Studying the diversity and values of fish in protected rivers of Iran (Lar and Haraz, Chalus, Sardabrood, Karaj and Jajrood) and identifying their important threats

Abstract

Introduction: The present study was conducted with the aim of investigating the diversity of fish
in the watersheds of the aforementioned protected rivers by determining their values and examining
the set of human pressures on them.
Materials & methods: Sampling of fishes of protected rivers was done by Electrofishing method
and using a small spring fin net (one centimeter), in 50 stations and seasonally, during the years
2020-2021. In addition, during various visits and according to the available statistics and
information, the major threats of these rivers have been identified & drawn and displayed in the
soft environment of ArcMap 10.7.1.
Results: Based on the results obtained, 47 species from 13 families have been identified for five
rivers, and the highest abundance of species for all studied rivers is related to the carp family
(Cyprinidae). In addition, 21 species have economic value, 21 species have commercial value, 29
species have sport fishing value, 15 species have aquarium value, 15 species have migration value,
and 27 species have conservation status, and this ratio is different in different rivers. In addition,
Haraz River has the highest value in comparison with other rivers in all the above cases. In
connection with all kinds of human pressures, Haraz River is heavily affected by sand harvesting
workshops, fish farms and tourist restaurants. Chalus river is mostly affected by urban development
and tourist restaurants and it has severe pollution downstream due to the activities of sand
workshops. Sardabroud river is mostly affected by urban and villa pollution. Jajrud River has been
affected by heavy water harvesting, agriculture and dam construction, so that it has completely
dried up in the lower part of the river. Karaj River is also affected by dam construction, restaurant
activities, sand harvesting and water harvesting by agriculture. Also the most important threatening
factors of these five rivers are include Indiscriminate harvesting of sand, Untreated wastewater from
fish farms, excessive harvesting of water due to agriculture in the summer season, pollution caused
by fertilizers and agricultural toxins, Urban and rural sewage, and numerous scattered restaurants
In the margins of these five rivers, dams and obstacles to fish migration, canalization, Indiscriminate
harvesting of fish, and the existence of non-native species, the intensity of which is different in
different rivers .
Conclusion: Since these studied rivers have significant conservation value for the country, they
need serious management and reconstruction by the managers so that their biodiversity and
ecosystem services are preserved .