TRANSACTIONS OF SECTION D. 785 
Cattegat at Hals. The distance between these two entrances is about ninety 
English miles. 
The fjord consists of several extensive broads connected with each other by 
sounds and narrow cbannels. The total area of the water-surface is estimated at 
416 square English miles. The average depth is between three and four fathoms, 
and the greatest depth is only twelve fathoms. Close to the shore, and where strong 
currents prevail, the bottom consists of shells, gravel, and sand, but elsewhere it is 
a soft blue mud, Zostera maritima grows in great luxuriance in most of the 
shallow reaches. In summer the temperature of the water of the Limfjord is 
several degrees higher than that of the North Sea and Cattegat, but in winter it is 
much lower, and the surface is then frequently covered with a thick layer of ice. 
The salinity of the water decreases from the North Sea towards the inner Broads, 
where it was often nearly fresh. There is scarcely any tide; the rise and fall of 
level, and the currents are chiefly determined by the action of the wind. The shores 
of the Limfjord are varied and picturesque, many of the hills being crowned by 
the characteristic Viking Mounds. 
The fjord has witnessed many changes. During the Stone Age the water 
stood at a higher level and was much salter, especially in the eastern part. This 
is proved by the position, far from the present shore, of the ancient kitchen- 
middens with abundance of oyster shells. This salt-water period was followed by 
several others, in some of which the water became nearly fresh; the oysters dis- 
appeared, and the fjord contained many fresh-water fish. The last great change 
took place in 1825, when the North Sea broke into the fjord near Thyborén. The 
ee in consequence, became salter, and the oysters subsequently returned to the 
jord. 
: The Thyborén Channel is now about half a mile wide: the navigable part, with 
a depth of eight to twelve feet,is kept open by the continual work of a Hopper 
dredger. The Nissum Broad, which is in direct communication with the North 
Sea by means of this channel, has an area of about seventy square miles. This 
Broad is every year crowded with small plaice. I estimate that there is here at 
least one plaice on every square fathom of the bottom, a calculation made by means 
of counting all the plaice fished with a plaice-seine on different places of the 
Broad, every haul describing an area of about one-quarter Ténde Land (1 Ténde 
Land =1;4, acre)! On July 1 last a haul was made here with a Danish plaice- 
seine, for the information of some of the delegates to the recent Stockholm Con- 
ference. The whole operation occupied less than an hour, and 3,400 plaice were 
landed on the deck of the fishery steamer Sallingsiind. The majority of these fish 
measured between seven and eight inches, a few were much smaller, and only one 
measured thirteen inches. 
No fertilised plaice eggs have ever been observed in this or any other part of 
the Limfjord, but plaice from two to seven inches in length come in from the North 
Sea in abundance in spring. Many of these migrate farther into the fjord, but 
others migrate out into the North Sea again, in winter, for specimens labelled in 
the Nissum Broad have been captured in the North Sea.” The plaice does not 
breed in the fjord; but the fry of the year immigrates in the course of the year 
from the North Sea. The plaice are so crowded in the Nissum Broad, that they 
do not grow fast from want of sufficient food. Labelled specimens were found 
to have grown only half an inch in six months, while other specimens from the 
Nissum Broad, placed in another Broad at the same time, increased five inches in 
length during the same period.® 
It may be mentioned here, that over the whole Limfjord quantitative examina- 
’ Comp. Report from the Danish Biological Station, vi. 1895, p. 23, 
* Comp. luc. cit. p. 6, and 8-10, and Table I. belonging to this Report, where a 
graphical scheme is given showing (1) that the size of the plaice increases with the 
distance from the North Sea; (2) that the fry of the year only is to be found in the 
western part of the Limfjord. 
5 Comp. Joe. cit. p. 20, and Appendix II. to this Report: ‘On the Labelling of 
Living Plaice in the Limfjord in 1895.’ 
1899. JE 
