| WO1985000726A1 | 1985-02-28 |
DATABASE WPI Week 197909, Derwent World Patents Index; AN 1979-B9383B
DATABASE WPI Week 198338, Derwent World Patents Index; AN 1983-769232
| 1. | A fish breeding net for sea fish farms and comprising a pullup line for use in the removal of dead fish from the net, c h a r a c t e r i z e d in that the net is so constructed that, in the stretched state of the net, its bottom slopes downwardly toward a net well, and that the pullup line is so mounted as to be able to pull the net well up to the surface of the water. |
| 2. | A fish breeding net according to claim ^ c h a ¬ r a c t e r i z e d in that the net well has an edge ring which is connected with the pullup line through a wire cross. |
| 3. | A fish breeding net according to claim 1 or 2, c h a r a c t e r i z e d in that, in the stretched state, it has substantially vertical sides and a bot¬ tom which slopes from all sides downwardly toward the net well placed in the centre of the bottom. |
When breeding fish in large nets which are immersed in the sea, it is important that dead fish are removed as quickly as possible so that they do not spread, in¬ fection and constitute an environmental danger to the living fish.
When a fish dies, it first sinks slowly to the bottom, but rises after a few days to the surface. The removal, which should preferably take place prior to the rising, has so far been effected by pulling the entire bottom of the net up to the surface of the water where the dead fish are sorted out. The pull-up operation may op¬ tionally be performed by means of lines which are at¬ tached to the corners of the bottom of the net.
The invention concerns a fish breeding net for sea fish farms, and its object is to provide such a net which permits more rapid and easier removal of dead fish.
This object is achieved in that the net is constructed as stated in the characterizing portion of claim 1, since, in this structure, the dead fish are concen¬ trated in the very limited area formed by the net well, from which they can be removed without difficulty when the well has been pulled up to the surface.
The handling of the net well can be facilitated con- siderably in that it has a rigid edge ring, as stated in claim 2.
A particularly expedient embodiment of the net is de¬ fined in claim 3.
The invention will be explained more fully below with reference to the drawing, in which
fig. 1 is a lateral view of an embodiment of the fish breeding net of the invention immersed in the sea,
fig. 2 shows the same, from above, and
fig. 3 is a lateral view, with the net well pulled up to the surface of the water.
In the drawing, the numeral 10 designates a fish breed¬ ing net which is square in horizontal section in the shown embodiment when it is stretched, as shown, by means of lines 11 in a frame 12 of rigid rods supported by a plurality of floats 13 with which it is connected by means of vertical rods 14. The floats 13 are prefer¬ ably spherical and consist of plastics.
In the stretched state, the net 10 has vertical sides 15 and a bottom 16 which slopes downwardly from the lower edges of these sides toward the centre where the net bottom is so shaped as to form a substantially cylindrical well 17, whose upper edge is stiffened by an edge ring 18 which may e.g. consist of a lead line. This edge ring is connected through a wire cross 19 with a pull-up line 20 by means of which the net well 17 can be pulled up to the water surface 21, as shown in fig. 3.
Dead fish 22 which sink to the bottom will sooner or later slide down into the well 17 with the assistance of movements in the water, and these fish can easily be removed from the well when it is pulled up to the surface by means of the line 20 at suitable intervals.
After the net well has been emptied, the line is re¬ leased, and the net bottom sinks back to the position shown in fig. 1.
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