Conductivity

To collect fish by electrical means we must create an electrified zone of sufficient amplitude to stun fish. A fish between submerged electrodes forms part of a closed circuit, and some current flows through it. The conductivity of the water and that of the fish's flesh are the main factors that affect electrofishing.

The conductivity of water depends on the quantity of dissolved salts and minerals in the water. The conductivity of potable waters in the United States ranges from 20 to 2,000 µS/cm. Sufficient current at realistic power levels will flow through water in this range to electrofish successfully.

Low Conductivity Water

Distilled water has a conductivity range of 0.5 to 5.0 µS/cm. If typical electrofishing voltages (100 to 1100V) are applied, very little current will flow. Too little power is transferred to the water (or fish) to be effective for electrofishing.

As the water conductivity decreases (with a fixed voltage) the total current decreases and the electrical power delivered to the fish decreases. If the power is too low, fish may not be stunned enough to capture. There are two ways to compensate for this situation. The first is to increase the applied voltage, although there are practical limits based upon operator safety and possible damage to the fish when they are close to the electrodes. The second is to increase the size of the electrodes which more efficiently transfers power to the water and reduces the intensity of the electric field close to the electrodes.

If a higher voltage is used, up to 1,200 volts may be necessary. Safety is reduced for the operators, and conditions are lethal for fish close to electrodes. It is better to keep the resistance constant by increasing the size of the electrodes. The only limitations are the weight that can be handled by the operator.

Fish Size

Among fish of the same species, the larger fish absorb more power than the small fish. The large fish receive a much greater shock than the small fish.

Substrate

Certain bottom substrates will conduct electrical current. These weaken the electric field in the water making fish capture less effective.

High Conductivity Water

High water conductivity is over 2,000 µS/cm. If a high voltage is applied, most current will flow through the water and the fish will hardly be affected. The electric current follows the path of least resistance and bypasses the fish completely. Therefore use low voltages and high currents. Currents as high as 60 amps are common, the limiting factor being the rating of the generator. The 7.5 and 9.0 GPPs can stun large fish in the interface between fresh and salt water as, for example, in taking Striped Bass for brood stock.

Very High Conductivity Water

Some brackish water and industrial waste water have conductivities over 10,000 µS/cc. Here smaller generators are unable to deliver enough voltage gradient to stun fish. Waters in this range can only be electrofished effectively with the larger model GPPs.

Fish Conductivity

A fish will receive the maximum shock through its body when the conductivity of the water is the same as the conductivity of the fish's flesh. Unfortunately, this is rarely the case. Each species has a different conductivity which affects their susceptibility to electric current.

Temperature

Water conductivity and effective fish conductivity increase with higher temperature. As reported for Carp:

Smith-Root encourages our customers to recycle used electrofishing equipment no longer in service. The enclosure and pack board of many electrofishers are made of aluminum or plastic. Electrodes are made of aluminum and stainless steel. The wires contain copper and the circuit board contain primarily plastic and copper, and most have small amounts of chromium, lead solder, nickel, and zinc. All of this material can be recycled. For assistance with recycling your used equipment contact your local recycler or waste disposal company. If they are unable to assist you they can usually direct you to a recycler that can. A short search of the internet will also provide a list of companies that can assist with recycling used equipment. One such internet recycling resource can be found at: www.recycle.net.

If you wish to disable your used electrofishing equipment before recycling it we recommend cutting the power leads off flush where they enter the electrofisher.

Batteries: The main batteries used with Smith-Root backpack electrofishers are sealed lead-acid gel-cell type batteries and can be recycled at most battery suppliers or by most waste disposal companies.

Tilt Switches: Smith-Root backpack electrofishers manufactured before January of 2006 contained a mercury safety tilt switch. Your recycler should be made aware of this so it can be properly recycled.

To insure proper operation of your electrofisher, the surface of the anode ring must be conductive. In normal operation it may become anodized and non-conductive, this condition is dependant on electrofisher settings used, type of ions in water, and length of time exposed.

Mechanical removal is the preferred cleaning method. To clean use a Scotch-Brite pad and rub the surface of the ring until it shines. It is sometimes helpful to use an abrasive cleaner with the pad. Wire brushes and some chemical cleaning solutions will also work.

A simple test with an ohm meter or conductivity tester will tell you if a problem exists. You should be able to lightly touch the ring in any two places and show continuity between them. If poking, rubbing or pressing hard with the test probes is required, there is a problem and the ring should be cleaned.

Mercury tilt switches were used in the following Smith-Root manufactured equipment:

• Type V Electrofisher
• Type VII Electrofisher
• Type VIII Electrofisher
• Type VIII-A Electrofisher
• Model 12 Electrofishers
• Model 15 Electrofishers
• LR-24 Electrofisher

When your Smith-Root equipment has reached the end of its life, please recycle with your local waste recycling facility.

Additional Information

• SRI Products Containing Mercury

Following these simple guidelines should ensure the return of equipment in good condition.

• Whenever possible, use a new box. The more times a box is used, the more it loses its original protective qualities.
• If you must reuse a box, make sure it is rigid with no punctures, tears, rips, or corner damage, and that all flaps are intact.
• Choose a box strength that is suitable for the contents you are shipping.
• Wrap all items separately.
• Use adequate cushioning material. You should have at least a 2 inch cushion around each item when packing.
• Before closing the box make sure there is no room for the item(s) to shift during shipping. Fill the box with as much packing material as possible.
• Use strong tape designed for shipping.

Limited repair service is available for:

• Model 11 Electrofisher
• Model 11-A Electrofisher
• Model 12 Electrofisher
• Model 12A Electrofisher
• Model 15 Electrofisher
• Model 15A Electrofisher
• Tanaka generators

No repair service is available on the following models:

• Type V Electrofisher
• Type VII Electrofisher
• Type VIII Electrofisher
• Type VIII-A Electrofisher
• Type XI Electrofisher
• Type XV Electrofisher
• Coffelt Mk 10 Electrofisher
• Coffelt Mk 18 Electrofisher
• Coffelt Mk 20 Electrofisher
• Coffelt Mk 50 Electrofisher
• Coffelt Mk 50B Electrofisher

Please contact the Smith-Root sales department prior to sending in your repair.

• Federal ID Number (FEIN): 91-0843323
• Washington State Resale Number: 578 089 196
• Dun & Bradstreet Number: 02 747 30 40

Provide proof of tax-exempt status
Smith-Root charges sales tax on orders shipped to Washington State addresses. To remove the sales tax from your order, provide Smith-Root Sales with a resale or exemption certificate from Washington State.

The Internal Revenue Service (IRS) oversees federal taxes. Sales tax is regulated by individual states. All orders are subject to tax unless proof of tax-exempt status is provided. Letters from the IRS do not qualify as proof of tax-exempt status.

Smith-Root accepts the following as proof of tax-exempt status:

• Resale certificates
• Multijurisdiction exemption certificate
• Individual state exemption certificate
• Exempt organization certificate
• Direct pay permits
• Manufacturing pay permits
• Government tax-exempt credit card

Placing a tax-exempt order by mail, phone, or fax
You must inform Smith-Root Sales of your tax-exempt status prior to placing an order to validate your exempt status. If you are a government agency using an exempt credit card, please be sure to declare this on your mailed or faxed order. Smith-Root will refund tax for orders placed on the Smith-Root.com Store for exempt customers or resale orders. Please contact Smith-Root Sales and provide proof of tax-exempt status after placing order online.

Send purchase orders and credit card orders to the following address:
Smith-Root, Inc.
14014 NE Salmon Creek Ave.
Vancouver, WA 98686
Place orders by phone with Smith-Root Sales at 360-573-0202.
Fax your credit card and purchase orders to 360-573-2064.