Journal of Fisheries

Fishery characteristics, population dynamics and the impacts of the invasive red swamp crayﬁsh (Procambarus clarkii) in the Nile River, Egypt

Sahar Fahmy Mehanna — 2024-10-23

Alien intrusive species are one of the extreme pressures on biodiversity for their rapid reproduction and adaptation to new environments. Crayfish Procambarus clarkii entered Egyptian freshwater ecosystems at the beginning of 1980's. After many years of negative effects of its introduction onto the Egyptian waters, it became one of the commercially important species. Population parameters of P. clarkii are estimated based on 1355 specimens collected from the Nile off El-Minya during 2019–2020. The isometric growth of the species under the study is confirmed according to the obtained b-value of length–weight relationship (LWR). Annual sex ratio (female : male) was in favour of females with an annual sex ratio 1.44 : 1. The values of growth coefficient (K) and the asymptotic total length (L_∞) were assessed for males, females and combined sexes. Using mortality estimates, the exploitation ratio was 0.64 year^–1. Investigation of relative yield per recruit (Y'/R) and analysis of relative biomass per recruit (B'/R) for P. clarkii in the Nile off El-Minya provides the highest (Y'/R) at E_max= 0.81 and the E_0.5 (utilisation level that preserves the spawner stock biomass at 50% of the virgin spawning biomass) was 0.38. From fisheries management point of view, the current exploitation level should be decreased to that maintain the spawning stock biomass (from 0.64 to 0.38).

Depuration kinetics of potentially toxic metals (Hg, Co and Cr) in Perna viridis: Implications for biomonitoring, environmental management, and planetary health

Chee Kong Yap — 2024-10-05

This study aims to study the depuration kinetics of mercury (Hg), cobalt (Co), and chromium (Cr) in the soft tissues of the green-lipped mussel Perna viridis, transplanted from one polluted site (Kg. Pasir Puteh) to two relatively unpolluted sites (Sungai Belungkor and Kg. Sungai Melayu). The effectiveness of P. viridis as a biomonitor for heavy metal contamination was assessed by monitoring the reduction in metal concentrations over a six-week period. The results revealed that Hg exhibited the highest depuration rates, with reductions exceeding 95% at both sites, while Co and Cr showed slower depuration rates, with significant site-specific variations. Health risk assessments, including estimated daily intake, target hazard quotient, and estimated weekly intake, indicated a substantial decrease in potential risks associated with seafood consumption as a result of the depuration process. These findings underscore the importance of considering environmental conditions when interpreting depuration data, highlight the role of P. viridis in supporting sustainable environmental management practices, and connect the health of marine ecosystems to broader planetary health and global sustainability goals, including the United Nations Sustainable Development Goals.

Zinc in commercial marine fish from Peninsular Malaysia: Biomonitoring, health risks, and UNSDGs’ connection

Chee Kong Yap — 2024-10-04

The present study aimed to determine the human health risk (HHR) of zinc (Zn) in forty species of marine commercial fishes sourced from Peninsular Malaysia and available between April and May 2023. These species exhibited concentrations of Zn ranging from 24.1 to 153 mg kg^–1 dried weight. These values fell below the maximum allowable limits established by seafood safety guidelines, indicating that the fish are valuable sources of the essential element. The Zn target hazard quotient values were below 1, suggesting that consuming fish containing Zn poses no non-carcinogenic risks. Additionally, it was discovered that the computed estimated weekly Zn intake values were lower than the established provisional allowable weekly Zn intake. It can be inferred that ingesting fish from Peninsular Malaysia would not expose consumers to any detrimental consequences regarding Zn levels. Although this is true, on-going surveillance via Fish Watch (biomonitoring of metal pollution using fish) is imperative to safeguard the well-being of consumers who significantly depend on commercial marine fish imported from Peninsular Malaysia. The study contributes to the achievement of the United Nations Sustainable Development Goals, particularly Goal 3 (Good Health and Well-being) by promoting safe consumption, Goal 12 (Responsible Consumption and Production) through sustainable fishing practices, and Goal 14 (Life Below Water) by emphasizing the importance of protecting marine ecosystems.

Genetic differentiation and heavy metal pollution influence on horseshoe crab Tachypleus gigas populations in Peninsular Malaysia: A comprehensive allozyme analysis

Chee Kong Yap — 2024-09-24

This study aimed study the genetic diversity and differentiation of Asian horseshoe crab Tachypleus gigas (Müller, 1785) populations across three distinct locations in Peninsular Malaysia: Kampung Pasir Puteh (KPPuteh), Kuala Sungai Ayam (KSAyam), and Kampung Pulau Sayak (KPSayak). A total of 28 individuals were collected, and their genetic structure was analyzed using starch gel electrophoresis. The study employed multiple buffer systems optimized for separating 20 different enzymes, each contributing to understanding the genetic variability within and between populations. The findings of this study, which revealed significant genetic differentiation, particularly between populations in polluted and less impacted environments, as reflected by high FST values and distinct clustering in the UPGMA dendrogram, are of paramount importance. The results indicate that environmental factors, especially metal-polluted sites at KPPuteh and KSAyam, have played a critical role in shaping the genetic structure of these populations. Populations from the two polluted sites, exhibited higher genetic diversity and greater deviations from Hardy–Weinberg equilibrium, suggesting localized selection pressures. Conversely, from a less polluted site, the unpolluted site at KPSayak population showed lower genetic variability and was genetically distinct from the others. These findings underscore the importance of considering environmental influences in conservation strategies for T. gigas, highlighting the need for site-specific management to preserve genetic diversity and ensure long-term survival of the species.

Bioaccumulation of iron (Fe) and lead (Pb) in various body tissues of Telescopium telescopium in Peninsular Malaysia: Implications for biomonitoring and sustainability

Chee Kong Yap — 2024-09-11

Heavy metal contamination in marine environments poses a significant threat to aquatic ecosystems and human health. This study investigates the accumulation patterns of iron (Fe) and lead (Pb) in seven different body tissues (cephalic tentacle [CT], digestive caecum, foot, gill, mantle, muscle, and remaining soft tissues) of Telescopium telescopium collected from Peninsular Malaysia. Using heat map visualization and correlation analysis, we examined the relationships between Fe and Pb levels in various body tissues. High positive correlations were observed in Fe levels between the foot- CT (r = 0.86), and Pb levels between the muscle and CT (r = 0.95). Factor analysis highlighted the complex interplay of environmental and physiological factors influencing metal accumulation. Our findings underscore the importance of considering multiple tissues for accurate biomonitoring of metal pollution in marine environments, particularly in the context of sustainability and, environment, social and governance considerations.