Journal of Fisheries

Identification, isolation and pathogenicity of Aeromonas salmonicida and his-topathology of infected Oncorhynchus mykiss in Punjab and northern areas of Pakistan

Sat, 15 Feb 2025 19:46:04 +0000

Aeromonas salmonicida causes furunculosis in the Oncorhynchus mykiss (rainbow trout) and the effective control over this infection requires knowledge of the genetic variability and epidemiology of A. salmonicida. Pathogenic strains were isolated from kidneys, muscles, liver and spleen of rainbow trout from the provinces, Punjab, Khyber Pakhtunkhwa and Gilgit Baltistan, Pakistan. On the base of 16S rRNA sequencing, physiological and biochemical characterization, isolated bacterial strains were identified as A. salmonicida (NCBI Ref. ArS-Pak-19 [MW307221], ArS-Pak- GB1-19 [MW720959], ArS-Pak-MRE-19 [MW720960], ArS-Pak-SW2-19 [MW720961], ArS-SW1-Pak-19 [MW720962]). Isolated strains were resistant to antibiotics like sulfamethoxazole, penicillin, vanomycine, rifampicin and bacitracin but were extremely sensitive to spectinomycin, ciprofloxacin, ofloxacin, levofloxacin and nalidixic acid. To check out the pathogenicity, rainbow trout were experimentally infected with isolated strains. Experimental fishes showed the same symptoms as were recorded in naturally infected fish including jaw bleeding, intra-abdominal fluid, intestinal bleeding and gill filament anemia. After ten days of post-challenge study, histopathological analysis revealed that there were severe alterations in the spleen, liver and kidney of the infected fish. The present study provides further research foundation and for upcoming research on A. salmonicida disease, its control and epidemiology.

Advancing fishing technology education and research: a 65-year legacy at Nha Trang University, Vietnam

Sun, 22 Dec 2024 12:03:39 +0000

As a coastal country, Vietnam relies on marine exploitation for food security and livelihoods. Training human resources to research, exploit, and manage marine resources is an important strategy to maintain rapid and sustainable economic growth and development. Official training in fishing technology at Nha Trang University (NTU) started in 1959. With 65 years of teaching, the unique program only offered at NTU, has made significant contribution to social-economic development in general and sustainable marine fisheries in particular. In this paper, we review the major achievements in teaching and scientific research in fishing technology at NTU as well as highlight the challenges and progress. Over the years, thousands of students have been trained under the fishing technology program and they then have worked all over the country, working in fisheries management, science, and services. Hundreds of research projects and peer-reviewed papers have been conducted and published. Those have supported fishing efficiency, environmentally friendly fishing methods, and effective management. However, the number of fishing technology students has decreased during the past few years because of unfavorable study and working environments where students are often exposed to commercial fishing vessels that frequently operate under rough weather conditions. Despite challenges and difficulties, NTU is determined to maintain the program to support the ocean economic development of the nation.

Molecular characterization based on cytochrome C oxidase I gene of the family Channidae from different riverine systems of Odisha, India

Sat, 07 Dec 2024 21:04:56 +0000

This study focuses on four Channa species from the northern part of the Eastern Ghats in India: Channa punctata (Bloch, 1793); Channa striata (Bloch, 1793); Channa marulius (Hamilton, 1822) and Channa gachua (Hamilton, 1822). The aim is to determine whether their molecular divergence aligns with their morphological distinctiveness. The molecular analysis based on mitochondrial COI gene sequences revealed distinct clusters for each species and genus, with K2P distances ranging from 17.28 – 27.96%. Notably, C. marulius was positioned in a distinct clade separate from the C. punctata, C. striata, and C. gachua groups. Channa gachua clustered with Channa rara and Channa kelaartii, suggesting a close evolutionary relationship. Channa punctata and C. striata also clustered together, reinforcing their status as sister species. Species delimitation using the Assemble Species by Automatic Partitioning method identified 10 partitions, with the most reliable delimitation showing a clear separation of Channa species of Odisha. These findings align with recent analyses and confirm that the molecular divergence among the four species is consistent with their morphological differences. The study underscores the importance of molecular methods in resolving taxonomic ambiguities and understanding species diversity. It provides a foundational molecular database for Channa species, supporting future research on genetic divergence and contributing to conservation and aquaculture efforts.

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

Sahar Fahmy Mehanna — Wed, 23 Oct 2024 14:04:20 +0000

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, Khalid Awadh Al-Mutairi — Sat, 05 Oct 2024 00:00:00 +0000

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.