• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    Abstract Disclosed is a method of deterring mammals, and in particular sea lions, comprising configuring an acoustic deterrent system to emit an acoustic 5 signal having characteristics which cause said mammals to be repelled from an area. The method comprises eliciting an acoustic startle response reflex in said mammals by emitting an acoustic signal which has an envelope with a slope of at least 0.8 dB /ms. The acoustic signal may also span a frequency band having a lower limit greater than 2kHz. Fig. 1 0.6 pain perception, y = x 3 -loudness, y = x 012 4 0 1 2 3 4 5 magnitude of physical stimulus Fig. 2
    公开号:AU2013204487A1
    申请号:U2013204487
    申请日:2013-04-12
    公开日:2014-04-03
    发明作者:Thomas Gotz；Vincent M. Janik
    申请人:GENUSWAVE Ltd；
    IPC主号:A01M29-16
    专利说明:
    1 Acoustic Deterrence of Mammals, and Particularly Sea Lions The present invention relates to acoustic deterrence, and in particular to an 5 acoustic deterrent device and methods specifically for deterring sea lions. Worldwide, farming of marine and diadromous finfish species has experienced tremendous growth rates, showing a ten fold increase over the last three decades. This increase in potential food resources presented in a 10 marine environment has brought about increased interactions with predatory species. One common group of predators is marine mammals who exploit food resources depending on their profitability and potential costs, which include dive depths as a major factor. The shallow depth of fish farms thus makes them particularly attractive to predators. 15 In particular, predatory behaviour of pinnipeds, particularly sea lions, is a major concern, causing a variety of economical and market related risks for the fish farm owner. Accordingly, there is much interest in developing anti predator control methods. 20 These methods include net modifications, lethal or non-lethal removals, population control and aversive conditioning. However, each of these methods has their own drawbacks. For example, the addition of a second net can cause tangling of predators and non-predatory species; and lethal 25 removals as well as population control may have an impact on populations and raise ethical concerns over the treatment of the animals. Culling of higher order predators can also have negative impact on predation rates by other predators, for example, pinnipeds forage on predatory fish species around the net pen which in turn potentially feed on aquaculturally 30 important species. Also, emetic aversion conditioning requires that 2 individuals learn to associate treated fish with sickness, and this can be hard to achieve when predator numbers are high. One anti-predator control method that avoids these pitfalls is the use of 5 acoustic deterrent devices (ADDs). These have traditionally been considered to be a benign solution. However, they do present certain problems with respect to the effects they have on other marine wildlife and with habituation, where a target species motivated by a food source ceases to be deterred by the acoustic signals. 10 If the source level of an ADD is sufficiently high it can cause temporary or permanent hearing damage both to the targeted species and to other wildlife, and the noise pollution is in general an environmental hazard. Further, both targeted and non-targeted species can be excluded from their natural habitat 15 within a wide radius of the fish farms. These concerns have led some governments to restrict or even ban the use of ADDs. A further problem is the habituation of the target species to the sound. In extreme cases, the sound which is intended to be aversive acts as a "dinner 20 bell" and actually serves to attract predators, rather than deter them. Also, if predator sounds are used as an aversive noise, habituation is dangerous for the target species once they had returned to their normal habitat. Also, existing power levels and signal cycles impose heavy duty cycles on the 25 batteries used as power sources in the transducer units. Accordingly, it would be desirable to provide an acoustic deterrent device that is highly effective, but does not damage the environment, is species specific for sea lions or Australian fur seals and avoids habituation. 30 3 According to a first aspect of the present invention there is provided a method of deterring mammals comprising configuring an acoustic deterrent system to emit an acoustic signal having characteristics which cause said mammals to be repelled from an area, by eliciting an acoustic startle 5 response reflex in said mammals, wherein the acoustic signal has an envelope with a slope of at least 0.8 dB /ms. "Deterring" is taken to mean discouraging or preventing a mammal from entering into or staying in a particular area. The startle reflex response is a 10 physiological reflex in mammals to particular sounds, which often initiates flight from the sound, thereby repelling mammals from a location in the vicinity of the sound. The startle reflex response should not be confused with an animal or person being "started" or "startled" in the colloquial or everyday sense. 15 Other optional aspects are as described in the appended dependent claims. According to a second aspect of the present invention there is provided an acoustic deterrent device comprising a signal transducer arranged to 20 transmit acoustic signals in accordance with the method of the first aspect. According to a third aspect of the present invention there is provided an acoustic deterrent system comprising a control unit, a power source, amplifier and transducer means, co-operable to perform the method of the 25 first aspect. According to a fourth aspect of the invention there is provided control software executable on a computer so that the computer is operable as the control unit of the fourth aspect. The control software can be provided 30 recorded on a computer readable medium, or made available for download.
    4 According to a fifth aspect of the present invention there is provided an acoustic signal which incurs a startle reflex response in mammals in order to deter them. The acoustic signal can be produced and used in accordance 5 with any of the previous mentioned aspects. Brief Description of the Drawings The present invention will now be described, by way of example only, with 10 reference to the accompanying figures in which: Figure 1 shows an acoustic deterrent system according to an embodiment of the invention; 15 Figure 2 shows a representation of Stevens Law; and Figure 3 which is a plot of signal power (re auditory threshold) in decibels versus time in milliseconds, showing the envelope of an acoustic signal such as that emitted in accordance with an embodiment of the invention, and the 20 slope of the envelope. Detailed Description of the Embodiments A variety of Acoustic Deterrent Devices (ADDs) are available to reduce or 25 stop predation of pinnipeds on finfish farms. These include for example the Ferranti-Thomson Mk2, Mk3 and 4X Seal scrammers, the Ace-Aquatec "silent scrammer", the Airmar Technology Corporation dB Plus II, the Terecos Limited type DSMS-4 and the Lofitech "universal scarer" or "seal scarer".
    5 As seen in Figure 1, an ADD comprises a power source 10 (usually marine batteries), a control unit 12, an amplifier 14 and an underwater transducer (speaker) 16. The embodiment shown in Figure 1 shows all of the power source, amplifier and transducer being below the water surface 18, but it will 5 be appreciated that any suitable arrangement of these components can be used, for example one or more of the power source and amplifier may be situated remote from the transducer 16 and as such could be above the surface 18, or as a further example, all the components could be underwater, not just the transducer. 10 The control unit 12 typically includes a computer that has a number of sound files stored on it which generate signals to be relayed through the amplifier 14 and broadcasted into the water. The control unit 12 also controls the timing of the sounds which are played. 15 Sound being played is characterised by its source levels, rise time, frequency composition and duration. Additionally, the inter-sound interval determines how quickly sounds follow each other. 20 The "source level" (SL) is a measurement of the acoustic output of the device at 1m distance. In the following text, source levels and received levels in general will be denoted in units of decibels (dB) measured with reference to 1tPa, unless a specific statement or context implies otherwise. The "rise time" is a measure of how long it takes for an acoustic signal or pulse to reach 25 its maximum amplitude. The term sensation levels refers to the sound pressure level by which a stimulus exceeds the species' auditory threshold (received level minus hearing threshold). Received level refers to the sound pressure level that reaches the animal's ears (source level minus transmission loss). The term sound exposure level (SEL) refers to the energy 30 flux density (being a function of sound pressure level and exposure time) and 6 is given by SEL = SPL + 10 log2o (exposure time) where SPL is the sound pressure level of a received sound. When designing an acoustic deterrent device there are various factors that 5 should be taken into account, including ecological impacts (on both target and non-target species), and problems and potential solutions. Ecological ImDacts 10 Species of concern Any animal that can perceive acoustic sounds can be potentially adversely affected by them. These affects can be wide ranging. For example, the Ferranti-Thomson 4X ADD has a power of over 200 dB re 1tPa at 25KHz and 15 the signals from this device can be audible to a harbour porpoise (Phocoena phocoena) for up to 10km. Hearing damage 20 ADDs could cause hearing damage to target species and to non-target species, which leads to adverse effects on individual animals and the population in general. Hearing damage would also reduce the potential efficiency of the ADD as it would become less audible to the affected predators. 25 Hearing damage first occurs as a temporary shift of the hearing threshold (TTS) that is fully recoverable after a few hours or days. However, exposure to higher intensity or longer duration acoustic stimuli can cause chronic damage and lead to a permanent threshold shift (PTS). In its mildest form this permanent hearing damage only affects the outer hair cells of the 30 auditory system. This leads to a very subtle rise of the hearing threshold, but 7 also destroys the cochlea amplifier causing a diminishing of the dynamic range and a loss of the ability to discriminate between frequencies. Hearing damage in any form is a function of sound pressure level (SPL) and 5 exposure time. A sound with a short duration can be safely presented at a higher SPL than a longer one. It has been suggested that stimuli of equal acoustic energy cause similar damage. The sound exposure level (SEL) or energy flux density has been suggested as a measure for defining safe exposure levels, where SEL = SPL + 10 logic (exposure time). However, data 10 on terrestrial mammals seems to suggest that the equal energy criterion underestimates the risk of hearing damage, at least for sound pressures close to a critical level of about 135 dB above the hearing threshold. No direct measurements of PTS are available for marine mammals, so 15 conclusions have to be drawn based on extrapolation from TTS data or human damage risk criteria (DRC). Temporary threshold shift (TTS) 20 Studies on odontocetes have found that sound exposure levels between 193 and 213 dB re 1pPa 2 s' can cause mild to moderate, but fully recoverable TTS. These values are about 100-130 dB re 1pPa above the hearing threshold of the tested individuals (sound exposure level -sensation level) . Studies on odontocetes have been used to estimate TTS ranges of ADDs for 25 single transmissions (i.e. short pulses) based on equal energy assumptions. Given these assumptions an Airmar dB Plus II device (having a source level of 192 dB re 1pPa) would only cause TTS in bottlenose dolphins at distances closer than 1m while a high power (200 dB re 1pPa) Ferranti-Thomson 4X device would have a TTS zone of about 2-3 meters. TTS zones for the 30 harbour porpoise would be 2-3 and 14-25 meters respectively.
    8 These TTS zones widen markedly for longer exposure times. Assuming an average sound exposure level-sensation of 115 dB re (hearing threshold in Pa) 2 -s the respective onset-TTS (SELSL) levels would then be 152 dB re 5 1pPa 2 -s, 158 dB re 1pPa 2 -s 145 dB re 1pPa 2 -s for the mentioned species respectively. Assuming spherical spreading, absorption losses of 0.7 dB per km continuous exposure to a 10s at 193 dB re 1 piPa (SEL=203 dB re 1 piPa 2 s) would therefore result in TTS zones of 345m for the harbour porpoises, 175m for the bottlenose dolphins and over 748m for killer whales. 10 Permanent threshold shifts (PTS) Human damage risk criteria (DRC) states that PTS will be caused at or after a critical value of 130 dB above the hearing threshold. Studies of terrestrial 15 mammals have confirmed that such hearing damage occurs quickly when exposed to sound pulses at 130-140 dB above the hearing threshold. Available data on harbour porpoises suggests that a PTS damage zone for harbour porpoises would be 30m, with a similar result for killer whales (Orcinus orca). 20 Extrapolation of thresholds or PTS from TTS data is problematic, but due to a lack of direct measurements in marine mammals and the difficulties of extrapolation from human DRC such an attempt is justified. Data on humans suggests that exposure levels causing TTS of 40 dB or more carry some risk 25 of causing a PTS. A temporary threshold shift that exceeds 40 dB carries some risk to become permanent and correlates with an increase of the sound exposure pressure level by 20 dB beyond the sound pressure level that causes onset TTS). When applying a sound exposure sensation level criterion of 115 dB re (hearing threshold in Pa) 2 -s and adding respective auditory 30 thresholds then a 10s emission from a seal scarer with a source level of 193 9 dB re 1pPa would the following damage zones: 18m, 35m and 79 m for the bottlenose dolphin, harbour porpoise and killer whale respectively Long term exposure over months or years requires even more conservative 5 criteria. Accepted noise levels at human industrial workplaces are 85 dB above the hearing threshold zone. An even more conservative 80 dB threshold would be exceeded within a zone of over a kilometre radius for the Airmar dB Plus II device which has a source level of 192 dB re 1tPa. In areas with dense fish farming activity, animals could be exposed to these levels for 10 extensive amount of time. As studies on humans have shown, initially harmless TTS can turn into PTS if recovery periods are insufficient or non existent. Hearing in fish is less well studied in general. However, fish are sensitive to 15 lower frequencies than pinnipeds or cetaceans and studies on fish have been carried out using signals with frequencies of 500Hz or less, which is within the most sensitive hearing range of fish. This makes it difficult to draw conclusions about the effects of higher frequency signals. However, increasing TTS with increasing exposure levels and weak temporary shifts 20 have been demonstrated in some studies. Masking It is important that the sounds produced by ADDs do not overlap with 25 communication or echolocation sounds used by target or non-target mammals. For a signal to be masked the detection of the signal should be influenced by a second sound - the masker, which will usually be centred at the frequency 30 of the signal. It has been well established that the masking effect is 10 dependent on the bandwidth of the masker until it reaches a so-called critical bandwidth. Therefore, noise only masks a signal if it contains similar frequencies to the signal of interest. Critical bandwidths in marine mammals are generally below 10% of the signal centre frequency. 5 Additionally, masking effects are attenuated if the masker and the signal come from different directions. In harbour seals minimum distinguishable audible angles for clicks are 4.5 degrees, and in bottlenose dolphins they are less than 3 degrees. Therefore, it seems that cetaceans and pinnipeds may 10 successfully avoid masking effects, but the potential to affect other marine mammal communication networks is high. Little is known about the impacts of masking on fish. However, their hearing abilities are generally less sophisticated than those of mammals which could 15 make them more prone to masking effects. Habitat exclusion As mentioned above, ADDs for seals have been shown to exclude non-target 20 marine mammals (i.e. cetaceans) from their habitat. This has been confirmed by several studies. Problems and solutions 25 Duty cycles If an existing ADD is used continuously, noise pollution is substantial. Duty cycles range from 3% in a Ferranti-Thomson model up to 50% in other designs. 30 11 Devices can include additional predator detectors so that the ADD is only triggered when a predator is present. This can be via direct detection of a predator, or from the analysis of the motion patterns of fish in the pens of the fish farm. Such systems are desirable and can be incorporated in 5 combination with the invention. Frequency bands The ADD system designed to illicit a startle reflex response described in 10 W02008/129313 specifically refers to the use of sounds with lower frequency bands, such as between 200Hz and 2KHz as pinnipeds' hearing is normally considered to be more sensitive than odontocetes' hearing at these frequencies. However, the inventors have determined that this is not an ideal frequency range where sea lions are the target mammal to be deterred. 15 Some ADDs operate at frequencies close to the most sensitive hearing of pinnipeds, that is between 20 and 30 KHz. However, these frequencies are not suitable because hearing thresholds in odontocetes are even lower in this band. Furthermore, most odontocetes have their most sensitive hearing in 20 the ultrasonic range between 30 and 50 KHz. It would therefore be desirable that no ADD should produce substantial energy above 20KHz. However, this is the case for the majority of available ADDs. Perception of received sound pressure levels 25 The general paradigm applied in current ADDs is that a high source level is expected to cause physical discomfort or pain and therefore results in an animal leaving an area. However, there are several problems involved when operating at the upper end of the dynamic range of an animal. Figure 2 30 shows a qualitative representation of Steven's Law where the magnitude of 12 sensation is plotted against a magnitude of physical stimulus for a sound. Two curves are shown, one shows the loudness of a sound while the other shows the pain perception. 5 Steven's Law gives an approximate model for the general relationship for the magnitude of sensation, T, and the magnitude of a physical parameter, <p, as follows: T = k(p -po)" 10 k is a constant, and <po is the lowest perceivable physical stimulus (threshold) and m is a modality specific coefficient determining the essential shape of the function. In the human auditory system, m is equal to 0.6 (this value is illustrated in Figure 2). 15 It can be seen that, as a generalisation, adding a defined sound pressure value (in Pascals) to the high sound pressure stimulus leads only to a small increase of the perceived loudness while adding the same sound pressure value to a low sound pressure stimulus would lead to a stronger increase in 20 perceived loudness. Thus, an increase in sound pressure in the upper range of the curve in Figure 2 disproportionately increases the risk of damaging the auditory system without yielding a much stronger aversive effect. The perceived loudness of a sound is generally measured on the sone scale, a 25 doubling of which reflects a doubling of perceived loudness. One sone is defined as a sound that is perceived as equally loud as a 40 dB re 20 tPa tone at 1kHz in air for humans. The perceived loudness in sone (L) can be calculated by the equation: L = 0.01 (p-po)- 0
    .
    6 , where p is the sound pressure in tPa and po is the effective threshold.
    13 In light of the potential hearing damage caused by the ADDs, the inventors recommend that no attempt should be made to increase the source levels of current ADDs or to use devices that emit sound continuously at source levels 5 at the upper end of the dynamic range close to the suspected pain threshold. Additionally, the critical level of 135 dB above the threshold should not be exceeded at reasonable distances from the sound source as the risk of damage originating from single short term exposures is substantially increased above this level. 10 A safe exposure level for seals would be a perceived sound exposure level of about 126 Pa 2 s-1 above the threshold, which equals a SEL of 183 dB re 1 ptPa 2 s-1. This was calculated for a 2.5KHz tone played to a harbour seal. 15 Recovery times in sound exposure scenarios that do not cause a TTS should be at least ten seconds to avoid accumulation of acoustic trauma. However, acceptable exposure levels should be calculated for the species with the most sensitive hearing in the frequency range used by the ADD. 20 Typesofsounds The proposed sound uses the mammalian startle response to elicit a flight. Startle sounds that are able to induce the startle reflex response so as to provoke a flight response and repel mammals from a location, exploit an 25 oligo-synaptic reflex arc related to emotional processing in the brain. In order to elicit the startle reflex response method it is proposed to synthesize and project stimuli with specific acoustic properties; none of which are employed in the current state of the art. In particular, the noise 14 stimuli has characteristics particularly chosen to elicit a startle reflex response in sea lions. In an embodiment, the deterrence system projects single, isolated pulses at 5 random intervals with a sharp onset time. In an embodiment, the pulses may consist of randomly synthesized white noise, which may be consecutively filtered to reflect the respective frequency band. The pulse duration may be shorter than 500ms, or shorter than 300ms, or 10 shorter than 200ms. The pulse duration may be in the range of 10ms to 500ms, or 100ms to 300ms. It is preferable that each interval between isolated pulses is longer than 100ms or longer than 500ms. In particular intervals between isolated pulses 15 longer than 1s, or longer than 10s may be preferable. In an embodiment, this interval may range between is to 60s or 10s to 60s. In another embodiment the higher end of these ranges may be greater, say 120s. In a specific embodiment, pulses may be emitted at varying intervals at a rate of roughly 2 pulses per minute. This helps sensitize the mammal to the sound, as 20 explained in greater detail below. Shorter intervals may cause "pre-pulse inhibition". This is the observed effect where, when there are (for example) three pulses in short succession and the first pulse does startle, the second pulse actually inhibits a startle response to the third pulse. 25 In an embodiment, the amplitude of the sound exceeds the animals' (here a sea lion) auditory threshold by more than 80 dB within 5Oms of its onset. Hence, projected sounds may have onset/rise-times between zero and 100ms at sensation levels (above auditory threshold) of at least 80 dB. In embodiments, these rise times may be between 0 and 20ms, 0 and 10ms or 0 30 and 5ms. In a specific embodiment the rise time may be between 2ms and 15 Sms. The rise time may be generalised such that the acoustic signal has an envelope with a slope of at least 0.8 dB /ms (decibel/millisecond). The envelope of an acoustic signal is a boundary curve that traces the signals amplitude. The envelope represents the magnitude of the 'analytic signal' 5 which is obtained by using a Hilbert transformation. This is illustrated in Figure 3 which is a plot of signal power (re auditory threshold) versus time, showing the envelope of the acoustic signal, and the slope of the envelope. The bandwidth of the sound may be as wide as possible with the desired 10 frequency-range and, in an embodiment, may span at least one third of an octave. The sound pulse may span a frequency band (20dB bandwidth) in the range of 4kHz to 20kHz. More specifically it may span a frequency band of 4kHz to 12kHz (centred around 7kHz: a 7kHz pulse) or span a frequency band of 4kHz to 18kHz (centred around 10-11kHz: a 10kHz pulse). 15 The startle reflex response is a physiological reflex to sound levels and has been shown to occur at specific source levels above and hearing threshold of a particular species. It is elicited through a relatively simple reflex and the underlying mechanisms are likely to be shared by mammals. The startle 20 reflex response is usually followed by a flee response in a direction away from the source of the sound. The startle reflex response has been well documented in rats, but mostly for experimental purposes to study the neuronal basis of simple learning behaviours (e.g. sensitisation and habituation). It has not been used in practice for a mammal deterrent device, 25 and has furthermore never been applied to the deterrence of marine mammals in a fish farm or any other practical environment. The inventors' research has shown that repeated exposure to the certain sounds leads to increased responsiveness i.e. target animals become more 30 likely to exhibit flight responses and start avoiding the area where they heard 16 the sound ('sensitisation') [Gotz, T & Janik, VM 2011, ' Repeated elicitation of the acoustic startle reflex leads to sensitisation in subsequent avoidance behaviour and induces fear conditioning ' incorporated herein by reference, BMC Neuroscience 12: 30]. This is the opposite of what has been found in 5 current systems where animals get used to the sound and avoidance responses wane. Also, where there is a strong food motivation (known to the target mammal) in an area, a target mammal may not necessarily be repelled by the first pulse of the startle noise, even if startled (i.e. the food motivation overcomes the startle reflex response). The sensitisation effect of the startle 10 sound proposed herein means that, if this is the case, the mammal will be repelled (and will stay away) after a subsequent exposure to the startle sound (i.e. after one or more subsequent pulses). An additional benefit of the proposed startle sound is that it can comprise 15 short, randomly spaced pulses with a low duty cycle. Therefore the energy consumption of the system can be very low, compared to current ADDs, and battery life increased. Each pulse may, for example, be less than 10 second, or less than 1 second. Similarly the duty cycle may be less than 25%, or less than 10%. 20 It has also been observed that broadband signals are perceived to be louder than narrowband signals when played at the same source level, and this can be used to increase the perceived loudness without actually increasing the source level. Thus, for both startle and aversive sounds, a signal is 25 intentionally constructed to be as broadband as possible within the designated frequency band.
    17 Preventing habituation Motivational factors clearly influence responses to sound exposure. An acoustic deterrent tested on well fed captive sea lions gives better 5 performance results than one tested on foraging sea lions around real fish farms, as food motivation would give sea lions a higher tolerance for loud sounds. Habituation could be avoided or at least delayed by a triggering method 10 which only plays sounds when sea lions approach. This can be triggered by the detection of a sea lion itself or by the analysis of changing patterns of motion in the swimming of the fish indicating that a predator is present. Using highly variable sound types should also prevent habituation, but no empirical data for animals in the feeding context are available to support this. 15 Studies in the startle reflex response of rats have indicated that habituation is not caused by an increase of the perceptional threshold eliciting the startle reflex response, but by a change of the slope of the function of the difference between an input signal (SPL) and an output signal (magnitude of response). 20 This supports the dual process theory of habituation meaning that the response to a repeated stimulus is influenced by a decreasing (sensitisation) and increasing (habituation) component. For ADDs this would mean that the source levels would have to be increased beyond the initial levels to yield the 25 same response as before habituation occurred. Given the abovementioned problems associated with high SPL noise, this is not a good solution. Ideally, one would aim to replace habituation by sensitization to a sound stimulus. This could be achieved by using high intensity sound intermittently 30 to sensitize a low intensity stimulus. Sensitization through electric 18 stimulation is not feasible since the seal would have to be very close to yield an effect. In one embodiment, the acoustical stimulus is repeatedly negatively 5 reinforced by an aversive stimulus. Classical conditioning paradigms could be used here. An unconditioned stimulus (e.g. startle sound) causing an unconditioned response (e.g. startle reflex response) is associated with a conditioning stimulus (e.g. an artificial acoustic signal with no biological meaning) which is then able to cause the conditioned response consisting of 10 the same behavioural pattern as the unconditioned response (e.g. startle and flee). Experimental Results 15 The test stimuli comprised filtered noise pulses with an effective rise-time of 2ms-Sms projected at a source level of approximately 180 dB re 1pPa. These pulses consisted of randomly synthesized white noise which was consecutively filtered to reflect the respective frequency band. The pulse duration was 200ms and pulses were emitted at varying intervals with 20 roughly 2 pulses per minute. Exposure periods were 5 minutes long in some experiments and 20 minutes long in others. Tests were conducted with sound pulses covering 3 different frequency bands: a) A sound/startle pulse centred around 7kHz (7 kHz pulse), 20 dB 25 bandwidth: 4khz to 12 kHz b) A sound/startle pulse centred around 10-11 kHz (10 kHz pulse), 20 dB bandwidth: 4 kHz to 18kHz c) The sound pulse used in the deterrence system described in W02008/129313. This is a pulse centred at 1 kHz with a bandwidth of 500 19 Hz to 2 kHz. Note that due to technical limitations this pulse was only played at a level 172 dB re 1pPa. Trials were conducted around two floating pen structures (Mission Bay & San 5 Diego Bay) which are used to keep bait fish for sports fishing. Sea lions (here Californian sea lions) use these bait docks to haul out and occasionally forage on escaped fish. Animals were flushed into the water and movement responses were monitored around the pens. Exposure to the 7 kHz and 10 kHz pulse resulted in clear avoidance responses as seen by a reduction of the 10 number of animals within 30m of the loudspeaker. Sound exposure also seemed to cause some groups of animals to leave the general area. The 1 kHz pulse was apparently less effective for deterring sea lions. Controls were carried out to quantify the general behaviour of the animals in 15 the water i.e. to detect if animals would leave the area anyway even if no sound was placed. During controls the same procedures were carried our as in exposure trials except that no sound was played during the designated 'sound periods'. The controls show that animals would have normally stayed in the vicinity of their preferred haulout place during the 15 minute following 20 the "pre-observation period", that is the 5 minute period immediately before the sound being emitted. Hence, the effect can be attributed to sound exposure. The results also show that the number of animals declined dramatically 25 during the 20 minute sound exposure period. Overall, this decline became stronger in consecutive 5 minute exposure periods. This was confirmed by visual observations of clearly identifiable groups which either abandoned the area around the pens completely or found alternative haulout space. Sea lions did not return to the area around the loudspeaker during the post exposure 30 period.
    20 Other applications Various improvement and modifications may be made to the above without 5 departing from the scope of the invention. In particular, while embodiments have been described with reference to sea lions in marine environments, it is to be appreciated that the principles of the invention can be equally applied for the deterrence of any mammal, in sea or on land. The economic advantages applicable to the fish farm industries could be equally applicable 10 to other industries like game reserve control and estate management.
    权利要求:
    Claims (33)
    [1] 1. A method of deterring mammals comprising configuring an acoustic deterrent system to emit an acoustic signal having characteristics 5 which cause said mammals to be repelled from an area, by eliciting an acoustic startle response reflex in said mammals, wherein the acoustic signal has an envelope with a slope of at least 0.8 dB /ms.
    [2] 2. A method as claimed in claim 1 wherein the acoustic signal 10 spans a frequency band having a lower limit greater than 2kHz.
    [3] 3. A method as claimed in claim 2 wherein the acoustic signal spans a frequency band having a lower limit greater than 4kHz. 15
    [4] 4. A method as claimed in claim 3 wherein the acoustic signal spans a frequency band of 4kHz to 18kHz.
    [5] 5. A method as claimed in claim 4 wherein the acoustic signal is centred around a frequency of 7kHz. 20
    [6] 6. A method as claimed in claim 3 wherein the acoustic signal spans a frequency band of 4kHz to 12kHz.
    [7] 7. A method as claimed in claim 6 wherein the acoustic signal is 25 centred around a frequency of 10-11kHz.
    [8] 8. A method as claimed in any preceding claim wherein the acoustic signal is comprised of randomly synthesized white noise. 22
    [9] 9. A method as claimed in any preceding claim wherein the acoustic signal has characteristics which sensitize said mammals such that repeated exposure to the signal reinforces the acoustic startle response reflex therefore increasing aversive responses in the mammals over time. 5
    [10] 10. A method as claimed claim 9 wherein said acoustic signal comprises isolated acoustic pulses, the method comprising repeatedly exposing the mammals to said isolated acoustic pulses so as to sensitize said mammals. 10
    [11] 11. A method as claimed in claim 9 wherein each interval between isolated pulses is longer than 1s.
    [12] 12. A method as claimed in claim 11 wherein each interval 15 between isolated pulses is in the range of is to 120s.
    [13] 13. A method as claimed in claim 11 wherein each interval between isolated pulses is in the range of is to 60s. 20
    [14] 14. A method as claimed in any of claims 9 to 13 wherein each interval between isolated pulses is longer than 10s.
    [15] 15. A method as claimed in any of claims 9 to 14 wherein said pulses each have a short duration, and the acoustic signal has a low duty 25 cycle, such that in use the energy consumption of the system is low.
    [16] 16. A method as claimed in claim 15 wherein the duration of each pulse is less than 1 second and the duty cycle of the acoustic signal is less than 10%. 30 23
    [17] 17. A method as claimed in any preceding claim wherein the duration of each pulse is less than or equal to 200ms.
    [18] 18. A method as claimed in any preceding claim wherein the 5 acoustic signal comprises single, isolated pulses emitted at random intervals, each having a short rise time.
    [19] 19. A method as claimed in any preceding claim wherein wherein said characteristics that repel the mammals by eliciting an acoustic startle 10 response reflex comprise a high amplitude and short rise time.
    [20] 20. A method as claimed in claim 19 wherein the amplitude of the acoustic signal exceeds targeted mammals' auditory threshold by more than 80 dB within 100ms of the signal's onset. 15
    [21] 21. A method as claimed in claim 19 wherein the amplitude of the acoustic signal exceeds targeted mammals' auditory threshold by more than 80 dB within 10ms of the signal's onset. 20
    [22] 22. A method as claimed in any preceding claim wherein the acoustic signal is as broadband as possible within the designated frequency range.
    [23] 23. A method as claimed in any preceding claim wherein the signal 25 bandwidth spans at least one third of an octave.
    [24] 24. A method as claimed in any preceding claim wherein said acoustic signal is emitted when the device is triggered by a sonar system detecting the presence of an animal. 30 24
    [25] 25. A method as claimed in any preceding claim wherein wherein incurring an acoustic startle response comprises the steps of: selecting a received level at a predetermined level above a representative hearing threshold of the targeted mammals; 5 transmitting an acoustic signal from a transmission point at a source level required, taking into account transmission loss, to create the selected received level at a predetermined distance from the transmission point.
    [26] 26. A method as claimed in claim 25, wherein the predetermined 10 level is between 80 and 130 dB above the representative hearing threshold of the mammal to be deterred.
    [27] 27. A method as claimed in claim 25 or 26, wherein the acoustic signal has a duration about as long as the acoustic integration time specific to 15 the targeted mammals auditory system.
    [28] 28. A method as claimed in claim 25, 26 or 27, wherein the acoustic signal comprises frequency components at which the aural sensitivity of the targeted mammals is greater than that of selected other 20 animals.
    [29] 29. A method as claimed in any preceding claim wherein said mammal to be deterred comprises sea lions. 25
    [30] 30. An acoustic deterrent device comprising a signal transducer arranged to transmit acoustic signals having the characteristics of an acoustic signal resultant from performing the method of any preceding claim. 25
    [31] 31. An acoustic deterrent system comprising a control unit, a poWer source, amplifier and transducer means, co-operable to perform the method of any of claims 1 to 29. 5
    [32] 32. An acoustic deterrent system as claimed in claim 31, wherein the acoustic deterrent system includes a control unit that operates under the control of control software executable on a computer so that the computer is operable as the control unit of claim 31. 10
    [33] 33. A computer readable medium comprising the control software operable to cause suitable apparatus to perform the method of any of claims 1 to 29.
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    同族专利:
    公开号 | 公开日
    AU2013204487B2|2016-11-10|
    引用文献:
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    法律状态:
    2017-03-09| FGA| Letters patent sealed or granted (standard patent)|
    优先权:
    申请号 | 申请日 | 专利标题
    US13/619,903||2012-09-14||
    US13/619,903|US8665670B2|2007-04-20|2012-09-14|Acoustic deterrence|
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