Volume 18, Issue 2 (Summer 2026)
3 2026, 18(2): 1-14 |
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Hashemi A, Doustdar M. Changes In Growth Parameters, Fishing Vulnerability Index (FV), and Population Growth Potential Index (FP) of Kawakawa (Euthynnus affinis) Over The Past Decades In the Northern Waters of The Oman Sea (Sistan and Baluchestan Province). 3 2026; 18 (2) :1-14
URL: http://jmb.ahvaz.iau.ir/article-1-1083-en.html
URL: http://jmb.ahvaz.iau.ir/article-1-1083-en.html
Offshore Fisheries Research Center, Iranian Fisheries Science Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Chabahar, Iran.
Abstract: (17 Views)
The Persian Gulf and the Oman Sea host a diverse range of aquatic species, among which tuna is of particular importance. Kawakawa (Euthynnus affinis) is one such tuna species whose catch has shown an increasing trend in recent years. Required data were collected through monthly sampling and biometry of fish unloaded at four major fishing ports (Pasabandar, Beris, Konarak, and Pozm) during two distinct periods: 1994 and 2024. Growth parameters including asymptotic length (L∞), growth coefficient (K), and theoretical age at zero length (t₀) were calculated using the Powell-Wetherall method, the ELEFAN optimization approach (in the R software), and Pauly’s empirical formula. Furthermore, the Fishing Vulnerability Index (FV) and Population Growth Potential Index (FP) were estimated based on fuzzy logic, combining habitat and population characteristics of the species. The results revealed statistically significant changes in the growth parameters of this species in 2024 compared to the base year (1994): the asymptotic length (L∞) decreased from 85 cm to 84 cm, the growth coefficient (K) increased from 0.30 to 0.41 per year, the growth performance index (Φ′) increased from 3.35 to 3.46, and the theoretical age at zero length (t₀) changed from -0.4 to -0.3. These changes indicate a pattern of accelerated growth, especially in the early years of life. Furthermore, the values of the Fishing Vulnerability (FV) and Population Growth Potential (FP) indices between 2001 and 2024 suggest that while the population's vulnerability has slightly decreased (from 36 to 33), its growth and recovery potential has remained at a favorable level (FP around 70). These changes are likely influenced by factors such as a dramatic increase in fishing pressure (an 18-fold increase in catch in Sistan and Baluchestan Province during the study period), as well as changes in environmental and ecological conditions. Based on these findings, it appears that the harvest from the Kawakawa stock is nearing its maximum sustainable level, and any increase in fishing effort could jeopardize the long-term sustainability of this stock. This information can be valuable for fisheries managers and experts in making informed management decisions, setting sustainable catch limits, revising fishing gear regulations, and enhancing monitoring systems to ensure the sustainability of this valuable stock.
Keywords: Euthynnus affinis, Growth Parameters, Fishing Vulnerability Index (FV), Population Growth Potential Index (FP), Oman Sea.
Type of Study: case report |
Subject:
Fisheries
Received: 2025/12/30 | Accepted: 2026/08/8 | Published: 2026/08/8
Received: 2025/12/30 | Accepted: 2026/08/8 | Published: 2026/08/8
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