Salt and Shad

Salt has been scientifically proven to have a number of benefits for freshwater fish including Shad.

Adding salt properly in holding and transportation tanks will help treat health problems and water quality problems.

Salt reduces the effects of stress in shad, especially during transport and in conserving energy for physiological emergency purposes, and in countering the electrolytes disturbances associated with stress-elevated adrenaline and cortisol levels.

Use of Salt in Transporting and Handling Shad.

When Shad are transported and handled, they are forced to expend extra energy for osmoregulation (water balance) unless salt is added to the transport water.

Shad tend to over-hydrate when held in fresh water during transporting, due to the influx of water across the gills and into the bloodstream.

To compensate for this water imbalance, fish pump excess water back across their gills.

Increasing the salt concentration of the transport water inhibits this process, making depletion of energy reserves less likely.

Salt can be added to the transport water to increase salinity from 0.1 to 0.3 percent (1,000 to 3,000 ppm, or 3.8 to 11.4 g/gal) ( 0.134041oz  to 0.402123 oz per gal), minimizing the osmoregulatory stress on shad during transportation.

If fish are being moved from one site to another -- for example, from a transport tank to tank at a holding site - add salt  to the receiving water.

An easy way to accomplish this is to add a small amount of water to the receiving tank, then add salt to create a 3 percent solution (30 ppt or 30,000 ppm); when fish are added to the tank, it should be filled with water.

Short-term exposure to a high concentration of salt produces an anti-parasitic effect.
Longer exposure to a lower concentration of salt helps to stabilize osmoregulation and increase production of the mucus covering the skin, which may have become damaged during handling.

The presence of salt does not repress stress hormones, it softens the side effects.

By adding salt you are increasing the salinity of the water to somewhere between fresh water and sea water (sea water average is 3.5%) which is called brackish.

After the stress of being caught and handled it is best to let shad recover in brackish water for 1 - 3 days.

Salt helps shad maintain their proper blood chemistry while under stress.

Sodium chloride (NaCl) is approved for aquaculture use as an "osmoregulatory enhancer." Salt can change the osmoregulatory balance (water balance) of aquatic organisms. It can sometimes be used effectively to control external parasitic protozoans by placing them in a condition of severe osmoregulatory shock.

Salt is used as a 0.5% to 1.0% concentration in water as an indefinite (long-term) treatment or as a 3% concentration in water for 1-10 minutes. Care must be exercised to avoid overtreatment which will place the fish in the same condition of osmoregulatory shock.

SALT Concentrations for holding Shad in Tanks.

The effects of salt on fish are determined both by salt concentration and duration of exposure. Seawater contains 3 percent salt by weight; this is equivalent to 30 parts per thousand (ppt) or 30,000 parts per million (ppm). Some parasitic infestations of freshwater fish may be effectively eliminated by dipping fish in a seawater solution for 30 seconds to 10 minutes, depending on the species. Weaker solutions containing 0.5 to 1.0 percent salt may be used as a bath for several hours to eliminate some freshwater parasites. Concentrations of 0.1 to 0.3 percent may be used to enhance mucus production and osmoregulation in freshwater fish during handling and transport. Very weak salt treatments, measured in ppm, may be used to control methemoglobinemia in some freshwater fish species.

Freshwater fish use cells in their gills to take in the salts that they lose to the water, which helps keep their bodies salty. Adding salt to the water when fish are stressed means that they don't lose as much salt from their bodies. The principle is much the same as a saline drip for hospital patients.

Some fish keepers and salt manufacturers recommend adding salt as a routine permanent treatment. Also using sea salt which is "(98% NaCl ) + 80 other elements (2%) is my choice vs pure salt (sodium chloride 99.9% or refined salt which contain only 0.1 - 0.5% other elements 

Stress in Shad

Shad stress out when caught, handled or being chased or transported. Stress is adrenaline released into the bloodstream. Adrenaline is followed closely by other steroids such as cortisol, which prepare the fish for its reaction. The result is raised blood glucose levels, red blood cell counts, heart and ventilation rates.  The digestive processes may cease temporarily.
e.g., escape (Mazeaud and Mazeaud, 1981).

Adrenaline disturbs ion transport at the gill membrane, and both adrenaline and cortisol cause temporary changes in gill permeability which, in fresh water, results in dilution of the blood by excessive gain of water, and vice versa in normal seawater.
(Mazeaud et al., 1977; Folmar and Dickhoff, 1980).

Blood levels of calcium, magnesium, sodium, and other vital electrolytes are pushed out of normal operating ranges for as much as 24 hours after stress such as being caught in a casting net.
(Wedemeyer, 1972).

Trying to restore physiological and metabolic order diverts precious energy, which leaves the shad less capable of fighting pathogens. Cortisol elevation itself suppresses immune system function.
(Barton et al., 1987; Maule et al., 1987).

A general recipe may be found in Spotte, (1970).

Alternately, concentrations of single ions or salts reflecting their occurrence in natural seawater may serve (for sodium chloride, this will be of the order 0.5 to one percent in aqueous solution, to achieve a final salinity of about half that of normal seawater).

The Bulk density of salt approximate (dry, ASTM D 632 gradation) 1.154 (72 lb/ft3)
Since 1 ft 3 = 7.48 gallons, the Bulk density of salt converts to 72 lb / 7.48 gal = 9.6 lb/gal.

And 1 gallon = 16 cups, so salt weighs 9.6 lb/gal X gal/16 cup = 0.6 lb/cup gallon of fresh water is about 8.36 lb

1.0 percent of a gallon of fresh water is 0.0836 lb.
 
For 50 gal: 50 X 0.139 cups = 6.95 cups
For 30 gal: 30 X 0.139 cups = 4.17

Calculating Tank Volume for adding Salt .

Conversions of salt dosages

1 pound (lb.) = 454 grams (g)
1,000 g = 1 kilogram (kg)

Once the volume is calculated in cubic feet, the gallons are determined using these conversions:

1 ft  = 7.48 gallons (gal.)
1 acre-foot (1 surface acre x 1 ft.  deep) = 325,850 gal.
1 liter (L)= 0.26 gal.

Calculating tank volume is an important step to effective salt application. Measurements used to determine volume are usually in feet and/or inches.
The most common shapes of  tanks are square, rectangular, or round.

Finding Volume of a square or rectangular raceway, tank or pond.
Volume (Vol.) = Length x width x depth

Example 1:

A rectangular tank is 12 feet (ft.) long, 3 ft. wide and 3 ft. deep.
What is its volume?

Vol. = 12 ft. x 3 ft. x 3 ft.
Vol. = 108 cubic ft.

Finding Volume of a round tank
Vol. = 3.14x (radius x radius) x depth

Example 2:

 A round tank is 12 ft. in diameter and 4.5 ft. deep.
 What is its volume?

 (Radius = 0.5 x diameter)
Vol. = 3.14 x (radius x radius) x depth
Vol. = 3.14 X (6 ft. X 6 ft.) X 4.5 ft.
Vol. = 3.14 X 36
Vol. = 508.7 ft

The most commonly used units of measure in aquaculture is the part per million, commonly referred to as ppm.
In percentage calculations, 1% equals 10,000 ppm.

How much salt is needed to make a 2% solution in a round tank ?

salt needed (g) = 0.00378 g/gal. x  3,805.1 gal. x 20,000 = 287,663g or 633.6 lbs. (287,663g = 633.6 lbs.) 454g/lb.

How much salt is needed to make a 0.5% solution in a 100-gal. transport tank?

0.5% = 5,000 ppm
Salt needed (g) = 0.00378 g/gal. x 100 gal. x 5,000 ppm
Salt needed (g) = 1,890 g or 4.2 lbs. (1890g = 4.2 lbs.) 454g/lb

The Use of Salt in Aquaculture UF/IFAS

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