Determination of the most suitable season for catching the Mesopotamian pike chub (Squalius lepidus Heck, 1843) using biological characteristics in ZayandehRud (Chaharmahal and Bakhtiari)

Abstract

Introduction: This study was conducted to determine the most suitable seasons for catching Squalius lepidus using the biological characteristics of this fish in ZayandehRud River, Chaharmahal, and Bakhtiari Province.
Materials & Methods: Sampling was performed to collect the Mesopotamian pike chub specimens monthly from December 2014 to November 2015. Cast nets, wire, and cotton gillnets were used to catch this fish. GSI index was used to determine the spawning time
and the weight method was used to determine the uniformity.
Results: The minimum, maximum and average absolute fecundity were 1102, 12453, and 4123±2122 eggs per total body weight, and the average relative fecundity was 132.4±41.2 (Eggs/kilogram of body weight, respectively. The maximum average diameter of eggs at the same time as the months of the spawning season was 1.85 mm and the minimum was 0.23 mm in December. The sex ratio of fish caught was 3: 1 (male: female). The maximum fork length and weight were 163 mm and 36.71 g for females and 197.2 mm and 50.45 g for males. Also, the average length and weight of this species increase with the approach of April.
Conclusion: According to the results of this study, it can be stated that October to April is the most appropriate time to catch this fish in the ZayandehRud River because the fish migrate to this river to spawn after this time. As a result, it is suggested to estimate the
population and the impact of environmental conditions on this carp family's biological and ecological characteristics in future studies to obtain comprehensive information related to S. Lepidus. It is also necessary to impose fishing restrictions to preserve the stocks of this fish from May to late July in the ZayandehRud River located in Chaharmahal and Bakhtiari province.