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. 
