Mechanism: How do pingers work?
Dolphin Behavior
Pingers emit a short sound at regular intervals, in a particular frequency within the hearing range of the species they are designed to deter. Most pingers have been designed for harbor porpoises, but more recent developments include other cetaceans.
The response of cetaceans to acoustic alarms is not fully understood. Different hypotheses for how exactly pingers affect marine mammal behavior include:
Startling
The sound may startle the porpoises, causing them to swim away from it
Alerting
On hearing the alarm, porpoises may investigate, prompting them to detect the net
Prey redistribution
Prey species may avoid the alarm, causing whales to follow
Annoyance
Dolphins may avoid the sounds for the same reason humans avoid traffic or construction noise
These hypotheses have been proposed for dolphins, whales, and porpoises, though only one is listed for each example. (Culik et al. 2001, Kraus 1999)
The response of cetaceans to acoustic alarms is not fully understood. Different hypotheses for how exactly pingers affect marine mammal behavior include:
Startling
The sound may startle the porpoises, causing them to swim away from it
Alerting
On hearing the alarm, porpoises may investigate, prompting them to detect the net
Prey redistribution
Prey species may avoid the alarm, causing whales to follow
Annoyance
Dolphins may avoid the sounds for the same reason humans avoid traffic or construction noise
These hypotheses have been proposed for dolphins, whales, and porpoises, though only one is listed for each example. (Culik et al. 2001, Kraus 1999)
Designing A Pinger:
Performance:
Basic considerations for an acoustic alarm require that it be waterproof, durable, and within the hearing range of the cetacean species it is intended to deter. In order to work while attached to the nets, pingers must tolerate pressure at depths. This can be up to 100 fathoms for swordfish gillnets and other high-seas fisheries.
According to National Marine Fisheries Service regulations in the United States, pingers are required every 150 feet of net, along the top and bottom lines. For an individual swordfish gillnet, this may add up to 40 to 35 pingers. Each pinger emits a 132 decibel sound for 300 milliseconds at a 10 kHz frequency, plus or minus 2 kHz.
(Chambers 2001).
Convenience:
Pinger design should also consider:
Commercially produced pingers range from $50 to $80 in the United States (prices as of 2001). Depending on the design, batteries in these models last between a month, a fishing season or an entire year. Lithium chloride, alkaline D and alkaline AA batteries may be used.
Additional features can include:
Maintenance:
Commercial manufacturers advertise pingers that last for up to a year, but all batteries and eventually the pingers themselves need replacing at some point. For some subsistence fisheries the purchase and maintenance costs of pingers may require that other more affordable approaches be taken to reduce bycatch (Kraus 1999).
Basic considerations for an acoustic alarm require that it be waterproof, durable, and within the hearing range of the cetacean species it is intended to deter. In order to work while attached to the nets, pingers must tolerate pressure at depths. This can be up to 100 fathoms for swordfish gillnets and other high-seas fisheries.
According to National Marine Fisheries Service regulations in the United States, pingers are required every 150 feet of net, along the top and bottom lines. For an individual swordfish gillnet, this may add up to 40 to 35 pingers. Each pinger emits a 132 decibel sound for 300 milliseconds at a 10 kHz frequency, plus or minus 2 kHz.
(Chambers 2001).
Convenience:
Pinger design should also consider:
- easy assembly
- easy attachment to the net
- durability
- battery life
Commercially produced pingers range from $50 to $80 in the United States (prices as of 2001). Depending on the design, batteries in these models last between a month, a fishing season or an entire year. Lithium chloride, alkaline D and alkaline AA batteries may be used.
Additional features can include:
- alarm turns off when not submerged, extending battery life
- alarm turns on only when echolocating animal approaches
- alarm deactivates after several days lost at sea
- digital microprocessor emits a variety of sounds to increase long-term effectiveness
Maintenance:
Commercial manufacturers advertise pingers that last for up to a year, but all batteries and eventually the pingers themselves need replacing at some point. For some subsistence fisheries the purchase and maintenance costs of pingers may require that other more affordable approaches be taken to reduce bycatch (Kraus 1999).
Examples Of Pingers:
Please note: this listing does not constitute endorsement by the Cetacean Bycatch Resource Center of specific commercial vendors.
| NAME | SPECS | SPECIES | SOURCE | DESCRIPTION |
| Fumunda Marine Products | Chambers 2001 | |||
| Lien pinger(Lien and Hood 1994) | 115 dB | Harbor porpoise | Koschinski and Culik 1997 | Mean closest approach 133m |
| Micro-controller Beacon Mode Devices | More complex sound across a wider band | Goodson et al. 1997 | ||
| NetmarkT 1000, Dukane Corporation | Chambers 2001 | |||
| PICE alarm, Loughborough University, UK | Eight frequencies between 20 and 160 kHz145 dB max300 ms | Harbor porpoise | Culik et al. 2001 | Mean closest approach 414m |
| Netmark 1050, Dukane Corporation | Hector's dolphin | New Zealand Dept. of Conservaiton |
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