JPS5857714B2 - Net depth monitoring method in purse seine fishing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for monitoring net depth in purse seine fishing.

In the purse seine fishing method, as shown in FIG. 1, a fishing net 3 is cast from a towing boat 2 so as to surround a school of fish 1.

After the side ends of the fishing net 3 sink into the water, the bottom side of the net is focused to capture the school of fish 1 in the fishing net 3.

In the above, when the seabed 4 is locally raised, there is a risk that the fishing net will be damaged by the raised part unless the net bottom is focused before the bottom side reaches the depth of the raised part.

Therefore, in purse seine fishing, a depth detector is often used to detect the depth on the bottom side of the net.

The depth detector is fixed to the bottom side of the net and transmits depth information detected by water pressure to the towing boat 2 using ultrasonic waves.

On the towing boat side, the fishing net depth is recorded based on the transmitted depth information.

This record is generally recorded superimposed on the underwater detection record detected by the towing boat 2 as shown in FIG.

In Figure 2, 5 indicates seafloor records, 6 indicates fish school records,
These records indicate records detected in advance by the underwater detection device of the towing boat 2 before casting the net.

Also, 7 is a record showing the depth of the fishing net, after casting the net at 21 points,
It shows the state of change in fishing net depth.

The fishing net depth recording 7 is carried out as is well known, for example, as disclosed in Japanese Patent Publication No. 37-3695.

In this case, the fishing net depth record and the seafloor record 5 do not match.

Therefore, conventionally, when the seabed line 5 is locally raised like 5', the depth of the raised part 5' and the depth of the fishing net have been visually compared.

Therefore, if the record of the raised portion 5' and the record of the fishing net depth are far apart on the recording paper, erroneous measurements tend to occur.

As shown in FIG. 2, this invention records a record line 7 representing the depth of the fishing net and a marker line 8 representing the shallowest seabed depth on the underwater detection record, and compares the two record lines to determine the depth of the fishing net. The purpose is to monitor.

This will be explained below with reference to the embodiments shown in the drawings.

In FIG. 3, a transducer 9 transmits ultrasonic pulses into the water based on a transmitter 10.

Then, the reflected waves from the water are amplified in the receiver 11,
Detected.

In FIG. 4, waveform a shows the transmission pulse of the transmitter 10, and waveform a shows the output of the receiver 11.

The output of the receiver 11 is directed to a recording pen of a sweep type recorder 12.

The sweep type recorder 12 records underwater detection signals by mechanically or electronically sweeping a recording pen.
At the same time as the transmission pulse a appears, the recording pen sweeps.

Therefore, on the recording paper, there is a sea bottom line 5 and a school of fish 6 as shown in Figure 2.
Underwater detection records are carried out.

In addition, while underwater detection recording is performed, the fishing net depth display line 7
will also be recorded.

The recording device for the fishing net depth display line 7 is well known, and for example, the device disclosed in Japanese Patent Publication No. 37-3695 can be used.

While underwater detection recording is performed as described above, the output of the receiver 11 is also sent to the submarine pulse selector 13.

The submarine pulse selector 13 selects submarine reflected pulses as shown in FIG. 4C from among the received signals (FIG. 4b) by utilizing differences in wave height values.

The selected seabed reflection pulse C is sent to the gate circuit 14.

The oscillation pulse a of the transmitter 10 is also guided to this gate circuit 14, and the gate circuit 14 is conductive from the appearance of the oscillation pulse a until the seafloor pulse is detected (FIG. 4d).

While the circuit is conductive, the clock pulses sent from the clock pulse generating circuit 15 are passed through as shown in FIG. 2e.

The clock pulse e that has passed through the gate circuit 14 is sent to a counting circuit 16 and counted.

The count value of the counting circuit 16 is reset every time the oscillation pulse a appears.

Therefore, when the submarine pulse C is detected, the counting circuit 16
The counted value indicates the seabed depth.

The count value of the counting circuit 16 is stored in the memory circuit 17 and the comparison circuit 18.
sent to.

The storage circuit 17 stores the count value of the counting circuit 16 each time the submarine pulse detected by the submarine pulse selector 13 is applied via the gate circuit 19.

The count value stored in the storage circuit 11 is sent to the comparison circuit 18 and compared with the count value of the counting circuit 16.

Comparison circuit 18 does not send out an output when the count value of counting circuit 16 is smaller than the value stored in memory circuit 17.

Therefore, when the storage circuit 17 stores 1 in the count value of the first cycle T1, if 2 is smaller than 1 in the count value in the second cycle T2, the submarine pulse P on the second cycle day
When 2 is detected, the numerical value stored in the memory circuit 17 is updated from 1 to 2.

Then, in the third period T3, when the count value of the counting circuit 16 exceeds 3 and the count value of the second period T2 exceeds 2, the comparator circuit 18 sends out the pulse wave f to the terminal P1, and at the same time the output of the terminal P2 is Invert to low level (Figure 4g).

The output g of the terminal P2 is sent to the gate circuit 19, and its low level duration TL shuts off the gate circuit 19.

When the gate circuit 19 is cut off, the submarine pulse P3 selected in the third period cannot pass through the gate circuit 19.

Therefore, the stored numerical value of the memory circuit 17 is kept at 2 as the count value in the second period T2.

Thereafter, the comparison circuit 18 similarly performs the counting circuit 1.
Each time the count value of 6 exceeds the count value by 2, the outputs f and g are sent out.

Note that the low level output g of the terminal P2 is returned to high level at the same time as the counting circuit 16 is reset.

The output pulse f of the terminal P1 of the comparison circuit 18 is sent to the marker pulse generation circuit 20.

Based on the pulse wave f, the marker pulse generation circuit 20
A marker pulse is sent to the recording pen of the sweep recorder 12.

Therefore, since the marker pulse is sent every time the count value of the counting circuit 16 exceeds the count value in the second period T2 by 2, the depth indicated by 2 in the count value is considered to be the shallowest depth, and the second A marker line as shown in the figure is recorded.

As a result of the above, on the sweep recorder 12, as shown in FIG. 2, a record line 7 representing the fishing net depth and a marker line 8 representing the shallowest seabed depth are recorded on the normal underwater detection record. .

Therefore, by monitoring the depth of the fishing net while comparing the recorded lines, it is possible to operate the fishing net without getting it caught on the seabed.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an overview of the purse seine fishing method, Fig. 2 is a diagram showing an example of underwater detection records, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a diagram for explaining its operation. The waveform diagram is shown.

Claims (1)

[Claims] 1. On the underwater detection record that records the underwater detection signal obtained by transmitting and receiving ultrasonic pulses from the bottom of the ship toward the seabed, the depth is expressed as the depth on the underwater detection record, and the depth is the time lapse of the underwater detection record. A recording line representing the depth of the fishing net that changes according to the above-mentioned underwater detection record and a marker line are recorded at the depth position of the shallowest seabed among the seabed records displayed on the underwater detection record, and the fishing net depth is monitored while comparing both recording lines. A fishing net depth monitoring method in a purse seine fishing method characterized by the following.