PH12014000265A1 - Device and method of attracting and exterminating invasive fish - Google Patents

Abstract

A method and apparatus for catching undesirable fish, such as invasive fish species, in particular knife fish found in Laguna Lake, Philippines, wherein the apparatus comprises a fish cage submerged underwater with floating containment for the circuit. The fish cage has at least one opening that serves as the fish entrance when the fish is attracted towards the lure. The attracting device, once acted upon by a force turn on a circuit for emission of electric field underwater. The electric field underwater will exterminate the caught knife fish. The method of catching undesirable fish comprises attracting said undesirable fish to enter a cage through underwater signal generation. The undesirable fish is then exterminated through underwater emission of electric field.

Description

RE -

DEVICE AND METHOD OF ATTRACTING AND EXTERMINATING = bi :

INVASIVE FISH = h

Field of Invention =

The present invention relates to a method and apparatus for catching and exterminating an undesirable fish species in a body of water = by attracting said fish species through propagation of acoustic signals x underwater or through emission of electric field underwater. Specifically, = the present invention relates to the use of sound waves to attract fish and exterminate the same using electricity. More specifically, the present invention relates to the use of sound and electricity to attract and exterminate an invasive fish, in particular, knife fish.

Background of the Invention

The presence of an alien fish species in a native body of water can contribute to the destruction of that water's ecosystem. Once infested by foreign predators, the environmental value of a body of water will diminish. Same goes with the economic value of a lake where fishes are cultured for human consumption for example, since the native fishes on the lake might get extinct.

In the case of Laguna Lake, a very, very important problem is the knife fish, a freshwater carnivorous predatory fish that eats other fishes.

The preys are mostly of very high economic importance in the Philippines, such as tilapia and bangus. Based on the research data of the present -10f28-

jy inventors, a kilo of this fish would mean that it has already eaten seven < kilos of different aquatic animals like shrimps and fingerlings. =o

Certain steps were presented to eradicate the presence of knife c fish, such as the use of manual fishing which is usually done using fishing = strings with hooks on each string and a live fish used as bait for the knife fish. It is known to be effective yet, has its disadvantages. Manual fishing = takes a lot of time and effort for fishermen to set-up the fishing lure. The 2 practice of manual fishing will take every day of each fishermen to prepare. Moreover, using live fingerlings would cost much for the fishermen if considered for a daily basis. There is also no guarantee that the caught fish is still there after sometime. Another problem of manual fishing is securing that the caught fish cannot escape or loose on the bait.

A medium that can help with this dilemma is through the use of electrofishing: the principle of emission of electric field underwater for the purpose of removing a species of organism in a body of water.

Also, the present devices that are used for electrofishing include a boat and a user to be able to run the device. A stand-alone system would help utilize more of the technology.

Using the technology of signal propagation underwater as an attracting medium for the fish is a solution for the manual fishing practice exercised by fishermen. It is known that acoustic signals when propagated underwater can be used as a medium for fish attraction.

Sound can be detected by fishes using several mechanisms which may include any of the following: inner ear, swim bladder, lateral line and skin -20f28-

A . sensory systems. The sound that they hear may be perceived by the fish - as its prey or its food. The sound sensing organs of fishes are not that = sensitive than other animals that is why they sense low frequencies = underwater. Hence, the use of sound waves to attract or lure fishes for = various applications is already known in the art. For instance, US6098331 refers to a device that emits sound and light to lure fish as a means of = attracting fish was disclosed, which uses both acoustic waves underwater © and light to attract fish. However, the present invention may only use ~ sound. In another device, US20110330265, a fishing lure is used through propagation of acoustic waves underwater. While US20110330265 and the present invention both use mere sound, the present application has separate compartment for the buzzer and for the circuitry, and there is no more necessity to have the whole device connected to a motor. In yet another device, US4583313 discloses a fishing lure that also uses underwater acoustic waves and has its circuitry and power source capable of being submerged underwater. The present invention has a separate containment floating above the water.

Overall, none in the prior art discloses a combination of circuits and power source that are submersible in the water and means to exterminate undesirable fish. -30f28-

Object of the Invention <

In view of the above, it is now the object of this present invention to z provide a device and method of controlling invasive fish through attraction 5 by sound and extermination by electricity. . -

It is another object of the present invention to provide a device and > method to control knife fish, an invasive species in Laguna Lake, =

Philippines. = ~

Brief Description of the Drawings

Figure 1 shows the over-all appearance of the invention.

Figure 2 shows the enlarged portion of the fish entrance.

Figure 3 shows a closer look of the attractor and electrodes.

Figure 4 shows the circuits used for the apparatus.

Figure 5 shows the block diagram of the method of catching knife fish.

Figure 6 shows signal frequencies for frequency attraction according to the present invention.

Figure 7 showsa block diagram of knife fish attractor and exterminator

Figure 8 shows an external circuitry of the present invention.

Figure 9 shows a fish attractor circuit according to the present invention.

Figure 10 shows an anode and cathode probe according to the present invention. -40f28-

Figure 11 shows a trigger circuit according to the present invention. ~

Figure 12 shows a voltage producer circuit according to the present invention. @

Are

Description of the Invention os

The present invention is a pioneering work in the field of © exterminating undesirable fish right in the water. In the corresponding = specifications, the present invention shall be described in detail using o knife fish (Chitalaomata), found to be an invasive fish species in Laguna

Lake, Philippines, as the source of experimental and field data. A person skilled in the art will appreciate that the present invention can be used to exterminate other species of fish by merely adjusting some features of the present invention. Also, a skilled person will also appreciate that the method and device as described herein may also be applicable in other bodies of water.

Detailed below is the basic construction of a device according to the present invention.

Shown in Figure 1 is the over-all structure of the invention, herein presented as device 1000 comprising a water containment 5 of the circuits and power source covered by a material 7. The containment is made secured from water by frame 2, 4 with attached floaters 1 to ensure floatation. The submerged part which is the fish cage is made covered by a net 3 that ensures control mechanism for the caught fish to escape.

Attached on the opposite sides of the net are the fish entrance6a, 6b. -50f28 -

0

Inside the fish cage are the submersible parts electrodes and fish attractor oO

It is important to mention that the number of fish entrance 6a may = vary from one to a plurality of openings, depending on the desired design - of the device 1000. =

The enlarged portion of one of the fish entrances are shown in -

Figure 2. The fish entrance is held tight by a round frame 12. Fastened to = the round frame are plastic stripes with pointed strips 11. The fish entrance is conical in shape. The smaller inside part of the conical fish entrance is held tighter by a material 10. The round frame is held tight by a string tied on the four comers of the cage 13.

The closer look of the submerged part inside the fish cage illustrated on figure 3.A pair of output electrodes 15, 14 that will be used to emit electric field underwater. Between the electrodes is the containment of a speaker described herein as buzzer container 17 used for propagation of acoustic signal underwater. The wire 16 enables the communication from the circuit in the water containment 5. The speaker inside the container pertaining to buzzer container 17,can propagate sound wave underwater through the holes 18 on the buzzer container 17.

The block diagram on Figure 4 shows the over-all circuit used for the system to function electronically. To achieve an automatic switch that will enable operation of apparatus only at night time, a light sensitive circuit 20 is used. The buzzer 25 is driven by an astablemultivibrator circuit 23 which is operably linked to said light sensitive circuit 20 by light -60f28-

sensitive switch 21. Saidan astablemultivibrator circuit 23 is equipped with 2 frequency adjust 25. The circuit that drives the condenser circuit 28 is = driven by a triggered timing circuit 27, which is adjustable by timing adjust >26. The buzzer is connected to astablemultivibrator circuit 23. All of the = circuits including the condenser circuit 28 draw voltage from a power = source 19. The electric field is emitted through electrodes 29, 30. =

Said light sensitive circuit 20isimportant to automatically operate © the device 1000 during the time when the invasive fish species is active to - hunt for food. This is important in the case of knife fish, which is a nocturnal predator.

When the apparatus is deployed on the body of the water deeper than the height of the fish cage, the apparatus will float through the help of the floatation medium 1. The circuits on Figure 4 and power source 19 contained inside the containment 5 are secured from water to avoid short- circuiting. The fish cage could be adjusted to a desired height or depth through the frame 2. The submerged part of the apparatus includes the fish cage, the buzzer 25 on a buzzer container 17 and the electrodes 14, 15. The buzzer 25 propagates sound from its container 17 through the water due to the holes 18 on the said container.

As sound travels through water, it attracts fish to enter the cage through the fish entrances 6a, 6b attached on the cage. Once the fish has entered the cage, it is securely caught due to the mechanism of the fish entrance Figure 2 in which the pointed strips 11 form a conical shape wherein the fish cannot escape. -7 of 28 -

When the fish entered the cage, the buzzer container 17 will attract v the fish furthermore to move towards it. Once the fish has created enough IS underwater current to move the container 17, the container will = automatically pull the switch 22 located in the triggered timing circuit on -

Figure 4. The triggered timing circuit 27 will turn on the condenser circuit o 28. The output electrodes 14, 15 submerged in the water will then emit an = electric field for a certain period of time. =

Now referring to Figure 5, there is shown the flowchart presented ~ as method for catching knife fish, comprising attracting the fish to enter the cage 201, which leads to luring the fish towards attractor 202, then electrocuting the fish 203.

In the following examples, the present invention is further described so as to provide a clearer view of its features.

Examples

A. Response of knife fish to different frequencies

In this experiment, signal with a certain frequency was used as the attraction medium for the knife fishes (see Fig. 6). To test what frequency best fits to attract fishes towards the device, the frequency is varied (expressed in Hz). Ranges of frequency from 100 Hz to 1 kHz was used as the operating frequency. Increments of 200 Hz was employed at each of the set-ups. The number of fish is held constant throughout. Also to ensure consistent results, three trials were done. The 6 experimental set- -80f28-

ups will be performed at the same time to neglect other factors that may - affect the condition of the fishes e.g. time of the day. =

Put

In another experiment, three knifefish with different sizes swims at = a random direction inside the aquarium. Table 1 shows the different = pes] frequencies applied to the acoustic sounder with the observation of the = group on how the knifefish responded. =

Table 1. Different Frequencies Applied With Observations °

FREQUENCY (Hz) OBSERVATION

Hz ¢ The three knifefish has a common direction which is towards the speaker o They stayed only near the speaker o The bigger knifefish attracts easily

Hz e They stayed at the center of the aquarium but they are directed to the speaker ¢ The bigger knifefish didn’t attract well

Hz e They stayed more closer to the speaker e They are more attracted to this frequency

Hz o The bigger knifefish attracts more but not as active as when the 20 Hz frequency applied

The other two knifefish didn't attract well

Hz e They are attracted but not too long

Hz and up e No response 10 B. Device construction and circuit variations

A prototype has been constructed according to Figure 7, which shows the internal circuitry of the device of the present invention. Inside the fish exterminator is a lead-acid battery which supplies voltage to two -90f28-

different circuits. The first circuit will emit signal underwater, which can be o

Feed accomplished by an oscillator circuit driving a certain frequency fed unto a = tend buzzer that would convert the oscillations into sound. The second circuit oo that will be connected to the battery source is the voltage producer. The += voltage producer would be comprised of a triggering device that would oo ; strike certain voltage when the fish enters the cage. The circuit - specifications inside the system are specified in Figure 8. I)

Fish Attractor Circuit.As shown in Figure 9, the fish attractor circuit is comprised of a 555 timer circuit that will produce signals with specified frequency. The signal that will be emitted from this oscillator will be converted into sound through the use of a piezospeaker. This piezospeaker will produce vibrations that will lure the fishes. Thus, making this module/circuit useful in attracting the fishes.

Table 2 shows the output of the created fish attractor. The desired frequencies were easily generated and the anticipated waveform is achieved. Thus, the created fish attractor is ready for the experimentation proper.

Table 2. Emitted Frequencies of the Fish Attractor

FrequencyEmitted | =~ Remarks 103.2 Hz Smooth Squarewave Output. Considered for 100 Hz requirement. 301 Hz Smooth Squarewave Output

Considered for 300 Hz requirement. 498.6 Hz Smooth Squarewave Output

Considered for 500 Hz requirement. 703 Hz Smooth Squarewave Output

Considered for 700 Hz requirement. 904.7 Hz Smooth Squarewave Output -10 of 28 -

-

After confirming that the fish attractor is capable of producing the - desired output, the device was subject to testing. The set-up of the ~ experiment done has been discussed from the methodology chapter of = this paper. The result of the experiment done is enumerated on the next - page. = ©

Submersible Probes. As shown in Figure 10, this part of the Hw system is comprised only of copper probes that is wired from the voltage producer. The appearance of the submersible probes are illustrated below.

Trigger Circuit. As shown in Figure 11, a trigger circuit is comprised of a 12V electromechanical relay and an IC NE555 Monostable circuit that will produce a DC voltage at a specified time. Once a pulse has been sent from the probes submerged in the circuit, the monostable circuit will produce a pulse for a certain period and will operate the relay also, at the specified time when the monostable circuit remains on. When the relay turns on, again, a pulse will be sent to another circuit, the PDC producer. The schematic diagram for this circuit is illustrated on the next page.

Voltage Producer.A voltage producer circuit is shown in Figure 12. This circuit will be the most important circuit inside the project because this will be the one responsible for the extermination of a Knife fish. The PDC producer circuit will sense a pulse from the trigger circuit, -110f28 -

once it received a pulse, an IC555 astable circuit will generate voltage ~ from the lead acid battery and then the pulsating DC from the astable = circuit will be fed unto a step up transformer. The high voltage will be = emitted through the submersible probes underwater. =

Fish Exterminator.The fish exterminator is comprised of a winding o of coils in series with some condenser capacitors (0.25uF). This will o produce voltage that goes up to kilovolts. Once the fish has swam near © the probes, there is a big chance of electrocution since there is a switch =o that will trigger the exterminator.

In another embodiment, the Knife fish exterminator is composed of the fish attractor circuit and the fish exterminator itself. The circuit for attraction will attract the fish from a distance. This can be achieved through emission of vibrations from the speaker submerged on the water that will represent as the live bait for the Knife fish. Once attracted, the fish will now enter the extermination zone. It is noted that when the fish entered the extermination zone (which happened to be the cage), the fish cannot escape. This is through the use of a trap door that will be attached at the nets. This will ensure that the fish even when not exterminated, cannot escape. The extermination zone is the inside part of the fish cage structure. In this zone, presence of electrical voltage can be sensed.

Voltage is emitted through the anode ring and the cathode probe submerged in the water.

C. Further Examples -12 of 28 -

.

Examples on Test for Attraction = [

After having the circuit checked for its proper function, it es underwent the actual testing. The test for attraction is performed in + a confined environment wherein different fishes found in the lake o including the Knife fish. Different frequency was used to determine = the frequency of attraction for Knife fish that will not attract other a fishes. ol

The first frequency tested was 0 Hz. The following data were gathered from the experiment.

Table 3. Number of Fishes Trapped at 0 Hz rn Trial Number

Rflefish | 1 | 0 | 1 | 1 | 3

Tilapia | 4 | 3 | 4 | 5 | 1

Dalag | 3 | 3 | 2 [| 1 | 4

Table 4. ANOVA Table for 0 Hz __Groups | Count | Sum | Average | Variance

Rowt | 5 | 6 | 12 [ 12 [

Row2 | 5 | 17 | 34 | 23

Row3 | 5 | 10 | 2 | 3

Rows | 5 | 13 | ae | 1s

ANOVA

Source of

Variation

Betw 4333333 | 2.088353 | 0.142064 | 3.238872 -13 of 28 -

Within Groups 2005 | | TT] rrr

Total | #62] 19 | | | [ ©

Pod

The F critical value at degrees of freedom at a = 0.5 is 3.238872.

Since the obtained F value (2.088353) is less than the critical value, the &

Null Hypothesis is accepted. Therefore, there is no significant difference i between the types of fishes in a particular frequency. ~

Table 5. Number of Fishes Trapped at 100 Hz = fred ron Trial Number + | 2 | 3 | 4 | 5

Kifefish | 1 | 1 | 2 1 0 | 1

Kandi | 1 | 2 | 1+ | oo | 2

Table 6. ANOVA Table for 100 Hz

Groups [Count| Sum |Average| Variance (Rwt | 8] 68] 1 os]

Rowz | 5] Ar] sal As

Rows | 5] 6 dz] or] (Rw4 [| 5] w] 28] 22] [

Source of P-value

Variation | Fe

Em [ro Tee [men

Groups [Within Groups | 188 | 6 | i475 i 10 5 -14 0f 28 -

Co 1 : Sa

The F critical value at degrees of freedom at a = 0.5is 3.238872. -

Since the obtained F value (5.957447) is greater than the critical value, = fod the Null Hypothesis is rejected. Therefore, there are significant = differencesamong the responsesof the different types of fishes in this = particular frequency. co

Table 7. Number of Fishes Trapped at 300 Hz ~ rn Trial Number >

Knifefish | 1 | 2 | 5 [| 3 [ 1

Tilapia | 1 | 2 | 2 | 5 [ 8

Kandui | 1 | 3 | 8 | 1 | 3

Table 8. ANOVA Table for 300 Hz

SUMMARY

_Groups [Count | Sum | Average [Variance

Rowt | 5] ~~ 12] 24] 28] | =

Rw2 | 5] 8] 36] 83]

Row3 | 6] | 32] 82] [

Rwd | 5] #5] 3] 8s]

Source of

Variation

Groups

Within Groups | 111.2] 16] 695 14s] tf

The F critical value at degrees of freedom at a = 0.5 is 3.238872.

Since the obtained F value (0.179856) is less than the critical value, the

Null Hypothesis is accepted. Therefore, there are no significant -150f 28 -

oo 0 differencesamong the responses of the different types of fishes in this . fed particular frequency. =o

Food -

Table 9. Number of Fishes Trapped at 500 Hz on

Trial Number ~ 1 [2 | 3 | 4 | 5

Knifefish | 3 | 3 | 4 | 2 [ 1 | =

Table 10. ANOVA Table for 500 Hz

SUMMARY

Groups [Count] Sum | Average [Variance | [

Rowt | 5] 8] 26] 13]

Row2 | 5] 16] 32] 62]

Row3 | 5] 17] 34] 13] (Row4 | 5] 24] 48] 82]

Source of

Variation 4.333333 | 1.083333 0.384365 3.238872

Groups

WithinGroups | 64] 16} 4] ~~ [ ~~ + rr rr]

The F critical value at degrees of freedom at a = 0.5 is 3.238872.

Since the obtained F value (1.083333) is less than the critical value, the

Null Hypothesis is accepted. Therefore, there are no significant -16 of 28 -

j fp differences amongthe responses of the different types of fishes in this ; particular frequency. = to =

Table 11. Number of Fishes Trapped at 700 Hz o

El Trial Number =

Knfefsh | 4 | 5 | 4 [4 [7 | ITilapia | 1 | o | 3 | 2 | 5Kandui | 3 | 3 [ 4 [| 1 | 2

Daag {| oo | 1+ | 3 | 8 | 7g

Table 12. ANOVA Table for 700 Hz

SUMMARY

Groups [Count] Sum | Average | Vamance

Rowi | 5] 24] 48] Ar

Rowz | 6] 1] 22] m7]

Rows | 5] 13] 2s] 4s (Rw4 | 5] 19] 38] t27]

ANOVA

Source of Tr

Variation

Groups

WithinGroups | 776| 16 485] (Total ~~ [988s] wf [

The F critical value at degrees of freedom at a = 0.5 is 3.238872.

Since the obtained F value (1.439863) is less than the critical value, the

Null Hypothesis is accepted. Therefore, there are no significant -17 of 28 -

J g differencesamong the responses of the different types of fishes in this + : [2 particular frequency. = [i ; = fa ‘

Table 13. Number of Fishes Trapped at 900 Hz - : . Trial Number =

Knfefsn | 2 | 4 | 3 | 4 | 3 | ©

Tapia | 1 | + | 3 | 6 | 4 | =

Kandui | 2 | 5 [| 7 [ 2 | 3

Table 14. ANOVA Table for 900 Hz

SUMMARY

Groups [Coun] Sum | Average | Vamance

Rowi | 8] | 32] or (Row3 | 5] 19 38] 47] (Rows [| 5] 7] 14 3] [|]

ANOVA

Variation | ewe | Pe

Variation

Groups

Wihin Groups | #48| 16] 28 | | 1

Tol [eos] de]

The F critical value at degrees of freedom at a = 0.5 is 3.238872.

Since the obtained F value (1.875) is less than the critical value, the Null

Hypothesis is accepted. Therefore, there is no significant difference : among the responses of the types of fishes in this particular frequency. -18 of 28 -

FI ho

A : os

Table 15. Number of Fishes Trapped at 1000 Hz =

Soe rn Trial Number oo

Knfefish | 8 | 5 | 4 | 5 | 8 | ~

Kandui | 1 | 1+ | 2 |} 5 [| 2

Daag [ o | 1+ [1 | 3 [ 4 | J

Fd

Table 16. ANOVA Table for 1000 Hz

SUMMARY

(Rows [| 8 1} 22 27} (Rows | 5] of 18] 27

ANOVA

Varaon | oo | | MF | Pee | Fe

Variation 37.35 3 12.45 3.890625 0.029029 3.238872

Groups sss] wo]

The F critical value at degrees of freedom at «= 0.5 is 3.238872.

Since the obtained F value (3.890625) is greater than the critical value, : the Null Hypothesis is rejected. Therefore, there are significant differencesamong responses of the types of fishes in this particular frequency. ~190f28-

:

Some factors that may affect the behavior of the fish were w neglected such as the water temperature, the depth of the water and the = water quality. =

Since the frequencies of 100 Hz and 1000 Hz had shown += significant differences in the responses of the fishes, these frequencies = underwent another statistical tool: the t-test. -

For 100 Hz =

Table 17. Number of Fishes Trapped at 100 Hz >

A

ER Trial Number + [2 | 3 | 4 [| 5 _Knifefish [| 1 | 1 [ 2 | © | 1

Tilapia | 4 | 5 [ 3 [ 3 | 2

Kandui | 1 | 2 [ 1 [| oo | 2

Daag | 3 [| 5 [ 3 | 2 [| 1 |]

Table 18. T-test Results for 100 Hz t-Test: Two-Sample Assuming Unequal Variances (@100 Hz) ] 1 Knitefish [Mean ~~ 00 4] 34

Variance ~~ [05] 13 1

EE =)

P(T<=() onetail 0002504957] -200f28-

t Critical one-tail 1.894578605 =

P(T<=t) two-tail 0005189913] | - t Critical two-tail 2364624252 | - fread

Jom oo >

The table above shows the result of the t-test done between Knife fish and Tilapia at 100 Hz. The t-test results to a negative value which : means that the mean of the Tilapia has a greater mean than the Knife fish. At this frequency, the tilapia is more attracted than Knife fish, therefore, this frequency is rejected if the device is used in a place where

Tilapia is abundant.

Table 19. T-test Results for 100 Hz t-Test: Two-Sample Assuming Unequal Variances (@ 100Hz) [Mean 000000 a 0 12

Variance | 05] = 07 tStat | 040824829]

P(T<=t) one-tail 0346899919] | 1 t Critical one-tail 1859548038 | |] -210f28- BN

P(T<=t) two-tail 0.693799838 t Critical two-tail 2306004135] - bo

The table from the last page shows the t-test result for Knife fish = and Kanduli at 100 Hz. It can be seen that the taathat is calculated returns = a negative value. Again, at this frequency, the Kanduli is more attracted 00 than Knife fish. This means that the device with 100 Hz frequency when placed in a fish pen with Kanduli in it would not be effective for attracting =

Knife fish. =

Table 20. T-test Results for 100 Hz t-Test: Two-Sample Assuming Unequal Variances (@100 Hz)

Knifefish | Dalag [Observations | ~~ 5] 5

EE DY] tStat 000] 2449489743]

P(T<=t) one-tail 0024912631 t Critical one-tail 1943180281]

P(T<=t) two-tail 0049825263 t Critical two-tail 2446911851

The table from the previous page shows the result of the t-test done at 100 Hz. The calculated tux retums a value of negative which means that the mean of the Dalag is greater than the Knife fish. At this frequency, the Dalag is more attracted than the Knife fish.

Co

For 1000 Hz -220f 28 -

Co: ~ rn Trial Number =

Knifefish | 8 | 5 | 4 | 5 | 6Tilapia | o | 1+ | 2 | 2 [| 3 | i.

Kandui | 1 | 1 | 2 | 5 | 2 | @

Table 21. Number of Fishes trapped at 1000 Hz ” J pt

Co

Table 21. T-test Results for 1000 Hz ot-Test: Two-Sample Assuming Unequal Variances (@1000 Hz)[Mean | = 56 16]gf 74714045208]

P(T<=t) one-tail 0001086284 t Critical one-tail 1.894578605]

P(T<=t) two-tail 0002172588 = t Critical two-tail 2364624252 | :

The table above shows the result of the t-test done for 1000 Hz.

The calculated tsi Which is 4.714 is greater than terial (wo taiy Which means that there is a significant difference between the means at 5% level.

Therefore, at this frequency, it can be said that the device can actually attract Knife fish and not Tilapia at 1000 Hz signal frequency.

Table 22b. T-test Results for 1000 Hz -230f 28 -

) . . t-Test: Two-Sample Assuming Unequal Variances (@ 1000 Hz) In ro - t-Test: Two-Sample Assuming Unequal Variances (@1000 Hz) o

TT Kobetsh | Kamawi (Mean ~~ 52] 22]

I t Stat 2651650429

P(T<=t) one-tail 0014590493 t Critical one-tail 1.850548038

P(T<=t) two-tail 0029180986 t Critical two-tail 2.306004135

The table above shows the result of the t-test done for 1000 Hz.

The calculated ts Which is 2.65 is greater than teiseal gwo tain=2.30 which means that there is a significant difference between the means at 5% level. Therefore, at this frequency, it can be said that the device can actually attract Knife fish and not Kanduli at 1000 Hz signal frequency.

Table 22c. T-test Results for 1000 Hz -240f28-

Co

Knife fish Dalag - (Mean 0! 0 s2] 0 18F

Observations | ~~ sf 5] os t Stat 300520382

P(T<=t) one-tail ooos4e8421t Critical one-tail 1.859548038 ~P(T<=t) two-tail 0016936842]t Critical two-tail 2306004135]

The table above shows the result of the t-test done for 1000 Hz. ”The calculated tgs which is 3.005 is greater than tetical (wo taip = 2.30 which means that there is a significant difference between the means at 5% level. Therefore, at this frequency, it can be said that the device can actually attract Knife fish and not Dalag at 1000 Hz signal frequency.

Based from the previous statistical tests results, the frequency that has shown satisfactory results in attracting the Knife fish is 1000 Hz.

Thus, making it as the frequency of operation for the device. :

In yet another experiment, a test for attraction revealed that for a frequency of 1 kHz, the Knife fish is attracted. The over-all mean of the : trapped fish exhibits effectivity of the created prototype. There were differences in the number of the fish that were not intentionally attracted ; but this is negligible. The test for extermination on the other hand, showneffectivity in killing the Knife fish.

Examples for Test for Termination -250f 28 - i oo Co

The Knife fish once attracted and had entered the cage cannot “ fro ] escape. Its movements inside the fish cage is sensed by a simple switch + trigger by the way of having a fish lure. In the experiment performed by =o poe i the proponents, the fish that has entered the cage has bumped into the += simple trigger inside the cage. -

The table below shows the result of the test for extermination. ~

Table 23. Number of Fishes Exterminated - a Trial Number

MN TT Ts [as (Knfefish | 7 | 6 | 2 | 3 | 5

Tapa | © | 1+ [ oo [| oo | 4

Kandi [| 0 | 4 | 1 | oo [| 1

Daag [| 1 [ o | 2 [| 1 | 0 |]

Based from the table above, it can be observed that the test for extermination revealed that majority of the fishes that were exterminated are Knife fishes. This proves that the device is capable of exterminating

Knife fish compared to other fishes that may be affected by some other : factors neglected in the experiment. -26 0f 28 - !

Claims (3)

Claims iN .

1. Device for attracting and exterminating an invasive species of = fish comprising a containment submerged underwater, said = containment further comprising a light sensing means that is = activated during the time when said invasive species of fish is ~ active for predation. Ee a

2. Method of attracting and exterminating an invasive species of fish comprising the steps of:

a. Attracting the fish to enter the cage,

b. Luring the fish towards an attracting means,

c. Electrocuting the fish.

3. Method according to Claim 2, characterized in that a light sensing means operates a device to attract and exterminate said invasive species of fish. -27 of 28 - :