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Natural Lakes and Reservoirs Requiring Stocking or other Management

(i) Yengi Kand Reservoir, Yengi Kand, Kharaghan District, Saveh Township, Teheran Province

This freshwater irrigation reservoir was visited on 2 December 1968 at the invitation of Mr. M.J. Eybergen, FAO/FFHC (Freedom from Hunger Campaign) Pilot Villages Project on Rural Development in Iran which has a field headquarters in Dusdj, 75 km from Asia-beg on the Teheran-Isfahan highway and 7–8 km from the reservoir at the village of Yengi Kand. The project is anxious to have fish stocked in the lake which does not have fish of any kind at present.

When completely filled to a depth of 3.75 m the reservoir has a length of about 1 km and a width of about 350 m. The surface area was estimated to be 35 ha.

A sample of water from the lake showed the following water quality characteristics:

Calcium-magnesium hardness435.0 mg/l
Total alkalinity210.0 mg/l
Chlorides*  17.5 mg/l
Conductivity* (micromhos per cm3)740    mhos

* Determined by the Teheran Water Board.

The water is therefore very hard, but the hardness is not due to the presence of salt for the chloride content is only 17.5 mg/l compared with 24,800 mg/l observed in Shurabel Lake, a lake saltier than the sea, at Ardebill. Hard waters, where the hardness is due to calcium and magnesium as in the case of Yengi Kand Reservoir, are more productive of fish and other aquatic life than soft waters.

The limestone in this area is of a highly soluble nature judging by the porous character of the limestone that is now being quarried at the reservoir site for the rip-rapping of the inside reservoir bank of Yengi Kand Reservoir.

There has been a dam and a lake in this area for about 150 years. The basin flooded is nearly flat. Gentle slopes approach the high ground or mountain to the south and the low hills to the north. Recent work on the dam has consisted of repairing it, raising it to a higher level and providing an outlet gate that could be raised or lowered by a screw axle (enclosed in pipe) operated with a wheel mounted on top of the dam. The outlet pipe is 0.5 m in diameter, and although the lake is not subject to floods, a spillway has been provided at the south end of the dam.

Streams from two mountain valleys approaching the reservoir from the south indirectly supply the lake with water, but the water used to fill the reservoir is diverted from these streams and led into it via ditches. Their flood waters do not enter it.

Recommendations for stocking with fish. In the consideration of what species of fish might be stocked in the lake, thought has been given to the amount of fluctuation that will occur.

Fluctuation in the spring and early summer are of the order of 80 cm per month or about 2 cm of vertical height per day. This gradual reduction in level can be tolerated by nest-building fishes providing relatively warm weather prevails at the time of spawning.

Maximum summer air temperatures in the area (2,500 m above sea level) were about 38°C in 1966 and 34°C in 1967. Considering the wide, shallow nature of the reservoir and the temperatures, it is believed that the lake should be stocked with warm-water fishes. Winter air temperature fell to -5°C in 1966 and -15°C in 1967. The lake freezes over under these conditions. Spawning temperatures suitable for the spawning of largemouth bass (19°C) will probably occur in mid-April and for bluegill (22°C) in late April and early May.

It is recommended that fingerling bluegill be stocked in the reservoir in late fall (October) at the rate of 1,250 per ha. At this rate a total of 43,750 bluegills (about 2 inches long) will be required. Largemouth bass should be stocked at one-tenth this rate, or 125 per ha. It will probably be most convenient to stock the total of 4,375 young bass in the spring when they are 1–1.5 inches in length. In any event, the largemouth bass should not be stocked before the bluegills are stocked, and they should not be stocked of a size capable of eating the bluegills stocked before-hand.

In the following season, the bluegills will probably grow to 6–8 inches in length, while the largemouth bass will grow to 9–11 inches in length. Fishing should not begin until the bass have spawned at least once.

The question has arisen as to how many pounds or kilograms of fish are likely to be produced per year in this lake. It is believed that the lake should produce 120 lbs of edible-size fish per acre per year. At 300 lbs/ha, the total production of fish might be about 10,500 lbs/year (4,773 kg).

An alternate stocking plan, should bluegills and bass not be available might include a combination of grass carp and souf. It is suggested that the lake be stocked with 200 fingerling grass carp and 20 fingerling souf per acre. At this rate 500 grass carp and 50 souf would be stocked per hectare, when about the same size or a total of 17,500 grass carp and 1,750 souf in the total area of 35 ha. The grass carp and souf will require restocking annually since it is not likely that they would reproduce in the lake.

(ii) Lapoo Lake

Lapoo Lake, west of Khalidj-e-Gorgan near Zaghmarz, is about 6 km long, 200–400 m in width and 2–3 m deep. It was visited on 22 October 1968, when at a low level. There is a winter flow of water into the lake, but no summer flow.

The lake is surrounded by bulrushes (sasin) and other marginal plants and contains large quantities of aquatic plants. The top soil is not more than 8–10 inches deep with sand beneath it. Ducks and coots were using the area.

Close to Lapoo Lake a stream of water of about 500 gpm was forded that was flowing toward the Khalidje-Gorgan. It was stained brown from marsh drainage. The water was relatively hard with a calcium-magnesium hardness of 230 mg/l. The total alkalinity was 210 mg/l.

This area appears more suitable for waterfowl management than fish management. No doubt the area could be made more attractive to waterfowl by planting additional waterfowl food plants, and by creating additional shallow-ponds by the construction of low dams.

(iii) Abbscabad Reservoir

This reservoir is located in the forested hills above Behshahr in a very pictoresque setting. It is an oval bowl receiving mostly surface water from several directions, but mainly from the east. When visited on 22 October 1968 the water was at the minimum stage about 2–3 m deep. Surface area was estimated to be about 6 ha (15 acres). At full stage, the area is probably close to 18 ha (45 acres).

Two species of aquatic plants, Elodea and Ceratophyllum, were present at scattered points along the shore, and there was evidence of heavy growths of Elodea when the reservoir remained nearly full for a considerable length of time. The Ceratophyllum contained freshwater shrimp, excellent food for the young fish.

The water was quite muddy at the time visited. Many small fish about six inches long, reported to be Siah Kole - Chalcaburnus chalcoides, were present.

There was no evidence of fishing for the species of fish present.

The reservoir is used to irrigate rice and cotton fields, and is therefore subject to great fluctuations in water level. Vertical fluctuations amount to about 10 m.

The bluegill - largemouth bass combination, have been considered as suitable species to stock in this reservoir. Bluegills might spawn in late summer, but largemouth bass might require annual restocking. There is the possibility that both species might spawn successfully in the spring, based on the evidence that the water remains high in the reservoir for a considerable time in the spring.

If such a combination should be desired, then prior to stocking, and in the autumn when the reservoir is at its lowest level, with no out-flow, the existing fish population should be exterminated with 1 mg/l of derris with a 5 percent rotenone content (3.8 kg per 3,785 m3.)

After bioassay shows the water to be no longer toxic to fish (probably after about two weeks), fish can be restocked in the lake.

(iv) Lake Ghoohrygol

This lake near Shebli Pass, 30 km east of Tabriz, was visited 6 November 1968. The lake has an estimated area of 1,050 ha (2,625 acres) and a maximum depth of 18–20 m. Water analysis showed relatively high total alkalinity of 350 mg/l and calcium-magnesium hardness of 140 mg/l. A sample of this water was observed to have a conductivity of 2,500 micromhos, chloride content of 74 mg/l, and total dissolved solids content of 596 mg/l. 1

Much of the lake appeared to be under 3 m in depth and coarse submerged vegetation was present over a considerable area of the lake, perhaps one-fourth of the total area. (A boat was not available for closer observation.) Many coots, ducks, and some geese were feeding in the lake.

1 Determined by the courtesy of the Teheran Water Board.

Trout were reported to have been stocked in the lake without success, and low oxygen conditions under the ice in winter were suspected of being responsible for the loss of fish.

The swarms of midgeflies occurring along the lake shore showed that the Chironomidae were successfully completing their life histories in the fresh waters of the lake.

The fact that trout were unable to live in the lake through the winter does not preclude the stocking of other species of fish less sensitive to low oxygen conditions.

Stocking plan. The Korpur is a species very tolerant to low oxygen, but it would not be as effective in controlling the submersed weeds as the grass carp. Therefore, a grass carp/souf combination might be stocked. It is suggested that grass carp and souf be stocked in the ratio of 20 to 1 when close to the same size to prevent cannibalism before they reach an edible size.

In stocking plans, the availability of fish is a first practical consideration. An initial stocking of only 20 grass carp and one souf per acre would require about 42,500 grass carp and 2,600 souf.

Alternate stocking plan. If bluegill and largemouth black bass are introduced into Iran this combination might also be tried in this lake.

(v) Lake Shuribol - Location: Ardebil

This salt water lake is at least 50 acres in area and about 2 m maximum depth. It has had twice or more area in past centuries. At present, there is a stream of about 40 gpm (2.5 l/sec.) of fresh water from an irrigation ditch entering it from the Aghlaghan Chay which flows by Ardebil. At Nir, this was a relatively soft water stream with a total alkalinity of 120 mg/l and a calcium-magnesium hardness of 100 mg/l.

The lake lies deep below the general ground level, perhaps 20 m below it. A sample of water brought back from Ardebil to the Teheran Water Board showed a conductivity of 60,000 micromhos, total dissolved solids content of 80,000 mg/l and a chloride content of 24,800 mg/l. It is, therefore, more salty than sea water.

Fish are not present in the lake.

The possibility exists for introducing the brine shrimp (Artemia sp) from Lake Rezaieh. Newly hatched shrimp would be most suitable as food for artificially hatched sturgeon, kutum, etc. It should also be noted that brine shrimp eggs are in considerable demand in many parts of the world as food for aquarium fishes. The potential world markets for brine shrimp should be investigated.

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