Background and Objectives: Conservation of stocks is a globally emphasized principle and a key criterion for the sustainable exploitation of all aquatic resources. The efforts of all fisheries managers focus on ensuring sufficient and reliable food supply from natural resources and meeting the needs of human communities, considering the permissible and proper levels of exploitation. The king mackerel is a tropical and subtropical species inhabiting the Indian and Pacific Oceans and is one of the economically valuable fish in the southern waters of the country. The aim of this study was to examine the fishing status, fishing indices, and population characteristics of king mackerel (Scomberomorus commerson) based on length over past decades from four fishing landing areas including Pazm, Konarak, Beris, and Pasabandar in the northern waters of the Sea of Oman.
Methods: Random sampling was conducted monthly during the years 2001 and 2023 from commercial catches landed at the selected stations, and samples were subjected to biometric analysis (fork length measurement). Fork length was measured using a biometric ruler with an accuracy of 1 cm, and fish weight was measured with a scale accurate to 50 g. Growth indices including asymptotic length, growth coefficient, natural mortality, fishing mortality, total mortality, exploitation rate, age at zero length, spawning potential ratio based on length, environmental tolerance or natural carrying capacity, and optimal catch length were calculated. Data analysis was performed using Excel, Rstudio (version 2024.12.0), and R (version 4.4.2) software at a significance level of 0.05.
.Findings: The mean length (range) of king mackerel in 2001 was 83 ± 22 cm (35-163 cm), and in 2023 it was 74 ± 7 cm (47-146 cm). The weighted average (range) weight of the kingfish in the year 2001 was 4359 ± 1301 g (ranging from 100 to 33000 g), and in the year 2023, it was 3075 ± 1751 g (ranging from 3800 to 13300 g). Considering the maturity length of this species (86 centimeters), the percentage of samples below the maturity length in the years 2001 and 2023 were 45% and 77%, respectively. The average length in 2023 compared to 2001 and the percentage of undersized specimens in 2023 compared to 2001 showed a significant difference (p< 0.05). The von Bertalanffy growth equation for this species in Sistan and Baluchestan province for the years 2001 and 2023 was calculated as follows: Lt = 175(1 - exp(-0.44(t + 0.22))) and Lt = 159(1 - exp(-0.45(t + 0.23))), respectively. The spawning potential ratio based on length in 2001 was 0.17 (range 0.14–0.19), and in 2023, this value was 0.09 (range 0.07–0.10)
Conclusion:Based on the obtained results, there are no signs of overfishing; however, it is recommended that a precautionary approach be considered in the management and exploitation of this species to avoid problems in the long term. |
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