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Seal scaring has had a very checkered history. The usual complaint is they work for a while then the seals get used to the noise (habituate) and so ignore it. The Ace Aquatec scrammer range in Scram mode makes sound so infrequently that this should not occur. On trial (see AA-01-043) the scrammer proved 100% efficacious against naive seals. Does the size of the fish matter? Seals are opportunists and, although they prefer larger fish, will attack any size. Ace Aquatec scrammers have protected fish from a few 10s of grams (smolts) to 5 kg fish. The system adjusts itself to the fish whatever their size and whatever their stocking density. Does the Scrammer work against all types of seal? We do not currently know the answer to this question. Ace Aquatec scrammers have been tested against the seals commonly found in Scottish waters (Commons and Greys). Ace Aquatec's ongoing trials programme is designed to address this very question and the results will be published as they become available. Why aren't the fish upset by the scrammer's noise? Fish have very different hearing from marine mammals and the higher frequencies of seal scarers are inaudible to the majority of fish species. For example if salmon could hum they could only follow you to middle C. How does the Trigger Device know that the fish are stressed? When an object is in their pen fish tend to swim around it, but when they are upset by a predator they bump into things in their panic. The Trigger Device monitors the vibrations of its casing and measures the severity of any impact. If the impact exceeds the current threshold the Trigger Device informs the system. Why doesn't the Scrammer respond to all detections? The Trigger Devices are very sensitive and will respond to the accidental flick of a fishes tail or any slight bump which occur normally. All these are reported into the scrammer which sorts them into Detections and Significant Events. In SCRAM mode 4 Significant Events are required in an hour before it will make a noise. Does the Ace Aquatec Universal Scrammer harm marine mammals? No. There is no evidence that any seal scarer has ever physically harmed a marine mammal. Any theoretical risk is eliminated by good design (see AA-01-044). Are divers upset by the noise of seal scarers? Humans are far less sensitive to underwater noise than are marine mammals, are most unlikely to be upset by seal scarers and will certainly not come to any physical harm from exposure to this level of sound. Users of the Ace Aquatec scrammers are advised to switch to LISTEN mode when divers are in the cages to eliminate the possibility of a diver being distracted by the sudden noise and making a mistake. Can I move the system to another site? Yes. Ace Aquatec scrammer are designed to be portable and easy to install. A copy of the User Guide may be found on this web-site which gives details. Does the Ace Aquatec Silent Scrammer suit all sites? Ace Aquatec scrammer suits most sites. The exception to this rule is when it is deployed with another type of seal scarer. Other seal scarers make noises randomly or nearly continuously and will inhibit the conditioning of the predating seal. How does the Trigger Device communicate with the Control Box? All Ace Aquatec scrammers are "wireless" but use sound rather than radio-waves to communicate information through the water. The quiet "beep-beep-beep" of the Trigger Devices is audible to the seal and is used as the conditioning stimulus. Ace Aquatec scrammers use a variety of power sources: 12V batteries (70AHr deep-cycle leisure battery is preferred but a wide variety from 30AHr automotive upwards is acceptable) and mains electricity (110 - 240VAC). It is recommended that an external 12V battery is always used so that the scrammer can draw upon this source should another not be available. Wind Generators are not recommended. Can I use the Ace Aquatec Universal Scrammer without Trigger Devices? The Ace Aquatec Universal Scrammer and its current successor (US2) can be programmed to make noises (up to 72 five second scrams per hour) in the absence of Trigger Devices (HYB mode). This mode is especially useful when used to warn marine mammals when - for example - underwater demolition is going to start. It is also useful for fishermen to encourage marine mammals to leave the vicinity during hauling operations. Do I need to complete the logging sheets? Ace Aquatec strongly urges you to complete logging-sheets daily. Not only is the information useful for you as an historic record to prove that the fish are not stressed it also can pinpoint problems before predation occurs and allows you to take appropriate action. |
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