far the introduction of this
standard was a great improvement on the earlier methods (ring standard). We have
however certainly not gone far enough in the direction of reducing the standard
and of using all that may be used.
The measurements on Tables I and II indicate that the oysters of the
Lim Fjord only with difficulty reach over 3——3!/, inches in length, since the
maximum of the adult falls there as a rule. Whether this is a consequence of
the fishery just permitting the oysters to be taken down to this size, or whether it
is because the oysters as a rule hardly grow over this size on the banks, is
difficult to say; but, so much is certain, that not all oysters can reach
such a size, and that the limit (37/, inches) is generally represented by compa-
ratively old and slowly growing oysters. Why should we retain this con-
siderable size? At most other places in the world. much smaller oysters are eaten.
One might think that the reason was, to be sure of keeping so many large oysters
that the stock would certainly be preserved, and this idea has also perhaps been
the reason for the retention of the standard in recent years; but the oysters re-
produce right down at a length of 2!/, and 2!/, inches long, and further it would
be much better for the preservation of the stock, if, provided that only a certain
number of millions had to be fished, a number of these millions were from among
the young oysters, as all the more large oysters would remain behind and the
7 Note. The measurements of oysters given in Tables I—III are made across the
oyster from the umbilicus down to the opposite corner; this was necessary in order to obtain
comparable data. It is often however not the largest dimension; sometimes they are broad
sometimes long. These measurements are therefore not directly comparable with the rectangular
8 cm.
standard now in force | | 3 cm.; as the oysters slip through this sometimes longways
sometimes broadways. according as they are short or broad, and if placed obliquely in the
rectangle oysters of ca. 8!/, cm. can pass through, especially if the fine corners are rubbed off.
Since further the oysters are here always measured at their shortest part, sometimes longways
sometimes crossways, this standard by no means makes all oysters from 8!/, cm. and less which
are included in the Table under-sized, but it has appeared from practical trials that many oysters
in the Tables of 9 cm. would be taken as under-sized. Before new standard apparatus is intro-
duced into practice, exact investigation of its practical applicability should be made.
35
larger give the most spat. If on the other hand all the oysters down to 2 inches
m length were allowed to be taken, certainly the stock would soon be destroyed,
but there would be all thé same many millions to be taken in the year for a number
of years, and of this there can be absolutely no question. The standard has as
mentioned certainly been retained in recent years to make sure of sufficient spaw-
ning oysters, whereas the standard under our conditions need only be fixed in
order to prevent the unsaleable oysters from being brought on land or destroyed.
It is in fact the question between the »reproduction theory« and »growth theory«, the
latter of which has now triumphed for example in the matter of the plaice, which
now concerns the oyster.
The lessees in the Lim Fjord are on the other hand interested in taking
as large oysters as possible, especially as the State is paid for each single oyster,
perhaps also because the fishermen receive payment from the lessees per 1000;
the large would naturally meet the higher tax per specimen better than the small;
but it is for the lessees to arrange this matter. The State on the other hand should
take care that the stock is so exploited that it gives a large harvest each year and
not as at present a small harvest with large prices. To let the oysters lie and
die of old age helps neither the State nor the public, nor the large fishing popu-
lation which has almost nothing to do with the fishery of these shell fish.
In 1886 the State stopped the oyster fishery because it could not yield
each day 1000 oysters over 3 inches per boat with 4 dredges under favourable
conditions; but what are favourable conditions? An oyster bank may be covered
with sea-weed or fine mud for some time, so that no dredging can be done; a
storm may then change the whole, so that many oysters can be dredged on the
same bank the day after. Why stop just at 1000 oysters of 3 inches per day?
From olden times 2'/, inches was the standard for oysters on the Schleswig and
»fladstrand« banks; for some reason or another this was raised to 3 inches in the
Lim Fjord in 1852 and for some later contracts; but in 1860 probably on the
recommendation of Eschricht the Government reduced it to 2!/, inches. But this
standard was not used by the lessees, they retained the old 3 to 3!/, imches. It
was thus the contractors who endeavoured to keep up the standard, and in the
later years since 1870 Collin has also kept this high standard. Any real reason
why just 27/, or 3 or 31/, inches should be chosen, I have never been able to
find, and it is indeed a very essential point, as just at this size we are near
to the limit which many oysters cannot reach.
In his Report of 1852 Krøyer states that the Lim Fjord oysters are not
so good to eat as the »fladstrand«; they are »insipid and sweet to the taste« the
consumers complained, and Eschricht in 1860 says that the oysters from the Lim
Fjord are of a »sweet insipid taste«, but he adds (p. 69), that he knew quite well
that oysters taste differently at different seasons and especially are not good in
summer (August); it was just in this month that both he and Krøyer tasted them.
But Eschricht also judges from the circumstance, that the Lim Fjord oysters are
so flat in the shell and therefore that they must be thin, and states that only the
large oysters come into trade from the Lim Fjord, because the dealers »wished to
conceal the slight thickness and fat by the larger circumference«. Eschricht saw
very well that the trade preferred to deal with oysters which were »far over
36
»under-sized« oysters, 37/,—4 inches or more and certainly 5—6 or 7—8 years
old«. It will be remembered that it was just under his régime that the Govern-
ment reduced the standard from 3 to 2!/, inches; and it was he who proposed
the introduction of quite a new race of oysters into the Lim Fjord. To these
older statements regarding the quality of the oysters I shall only remark, either
that the judgment must have been wrong, just because they were only tested in
the summer, or that the oysters have improved since then; the quality now is
good except in one or two years and naturally in the summer, and then the qua-
lity is not good both of the large and the somewhat smaller. The fjord cannot
always offer such good oysters as the best Dutch, and the dark gills especially are
a drawback for many; but that there should be a difference in quality in the
oysters from the Lim Fjord, when 3 or 25/, inches, I refuse to admit; it is in
any case a matter of taste, and if both kinds could find buyers — that is
the main thing. I believe that it is in these small matters of taste, that we
must seek for the reasons for the high standard and not in a concern for the pre-
servation of the stock, and it was in my opinion therefore doubly unfortunate,
that the fishery was completely stopped in 1886 from a fear of overfishing; there
was in reality no danger of this, and we did not learn how great a production of
the smaller, but saleable oysters the fjord was capable of. For every cm. the
standard is reduced from the present 8—9 cm., the fjord will perhaps be able to
give just, as many times as large an output. I would repeat, that the Govern-
ment in 1860 endeavoured to act upon this principle; to have departed from it is
unfortunate. ÅA reduction of the standard from 8 to 7 cm. would be of great
importance for the production; and with this we might well be content for the
time being; results would not fail to appear, so extremely little is required here in
the matter of the average size of the oysters. If the fishery had at that time
been completely stopped on some good banks, e.g. on !/,,th of the area, distri-
buted throughout the whole of the fjord, so that they might have served as
reserve or culture banks from which the spat could have been obtained for the
whole of the fjord, whilst dredging was permitted on all the other banks without
any standard size for the oysters, then we should now know more than we do of
what the fjord can produce in the way of young, rapidly growing oysters. Here
»closed waters« would have been of use, since the oysters really spawn in them
— on the other hand fishes as a rule do not!
Under the remarks to a proposed law draughted by the Government for
a temporary closure of the oyster fishery in the Lim Fjord (»Ordentl. Samling«
1885), we find: »It was thus not known whether »too much dredging« or »unknown
causes« had led to the decrease«. But something would have been known if the
proposed »experimental closure of the banks in certain large areas of the fjord«
had only been carried out; since if many oysters had been taken on the closed
but not on the dredged banks, then the »unknown causes« would have been eli-
minated; if on the other hand the stock became reduced everywhere, it would
then have been shown that the closure was of no use. But complete closure was
enforced for 4 years, with the result that after its termination no more oysters
were fished than before the closure; within recent years however some few hundred
thousands more have been fished (see Appendix I p. 20). We thus do not know
37
either whether the closure has been of use to the large oysters; the people at
least have gained no advantage thereby, and the amount received by the State is
almost the same as when the closure was imposed. To this poor result the Ger-
man import duty has naturally contributed as we were thus excluded from com-
petition, having no counteracting duty, and a considerable quantity of cheap young
foreign oysters are now imported. Denmark should at least endeavour to supply
itself with oysters, rather than let them perish in the Lim Fjord; even if it is
impossible to say how much the fjord can continue to give in the year it is my
belief based on personal observation that it can give much more than it now does,
and endeavours should therefore be directed in future to fish up more oysters
than is now done. This is not the place to discuss in detail how this should be
arranged, but the points of view which form the hasis for the present contracts
are wrong. The main thing muat be to get as many oysters taken as the fjord
will at all allow, without any regard for the price they obtain per oysters; in this
way both the public and the State will be best served. The fjord is too large to
be merely the basis of a small business for some relatively few private persons
and fishermen.
If I believe that I can see more clearly into these matters than those who
have hitherto had to do with the administration of this matter, this is inded quite
natural, as I have my earlier experience to build upon, also because more is now
known of the biology of these animals than was known 10 years ago, but in great
part also because I have been personally interested in this and related matters
since 1883 and have obtained means from the State in order to study them in
nature. It should be understood therefore that I do not lay it to any one's charge
that we are so far behind in this matter; but it has been expensive both for the
State and for the oyster-eating publie that careful biological investigations were
not made here much earlier. It was only after my appointment as Adviser to the
Department in 1905 that I became aware how much was to be done. It is certain
that many years will yet go by before we learn to use rightly the valuable asset,
which came to us when the Thyborøn canal was broken through and which the
modern sand-dredgers annually contribute to ensure.
It has often been maintained that oysters are only a luxury, and it did
not matter whether they were dear or not; but in several other lands the oysters
are no luxury and if they need not be here so much the greater advantage for
us; the main thing is only, that the State must obtain more profit from a more
intensive fishery and that all the oysters which could be produced should be
brought upon the market, so that the price is determined accordingly; in this way
also the public is best served.
Since I have advised in the foregoing a more intensive fishing in the
Lim Fjord, it might well be thought that artificial culture could be employed
to help out or to support the production, as is done im most other lands. ,
All that has -been done in this regard in our country has come to nothing; I do
not mean here the regulations for preservation of the stock or the 3 and 3!/,
inches standard size and the like, but what has been done directly to increase the
production, such as transplanting of oysters, laying down of oyster ponds etc.;
these have all been without result at any rate at the present time. In my opinion
38
the reason for this is certainly to be sought for in the erroneous principles which
formed the basis for the undertakings. As mentioned above, Eschricht advised
the introduction of foreign oysters, but this was certainly never done by the
State; on the other hand, I have been informed by a man by word of mouth that
he much later placed some foreign oysters in the fjord, namely Arcachon oysters
ca. 10,000, and even American »hlue-points«; but most of them died, he said. I
believe that even if other European races had been introduced, they would all in
the next or within a few generations be converted to Lim Fjord oysters; just a3
the conditions now transform the oysters there. Further it was indeed foreign
oysters which entered the Lim Fjord, either through the Thyborøn canal as spat
from the North Sea or perhaps from the oysters planted out by Amtmand Faye.
Eschricht who had been in France when Professor Coste began his experiments
in laying out oyster beds, was obviously much influenced by the ideas of the
latter. As is known Coste's experiments proved to be failures in several ways.
But the idea of: forming new oyster hanks lived long in Denmark. It was the
basis for the later much disputed transplantation of standard oysters in the Lim
Fjord and for a »law on the oyster fishery and oyster culture« by which the Finance
Minister was empowered to offer a »grant in aid of experiments with the oyster
fishery, such as transplantation of oysters and laying down of artificial oyster banks
and oyster parks at such places in Danish sea-territory, where the oyster fishery
had not previously been carried on etc.«. Many fruitless experiments were then
made right down to Lolland; some of the best known were those conducted by
G. Winther in Aarhus Bay. All were absolute failures and Winther judged
very rightly that the reason lay not in the bottom conditions but in the conditions
as regards salt and temperature. This great belief in the possibility of being able
to form new banks, not only in our county but also in Germany, was based on
the fact that old oyster shells were found on most of our coasts and it was known
that oysters had come into the Lim Fjord; it was naturally thought that the earlier
banks had been destroyed by over-fishing and that they could now be easily renewed.
How completely wrong this view was, was shown first by the author in 1888; I
showed that the hydrographical conditions had changed in our waters within the
Skaw since the »kitchen midden« period, so that not only the oyster but a series
of other forms had died out there since the stone age, as they could no longer
live under the changed conditions. The scattered occurrence of oysters in
certain parts of the Kattegat may be considered as an oft repeated experiment on
the part of nature to plant the spat coming from the North Sea in the Kattegat
again; but it proves that banks can never "be formed uuder the present conditions.
With this explanation of mine we enter upon a new and more correct way of
thinking, namely, that nature itself does all that is possible to bring the oysters
to new banks by the distribution of the spat, which is carried many miles by the
currents, and therefore that the oyster is found everywhere whére it can
live. If we would lay down oyster beds we have only to change the conditions
and the oysters would come of themselves. In this way they came into the
Lim Fjord when the conditions changed, and they have in spite of all
statements to the contrary certainly spread themselves over the whole fjord very
quickly; only it took some time to observe them, and it also took some time per-
39
haps before they became abundant at all places. Starting from these new principles
we see that all removal of adult oysters »for transplantation« in the Lim, Fjord is
meaningless.. Nature can well look after the spat itself and the Lim Fjord is
swarming with these when the temperature is suitable. For the same reason the
formation of ponds for adult oysters in the Lim Fjord is superfluous, so long
namely as the oysters spawn in millions in the fjord. The serious qustion
here is to help more of the immeasureably great quantities of the spat
to become full-grown oysters than now happens; since obviously by
far the greatest part of the spat and of the just fixed young oysters
perish, because they fix themselves on unsuitable places, are sought after by so
many different enemies etc. It is so much the more advisable to aim at this,
since it is perhaps not every year that the temperature in the Lim Fjord is
sufficiently high to permit of the oysters spawning in large quantities; if a more
intense fishery is agreed upon this must be carefully watched. Further, it is far
from being the whole area the adult oysters can live in which is specially suited
to the production and further development of the small fry. As mentioned before
it seems to be especially the warm shallow waters which are suited in summer
for the welfare of the fry. Here some preliminary experiments should he made,
only on a somewhat greater scale than I have hitherto experimented, to take the
spat on collectors and bed them out before ihe winter on closed areas in deeper
water and study their further fate and thus the possibility on the one hand, of
recruiting on a large scale the stock of the fjord if such should be necessary, and
on the other, of experimenting whether certain banks could be used for a more
rapid growth of the young oysters. Such experiments would cause little. expense
and if successful and thereupon carried out on a larger scale would be remune-
rative.. They might also perhaps be made by private owners on their own small
banks just as is done in Holland, amongst other countries. I shall not enter into
the details of the arrangement of this matter either; what I wish to do in the first
instance is to bring the whole matter of the oyster fisheries in the Lim Fjord
into the full light of the new experiences both scientific and historical which are
now available.
What may in time be obtained from the Lim Fjord oyster fisheries if the
right methods are introduced, no one can say; but in Holland ca. 25 millions of
oysters are obtained yearly from areas which are only ca. "/;th of the area of our
banks. I may warn against believing that we can reach up to numbers such as
these; but it is indeed a long spring from 1 million oysters to 25 millions on an
area of one-fifth the extent.
The Future.
The oyster fishery in Denmark has always been considered as crown pro-
perty, and the Government has therefore had the free disposal of its exploitation,
has it in fact even now. The State should therefore obtain some good return
yearly, the size of which is determined partly by the foreign oyster market, the
existing import duties, the pleasure and pocket of the public and the productivity
of the Lim Fjord. Of these 4 factors the foreign market is to a certain extent of
6
40
no influence; only ignorance of its low prices seems to play any great part on
our market; this state of affairs might easily be altered. To favour our market
practically nothing has been done from the Danish side in the way of duties.
The desire to purchase on the part of the public has been reduced considerably
since the seventies; the extremely high prices of our home oysters, which with the
help of the middlemen also influence the price of the originally cheap, foreign
oysters, have broken off the general public from eating oysters. In earlier times
when the oysters were bought for about a penny each the oyster-eating public
was much larger and there were then oyster cellars in Copenhagen. Now hut few
people eat oysters and for these money is of no consequence; the price is now at
least 27/,d each. The result is that but few oysters are eaten or fished. The
productivity of the Lim Fjord is not utilized to anything like the extent it could
and should be. I shall here leave out of consideration the import duties and the
foreign market, as I believe that at the present they are by no means so impor-
tant for us as the two other conditions, the desire to purchase on the part of the
public and the exploitation of the stock of oysters in the Lim Fjord; both of
these should be increased and in this way the State would gain and be certain
of holding its own against all foreign competition. One result of a more intensive
fishery would be cheaper prices owing to the larger numbers of oysters on the
market, but the total value would only be increased if at the same time the desire
to purchase increased. Whether this will increase quickly or slowly is not easy
to determine, and it will therefore not be possible for a contractor to be so certain
of his tender in the first years as later, when the matter has again come into
order, and it is therefore a question whether the State should not itself in the
first years undertake to carry on the oyster fishery even for some years after the
present compact runs out in 1910. The State takes some risk in doing so, but
no one is in a better position to do so; and the State would thus win experience
both with regard to the right size of oysters that should be fished, and of the
numbers that might be oltained yearly. The State has always the freedom namely
to make experiments without binding itself to any agreement for a number of
years, as the contractors must do. If the fishery paid better than now the State
would naturally reap the advantage; but the most important matter is that we
should in this way obtain a solid basis of knowledge for the judgment of the
matter. My plan would be that the State should have small steam-boats, such as
are used in Holland for this purpose, which could dredge up the oysters espec-
ially im the autumn so long as there was open water, and either at once or
gradually get the stock in hand sold by auction at the Lim Fjord and in Copen-
hagen. Motor boats might also be used perhaps in the shallower waters and pole-
dredging might be carried on on as large a scale as possible. Lastly, experiments might
easily be made in transplanting oysters from shallow to deep water and on the
whole experiments for a rational increase of the stock; if the State will mot make
the first of these experiments, they will scarcely ever be made; that at least may
be learnt from the previous history.
If however the decision is made to let out the fisheries again, then there
js no doubt that the method of payment for each single oyster taken (now over
3 farthings) must be given up; a sum should be given for permission to fish for
41
example 4 million oysters of over ca. 7 cm. yearly, but with the obligation of
fishing at least 5 millions. I do not doubt that the State would in this way obtain
a better yearly return in money than it now does, and it is quite possible that
the oyster would also become a cheaper and commoner article of food than at
present; but the contractor could not be compelled to sell the 3 millions; and he
would not do it if it paid him better to sell 2 millions at a higher price. Even
to bind themselves to fish 3 millions would have a deterrent influence on people
who did not know the fjord, but we have seen how in the earlier contracts the
lessees engaged themselves to fish 1 million of large oysters of 83—9 cm. (1875),
so that this was scarcely any great hindrance. The mischief involved in contracts
now is as mentioned the impossibility of determining heforehand with accuracy,
when the desire to purchase oysters can be again roused on the part of the gener-
al public and to what an extent this will happen; and the contracts must run
for a fairly long period, ca. 5 years; it will be difficult to obtain good contract
prices for a shorter period. It might perhaps he possible to combine the two sys-
tems, since the fjord is far too large to be fished intensively and thoroughly by
one man unless he has abundant means at his disposal. But if the State took
charge of the fisheries in certain parts of the fjord and let out other parts, it
would then still remain master of the market to a certain extent and be able to
judge for itself. It is hardly possible that any great remuneration will be gained
in the beginning by such a method; the contract might however advisably be
extended over a number of years and would thus give a lessee an opportunity for
and interest in carrying on a rational fishery. Experiments in this direction should
under all circumstances be made for small areas; the only difficulty is to obtain
qualified persons for the work. In this way we should approach to the method
of fishing in foreign countries: a number of small parcels or lots in private hands
and a verv intensive fishery. We should then also learn gradually what regions
were best suited to the fishing by the State with steamboats and dredges and
those suited for the smaller private method of fishing. The State should provisio-
nally chiefly regulate the import to the market and be responsible for the suffi-
cient preservation of the stock. If men with sufficient experience and means should
appear in the course of the next 3 years hefore the present contracts run out, it
would be a great boon for the future of our oyster fisheries; we could then always
discuss what methods of fishing it would be advantageous to follow.
Explanation to the Chart of the Lim Fjord Oyster Banks.
1907.
The places marked in black indicate where so many oysters are to he
found that it would pay to dredge for them, or where they have been in quan-
tities to attract notice; scattered oysters are to he found everywhere between these
so-called »banks«. I may however remark that practically no oysters are to be
found in the most western part of Nissum Bredning, nor in the north-eastern part
of Løgstør Bredning, the reason being assuredly that the sand bottom here is too
movable and barren. The reason why they are not found outside the sand bottom
in the north-eastern part of Løgstør Bredning is perhaps that the vegetation here,
especially of Zostera, is so rich; for the same reason but few oysters occur in the
waters between Jegindø and Visby Bredning's southern portion; further in Louns
Bredning and Skive Fjord the salinity is too low for oysters; this applies also to
the narrow eastern Lim Fjord, east of 'Troldholmen, which is therefore omitted
from the Chart. With these exceptions oyster banks are to be found everywhere
in the Lim Fjord along the beach in the neighbourhood of »Skaaret«; they are
present close in to the land in 2——3 feet of water and they go out to deeper water
of 3—4 fathoms, but as a rule they do not go far from the 3-fathoms line. This
is at once evident from observation of the Chart. The reason for this certainly is
that out on the true deep clavy beds, which form the bottom of the Lim Fjord,
the ground is too soft and the clay or mud too shifting for the oysters. As ex-
ceptions to this rule may he mentioned the large bauks to the west in Nissum
Bredning, to the north-east in Thisted Bredning and in the north-west of Løgstør
Bredning. The bottom must he of a special nature here to make it possible for
the oysters to live at these deep levels.
Table I. 1895.
Measurements of Oysters, in inches.
e indicates oyster with spat.
… …….I1=0 es
No. 1. No. 2. No. 3. No. 4. No. 5, No. 6. No. 7.
Entrance to Lysen. Entrance to Lysen. Entrance to Lysen. Refshammer. ebygaards Hage. Faarup Vig. Studeholmene.
25. May. 26. July. £ October. Pole-dredge. Pole-dredge. Pole-dredge. Pole-dredged.
Soft ground with stones. 12. May. 16. May. 8. July. 8. July.
2—4 fathoms.
5 inches
00 o
000 000 o
0000000 000 o 00 o
4 00 00000000 0000000000000 00000000000000 o 00 0000
00 o000000000000 DO000000000000000000 O000000000000 oOo …0…0000
00000 G00000000090009000000 UQGQGQQO0000000000000000000000000000000000 OO000000000000000000 000 . 0000000 00000000
000000 OG000000000000000000000 OOO00G00000000000000000000000000000000000 o00000000 000000 te0000000000 00
8 0000000 …0000000000000000000000000000 o0000000000000000000000000000000000 o0000000000000 000000 10000000000000000000000000000 o00000000000000
0000000 O0Q0000000000000000000000000 o00000000000000 0000000 0000 O0000000000000 0000000
00000 18000000000000000 O0000000000000 o0 o O000000000 o00
0000 (00000000000000000 O00000000000 00 000000 oo
20 o000000000 o0000000000000000000 o 0000 000
000 0000000 000000000 000 00 000000000000 o
00 0000000000 0000000000000 o 00000000000 000
000 0o00000000000 0000000000000 o o 0000000 00
1 000 o0000000000 O0000000000000000 00 o 000 o
0000000000000000 0o000000000000000 000000 oo 000
Do000000000 o00000000 000 00 000 00000
00 00 000000000 0000000000 o 00
0 1 0000000000 i 0000000
No. 8. No. 9. No. 10. No. 11. No. 12. No. 13.
Trehuse. Bjørndrup. Snaven on hard ground. Feggeklit. Feggeklit. Skidenholm.
10. July from 2—4 fath. 31. July. 31. July. East of Ejerslev Røn.
26, —27, Julv. ground. Hard ground. 1. August.
Not diving at that time. Diving. Diving.
& inches oo . o
000 00 one at 514" o
se 000000 000 o 00
000 00000 0000 o 00
4 00000000000000000000 …0000000 f80000000000000000000 o0 000 00
es (0000000000000 OOG000000000000000000 Ge00000000000000 000 ………0000000 000
80000000000000000000000000000 800000000000000 ee00000000000000 000000 000000000000000000 000000
O0000000000000000000000000 G0000000000090000000000000000000 0000000000 000 o00000000 000000
3 eee0000000000000000000000060 00000000000000000000000000000000 80000000000000000000000000000000000 oc000 000000000000000000000 00000000000000000000
888800000000000000000000 o0000000000000000000000 000000000000000 0000 o0000000000000000 0000000000000
o0000000000 000000000000000 000000000000000000 00000000000 000000
. D000000000000 0000000 oo o0000000000000 000000
2 000000000 000000000000000000 00 00000000000000000 0000000
000000 DO00G000000000000000010000 Doo £ o G0000000 000000
0000000090 o000000000000000000000000 0000 00 o 000000
0o00000000 00000000000000000000000000000000000 000 oo 000 00000
1 000000000 o00000000000000000000000000 000 00000 000 (od
O00000000000 UGOO00G000G0N0000600000000000000000000000000 o 000 000000 00000
00000000000 00000000000000000000000000000000000000 00 00000000 00000000000
o0000 o o o
0
RR Es RR RE RER ET SE LEE SE SEELEDEEETE ES LEE ES ESSEN
No 14. No. 15. No. 16 No. 17. No. 18. No. 19. No. 20.
Hanbjerg. Hilligsø Banks. Oddesund. Sallingsund. Kaas Hoved and Nissum Bredning. Nissum Bredning.
6. August 15. August. 14. August 24, August. Nygaards Hage South of Oddesund. North of Oddesund.
Hard ground. Hard ground 28. July. 5. and 6. August,
inches oo o o 00 o o
o ye er o 00 1 at 54" o 00
000 000 1-at 61” 00 0000000 0000
o0 Q000000000 o o 000 o000 Q000
då 0000000 00000000000000 00000000 00 000000 000000
00000000 00000000 00 0000000 Q0o00000000 00000 00000
0000000000000 o00000000000 o00000000000 0000000 00000 00000
90000000000000 0000 000000000 000 o Så
3 8e00000000000000000 Doo oo e00000000000 00000 D000
0000000000 o o 0000000 00 00
00000000 000
, 29000 o 55 i ad
2 000000000 0000000 000
000000000 o 00000 000 Øl
00000000 o 00 0000
000000000000 o 000 o00000000 oo
1 000000000000000000000000000 000 o 000000 0000000000 00000 o
000000000000000000000000000000 o oo 000000 0000000 000000 0000
0000000000000000000000 o o 00 00000 00 = 00
0000 00 o
(NV)
EET SFO] SEERE EDEEEGEÉEMR ELSE SS SEEDEDE OCES ES æ— See er
Table il,
Measurements of Oysters in inches.
e indicates oysters with spat. O and I indicate the year groups.
TTT UUO eee
No. 1. No. 2. No. 3. No. 4. No, 5. No. 6. No. 7.
Refshammer. Faarupvig. Ravnedybet. allingsund. Oddesund Syd. Sallingsund. Hanbjerg.
Dredge. Dredge Dredge. Pole-dredge. Dredge. South of Højriis. Dredge. -
22. January 1896. January 1896, 4. May 1896. 23. May 1896. 7. June 1896. Pole-dredge 16. June 1896. 12. June 1896.
2—3 F.
5 inches. 00
o o o one at 54 inches.
00 000 , 00 000 00000
0000 000000 00 0000000 oa 0000000
4 00000000000000 0000000 000 00000000 0000000000000000 00 00000000
O0000000000000000000 0000000000000 0000000 00000000000 100000 …0 8e8…00000000
000000000000000000000000000000000000 00000000000000000000000000 00000000 00000000000000000000000 . 0000000 20020000000000000
00000000000000060000000000 00000000000000000000 0000000000 00000000000 0000 000000 98888800000000000000000
3 00000000000 00000 10000000000000 00000000 0000 00000000 80080000000000000
00000 0000000000000 0000 000 00000000 00000000000000000 … 12800000000000000000
000 00000000000000 000000 00000 120000 18000000000000000000 88888000000000000
00 00000000 000 0000000000 000 0000000000000000 o
2 000 00000000 000000 00000 0000 0000000 00000
00000000 000 000 000 0000000000000 00.
00000 1000000000000 000 000 00 0000 000
00 00000 000000 000 00000 000000
1 00000 00 00000000000 o 00 0000 000000
00 00000 O000000000 oa o 000
o 00000 000 o 00
000000 o o
(N 000
GE —— ————
No. 8. No. 9 No. 10. No. 11. No. 12.
Langehage. Langehage. Langehage. Bjørndrup. Bjørndrup.
Dredge. Dredge. Dredge. Dredge. Dredge.
8. April 1896, 1. August 1896. 19. October 1896, 27. —29, May 1896. 18. September 1896.
5 inches
000 00000 o
00 000000000 0000000
4 00000000 0000000000000000 00000000000000000000000 00000000000 0000
D0000000000000000 00000000000 0000000000000000000000000 00000 0000000000000000000
0000000000000000000000000
0000000000000000000000
3 0000000000000000000
DOO0GG0G00000G0000000
0000000
00000000000000
2 00000000000
00000000
0000000000
0000000000
1 00000
00000000
00000000
000
0 00000000
No. 13.
Spat on our collectors.
8, August 1895
5 inches
900000 fo)
060000000000000000 0
0
B0000000000000000000000000
006000000000000000000000000000
O000000000000000000000000006000000000
B000600000000000000
000000000000000
000000000000
00000000000
00000000
000000
00000
000000000
00000
000
No. 14.
Ørodde.
Spat on tiles.
Spat on granite stones
in well from
DO00000000000000000000000000000000000000000000
H000000000000000000000000000000000000600000000000000000000000
D00000000000000000000000000000000000000000000
VOODDDDDDHADDGD0DSDDDDDLADDDDDDDDDDDDDDDDDDD0D
D00000000000000000000000000000000000000
O0000000000000000000000
00000000000000000
000000000000000
00000000000000000000
0000000000000000
000000000000000
0000000
000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000
No. 15. No. 16.
Spat from 1895
on granite stones
24, September 18 summer of 189% in well.
8. April 1896, 29. October 1896.
00
00000
o 000 000
000 Mm 000000 00000
900000000000000 0 00000000 I o
0000000000000000000 00
000
No. 17.
Spat on sandstones
0
No. 18.
000000000000000000000
000000000000000000
O0000000000000000800000000000000
DOO000000060000000
00000000
00000000050000000
O00000006000000
0000000000
DOG000000
00000000
0000000
000
aben apr ref st
Spat on welled box
in well from 19, September 1896,
summer of 189:
April 1896.
000000000
00 0000000000000000000
00000000 00000000000000000000000000000000
000000000000000 I 000000000000000000000000000
00000000000000 0000000000000000000000
00 000000000000
0
0000000000000000000
000000000000000000000000000000000
00000000000
000000000000000
0000000000000
000000000000000000000000
00000000
00000000
0000000
0000000
00000
0000
00000000000000000000000G000000000000
00000000000
0
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Measurements of Oysters from Volstrup. In centimeters,
e indicates oysters with spat. 0 and I indicate year groups.
EEEEEEEEEEEEEEEEEEEEEEEEEEELELL ÆT EEN EEEEEEEEEEEEEEEEEEEEEEEEEEFELEEEEEEPEEEEEE Gr dd
No. 1. No. 2. No. 3. No. 4. WE
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26. April 1906.
00
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No. 7.
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18. June 1906.
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5. Angust 1905.
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ca. 20 spec. under 1 Millimeter.
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V oystrrBaret inthe Tim Fjord Feer UR flot formation.
(East of Lågstår according tothe older Chart of Collins.)
Thenumbers indicate salinity in% eo during he period
Sept. 4th=11 th. 18; 890
…… & fathorns line. 1907
Thisted.
SCALE IN MILES.
Thyborøn Kandt
Skive 4
Volstrup Of Handbjerg
Surface temperatures.
Oddesund 1893-95.
i: oa Nykobing (M) 1895.
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Second Report
on the
Oysters and Oyster Fisheries in the Lim Fjord
with 6 Tables and 1 Appendix
by
C. G. Joh. Petersen.
Technical Adviser to the Department of Agriculture in matters concerning
the oyster fisheries.
Contents.
Introduction SME ENA SD ERE DDT Eg ETT OT Oken FO DOS ANSE ERE:
ikenethilorkoysterskobtamedibyspole-dred ge Ret es ERE SE ERE eee
Lensth"ofoystersobtained: by "dred ger SEERE EEN ERR
ASKO OSTE SE eee En re eee ner Eee,
The present standard for oysters 8X3 cm. and its applicability to oysters obtained by
pole: dress SEE EEN EET EET ERNE
Benethrorfoysters fo btane LED yYE div REE NE REE EEN EEN EN eee
Influence of the standard size (8 x 3 cm.) on the fishery as a whole and also in earlier vears
-
Asnew smaller standard Se STEEN Een
Number of oysters in the Lim Fjord at present, estimated from diving and pole-dredge
HON MD KO EGEDE REEL ES ISAR TD AD TEE SEE TO DRE EET OSS GES ER SOE d Ro aen
IU TSK and SYNS ES ERR SEE EET ED EA To EET ED SE ED BØNNEN dt
6 tables and 1 appendix (A): statistics of the number of oysters taken by the lessees during
12
the: last”7 years from: 1999-79 ES SR sr En ne eee EN IE 22—23
IØ my »First Report on the oysters and oyster fisheries in the Lim
Fjord«, Report XV for the year 1907, it was explained that many oysters in the
Lim Fjord could not reach the standard size 8 X 3 cm. fixed by the Government ;
that this should therefore be reduced and that the fishery should be carried on
more energetically on the whole than was at present the case, as far too many
oysters died of old age without being of use to anybody. To be able to give
definite figures for the further elucidation of these questions, I undertook a series
of investigations in 1907 on the stock of oysters in the Lim Fjord at a number
of different places. These investigations might easily have been carried out on a
larger scale and with larger quantities of oysters, but I believe that what has been
done is sufficient, on the one hand to throw light on many points where such was
very necessary and on the other to provide a comprehensive view over many
points where such was advisable.
The investigations have been specially directed to determine, how large
the oysters were which were taken by means of the pole-dredge, the dredge and
diving respectively on the different hbanks, thus in other words, how large the
oysters were which were growing at the different places; secondly, how the present
standard 8 X 3 cm. and the standard proposed by myself, which is 1 cm. smaller
(7 X 3 cm.), suited these oysters. Further, it appeared during these investigations
that diving enabled a good estimate to be made as to how many millions of
oysters were living in the fjord at the moment. Such diving investigations were
therefore carried out. Lastly, various other investigations of biological interest
were undertaken, amongst these marking of oysters.
Table I shows the length of oysters obtained by the pole-dredge
at various places in the Lim Fjord. The oysters were measured lengthways, that
is, from the point of the shell at the hinge to the opposite edge. When the oysters
are measured by the inspectors with the 8 x 3 cm. iron standard, they pass through
this sometimes lengthways, sometimes broadways. Such a method of measuring
could not be used for these investigations, as according to it an oyster 8 cm. in
length would sometimes he a standard oyster if it were thick and broad, whilst on
the other hand an oyster of 10 cm. might be undersized if it were thin and
narrow. We shall see later regarding the relation of this standard. to the length
of oysters.
The Table shows in the last column, which gives the number of all the
oysters of the same length from 1—12 cm. taken in the pole-dredge, that 8 cm.
4
as a rule is the most frequent size, next 7 cm. and then 9 cm. At many places
in the fjord the oysters are smaller than at others, as 7 cm. is sometimes more
frequent than 8 cm. (see Table TD); but the time of year has no influence on
the size at 7—8—9 cm. The localities on Table I are arranged chronologically
from 83/IV—8/X 07. By far the great majority of the oysters taken by the pole-
dredge measured 7—-9 cm.; of the larger from 10 to 12 cm. only a few hundred
specimens were found, and of the lower from 6 to 0 cm. a good many were indeed
taken hut not nearly so many as of the three sizes 7—9 cm. together. The maxi-
mum for the oysters taken by the pole-dredge is thus at 8 cm. as a rule, but it
would be easy to show a number of banks and large parts of others, especially in
very shallow water, 2—4 feet, where the oysters taken by pole-dredge had their
maximum at 7 cm. It should be remembered that the last column in Table I
only gives an approximate picture of the sizes taken by the pole-dredge, as the
figures of the column have becn arrived at by summing the oysters together from
localities where they have a somewhat different relative size; the totals show
however that the average size for oysters taken by the pole-dredge falls
at 8 cm., 7 cm. coming nearest afterwards and then 9 cm.
ÅA smaller maximum can be noticed amongst the lower sizes, 6—0 cm.,
at certain localities, for example, at Langer Hage 12. April, Trehuse 8. April and
Feggeklit in April. This maximum which represents 1 to 2 younger annual groups
is not always situated at quite the same cm. in the Table; it is most distinct in
the spring at 2—3 cm., but often becomes less distinct in the course of the sum-
mer when the small oysters grow up and gradually join on to the large group;
see for example the Feggeklit measurements. It is not always easy however to
follow the growth from the Tables; but in nature we can often see the new, thin
outer margin on the shell which the small oysters have added in the course of
the summer. It is naturally through the growth of these younger annual
groups that the large group at 7—9 cm. is maintained throughout the year. It
represents also the adult oysters, which grow but little but begin to spawn at 6—7
cm. and die at 8 cm. Tnere seems therefore here, as in so many other animals,
a certain amount of simultaneousness between the stoppage in growth and appea-
rance of reproduction.
It might well be imagined that the presence of so many of these small
oysters, which we took with the pole-dredge, and also certainly at many other
places not investigated, was due to too severe a fishery; we know for example
that the stock of plaice can be over-fished so that only the young, small indivi-
duals remain: hut there can be aåbsolutely no talk of this as regards the oysters
in the Lim Fjord; the pole-dredge has not heen used on several of these banks
by the lessees during the last 7 years, and but little of this kind of fishing on
the whole has been done in the last 4 years, so that overfishing cannot be thought
of (see below Appendix A: Statistics of the standard oysters fished by the lessees
from the season 199% to 199%). During the last four years only 88,000 oysters in
all have been taken by pole-dredging, and these in Sallingsund, Livø Bredning and
at Fur; in 1998 and 19%£ no pole-dredging was done. The lessees were able to
obtain sufficient oysters from the regular boats for dredging and diving.
The illegal fishery carried on in the Lim Fjord might also be thought ot
[2]
and especially naturally with regard to the oysters taken by pole-dredge, which
often lie in so shallow water that they can be taken by hand. Several cases of
such a fishery have come to my knowledge at second or third hand, but I am
certain that it is only carried on to a relatively small extent and there can be'no
talk of trading with such oysters on a large scale. We have, in short, nothing
to do with overfishing here; these oysters taken by pole dredging could never be-
come larger than as shown in the Tables at many of these places in shallow
water of 2—6 feet: they are already full-grown and ought to be fished.
In calling oysters of 7 (8) cm. and upwards full-grown oysters, this should
be understood as meaning that many oysters never become larger than 7 to 8
cm. but die of old-age; others become, as the Table shows, 10, 11 and some few
12 cm.; these must be regarded as mainly exceptions, just as we find some men
taller than others. Ås there are fewer oysters at 9 cm. than at 8 cm., we may
conclude that many die of old-age already at 8 cm. in length. The reason why
the oysters in shallow water do not become so large as those in deeper water, I
am unable to completely explain; it must he taken as a fact that such is the
case as a rule.
How large the areas are where these pole-dredge oysters occur, it is im-
possible to say from lack of sufficient information regarding the shallow water
banks; but I have seen these oysters along many miles of the coast. When the
algal growth is feeble in the spring, it is easy to see the oysters: by sailing over
the banks im a small boat; in clear weather they can then be observed on the
bottom if the water is clear. During these investigations two men have often
fished many hundreds of these small oysters in an hour with two pole-dredges, i.e.
small nets or dredges at the end of long poles by means of which the oysters
lying on the bottom can be reached and taken up. It is not only however with
regard to the length that the pole-dredge oysters are smaller than. the deep-water
oysters (from 2—5 fathoms in the Lim Fjord), they are also thinner. Further,
they have smoother shells, gnawed by various gastropods, and with their hard and
clean shells resemble the small Dutch oysters so much esteemed by many, with
which at any rate in good years they might well be compared in every regard ;
also in regard to size.
Table II shows the length of dredged oysters from a number of places
in the Lim Fjord. Here as with the previous the oysters are measured length-
ways. All the dredged oysters were taken by the »Sallingsund« in water between
1//, and 5 fathoms, thus in deeper water than those taken by pole-dredge. The
latter as mentioned were all taken by the small boat of the »Sallingsund« in 2—6
feet water. Whilst the oysters taken hy pole dredge have their maximum as &a
ruie at 8 cm., the dredged oysters have theirs at 9 cm., thus considerably larger.
The size is not the same everywhere, but varies somewhat between 8 and 9 cm.
at different places. Here we also find an adult group which remains unchanged
at the same size at all times of the year, but from 9 cm. upward against 8 cm.
and upward for the oysters taken by pole-dredge. Amongst the smaller oysters a
maximum at 3—4 cm. can be seen in spring; in autumn it has a tendency to
rise and join on to the full-grown group; see for example Trehuse, Feggeklit east
and Revelkær Hage.
It might be thought perhaps as regards the dredged oysters that the
adult group was artificial, partly caused by overfishing; hut it also appears here
in nature that the growth is easy to observe in the young oysters under 7—8
cm. and seldom well marked in the larger; further, reproduction begins at 6—7
cm. in length; and lastly, from the calculation below of the small product of the
fishery and the rich stock in the fjord, we know that so little fishery has been
carried on during the last 23 years, either not at all or only about 1 million yearly
that it could have absolutely no influence on the appearance of the adult group;
at any rate not on the stock of the fjord as a whole. It might be thought that
the fishery had some influence on the well fished banks; but even here no de-
crease in size could be observed; for the time being only the number of oysters
has been influenced and that only to a very small extent. The fishery hoth by
diving and dredging is so carried on that a bank is never fished clean, only
approximately; fishing is carried on over the whole of the fjord wherever most
oysters are supposed to be and where the wind and weather and the convenience
of the fishermen are most suited and suitable. On the other hand Table II shows
that the oysters in Nissum Bredning are larger than in the other regions; and it
has always been so, so, far as is known; here 9 and 10 cm. are equally frequent,
elsewhere it is $ and 9 cm.
The oysters in Table II were dredged in the period from the 9th to 20th
April by means' of a ca. 1 fathom broad dredge, like those used by the oyster
fishers on the banks in the North Sea; this dredge was sometimes provided with
teeth sometimes not. After April 23rd however two smaller dredges fastened
alongside one another, the one with teeth the other without, were used; their spread
was thus almost over a fathom from side to side and seemed to take just as many
oysters.. The oysters dredged at Trehuse on April 23nd were taken partly with
the large, partly with the small dredges.
It would be desirable to know more regarding the age of oysters at
any definite length, but the statistical method by measurements as the Tables
show gives but incomplete information, clearly because the growth of oysters is
different under different conditions and perhaps also in different years according
as these are warm or cold. Thus I have long regarded the oysters under 7 cm.
in the Tables as containing 2 annual groups coalesced with the usual maximum
at 2—4 cm., and I have been further strengthened in this view during this year.
In May 1907 I was able to examine a tarred raft in the possession of a fish dealer
which had lain in Nykøbing harbour since Whitsuntide 1905, thus from the middle
of June 1905, and was now in the spring of 1907 taken up to be dried, cleaned
and tarred. Two annual groups were fixed on the raft in May 1907, each numer-
ous, one from 1906 of ca. 2 cm. in length and one from 1905 of 4-—6 cm. If
this was the general growth in the fjord, all oysters of 7 cm. and above should
be 3 years old and more; but I do not think that the oysters on the banks would
grow so quickly as those on the raft or on other similar artificial objects; of this
I have already had previous evidence. But in the estimate that the oysters of
4—5 years old on the banks are 7—8 cm. and more I do not think we are much
in error. To investigate the point more closely we must find a suitable method
of marking oysters. I have heen recommended from Holland this year to try
-I
painting the shells with red lead or tar; but these are not sufficiently durable for
our purpose; it is only recently that I believe I have found a better method. It
will certainly prove hy this method that the oysters on the different banks grow
as a rule fairly quickly, until they reach 7—8 cm. in shallow water and 8—9 cm.
in deeper, but much more slowly after that or not at all. É
The present standard for oysters consists of a quadrilateral iron
frame, with an opening of 8 cm. on the one side and 3 cm. on the other.
All oysters which are able to pass through this frame, whether lengthways
or broadways, by turning or twisting, must be returned to the water if taken up
by the fishermen, in order to be allowed to grow larger before being fished up
again. I have closely investigated how this standard works in practice by using
it on a number of the oysters fished during these investigations, especially on
those taken by the pole-dredge and by diving.
8 cm.
(1,
&
natural size.
"I G
-
As the oysters under 7 cm. must be considered as a rule unfit for the
market or food, at least as regards the race which occurs in the Lim Fjord at
present, I have only used the standard on oysters of 7 cm. and upwards. Of
these (see p. 15 Table Ia) 1612 oysters taken by the pole-dredge on May 2dth and
July 19%th at Feggeklit, on July 3rd in Faarup Vig, on August 29th in Venø
Bugt and on låth—17th August at Trehuse have been examined. Of these 1612
oysters only 178 were standard size, as all at 7 cm, went through the frame of
8Xx 3 cm., almost all at 8 cm. and ?/,ths of those at 9 cm., even 15 at 10' cm.
passed through; only the 12 which were 11 cm. in length were all standard size
(see Table Ia, last two columns). All fishing with the pole-dredge is therefore
practically impossible at many places in shallow water according to this standard ;
and even if pole-dredging would pay, yet most of the oysters, namely almost all
at 8 cm. and Z/,ths of those at 9 cm., would die of old age without being fished;
since the oysters at 8 cm. and above must as a rule be considered as full-grown
at these places (Table I, p. 14).
Even if pole-dredging did pay the fishermen, especially in earlier years,
with the same standard, this was due on the one hand to the fact that the oysters
on a few of the banks as already mentioned were of much greater size, and on
the other that in good weather pole-dredging can be carried on in deeper water
than we fished. What I wish to emphasize on this ocecasion is the fact, that there
are large areas on which the oysters when full-grown are so small that they cannot
be fished according to the present standard. For the oysters taken by dredge and
by diving, which are almost always fished in deeper water, 1!//,—5 fathoms, the
conditions are less unfavourable, as the oysters there are all both longer and thicker.
Table III shows the length of all the oysters obtained by diving
” at 15 places during my investigations. The localities are situated between Løgstør
and Thyborøn. The method of fishing was to anchor the usual boats for oyster
diving on the bank by means of two anchors, so that they remained quite steady.
The diver had a definite length of line each time, so that the depth being known
we could approximately calculate how far he could travel round about the bank,
and therefore how large an area had been fished. All the oysters on this area
were as far as possible taken up and measured; hut it is impossible to fish the
bank quite clean on account of various practical difficulties; sometimes the diver
would estimate that ca. 50 oysters remained, for example, where there were large
stones on which they were too firmly fixed. On muddy ground some might easily
be covered by mud, and the water here is easily disturbed so that all the oysters
could not be seen. It appears from Table III, that the full-grown. group is most
strongly represented at 3 cm., just as for the oysters taken by pole-dredge, then
at 9 cm. and not at 7 cm. as for the latter. A maximum for the young oysters
occurs at 3 cm.
Of all the 3404 oysters over 7 cm. obtained by diving, 3318 were tested
by the standard 8 x 3 cm. (see Table III); only 1845 did not pass through this;
some right up to 10 cm. could pass through like the oysters taken hy pole-dredge;
at 8 cm. only 27 9/, were retained, at 9 cm. 70?/,. The details of these measure-
ments appear in Table IIIa. I have given the Tables with the details appended,
because they give a good view over the relative numbers of the oysters at differ-
ent sizes living at this moment in the Lim Fjord. If the size of the oysters in
the Lim Fjord should change, we have here a material by means of which we
can detect the change. It is just such a material we lack for the plaice fishery
im the Kattegat for the years about 1880. É
That the Tables over the diving investigations have also an other and
special worth will be shown later.
Table II over the dredged oysters shows that they in general have their
maximum at 9 cm., 8 cm. is the next almost as frequent and then 10 cm. They
are thus distinctly larger than the oysters obtained by diving shown in Table III.
This difference may arise from the fact that the diver took up all the oysters,
both large and small; under ordinary conditions he only takes the large; but it is
well-known that diving brings up more undersized oysters than any other mode
of fishing. There is room here for individual choice. By means of the method
used in the diving operations in the present instance we obtain the best picture
of the kind of oysters which actually occur on the banks, since all are taken up
as far as possible. We endeavoured to do something similar in our experiments
with the pole-dredge; but it is remarkable that the dredge has a tendency to leave
behind a certain intermediate size of oysters; this feature will certainly prove to
be different under different conditions and with dredges of different construction.
The important thing is that both our pole-dredging and diving experiments
may be considered as giving the best possible information regarding the stock of
9
oysters actually at the places investigated. The standards 8 X 3 and 7 X 3 have
therefore been specially experimented with on the oysters obtained by these me-
thods of fishing.
We might now say, to make the matter more easily understood, that the
pole-dredged oysters are full-grown at (7) 8 cm., those obtained by diving at 8 (9)
cm., the dredged oysters at 8 (9) cm. All oysters which are at least ca. 8 cm.
and above should really be fished for; but the present standard allows only ca.
1/,th of those at 8 cm. and only 70'/, of those at 9 cm. to be taken.
No investigations from earlier times are known to me which
would in any way indicate that just this standard of 8 X 3 cm. is the
correct one. Professor Eschricht and the Government always held to a smaller
standard in earlier years.
The statistics for the years 1870—1877 give us distinct evidence that
many of the large oysters occured at that time in the fjord, as ca. 45 millions of
them were fished during the 7 years; but then they seem to have decreased in
number, not that they were all fished out, but the regulation that a boat must be
able to take at least 1000 of them in one day made further fishery for them im-
possible. I do not believe in the rumours that a storm and flood with ice to aid
them destroyed this stock; all evidence of this is quite wanting. It has been said
that many dead but still connected shells were found on the banks, but such are
found every year. Whether they have just died or have lain on the bottom for
several years cannot be determined, as the soft parts of the oyster soon disappear
when the oyster dies so that no trace of them can be found a few days after.
This point has been investigated by placing dead oysters on the banks at Fegge-
klit. Within three days all the shells had been cleaned by the flesh-eating animals:
gastropods, crabs and worms; even within 10 hours all the soft parts had been
completevely removed. I judge of the conditions in the seventies in this way,
that a drecrease in the stock of the large old oysters could really be noticed; I
belive that a vearly fishery of ca. 6 million is quite respectable, especially if
regard is taken for the restrictive regulation of 1000 oysters per boat per day.
This regulation was probably introduced in part because it did not pay to fish
when so many could not be taken as a rule. We have here therefore some
evidence of what the Lim Fjord can vyield in this way: 6 million of old oysters
each year for 7 years. All foreign countries and also in part our own have now
become accustomed to eat smaller oysters; the Dutch and English small oysters
flood the present markets over the whole of North Europe; and the duty in foreign
countries favours to a great extent the small oysters, being per kg. and not per
oyster; lastly, what is of most importance to Denmark, we would clearly produce
several millions of oysters with a smaller standard size than the present. If we
only enrolled soldiers of 72 inches and above, we should have many fewer than
if we took them down to 64 inches; similarly with oysters; if as at present we
only take those about 9 cm. we have relatively few; a reduction of 1 cm. in the
standard would give many more. A reduction from 9 to 8 cm. would be for
oysters just the same as a reduction from 72 to 64 inches for the soldiers, as
12—, The oysters are so short that 1 cm. is of verv great importance.
In order to test how a smaller standard of 7 x 3 cm. would work com-
9
10
pared with the present 8 X 3 cm., I got some of the former size forged and Table
Ia shows the result for the oysters taken hy pole-dredge, and Table III and INa
for those obtained by diving. Of the 1612 pole-dredge oysters investigated by
both standards the large gave only 178 standards the small on the other hand
749 or quite 4 times as many. It kept almost all the oysters of 9 cm. in length,
somewhat over the half of the 8 cm. and hut few of those at 7 cm.; the last
because they were fairly thick and could not therefore go through the standard.
Just for this reason the standard was made like a frame, as these small, thick
oysters are old and grow no further.
From the purely practical aspect this standard gave very fine saleable
oysters, the smallest of which apart from cousideration of the price 1 would rather
eat than the large; their shells are clean and solid, not double nor containing evil-
smelling water, as is often the case wlth the large oysters.
Table III shows that of 3318 oysters obtained by diving which were
measured, 1485 were standards according to the large standard, but 2520 accor-
ding to the smaller; thus well towards the double. As the oysters taken by dredge
and diving are always longer and thicker than the pole-dredge oysters, the dispro-
portion under the large present standard is not so great in their case as for the
oysters taken by pole-dredge; but with the small standard nevertheless, a. boat
would quickly fish almost twice as many oysters as it does now. As these smaller
oysters are considerably younger than the large, the stock would he renewed all
the more quickly, and the introduction of such a standard would prevent so many
oysters dying of old age, such as is now the case. How large the production of
the fjord would increase through this apparently small reduction of the standard
size, it is impossible to say; but with the same number of fishermen and the same
amount of work, the catch would at once be doubled.
If m 1886 the standard for oysters had been reduced this one cm. instead
of total closure for 4 years being enforced, things would certainly have been much
better. I shall endeavour here to show that the stock in the fjord without its
productivity being lessened may be considered as capable of supporting such a
more severe fishing.
Sample dredgings can only give a momentary picture of whether many
or few oysters can be fished on a bank; this may be covered by dead zostera so that
the dredge takes hardly any oysters even though many may be there. On sandy
bottom also the oysters are said to he able to lie buried in holes formed by them-
selves, over which the dredge passes without taking the oysters. If poor results
are thus obtained from dredging, great care must be taken in drawing conclusions
as to the richness or poverty of the oysters banks. Even if the dredge is working
ag well as it can, yet it springs over a number of oysters, so that sample dred-
gings can never show how many oysters there actually are on a definite limited
area. It is quite different with pole-dredging and diving. In fishing with the
pole-dredge stakes can be driven into the ground and all the oysters between these
fished up. Ås the area between the stakes can be easily measured it is possible
to calculate how many oysters there are per square foot of ground. I have made
some trials in this direction during the year and found for the west side of Fegge-
klit that there was approximately one oyster to each 40 square feet; ca. 11,200
11
square feet were investigated and only the oysters over 7 cm. included. On the
east side of Feggeklit 1000 square feet were examined and 291 oysters over 7
cm. were found; thus a little over 1 oyster per 4 square feet. The numbers on
the actual pole-dredging banks will probably lie between these two densities; but
as we have absolutely no chart over the extent of these banks in the fjord,
because practically no: fishery is carried on where the smaller oysters live, we can
for the time being form no estimate of how many million oysters of this kind
there are in the fjord; this must be learnt in the future; but I am certain that it
is a matter of long, narrow stretches of altogether several miles.
It is quite different for the dredged banks on which diving is also done.
From early times they have been numbered and mapped out by the lessees and
inspectors in company. Such a chart has been published in my earlier Roport
(XV). Although this chart cannot make great claims to being very accurate, as
regards the size of the areas, yet it is possible by means of it to obtain a fairly
correct picture of the extent or surface area over which the oyster banks in the
Lim Fjord extend in all. This has been calculated to be 2,,, Danish square
miles") or 1676 million (] feet. All the banks marked on the chart are included
here with exception of those east of Løgstør. Further the large new bank, which
embraces the three fairly large banks on the chart N.E. of Feggeklit, is included
according to the boundaries at present known.
In order to obtain some notion of how dense the oysters are on the banks,
15 diving experiments were made, distributed over all the districts, as already
described on p. 7. We were not content only with the area calculated from the
length of line given out to the diver and the depth of water; the diver himself
by means of a leadline measured the diameter of the circle fished over by him on
the bottom; both metods agreed very well. The details of these experiments can
be seen from Table IIIa. The number and length of all oysters over 7 cm. are
represented; Table III shows likewise the number and length of the smaller oysters
obtained by diving and it is also stated how many standard oysters there were
according to the two standards 7 Xx 3 and 8 X 3 cm.; further, the area fished over
is given in square feet and lastly the number of oysters over 7 cm. found per
square foot or the density is stated. The latter varies from 0, to 0,,,, i.e. from
0,75 per 100 [] feet to 11 per 100 [] feet. We thus see at once that the oysters
are nowhere lying in layers on the top of one another. The expression »banks«
should be understood as meaning banks on sand and stones on the fjord bottom
analogous to fishing banks; the oysters themselves cannot form banks, at least
not the living oysters. Dead shells might however be deposited on the top of
one another generation after generation and at last form a thick layer.
There are many oysters nevertheless on the banks. The total area of
these according to Table IV is 1676 million [] feet.
To come to as exact a result as possible, the density found in each district
by diving was made the basis of the calculation as to how many oysters were
found there. We see that the density is very low in Nissum Bredning, 0,,;; oysters
per 100 [] feet, but large at Trehuse, Hannæs, Visby Bredning and Kaas Bred-
1) 1 Danish square sea-mile —= 7407”? ] meters = ca. 16 Eng. square nautical miles.
12
ning, namely about 11 oysters per 100 [] feet; hut we also notice that these
densities do not vary so extremely ås to prevent us from obtaining some estimate
of the size of the stock by their means.
The areas given on Table IV have been found by Engineer-Captain, Cand.
polyt. J. Bast, who has also helped me with the preparation of the Tables, in the
following manner:
By means of tracings on the original marine chart, on which the oyster
banks were marked off and which — greatly reduced — is reproduced in the
Chart accompanying my above-mentioned Report of April 1907, the separate small
areas within each main district (Sund, Bredning or Vig) are brought together side
by side to one, as far as possible, »compact« area; by means of the planimeter
this is then measured in [] miles of 1852? [] meters — ca. 5900? [] feet = ca.
34,810,000 [] feet, and the result is then stated in millions of [] feet for each of
the 9 main localities dealt with.
On summing together the numbers of all the oysters over 7 cm. in the
different districts we find that ca. 90 millions of oysters live in the whole fjord;
of standard oysters according to the present standard ca. 40 millions; according
to the smaller 7 x 3 on the other hand ca. 70 millions.
Ås mentioned, no attention is paid in this calculation to all the smaller
oysters which can be taken by pole-dredge, as the extent of the banks is not
known, nor to all the scattered oysters which are found for example over almost
the whole of Livø and Løgstør Brednings, and which are often taken in numbers
in the flounder set-nets and seines.
Owing to the small number of oysters taken by diving in Nissum and
Thisted Brednings the calculations for these are less trustworthy; the density is
perhaps too low in both cases; I thought it superfluous however to make more
of these experiments; for the time being there are certainly sufficient oysters to
begin with.
However approximate the whole calculation may be, owing to difficulties
in determining the exact extent of the banks and the density everywhere on them,
I believe that all will agree with me that there are several scores of millions of
oysters in the Lim Fjord at this moment, both according to the present and espe-
cially the smaller standard; and therefore that far too little fishing is carried on
when as now only ca. 1 million oysters are fished in the year. As the oysters
grow up within 4—5 years, the return or output must be based upon a much
shorter number of years than as now upon scores of years.
To state how many millions might be fished yearly without reducing the
productivity of the stock is impossible, as we do not know the scale on which the
stock is annually on an average renewed; but if 5 millions were taken yearly
according to the smaller standard, there would certainly be at present no danger
of overfishing; and for the time being the market can scarcely take more.
If we ever should come to the time when we can use more oysters than
the Lim Fjord can yield without help, it will then not be impossible probably to
improve matters by means of the experience learnt in other countrios. As Eschricht
proposed in earlier days, it would be possible to introduce other races of oysters,
not to improve the race in the Lim Fjord, but to allow them to grow up to
13
market size Experiments in this regard as well as in various ways might be
commenced already, so that we may be fully prepared to carry the matter further
if necessary, as we might even be obliged once again to completely close the banks
as in the years 1887—1890. The stock on the natural banks especially should
not be over-taxed without full preparation and knowingly. It must be the care
of the person who is entrusted in future with the superintendence of the Lim Fjord
banks to follow the course of things from year to year, so that he may be prepared
in good time to meet all difficulties arising from a future severe fishery. Changes
in the natural conditions might of course place insurmountable difficulties in the
way; the closing of the Thyborøn Channel alone would destroy all oyster life in
the fjord. Such an expert should be well aware of the responsibility, which may
arise from fishing too little and from fishing too much of the stock.
Accurate knowledge of the fjord and of the oyster fisheries as a whole, as
also of the experience won in foreign countries should be required of him and
his responsibility may be great enough even with this knowledge. Only by making
continued biological investigations will he be able to justify his acceptance of the
post. The early history has shown very clearly what the lack of sufficient inves-
tigations leads to, both for the State and the public.
14
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SEJE Ka MERE FRE: Fre SE Fre PAR LF RES (6 BEER Be 0 i (OM Kor ==. ty
6 ….…… . 2 mare . sl ormeres KO OD |OLDIG s… |. s|esr…e …. 0 0 DO fg) "2 "TUu0 ZI
twunN | munx wuny | wnN WuN | HUN | TUNN | nN Qsu9T
z z ce 9 c9—6e| 9 e—2 RE 9—8/9—8jG—z Er ere ger RG Slang 3997
OSS VEG VSEL bre) CG--G|ES 9 9 Sæt (a GE PG EGO Pk GS 9] S) (ægte ut udeq
| føre + — | == =
0, | 2 B Ø, | og e (& ag > ae | 08 — | å |S'æ| 2 || | 09 —|E 8 | 08 ØD,
ES ER ES ER øv USE DS EOS ke El) BRcDEN Ep BT ER 157 SN ært S CSR) KRAN BOSSE Mas AS (RS
RESENS NERS DES er | 9 +lÆlS | ZIZS) Kloss ÆlS ISEN) 2
2 (g Re ( = ER ES SEES SENSE HED = | Siel REN LD
RS HEE BER KR re FREE rn ES SR FREE HR 550 (RE ERER HKSSA Jose 5) ESEA hbe BE RES se
SEE oe FN h554 8eE ENE RsS EGE Kos) ER ER HD SEND SEE KEN ESR NERIFÆNSE
, = ( n Es 2 ml (& mal SE: en Sl ad | S SMS DS = (u S
= & FÅES En É a SE å ER (5 SE ss 5 S$
| ; SS ke VE SE SE ok HS & &
SØE =
"Tog L
"LOGI 49q0399 07 flady Ww033 uonejg jedrfojorg ou; Åq afpesp-øejod ey; 4Wm poysy ssejs4g 943 fe Jo y6ue]
1907, tested by the standards 8 X 3 cm. and 7 X 3 cm.
Qysters of 7 cm. and above, taken by pole-dredg
Table la.
TBS «
jøng øu9A
puns øu9A
» f punsbunjes
asnyøJst
= f punsbujjeg
asnyaJg
buiupaug 21Ø3s6Ø7
ysea 11496694
punsbunjes
Gia dnaeej
… | Gulupaug 291s6Ø7
jsea 111496694
» | furupaug Jøjs6ø7
1S9M 311496634
Date
'spivpuejs 29818[« puXZ
aq £q p2159) s199SÅ0 JO "ON
NM
T810L
stu GX g
ROD WWW OD
sr e & po AW
dy 5 rd
n es = = Ej RER
== | Er ES |
== KREBSEN REE = wm om o | ca
nm 47 =: GS OG rr
—” on == we | ra
I aa |
3 |
= É é =æ] == pr, (ed —
sy d bs 5 SÆS 2 ra
== FREE
SS = mc Es T K
n ENES SIN Te NFA E (7)
SÆR | = == IN OD
— - = ca. cd —
z
1830.
mråd0o00o0o (
"TION
stu Z> EESTI er
. = - or]
"TUN Mee: ER T SSR
TUDN = rr W mo —
- Aa 5 00 oc
[8305 =
sd gX8S HH ON GO ca
"TUDN ==
Tod GO mr —
NH mm Na
SKETE KE] cz
co H W
T210L =
stTgX8| WOOoOom oOo 10
= HERO ca
WNQ QW w
. r rr oa
TUN al .
TUDN N AW rr & 60 co
2 rr mm O 4 co
TeJ0L rd
stu CX 8 Or QL SO ODO 1Q
"UION FÆN SS
STage<) I Mm mi <O 063 6 9
== Aa co HH =>
"TUDUN rl
T830L = (=
Fugees REESE >
TUDN SX | £2
sum ex] rr oOoO mm &o | ar
G FIE DOT El —
TUDN rd
UUDN Fra or HH
= ri f O QW S-
— rr Cr
Length
cm
sunde — 20
"TUUN re 2
suagxrl VON EN =
g iz UK SO NI D=AEr ==
UINN N
TUUN HESS RE ==
[e30g — (ST
er
stu EX 8 Q WM AW O =
UUUN
STU gX), i cm 0 mr o sa
TION Sean i
TUIUN SE
16
Length of Oysters dredged by the
Volstrup. Langer: Revelkær-Hage Trehuse | Feggeklit
Hage
ER 2 182) 2 21 11—3; 31 2 —419—4 2—afs—4 By | Og 3 me 3 ES
Bam || ø | SEER | REE EEN DE | me
minutes: | 90 120 20 125|/10120) 15 | 20 | 40 | 15+60f 30 | 20
Length Num. | Num. | Num Sum, | Sum. fNum. | Num. | Num. | Num, f Sum. | Num | Num. | Num. | Nam. | NXum. | Num. | Num. | Num
SKE LOSEN ÆRE EGE STORK SESESTRER FL BREST URE ES RES ] DERE A SEER I REE SSR ES HVASS SEER IRS SE AES BE On ISRADIQ
ene URE CAN SOE 8 KØR SASS Kes BBS Nee ea Ene al FE I MA den ÆRES SK SA ERE "eg SSR ED SE
BRS SES arsen sn BORDET ad 1 BSN FSR NESS HESS ESS ge 1
12 — 4!. 2 1 1 0 SE SIE 2 5 4 5] 2
11 — SPA hå 27 12 ZA 1 IL VE 1 22 8 ig 1183 9 18 181122 HR DÆ
10 — 85 | 36 58 IIs 15 16 i | 12f 47 20 ig GE 39 38 26| 34| 44
9 — 1125! 50 81 39 39 36| 22! 23 32| 75 42 41 94 47 67 21 ESS EO
8 — 91! 54 47 43 48 67| 44| 28| 27| 75 33 62 13 51 B7 2015525 1k53
7 3020 19 23 16 37 | 24 | 24! 23 55 33 31 50 NS) 29 3 12 S
6 — 12 14 8 5) 11 KNEE BI NEP? 65) 9 iD! 11 2l i! 1 3
d — 19 35) 5 9 8 SIE G LD all 9 6 10 24 47 4 0 4
då — 14 10 8 5 5 2)" 19 Sy Kart 23 19 19 36 59 12 5 3
3 — 23 9 10 8 14 1 8 5» 11165 44 25 Ad 19 37 23 4 S
2 — 15 7 (Te 6 22 3 4 637 40 12 20 8 37 11 1
= 2 (i Ls] SS es SNEEN 26 1 2 12 39 re RR Fee 4 EUR Dan
457 | 160) 596 | 176 | 164 12431117 | 1371147) 449 | 297 1931 | 354 1 275 | 419 1148) 14217169
17
Biological Station from April to October 1907.
FE SER ra ae w AE e: É : i
"Is | lo az 4 | El 10 | IL: | Sy 10 Na | 5 la | SES) /5 I: E fla 1/10 | nle "lg Elo
æ z w | o >
= s == alles be E= = > b—
Ss md = SE ESæ FSbSy ES = = HH e |Numhber
Sennels- Kjeld- ar | SKE DIS ol ØE] VSSE NREN ESS
east Q HER RER 5 20) er HERE SA) SAR Hr She er 2 and
bank gaard SET er ES FE88 fæ Er RS RS RE
== 3 S SS ss] 2 = s E E | Length
æ ÅR - E29|SE =m S= F= æ
LE | z sm ER =
| tE =
(| | |
4 | 4 |(3—31| 3 | |2—3 SR |2—s 3 1|3—5] 3 14 4—41 4—41|
| | | | |
| 2] | 41)
3 É 4 É 4 (4 Ø 1 3 2 Total
30 | 80 | 40 | 60 40 30 | 20 25
Num. Num Num Num Num Num Num. | Num Num Num Num. | Num Num Num Num | Num Num Num
RE ar] LSE RS ET SE [er DERE Sr VOSS FESTE) USE STEN ØS GEESE] (SS EEN DERES FEEn EGE Edie 1
EL EEESSET DÆSELEN rr ak EMEA UL SNS DYRESTE DT REDE EEN EET RE SR ol GELSE AA
|
nn HEE ERE SES ERERT TØRSEESES KØERNE » 1 za ESAE USENSENS | ENESE Er FA SEES RENSES SE BEDES E 8
2 UT SR 18 140 4 One 1 1 6 1 ARNE il 61
12 25 10 13 1 4 8 18 1 1744 FSR See 2 6 94 | 5 7 4 1 369
29 43 12 924 23 ilkj PAN 0E99 Fars 5 23 32 ”E 10 21 8 863
39 34 41 65 49 37 1 rs42 18 2 3 67 62 4 9 43 21 1456
PE HE2 0 RES S8 870 625 GTR RTGE KE25N RE 9) | ET53] STE To 38 ER so 28) 1380
id 14 29 27 40 26 1 12 2 5 4 31 19 | 2 3 32 UEELG 742
2 12 Ss 3187 3) 31 DE 2 3 ly BAl Fess 11 9 7 1 5 10 300
6 13 0 32 4 VA: HM KREDAREES | rar Gik 10 DN| 2 1 3) 4 324
8 5 0 17 g POP SET se] i EN SERES an ES, 7 7 6 0 0 PA 383
ANNA BE BI DN] |, Are |ESER ERE GTA les Hø (58) UREKS MEE 75 ye Bk zip
2 7 7 3 I SEN 1 1) AGRE ANNES 5 11 ) he] LØRBE GRÅ 1 4 293
sen KS LER Re or ea ESS M.D ab Foto tg: JN fg AA DSA ROM SET 50
135| 179 | 166 | 283 | 213 | 245 67 | 144 58 58 16 | 220 | 230 45 39 | 164 | 101 6744
cs
18
Table Il Length and number of all the Oysters taken by
Date lz Sl le 4/7 "l, "1 7 ar si
= T SES NSSS ONE
(ml sr reg w
Ep 2 2) 2) 2 2/2|2| =| 2 2| 2! 2'? |sz
oo £ F E = '= '= (== ca == '= = '= sc xZOo|S'E
SEE % > > > > > > > 3 |0E£ |'35
En] = | (3 (7 [2] (27 ea (1 [:27 [7 [2] >? oo
za £ pm E= — Bx = = = — E= E=< SEE [=
E | må cå cå cå 5 s 5 må cå cå m 8 |små
a|s > å =
35/8” 25',5'52 | 3 RES BE IE RE OSS
o s= (CREEK = an | az enn! a> =% (=K- HE ar—-]
SEES 89 Sa lis 92 £ø|om|zg% | s% == ==
=> | Mm Se |me = SEERE == HE
853 | 5 S- 27/8 LESS MES se |s2 3 |E£ |g8SlSg3
2 »—|9 … g » == (Æ=5 3 == cc …= = Si (x9| 2
os |3 cz 5 = E SES 4 Es E nn |S2|/5S
v'ø | £ es |E e == t> D = (== s == FF E=
Es & ke RD ESKE ES BOSE É SR hes" KR sy AE
så|KF Bu == cc (72) > Sr z ø SER KO ; cc
z | ED ER Een HE 5 8) Ed 2 ED) See VE EAN Wi
Depth in z a 1y 3) 13) | B] | < ( a | 91) c > >)
å 3 ED 4 4!|, 3) BME SE 5) 7) D SAVE 2 73) 7) Total
fathoms | 2 | 2
Length Nam Num. || Num. | Num, | Num NUme |HNNm Num Num Num Num Num. Num Num. | Num.
LÆREN SE ETA RE BESS BAREN FEE FN GE sent ENE NE EA ESKE ISS SES se EET ED Jo EA RD SA Nd Fra ao 1
FEER MY BE REE IEA EDORED AL FSRADRE OY RØRE AT FREIRE Fed 2 LE HO ae FRAESN NER N VARRRE 13
12 — 2 10 AS ERRRE DE Fa ESETS FK ØRSS 29 TØ! SE SESLE | tra ESS 7 3 SV FRR es 59
11 — 9 SØ 16 ES 4 i! 38 6 SER 13 14 Bi nen 3 156
| |
10: — 40 sites 41 26 NA 24 14 16 10 21 36 4 16 401
9. — 107 STE RODE ENO TE ETS | 56 | 39 20025 8 PBE OIR EA 81 847
|
8 — 194 | 109 | 23 | 124 | 136 | 19 | 65 | 48 | 47 il yt 267207 149235 15] 1191
| |
T — Ib bt 81 15 63711 5) 30 16 47 DIN 2 TOM ES 5 | 122 736
6 — 20 20 3) 22 46 | 3 16 19 16 3 | ESTRRDER hrBal 29 BE Es4 237
db — 25 10 2 10 > OM EEG | 22 2å 14 6 | es Gr eee bong 7 174
| |
4 — 31 235 3) 6 71 2 24 11 BOSSE | EVE e 2 SA SEE le (9 203
== Anti HESS 0 HS EO ETON SE se SE bragt sen Hess Er Rk | 10) 216
2 — 28 13 8 2, SAT (se U 10 ey ERE SER NEN HERA SØS AN: 1 3 105
1 Ba KDE ER TALT VG 9 TE G tggt. Sl LESS EN Kenan ERR GBA TE RSGE FRASER REDE (MæS 27
sø r ke2 i wz i z | FEE EENDE HEE
Mota ES RE ra ERE FEER] REESE |FSEESRER Enns FEER renee KEE AES L RS En Be ISEVESSE bose SR Se FESTER
I | | | I
&
not tested by the standard.
diving in spring and summer 1907,
Table IV.
Estimated area and number
5 | E
Z z i= [=|
n Standard oysters. c S SØE
> = > E: - 2
z: = 8 O u &
E with with RE Se =. fE
— > bel
SE "5 3cm: SEE z 8 E | 2 s
gel z = > i" gr
ø standard standard The oyster banks in = Å ES
Z |
Livø Bredning ele 4
Sallingsund ESS =— 4 205 REEOSE Skr
SER | | Løgstør Bredning .…...…. = 1Xx 89. Or 2457
KR 1 100 1 100 y
| Visby dog TESS — ASÆNDSS OS 10,5
12 12 100 12 1. 100 SR ; | j;
| z | Thisted [ORE Er — 4 48.5 0 rd
52 52 100 52 100 6 |
É | | VenøkBarbrine are eter 4 45. Os TO
142 142 100 142 KDE ØR SONY z
3 | | Nissum Bredning 2004. — 4 x 116. VS (lo:
384 384 100 SF Gr] IE df
g RÅ i, Kaas (OS FRR — ASSER: OS Ar
826 797 96 SVANE ERE (0) å |
<! Risgaardszido) HET — ASE R2OR (6 ER
1170 920 vy 315 27 za jer g
751 210 29 19 3 Total.… 4 x 419. (0-67) re
| =2.,, 0 miles!
Thus, according to Table IV the oyster banks in the Lim
Fjord have a total area of ca. 2., Danish [] miles with a stock of
ca. 89 million oysters of 7 cm. and above. Fron the measurements
we find that of these:
2520 3 AA
å: | al 3378 = 2- 76"/, = ca. 67., millions 7 X 3 cm. oysters.
| 3
|
3318 | 2520 | 1485 1485
3318 — 2- 45%, = ca. 40 millions 8 X 3 cm. oysters.
£ The details are given in Table III a.
20
Length and number of Oysters 7 cm. and above,
Table Ill a.
> [— > [— [— i == =
z == E £ K= == E Ej
- = FH z E = = ca
o > HEN > > > kj
- (22 = ao (2 (2 (2 oa
CR" - Em = = z =
5 Sera = cå ca ca co Z
> >
[== f- rv
od > S 2 ste == [9 rr 3
xx bd 2 Z = um br ad 2 =
rr — S (72 z "2 gø n
8 & = w (Ju xx (dd k = > '=
2 & CJ == ea = (== =
= O [| == Cl RET] E
4 å: o br - =
DER ao w BD 8 = =
ES z & = = =
- E = == = o = FF
o aa ==) = > s =
SEER us . Cs o > s
z x — ui = cc (7 >
) 1 6) ON
Date Is z FEER if K
sal 9 See Tess Ses | LÆS IErES es
sindliadi JleBimFi ;imadlmnt s;loPlmnl slædliodal sf simnR|nn
STN NE SØG TVEGIEN ev va VVM / å / N i É: SAOTRI "
ER SEERNES ÆT BSN BKK KT KEE DE DT
S "| lo FR ler 0 -F8R == jr læ . lo JS 2 | eN FE SE] SES | of r 27
BEES BESES ER RES SD ISÆR EERS RRS LSE SETS SEERE SES
SEES ES 3 ES: ES SEES SE SEESER
Foss sister 5 se] se FEE RSS ENES FS RS es Er SS:
cm. aladlkgsi ss g| ar gsleg ag slkglag| el ale gleg
al 9 ole ske eo oilkke ses
Length
14
13
12
11
Density N: A.
Average density
pr. Bredning
taken by diving in spring and summer 1907 at the places mentioned:
=(68X 8)—P0PE | 3 5 DSE
JM posn S8A4 47 19499509T8 in ISA SE br
fposnJOUuSs8A p18pu8Js 10Js40 | Eg 9g .
oq) ouzo nW pue Imme IV | S LER do ha
1s="'Ø'TWwW Uua | | ca SS Ga 2 0 SS
28 "UN E | = DD
burupayg spavebsig ER lie - N - - —— — = z
u u Is="Ø To | SEDEÅNE S s S sæ
BENE: T i (I ; S
'spidspaon spunsbpurg 5594 AMLDIN ER SER AS
"ZX TUDN cd Om er | mM >
is | | oOo 0 AW | I
T230 1 L == or co
1s="Ø"'wW ENE SENKSES | Na
buiupaug spavebsig gX8g tunN | G on =
1s="Ø Wu k Ho rr | IQ S =
fabeH spivebsigy GX) "UWUNN (ol RR | É rå ==
"UaNYEN JO 'N "we ”UINN | | Ha c 1Q s O
TEJ0T |
1s=TØ Nun Togo | STIER
cex8g WnN - D
buiupaug see SE 2 - - — S
lupalg y 19 Ø NI Wo rr | > st E
"TUN SE bra i =
'dnapøds 40 Å sag] tg
| kr SE SES SEE ES
! = QX mm | 4 =
i RS Ene Se ON et ES SEER DE ESS] LE
no="Ø wo OS FEAT SESE] i Gå
| ED SNEEN I vr CM Ned | (hud ss
huiupaug seey RES USTA LET EFTER EER A
USE TAG ANE REESE RES i 8
punjowweg GÆLETETN Estere ESSEN US S
"NT: "CUNN SEE SES E=
| 0. SÅ ==
ft ræs SE ME KM AE
buiupaag Wnssin SNE UINN SEERE = E
"aUJ9JINW 340 'S T8J0T, co =
| is=Ø Wo op Ha mM oOo ge)
<x8S WNN (== sd
furupaug wnssi SS SE SE NERDIDE - - — == > cc
upoJg IN IS ="Ø MU TTI SES RSS 18 A z
'Uauuøgq J0 "N SES LEN 2 Er me] eg =
NE RK op Ie em 0 =z
TB10. | 22 eg
YS ==" TI N ad ar) Se. ri væ d &
2Xx8 "UNN =
ång øua Ene h gr EL d = =
wong A SØ uw » don | R Z E
'øbeH spe BAN ER SEERNE 2 = cc] åg =
?N: DESK cc =D == Em SX RB
8707, -
TO RIR 0 0 ==
2 (=)
renser SE] He SG
jøng øugA SET EAR E "8 p. i
NH MW g3 N ES i
6 | Fr s >
dnays10A Blood 0 |IN 5
GU on ar 00
IEZONE ER
Do
Do
Appendix Å.
Statistics of the number of oysters taken by the lessees during the last 7 years,
from 195% to 1906.
The statistics show that the oysters in the Lim Fjord have heen chiefly
taken in recent years by means of diving and dredging; pole-dredging has only
been of subordinate importance and has not been carried on at all in certain
years. The reason is not that the fishermen have no desire to pursue this method
of fishing, but the lessees could obtain a sufficient number of oysters with the
dredging and diving boats belonging to them. Ås will be seen, most of the oysters
are obtained by diving; Thisted Bredning with the large Livø Bredning (Livø and
Løgstør Bredning together) with Fuur Sund yield the largest quantities of oysters
(diving). Dredging which has considerably increased since 19%3 proceeds mainly
on the large banks N.E. ot Feggeklit in Livø Bredning. Each year a certain
portion of the Lim Fjord is quite closed to fishing; the lessees themselves propose
what portion. We can see nothing in these statistics which would indicate that
the quantity of oysters has anywhere decreased, even at the places most fished;
even the large dredged bank N.E. of Feggeklit seems to remain just as rich,
although dredging is carried on there every year. The reason why so much dred-
ging is done there is that the true dredgers have permission from the Govern-
ment only to fish there and in Nissum Bredning; this bank lies nearer the depot
(Nykøbing) than Nissum Bredning. It will be noted in the statistics that dredging
was carried on a single time outside these two localities; this occurred because the
diving boats have also permission under unfavourable conditions when the water
is not clear enough for diving to fish with the dredges.
Ås exactly the same boundaries are not maintained in the statistics each
year, for example in Livø Bredning, Risgaards Bredning etc., we can only place
general reliance on the data. It seems to be the rule that most oysters are ob-
tained on the banks which look towards the west and north, thus right on the
west and north coasts of the land. Of such hbanks well-fished by divers may be
mentioned the banks in Thisted Bredning east and south, in Venø Bugt south and
east, in Risgaards Bredning east, m Fuur Sund east, in Vilsund east. The reason
for this, I should imagine, is that there is very little growth of weed here, the
prevailing westerly and northerly winds causing so severe a wave-motion that the
vegetation is kept under more than on the coasts sheltered from these winds.
Several things I have noticed during this past year whilst dredging seem to indi-
cate in my opinion that there is in general a less dense growth of weed on the
coasts named. This weed (Zostera) is naturally also a great hindrance in the way
of the divers, preventing them from seeing and working; but whether there are
really fewer oysters on the coasts mentioned than on the others, that is another
question. It will probably be very good for the oyster banks if the growth of the
weed were kept down at many places by means of dredging. I may mention in
this connection. that it might well pay to sell the weed dried to- foreign countries
as packing material. This is done in the Lim Fjord or was at least a short time
ago. It is possible that more might be done with this industry.
"Arfenuae uom re T J0A0 OT & snyT,
| | Il |
38 T "9 | 000'690'T "Ed | 000'060T 789 || 000F20T 789 || O0O'GETT 789 | 000'600T "82 |" "18307,
| || | | || |
9gg | 9TTE | ogre | 0 |T6T |P26 | FT |T6 | F9G |
I
OVO EG. "89
| SR RS
| | | | ||
[887 | 608 | FI | GTI 6ø8 "””spugsnoy) [8907],
0 |Søg!| org TGT | 96T |802
198
0 ES Rye
frrrr rr" Sulupolg SpPIBBosSnyg
|
upolg tøJjssør pur "upolg øAv]
SORRING GES SETT
||
SETE aeg IE KSA oe Oben os edb. "UILST (| Suupoag £qstA put punsrA
SP vr PG0I j F6G||8 |" od] Tor lo 3 loge l EA Eg TTU DOT POST
Hæg | ||
BEER RK ØER |. … . …………f. . "| og ……» | FI … … 0 FSR SSAESSESS punssunes
ogt kur] 022 SE EGE BESS. SEES BOD BORE SEES PNSE] så dm]
LOSE ED loge E|rsese SS orne SSSE BEDS FS] SORT DE | i USS ser narg SBUY
| | | |
SOME pøS Sta ESS hrren || Estere SK re) SEEK SEER Fole ZOUDIODDSES Cy 190 …e "lø | EL secs SES A SSR ØUDA
ll, VSEL Ha orne, 2
a FyG anse lenne | goT | 0 0 0 JER ERE ad 10 0 n BE KAAS far ses |balskes 5 Sumuparg TUNSSIN
| |. | | | ES DEN REE SS | vRE] |
ES 0 ce eee eee eee
zl | < a | & | lee SEER ars sr eg
Bee 38' 8 <l (SE) 2 | = 'g2 gt || d (= åg g 2, åj <, | spuesnou) Ur 1oqtunnN
2/5 eks É BIRTE BER E|EBSE|EIRE RE] | spuwsnoyp ur soqomy
2 (SEE HERE oss bro oe De I ORE ge. JOR FORT Uger ESTART ge NERFE Tor | og
Ø o2 =p == II Es el ze == er | FE VRE,
BE DE EGE | | | |
SÆR] ESSEN) £O==906T || 90—2061 || Co—F06T || F0—€06T £0—0061 GO—TO6T || 100061 |
og | | !
ll il ll i
6I 0) ji6l uosees oyj Wo3y søgssøj 94) Åq poysy sJejsÅg JO Jøqwnu ou Jo sanysyejs
få i g f n |"
( n z k: É - Ni ard
art, p ze £ i:
” Fy (
vig
ne Rk i
Wi mn £ d> YU i
CA « 2 i
” 3 ON i;
. 5 ” Pr se Rs KØBERE RUSSER,
Fæn yt ENGER sæ
4 UR i
EAN ge: 55 LEE SN
Ago Te
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rn
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