The Lar River and its Tributaries
The Lar river originates from a mountainous area located 30 km north of Teheran at an altitude of 2 540 m above sea level. The river flows through a wide flat valley surrounded by mountains and at Pulur (85 km north-east of Teheran) it falls into the Haraz river which runs toward the Caspian Sea.
The Lar river is created by two streams flowing together: the 2 km long Kharsang Stream and the 3 km long Sefid-Ab Stream. The Sefid-Ab is fed by waters of the Gel Gash Stream (See “The Lar River and Prospective Artificial Lake” Sketch, Fig. 3). These streams are fed by springs and their bed is composed of rubble and coarse gravel.
The Lar river's section (extending from Sefid-Ab and Kharsang forks to the Game and Fish Department Guard Station at Kamardasht, where the Chelbareh Stream joins the Lar) is 12 km long and its width ranges from 5 to 10 m. This stretch of the Lar is locally called Bastak and it flows underground for about 5 km. The water flows overground in this section only during the period of the springtime floods. The river bed is composed of coarse gravel here.
The Chelbareh Stream's total length equals 10 km but its upper section is dry in summer over a stretch of 8 km and, therefore, it is actually only 2 km long. The stream is 2–5 m wide and 20–30 cm deep. This tributary is fed by springs and the Mian-Do-Ab Stream also enters it. The bed of this tributary is covered with stones and coarse gravel.
The section of the Lar river from the Game and Fish Department Guard Station at Kamardasht up to the Gozaldareh Guard Station is 5 km long and its width ranges from 8 to 25 m. The river bed in this section is composed mainly of coarse and fine gravel. Two tributaries called Siapalas and Alarm enter the river in this section.
The Siapalas flows through a valley and its length equals 6 km. The upstream section of this tributary is dry for some 2 km. The stream is 2–4 m wide, 20–40 cm deep and is fed by the waters of two brooks and some springs. The bed is silty and covered with rubble. The current is slow. The temperature of the water is as high as 20°C in summer.
The Alarm is a 7 km long stream. In summer however, about 5 km of its upstream section are dry. The downstream section of this tributary is fed by springs and it is 3–5 m wide and 20–50 cm deep here. The stream's bed is sandy and covered with fine gravel. The water temperature reaches 12°C in summer.
The length of the Lar river's section from the Game and Fish Department Guard Station at Gozaldareh up to Delichai Guard Station equals 14.5 km. In this section the river flows through a wide valley. The river bed is sandy and composed of fine rubble, coarse and fine gravel. Two tributaries - Aberu (local name Ab-Sefid) and Delichai - fall into the river in this section. The Lar flows further through a rocky canyon toward Pulur where it joins the Haraz river.
The Aberu (Ab-Sefid) tributary is 9 km long. It is created by streams running down the slopes of the surrounding mountains. The tributary's upper part dries up in summer and is only 5 km long in this section. The downstream section of this tributary is 1–3 m wide and 20–40 cm deep. The river bed is sandy and in some places, clayey. It is covered with boulders. Rubble or gravel are almost nonexistent here. The bottom of this stream has some deposits of silt. The water temperature was about 13°C in summer. In winter the surface of the stream is covered with ice.
The Delichai is the largest and most powerful tributary of the Lar river. It is 15 km long. The width of this branch ranges from 4 to 10 m and its average depth is 20–30 cm. However, in some places, this tributary is as deep as 1–1.5 m (in bottom depression areas). The tributary is fed by the waters of springs. The water temperature is about 11°C in summer. The bed is sandy and there are very large rocks on it. Over the total length of the tributary, the river bed between the rocks is covered with coarse and fine gravel. The tributary flows through a narrow and almost impassable canyon. Only its downstream section runs for about 2 km through a wide flat valley, and in this area it falls into the Lar river which flows further toward Pulur. Therefore, the total length of the Lar river, excluding the length of the tributaries, equals 39.5 km and it is 10–30 m wide. The average depth of the river is 20–30 cm. However, some sections of the river are 1 to 1.8 m deep (bottom depression areas).
The Lar river bed, over its total length, is sandy and only some sections of it are clayey. It is composed of rubble, coarse and fine gravel.
The water in the river is transparent almost throughout the year. The suspended solid matter of mineral origin was not detected in the water. But in the snow-melting season (20 June to 20 July) and in the season of heavy rains the soil particles (clay, sand) are washed down from the mountains into the river and the water becomes turbid.
The water of the Lar river had the following chemical characteristics:
Alkalinity - 150 mg/l
Calcium-magnesium hardness - 160 mg/l
Dissolved oxygen concentration - 9–12 mg/l, high saturation rate.
pH - 8.1–8.2
The temperature of the river's water fluctuates in various seasons of the year. Thus, in autumn and winter the water temperature is 2–5°C, in spring 7–10°C, in summer 13–16°C.
The water temperature conditions indicated above appear to be ideal for most Salmonidae species including trouts.
The river's food productivity also seems to be highly favourable for the fish belonging to these species as regards both quality and quantity of the foods (R. Ralonde and P. Walczak, 1970). The number of the benthos organisms fluctuates between various sections of the river. The greatest number of the organisms have been detected in the middle section of the river, the lowest number - in the downstream section. The benthos is represented in the Lar river by the following organisms: Chironomidae, Gammaridae, Ephemeroptera, Plecoptera, Trichoptera, Diptera, Homiptera, Oligocheta, Acarina and Gastropoda.
The Lar river and its tributaries' ichthyofauna consists of brown trout (Salmo trutta) and rainbow trout (Salmo gairdherii) composed of 93 percent and 7 percent of the river's total fish population respectively. It should be mentioned that about 90 percent of the total trout population inhabit the main river while not more than 10 percent of the trout live in the tributaries. The trout grows and gains weight mainly in the middle section of the river, i.e in the section from Kamardasht to the area where the Delichai falls into the Lar river. The sections located upstream and downstream of the above mentioned area have considerably worse conditions for trout growing and weight gaining.
The trout spawn both in the Lar river and in its tributaries, 80 percent of the spawning grounds being located in the river proper and the remaining 20 percent - in the tributaries.
The distribution of the spawning grounds over various sections of the river and the tributaries can be expressed in percent as following:
The Lar River Sections
|From Pulur to the Delichai tributary||- 3 %|
|From Delichai to Gozaldareh||- 32 %|
|From Gozaldareh to Kamardasht||- 44 %|
|Upstream sections from Kamardasht||- 1 %|
|Total||- 80 %|
The Tributaries of the Lar River
|Siapalas||- 0.5 %|
|Alarm||- 7.0 %|
|Ab-Sefid||- 1.5 %|
|Delichai||- 11.0 %|
|Total||- 20 %|
It is evident from the above figures that 76 percent of the spawning grounds are situated in the stretch from Delichai and Lar confluence area until Kamardasht. Of all the tributaries, the most important for spawning of the trout are Delichai and Alarm having 11 percent and 7 percent of total spawning area respectively.
Sport fishing takes place on the Lar river attracting sportsmen from Teheran who have to buy trout fishing permits available at the Guard Stations. There are five Guard Stations on the river: three round year Stations (Pulur, Gozaldareh, Kamardasht) and two Stations operational only in spring and summer seasons (Delichai and Sefid-Ab).
In order to maintain the trout stocks in the Lar river at present level and prevent them from decreasing, the Game and Fish Department regulates and limits trout fishing. The Department exercises control over fish catches and fixes time for the beginning and the end of the fishing season. The Department also determines the minimum size of the fish caught and the fishing areas. Thus, in 1970 the following trout catch regulations were in force on the Lar river:
In the spring and summer seasons of 1970 the Guard Stations issued 2 589 permits; according to these permits, 43 570 trouts of 20–45 cm body length were caught in the Lar river and its tributaries. The maximum length of some individual trouts caught in this river equals 63–83 cm. The data included into Table 8 defines the number of permits sold this year and number of trout caught in various sections of the river.
It is evident from the data in Table 8 that the average number of trouts caught per one permit was 16.8 fishes.
The fish was caught on the stretch from Pulur for two km upstream of Gozaldareh and also in the downstream parts of the tributaries running into the main river in this section. The total length of the fishing areas amounted to some 30 km. Therefore, the average number of trouts caught per one kilometre equalled 1 452.3 fishes.
If the average weight of one landed fish can be taken as 150 g, it appears that the fishermen caught 6 535.5 kg of fish during the fishing season which corresponds to 217.8 kg of fish per one km or the same amount of fish per one ha of water surface area (the average width of the river, including tributaries' fishing areas, is 10 m). Much the same data on catches in the Lar river and its tributaries have been recorded within the last five years. This is an indication of the fact that the trout stocks in the river are rather stable. These figures also characterize the natural fish productivity of the Lar river as exceptionally high and therefore this river can be placed among the best trout streams of the world.
It would be desirable to maintain in the years to come enforcement of the fishing limitations in this river by the Game and Fish Department. However, such a measure would be efficient only in the case that the river's ecological conditions were not to undergo changes and trout reproduction would be preserved, since construction of a high dam and subsequent creation of a reservoir could result in disruption of the trout reproduction in this river.
The Lar Dam and Reservoir Construction Project
The project providing for creation of a reservoir on the Lar river is being worked out by the Ministry of Water and Power of Iran. The project envisages the construction of a high dam located 300 m downstream from the area where the Delichai tributary flows into the Lar. Here the Lar river is 11 m wide and its average water discharge of many years equals 13.6 m3/sec.
The planned dam will be 105 m high, with a foundation accounting for 10 m of its height. The reservoir will be 18 km long and its width will be ranging from 1 to 6 km. The inclination of the reservoir's bed will be 0.55 percent. Total water surface area of the reservoir will amount to 33.5 km2 and the volume of water - 960 million m3. The average annual influx of water from the Lar and its tributaries will be about 429 million m3. Besides, the rains and snowfall which are heavy in this area will supply an additional amount of water to the reservoir every year.
The creation of the reservoir serves the purpose of supplying water to Teheran with adjoining rural areas and the production of electric power.
The prospective reservoir's annual water consumption will be distributed in the following way: about 100 million m3 of water will be supplied to Teheran and 289 million m3 will be used for irrigation of some 105 000 ha of land in the Mazandaran plains.
A canal connecting the future artificial lake with the existing Latian Reservoir may be constructed in the future. The water flowing through a canal from the Lar Reservoir into the Latian Reservoir will be used for irrigation of Varamin and Garmsar areas. Besides, using the difference in altitudes between the Latian and Lar reservoirs, it is planned to produce annually around 100 000 kw of electric power.
Predicted Ecological Conditions in the Prospective Lar Reservoir
The terrain which is to be flooded by the waters of the Lar Reservoir and which will serve as the reservoir's bed has comparatively flat relief. It is void of trees and bushes. The soil is sandy and the bed of the river, as well as the bed of its tributaries, is covered with rocks, rubble and gravel.
One of the important characteristics of any artificial lake or reservoir is its water supply and consumption rate which defines, along with other environmental factors, the ecological conditions under which the fish are going to live.
The water of the Lar Reservoir will be consumed mainly in summer and to a lesser extent in other seasons. Therefore, the water in the reservoir will reach its minimal level in late summer and in winter when the level will be considerably lowered due to decrease in water volume by some 30 percent or more. The annual replenishment of the reservoir up to a water-level specified in the project will take place during the springtime floods.
Taking into account the future dam's height, total length of the reservoir, planned volume of water and the relief of terrain, it can be predicted that the reservoir's depths will be dissimilar in various parts of its area. Considering the initial data of the dam construction project, as well as the topography of the basin to be flooded, at maximal water-level the reservoir's depths will be distributed over its area in the following way (See “The Distribution of Depths in Prospective Artificial Lar Lake”, Fig. 4).
The reservoir's lower section constituting 40.3 percent of its total area will be the deepest in comparison with other sections: its maximum depth will be 85 m; minimum depth - 0.2 m. Lower section's average depth will be 40 m.
As regards the depths, the middle section with area equalling 41.8 percent of the reservoir's total area will be intermediate between upper and lower sections; its maximum depth will be 70 m; minimum depth - 1 m; average depth - 25 m.
The reservoir's upper section which will constitute 17.9 percent of the reservoir's total area will be shallower than the lower and middle sections: maximum depth will be 25 m; minimum depth - less than 1 m. The upper section's average depth will be 8 m.
Considering the future reservoir as a whole, it is possible to estimate the distribution of depths over its area as follows:
|5 m and less||-||20 % of the total area|
|from 5 to 15 m||-||18 % " " " "|
|" 15 to 25 m||-||20 % " " " "|
|" 25 to 50 m||-||24 % " " " "|
|" 50 to 85 m||-||18 % " " " "|
Unlike the Lar river, there will be no current in the future reservoir. Only slow but steady substitution of water will take place throughout the year. The lack of current is explained by the reservoir's large area combined with a great volume of water and small influx from the Lar river.
Owing to the reservoir's large dimensions, its water surface will be rough with intensive intermixing of water in spring, summer and autumn. There will be five bays located in the lower reaches of the Lar river tributaries. The water in the bays will be less rough than in the main reservoir.
The lack of current will result in gradual siltation of the reservoir bed caused by the deposition of suspended mineral substances brought into the reservoir from the Lar and its tributaries in the seasons of springtime floods and heavy rains.
Due to the fact that the reservoir will be replenished up to the water-level specified in the project mainly with flood waters, the water will contain a considerable amount of biogeneous elements and organic matter in summer.
The pH value (logarithm of the reciprocal of the hydrogen ion concentration) will fluctuate in various parts of the reservoir from 7.8 to 8.3 throughout the year.
The dissolved oxygen contents in the reservoir's water will also be dissimilar in various seasons of the year. In spring, summer and autumn the oxygen concentration in the water will equal 7–10 mg/l. In winter it may go down to 6–8 mg/l in the upper layers of the water and not lower than 4 mg/l at the bottom.
The water temperatures will vary directly as the temperatures of the air of the surrounding country. The temperature of the Lar river and its tributaries will also influence, though to a lesser extent, the reservoir's water temperature owing to the lack of current and very slow water substitution.
The air temperature of the future reservoir area is peculiar to the continental climate characterized by cold winters and relatively mild summers.
On the average, there are 170–175 days with below-zero air temperatures throughout the year in this area. In winter, it freezes hard and the air temperature goes down as low as 35°C below zero. January and February are the coldest months with monthly average air temperatures being 12.0°C and 12.6°C below zero respectively. In summer, the absolute maximum temperature of the air reaches 30°C in the area. July and August are the hottest months of the year when monthly average air temperatures are 16.0°C and 17.0°C respectively (some years 18.0°C).
Proceeding from the data obtained from the Lar Meteorological Station which carries out daily observations on air temperatures in Gozaldareh and the adjoining area throughout the year and considering the temperature of the water in the Lar river and its tributaries, it is possible to foretell the future reservoir's monthly temperatures of the water:
|January||-||from 0.5°C to 3°C|
|February||-||from 0.5°C to 3°C|
|March||-||from 0.5°C to 3°C|
|April||-||from 1.0°C to 4°C|
|May||-||from 6.0°C to 8°C|
|June||-||from 10.0°C to 14°C|
|July||-||from 12.0°C to 16°C|
|August||-||from 14.0°C to 18°C|
|September||-||from 11.0°C to 16°C|
|October||-||from 9.0°C to 12°C|
|November||-||from 3.0°C to 6°C|
|December||-||from 0.5°C to 4°C|
The water in the reservoir will freeze and be completely covered with ice in early December. The ice cover will last about four months and a half. In April the ice will start to melt and at the end of this month all the area of the reservoir will be void of ice.
In autumn and winter the temperature of the lower layers of water will be higher as compared with the upper layers. By contrast, in spring and summer the upper layers of water will be warmer than the lower ones.
Based upon the above-mentioned abiotic environmental factors active in the future reservoir, it can be assumed that the food organisms would be represented by river and lake forms. The river forms of food organisms will be concentrated predominantly in the reservoir's upper part and in the bays where the Lar river tributaries will be falling in.
The following benthos organisms are expected to inhabit the lake: Chironomidae, Oligichaeta, Trichoptera, Hydropsyche, Hydroptila, Neurclipsis, Gammaridae, Malusina, Ephemera, Pisidium, Dreissena, Ancylus, Simulium, Kelmis, Limnius, Aphelochirus and some other organisms.
In spring, summer and autumn, phyto- and zooplankton will be developing in the reservoir. The phytoplankton will be represented by diatoms (Diatomeas), green Chlorophyceae) and blue-green algae (Cyanophyceae). Copepoda and Cladocera will rate first among the zooplankton organisms as regards their number and biomass.
It is not improbable that soft submersed and coarse emergent plants would grow in some areas of the reservoir, especially along its shoreline and that some duckweed (Lemna) will appear there.
The natural fish productivity of the reservoir is expected to be 15 kg per ha. It would be impossible, however, to obtain such fish productivity with a very limited number of trout preserved after impounding of the Lar river which will possibly be coming into the reservoir only for weight gaining but will not spawn there due to lack of appropriate conditions.
Therefore, there are no valuable species in the Lar river and tributaries which could spontaneously populate the reservoir and find there conditions favourable for their natural reproduction. In order to utilize effectively the reservoir's food productivity and to harvest annually a stable crop of valuable fish, it is therefore essential that measures on controlled population of valuable ichthyofauna be taken implementing methods of artificial pisciculture.
Trout Stock Losses in the Lar River and its Tributaries Caused by Creation of a Reservoir
After the filling of the reservoir, the section of the Lar river bed from Delichai Guard Station up to Kamardasht Guard Station will be flooded and hence, eliminated. The reservoir's ecological conditions will differ drastically from the present ecological conditions of the Lar river and its tributaries. Therefore, the creation of the reservoir will cause losses in the trout's main spawning grounds and result in elimination of this section's richest feeding areas.
Many existing spawning areas of the tributaries' lower reaches will lose their importance because these areas will go under the water and create the future bays of the reservoir.
With the expected water consumption rate it would be impossible to achieve a water discharge through the dam into the Lower Lar equalling the present rate. As a consequence the Lower Lar from the dam site till Pulur will be lost not only for spawning, but also for growing and weight gaining of the trout.
From the above-mentioned facts it may be concluded that after a dam has been constructed on the Lar, the river will be preserved only in its upper part. Its length will be 13 km which is one third of its present length. Almost all of the trout spawning grounds will disappear. The spawning grounds which will be lost will amount to 79 percent of the total spawning areas existing now both on the main river (80 percent) and on its tributaries (20 percent).
Extensive damage will also be done to the spawning grounds located in the tributaries of this river. Its total area will be reduced by 50 percent. The Siapalas Stream will be void of any spawning grounds at all. The Alarm and Ab-Sefid Streams will have only 0.5 percent of spawning grounds each. In the Delichai tributary, 9 percent of the total spawning areas existing now in the Lar river and its tributaries will remain undestroyed.
The total amount of losses in spawning areas of the Lar river and its tributaries will be as high as 89 percent.
Thus, the creation of a reservoir on the Lar river will cause disruption of trout natural reproduction and a sharp decrease in its number. The present stocks of the trout will suffer a 9-times decrease or even a heavier loss.
Suggestions for Reproduction of Trout in the Lar River and its Tributaries
As indicated above, the creation of a reservoir will result in a severe decrease in trout stocks of the Lar river and its tributaries. In order to prevent this valuable fish from future gradual disappearance and to keep its stock at a sufficiently high level, it is necessary, prior to creation of the reservoir, to carry out some land-reclamation measures for improvement of the trout's natural spawning and growing conditions.
Therefore, it is essential that the 5-km long underground section located in the Lar river's upper part, near Kamardasht be eliminated. There are three possible variants of effectuating this project:
If the river's underground waters flow at a depth not exceeding 1 m, it should be sufficient to dig out the river bed over its total length of 5 km.
If the underground waters flow at a depth exceeding 1 m, it is advisable to construct a canal which will divert the water from its underground course and direct it into the lower part of the overground bed, i.e. it will connect the river's upper and lower parts preventing the water from going underground.
If the water from the river bed's upper part goes deep under the ground through a small-size hole and after flowing under the soil for 5 km discharges into the lower section of the overground river bed, then it is advisable to cement up the hole diverting, by this means, the water into the overground bed where springtime flood waters flow.
It will depend on geological and hydrotechnical investigations as to which one of the above-mentioned variants should be implemented.
It is estimated that two or three bulldozers will be needed for carrying out work on the elimination of the underground channel.
It will also be necessary to create some artifical spawning beds for the trout in the Upper Lar encompassing the section from Kharsang - Sefidab forks till Kamardasht by spreading gravel on the river bed after every 0.5 km. The area of each spawning bed should be around 100 m2 and thickness of the gravel layer - not less than 10 cm. Similar work on creation of artificial spawning beds should be carried out also in the lower part of the tributaries where these streams flow through a wide flat valley at present and which will be located in the bays of the reservoir.
All the expenses on implementation of the indicated land-reclamation works should be borne by the Ministry of Water and Power of Iran which is planning to create the reservoir by means of impounding the Lar river.
Recommendations for Controlled Population of the Lar Reservoir with Valuable Ichthyofauna
The prospective Lar Reservoir can be utilized not only for fulfilling the requirements of Teheran for water-supply, irrigation of rural areas and production of electric power, but also for the fish cultivation with the aim of supplying local people, including the inhabitants of Teheran, with fish.
It is possible to make use of the reservoir by means of establishing a lake fish cultural station there. However, creation of a fish cultural station on an artificial lake would be a much more complicated task as compared with any natural lake project because every natural lake has its own historically established ecological conditions and a peculiar composition of ichthyofauna. One of the distinguishing features of the future reservoir will be an unstable water-level which will be determined by water discharge and supply periods. As a result of continuous physical, chemical and biological processes developing in the reservoir, the ecological conditions prevailing during the first years of the reservoir's operation will undergo changes in later years. The changes in life conditions of fish will cause changes in composition of ichthyofauna and the number of fish belonging to various species. Because of these factors, it is difficult to establish a fish cultural station on a reservoir having a large area. Therefore, a fish culture station created on the Lar Reservoir will be successful only when there is spontaneous development of ichthyofauna, when a body of water is usually populated by non-valuable coarse fish is avoided and appropriate measures are taken on controlled population of the reservoir by means of introducing valuable species with regard to the reservoir's ecological conditions.
Proceeding from the reservoir's ecological conditions predicted in this report, it is believed that the reservoir could be populated with valuable species of cold-loving lake fish. But such forms of fish are almost nonexistent among the ichthyofauna of Iran since there are no cold-water lakes in this country with historically established conditions for valuable fish reproduction. Of the local ichthyofauna, only rainbow trout (Salmo gairdnerii) can be recommended for stocking of the reservoir. However, it will be impossible to harvest the required number of the fish of this species. In that case, the fish crops which could be obtained annually in the reservoir will not be ensured because only a part of the reservoir's food resources will be used, while assumed natural fish productivity of the reservoir makes it possible to catch more fish. Therefore, fish cultural programmes will succeed in the reservoir only in case that some other cold-loving fish, which can be imported from abroad for their acclimatization in this country, inhabit the reservoir in combination with the rainbow trout. As far as possible, these fishes should have dissimilar ranges of food, i.e. some species should feed mainly on benthos organisms, other species - on plankton. Certain fishes should prefer predatory mode of life and feed on the coarse fish which will appear in the reservoir.
Therefore, the following species of valuable lake fishes belonging to the Salmonidae family can be recommended for acclimatization in the Lar Reservoir: Great Lakes char (North America) - (Salvelinus namaycush), Sevan-lake trout (Salmo ischchan) and Siberian “pelyad” (Coregonus peled). The average weight of these fishes ranges from 1.5 to 5 kg. Some individual specimens of the Great Lakes char can have considerably greater weight (20–40 kg). This fish is a good object for sports fishing but it would not be numerous enough for commercial fishing.
Acclimatization of the species indicated above can be effectuated after importing from the U.S.A. or the U.S.S.R. their fertilized eggs at the stage of pigment formation in the embryo's eyes. Once delivered to Iran, these eggs could be incubated additionally in Karadj Trout Hatchery “Mahi Sara” located in the vicinity of Teheran. The hatched larvae should start feeding and after transformation into fry, it can be released into the Lar Reservoir.
It would be necessary to import into Iran the following total amount of various species' eggs respectively: 100 000 eggs of char, 200 000 eggs of Sevan-lake trout and 160 000 eggs of Siberian “pelyad”. The eggs could be delivered to Iran in two stages during a two-year period, annual delivery of each species' eggs equalling 50 percent of the above-mentioned amount.
The species recommended for stocking of the reservoir will be able to find areas for spawning in the bays created by the upper part of the Lar river and the lower reaches of its' tributaries. However, in order to ensure reproduction of this fish, it may be necessary to construct a fish hatchery having facilities for procuring eggs from mature brood fish, egg fertilization and incubation, hatching the larvae and rearing young fish for stocking of the reservoir. This measure will make it possible to obtain high and stable catches, since the fish recommended for introduction into the reservoir are chosen with provision for total utilization of the reservoir's food resources. For example, Sevan-lake trout and rainbow trout will feed mainly on benthos organisms, Siberian “pelyad” is a plankton feeder and the char will prefer a predatory mode of life and consume small-size coarse fish which will inevitably appear in the reservoir.
Annual average catches in the lake will amount to 50 t. In this case, the following ratio of various species caught annually should be adopted: Char - 20 percent, Sevan-lake trout - 40 percent, Siberian “pelyad” - 35 percent and rainbow trout - 5 percent. These fishes can be caught with seines and nets.
The Ministry of Natural Resources of Iran and the Game and Fish Department should carry out work on creation of desirable ichthyofauna in the Lar Reservoir, exercise control over the reservoir's operation, take necessary action on regulation and limitation of fishing, effectuate artificial fish culture and protect existent fish stocks.
In the upper reaches of the Lar river (upstream from Kamardasht area) it is necessary to eliminate the river's 5 km long underground stretch. Three variants are suggested for carrying out this work.
It is essential to create artificial spawning beds in the Upper Lar and in the lower reaches of its tributaries.
The future reservoir on the Lar river can be stocked with valuable cold-loving lake fish belonging to Salmonidae family: Salvelinus namaycush; Salmo ischchan; Coregonus pelad; Salmo gairdnerii.
For acclimatization and future reproduction of the above-mentioned species, it will be necessary perhaps to construct a fish culture station there for incubation of eggs, hatching the larvae, and rearing young fish.
Annual fish catches from the reservoir will equal, supposedly, about 50 t. The following ratio of various species caught annually should be adopted: Salvelinus namaycush - 20 percent, Salmo ischchan - 40 percent, Coregonus pelad - 35 percent, Salmo gairdnerii - 5 percent.
The Ministry of Natural Resources of Iran and the Game and Fish Department should carry out work on controlled population of the reservoir with ichthyofauna, exercise control over the reservoir's operation, regulate fishing, limit the fish catches, undertake artificial piscicultural measures and finally, preserve the fish stocks.
Both piscicultural and land-improvement works should be done on the Lar river to preserve the existing stock of trout and a fish culture station should be established there so that a desirable ichthyofauna will be created in the reservoir which will come into being on this river after implementation of the dam construction project.