Pisces Pregnantscorpio Dad?

electrofishing - useful tool or dangerous? Healthy as a fish

A typical sampling operation by elettrostorditore that in this case also involves the writer (photo by Pasi Lenpinen)

Purtroppo recentemente (ma non solo) mi e' capitato di discutere con delle persone su internet che sostenevano che l'elettropesca e' la rovina degli ambienti acquatici.

Ora siccome non mi piace ripetere le cose mille e una volta ho deciso, anche su esortazione di alcuni utenti del forum esox2000, di scrivere un articoletto a riguardo. Almeno la prossima volta rispondo con un semplice link.

Cerchero' brevemente di dare un'introduzione alla teoria dell'elettropesca e vedere qualche caso pratico. Vedremo quali sono i vantaggi e gli svantaggi di questa tecnica e da dove derivano le convinzioni di alcune persone.

Sara' difficile convincere qualcuno del contrario with words alone, so before you even start call anyone who has doubts about what I wrote to arm themselves and follow a group of waders that intervenes with the electrofishing to realize that if that person and say 'true or not. It 's a very simple thing, you do not even miss a full day of fishing, just half an hour, and costs nothing.

That said, let's start ..

The electrofishing is based on a principle very simple: when immersed in an electric field undergoes a fish effect of muscle contraction that leads him to swim along the lines of that field. If close enough to the electrode contractions become tetanic, that 'the muscle gets stuck in a cramped and fish and' immobilized. Upon termination of the action of the field rapidly returned to normal muscle function 'allowing the release of the fish healthy.

eletttropesca There are several types, with different equipment and different effects, but we shall see here just a few practical applications are endless. The typical

elettrostorditore consists of a portable battery and a control module to adjust the shocks, and the weight 'of about ten pounds and moves comfortably in the shoulder. The current is modulated in frequency, voltage and type of discharge. At the exit of current there 'an anode with a control button, located at the end of a bracket provided with a cathode copper network and being dragged behind the operator.
time ago, must be carried on their shoulders a small gasoline generator with all the problems .. the case today with the only battery you can reach thousands of times and using the instrument for a day without recharging. There are more tools 'for use with powerful boats, small generators are basically coming to a few thousand volts, the only difference' spectrum of action (most areas 'deep or more' wide).

elettrostorditore A laptop (original image of the U.S. patent)

Basically there are two major types of electrofishing, the one with direct current (DC) or the alternating current (AC). In a DC field to the electrodes maintain the same polarity 'in action while in a field with the AC polarity' is reversed at regular intervals.
The main differences in practice are: AC DC



• Stunning temporary, fast recovery extended
• Stunning • Extended (high consumption) • Range limited (low)
• The fish tend to swim toward the anode • The fish do not swim toward the anode
• Damage • Damage moderate minimum
• Effective in murky water / vegetation • Effective in open waters


Perhaps the most 'common' that carried out by pulsed direct current (PDC), where the direct current circuit is opened and closed at regular intervals of frequency. This allows you to make more 'effective eletrotassi (swimming towards the anode) and generally increases the effect of current without increasing the damage.
The AC is mainly used instead of the boat in open waters, or more 'deep.

Una barca usata per l'elettropesca in acque aperte e profonde (foto US Fish&Wildlife)

Per poter usare uno di questi apparecchi generalmente bisogna essere in possesso di un certificato che confermi l'esperienza dell'utilizzatore e ovviamente di un'autorizzazione all'esercizio di questo particolare metodo di pesca a fini scientifici. Ci sono regole abbastanza strette su cosa si intende per certificazione minima e differiscono da paese a paese ma comunemente comprendono norme di sicurezza e pronto soccorso oltre ai principi basilari di funzionamento.

Le macchine sono infatti dotate di regolazioni che servono ad adattarle a seconda della situazione e delle specie presenti.
very important parameter is the conductivity 'and the water temperature, as well as the length and type of species to catch. Fish more 'long and devoid of scales through more' field lines and are more 'vulnerable to the current fish and more' short and thick scales are much less affected. We
some practical example:
- The eel and 'very easy to take being very long and with a skin without scales
- Carp and' very difficult to take because 'squat, with thick scales
- although Pike long is not 'always easy to take, if you find a few decimeters from the electrode is stunned muscle contractions otherwise normally do they make a snap him outside the scope

A small pike recovered during sampling, this fish 'back into the water without any problems despite its size

With these simple assumptions and' quite easy to see how statements such as "effective as a stunner if 20kg weight on anything that is less than would be irreparably damaged" are completely unfounded. It 'much more' easy to die or suffer damage to a large fish than small fish or invertebrates. E 'in a campaign of bad-information on the subject, I do not know what arising from releases intentional and how much from the events of (poaching with the electric current, something quite different) but certainly deeply flawed.


Fishing with the elettrostorditore does not allow some to sterilize an entire water course (I wish it were so 'easy) but causes only minimal damage. The typical damage are derived from the muscle contractions that can cause bruising (visible as dark spots on the skin) and cause deformation of the spine.

caused damage to the spine of a fish during electrofishing (image electrofishing.net)

Had the effect that many say would not be the most 'used for the treatment of valuable species such as trout and salmon (eg for the recovery of breeding or for the verification of new-borns).


The elettrostorditore and 'rather a valuable tool because it' allows scientists to sample a stream without damaging it deeply. The stunned fish are caught with a simple network and can be manipulated and measured placed them in a bucket with a sedative (MS-222, one of the most 'used), you can collect genetic samples, and more immediately after the fish can be issued free in their environment. At the same time you can 'remove all the unwanted species without damaging the valuable species.

elettrostorditore Obviously, as all units can 'also be used incorrectly. In this case it may 'actually cause serious damages, even unto death. Not at all field operations should always be coordinated by an expert who always tries to minimize damage to other species and focus on the effects on species and sizes involved. A complete and comprehensive analysis of the damage that this tool can 'cause you can' read the document prepared by Snyder. Ultimately

and 'therefore unfounded the rumor which would be an instrument elettrostorditore the harmful and dangerous. E 'likely that this error stems from two factors:

• the confusion between elettrostorditore and electrofishing for scientific purposes or for intervention programs with illegal fishing by electric current (which usually tends to kill more' than to stun)
• the express intention of impeding containment programs of alien species that employ elettrostorditore creating discontent among fishermen

Bibliography:
- Cowx (ed) Fishing with electricity
1990 - 2003 Snyder
- Electrofishing.net