The following hydraulic engineering measures are recommended in order to enhance and accelerate the restoration of Anzali Lagoon to its former brackishwater status:
construction of a canal on the northwestern bank of the Lagoon to connect the western basin with the Caspian Sea. According to preliminary investigations the canal should be dredged in the vicinity of the villages Gluga and Sandochin. The capacity of the canal is calculated to provide 0.6 m3. s-1 of seawater. The canal should be equipped with gates and sluices allowing the seawater inflow to be regulated. Pumping facilities should also be planned, although at present the Caspian Sea level is higher than the western basin water level. The purpose of this canal is twofold:
to ensure the immigration of diadromous and brackishwater fish species such as Rutilus frisii kutum, Stizostedion lucioperca, Vimba vimba, Abramis brama, Chalcalburnus chalcoides, Liza auratus and Alosa caspia;
construction of a canal on the southwestern bank of the western basin, diverting the Bahambar River to this basin. The capacity of this canal should be 1.6 m3.s-1. This canal should be equipped with gates and sluices. Its purpose is to regulate salinity in the western basin. Preliminary calculations show that with fully open sluices of both gates the resulting salinity will be around 3%. Salinity could be increased up to about 6% without any adverse effect on fishes or Phragmites stands. Recent experiments by Konstantinov and Martynova (1990) show that salinity values of 3–5% have a positive effect on the growth of fish such as Cyprinus carpio, Ctenopharyngodon idella, Aristichthys nobilis, Acipenser gueldenstaedti and also enhance their resistance to oxygen deficiency;
dredging the western basin in order to remove muddy sediments and to deepen it. Dredging should begin in the eastern part of the western basin where the sediment deposits are deepest. Dredging should start after the construction of the canal between the western basin and the Caspian Sea as the inflowing sea water may speed up the outflow of sediments. The excavated sediment should be used for construction of a dike along the southern shore of the western basin to prevent the rice-fields from flooding;
construction of a network of dikes and canals diverting water from some rivers, into southern and eastern basins of the lagoon. The rivers chosen should be selected after previous consultation with the fishery officers, and those rivers which provide the spawning grounds for migratory fish should not be used for this purpose. The reason for this recommendation is that at present most flood waters do not enter these basins and their flushing effect is thus minimal. It is expected that the dissolved oxygen levels in the southern and eastern basins would significantly improve and this would contribute to the restoration of fish communities there;
construction of rocky chutes in all inflowing rivers where weirs prevent upstream migration of spawning shoals. Principles regarding their construction may be found in papers by Lusk (1979, 1980).
If carried out, the above proposed works should ensure a rapid recovery of Anzali Lagoon. The yield of Rutilus frisii kutum, Abramis brama, Cyprinus carpio and Stizostedion lucioperca should increase as a consequence of improved dissolved oxygen concentrations and rehabilitation of the spawning grounds. The quantity and quality of fish catch should also improve following the immigration of Liza auratus and clupeids into the lagoon.
Construction works could be designed so that Anzali Lagoon becomes a highly productive and well managed coastal lagoon similar to those along the Mediterranean coasts of Italy and France.
These recommendations should be further discussed with Iranian environmentalists. At present the situation of the Lagoon is in a state of change, affected by the continuous rise in the Caspian Sea level, and with the possibility of additional impact of man-induced global climate change.
At present, the worst polluter is the sewage from the city of Rasht, entering the Pirbazar River and is thus carried to the Lagoon.
The cheapest and easiest way to deal with the sewage is to divert the Pirbazar River directly into the Caspian Sea. However, this could create pollution along the coast where there are now important fisheries. A possible solution could be to build an efficient sewage purification station for Rasht with primary, secondary and tertiary treatment facilities.
Azolla mats have to be repeatedly removed from the channels of the southern and eastern basins. Extracted Azolla can be used as green manure in rice culture and also as feed for fish in pen culture, for chickens, ducks and geese. Harvesting of Azolla can be mechanized using engine-operated equipment as, for example, the French system Barracuda.
Rational fishery management of Anzali Lagoon and its watershed needs to be introduced. Fishery regulations should be enforced to protect the existing fish stocks, support their rational management, and to develop the fishery.
It is therefore recommended that:
a frame survey on the Anzali Lagoon be carried out. Data on fishing effort and fish yield should be collected. A lagoon-wide statistics collection network should be established as soon as possible;
all fishermen should be registered and observe the fisheries regulations issued by SHILAT; poaching must not be tolerated;
fish protection measures be enforced, especially those concerning spawning grounds. Any type of fishing in all incoming rivers must be prohibited between 1 February and 30 April (12 Esphand-10 Ordibehesht). The rivers must be controlled by guards;
the fishery in Anzali Lagoon and its tributaries must be regularly monitored by the SHILAT Fisheries Research Centre (FRC). Water salinity, dissolved oxygen concentration and basic biological information on the economically important fish species should be regularly sampled and evaluated;
a comprehensive biological analysis of the Rutilus frisii stock, including age, growth, mortality and biomass, using tagging techniques is needed as knowledge of this highly important species is still poor;
the FRC staff in Bandar Anzali be trained in basic ichthyological, ecological and limnological principles and fisheries management. The course should pay special attention to the Caspian Sea and freshwater habitats, and identification of their fish population;
the fishery for crayfish in Anzali Lagoon tributaries be regulated. Harvesting periods should be 5 May–21 June and 23 September–1 November. The lower size limit should be 100 mm TL which is equivalent to 47 mm carapace length (CL) and/or 35 mm orbital carapace length (OCL). Not all streams should be set with trap at the same time. Crayfish should be harvested once a year in all streams, or twice a year in one half of the streams one year and in the other half of the streams the next. Harvesting of crayfish should be strictly controlled and the population size of the crayfish regularly monitored.
There appears to be a conflict of interests between SHILAT and those of the Environmental Protection Organization (EPO). SHILAT and EPO should agree on strategies for management and utilization of natural resources such as the fish and wildlife of Anzali Lagoon. The Lagoon should be managed by one executive body only.
The FRC library in Bandar Anzali is in a very poor state, badly organized and with publications of little use to the staff. It is strongly recommended to purchase some basic reference books and taxonomic publications as listed by A.B. Viner (IRA/89/022, Field Document 1, February 1991).
