Journal of Fisheries

Impact of high intensity ultrasound on the quality and preservation period of blue shrimp (Litopenaeus stylirostris) muscle

Wilfrido Torres-Arreola — 2025-05-27

Due to the limited shelf life of aquatic products, the use of advanced technologies to extend their freshness has become more popular recently. This study aimed to assess the impact of high-intensity ultrasound (HIU) on the quality of blue shrimp (Litopenaeus stylirostris) tails during 20 days of ice storage. Shrimp samples were treated at 70% amplitude for 0 (C), 30 (T1), 60 (T2), and 90 (T3) minutes. Key quality parameters were analyzed every 5-day. The initial total bacterial count (TBC) was 2.02 log CFU g^–1, increasing to 6.09 (C), 5.32 (T1), 5.01 (T2), and 5.34 (T3) at the end of storage, with the control samples exceeding the acceptability limit. In terms of color, the initial L* value was 52.96, increasing to 62.96, 57.69, 57.94, and 57.78 for C, T1, T2, and T3, respectively. No significant differences were observed among treatments in pH (ranging from 7.22 to 8.33), shear force (from 15.40 to 18.50 N), water-holding capacity (from 93.02 to 98.23%), TVB-N (from 24.11 to 31.61 mg 100g^–1), or non-protein nitrogen (from 0.78 to 0.48%). Likewise, SDS-PAGE profiles showed no visible protein degradation. These results indicate that HIU, particularly at 60 minutes, can extend shelf life by delaying microbial growth and preserving color, without adversely affecting the physicochemical or structural properties of the muscle.

Anesthetic efficacy of Mentha piperita and Mentha spicata essential oils on rainbow trout (Oncorhynchus mykiss)

Secil Metin — 2025-05-15

In the present study, anesthetic effects of Mentha piperita and Mentha spicata essential oils were investigated on rainbow trout. For this purpose, five treatments of the essential oils (50, 100, 200, 300 and 500 mg L^–1 concentrations) and one control (2-phenoxyethanol; 0.3 ml L^–1 concentration) have been used for rainbow trout (Oncorhynchus mykiss; mean weight of 15 g). In addition, the mean lethal doses (10 minutes LC₅₀ concentration) of the essential oils were also determined. Mentha piperita and M. spicata essential oils at 200, 300 and 500 mg L^–1 doses showed better anaesthetic effect than control (p < 0 .05). The ideal anesthetic dose of each essential oil was 200 mg L^–1 (p < 0.05). At this concentration, deep anesthesia (Stage IV) induction time for M. piperita and M. spicata on rainbow trout were found as 169.66 s and 65.0 s, respectively. The recovery times at 200 mg L^–1 concentration were 188.0 s for M. piperita and 65.33 s for M. spicata. The lethal dose of both essential oils in fish was 150 mg L^–1. This study suggests that the essential oils of M. piperita and M. spicata are both effective anesthetic agents for rainbow trout.

Application of machine learning to growth model in fisheries

Semra Benzer — 2025-05-10

Traditional growth models, such as length-weight relationships (LWRs) and the von Bertalanffy (VB) growth function, have been widely used in fishery science. Their limitations in capturing nonlinear patterns necessitate alternative approaches. Machine learning (ML) techniques have recently gained attention as a powerful tool for enhancing predictive accuracy in biological studies. In this study, the growth parameter of Eastern mosquitofish, Gambusia holbrooki (135 females: 21–58.78 mm and 0.152–3.424 g; 59 males: 19.25–43.20 mm; 0.108–1.075 g), was determined with traditional LWRs, VB, and machine learning algorithms. The LWRs growth equations of female and male individuals were W=0.00002102 L^2.8849 and W=0.00003064 L^2.8212, respectively. The VB equations were determined L_t=80.990 [1–e^{–0.990(t+0.208)}] for female and L_t=64.172 [1-e^{–0.610(t+0.271)}] for male. In general, the performance of both methods (VB model and ML algorithms) in predicting lengths, as measured by Mean Absolute Percentage Error (MAPE), was satisfactory, with the VB model demonstrating slightly superior performance (2.734). In addition, the ML algorithm gives better results in length data prediction with multilayer perceptron and in weight data prediction with Sequential Minimum Optimization (SMO) algorithm when ML algorithms are examined. The diverse ML algorithms positively impacted the investigations addressing growth-related issues in fisheries.

Impact of environmental factors on the dietary preferences of Salmophasia bacaila in the Dhepa River, Bangladesh

Md. Afzal Hossain — 2025-05-07

This study investigates the environmental variability and gut contents of an indigenous fish chela (Salmophasia bacaila) in the Dhepa River, Bangladesh. We conducted fish sampling and measured water quality across three sites from September 2017 to February 2018. The results revealed significant fluctuations in water temperature, dissolved oxygen, and pH (PERMANOVA: p = 0.001). There was spatio-temporal variation in water transparency (PERMANOVA: p = 0.001). The prey analysis identified 13 prey groups in the diet of fish, predominantly consisting of phytoplankton (92.9%), while zooplankton contributed only 7.1%. Twenty phytoplankton and seven zooplankton genera were recorded in the guts, with significant temporal variations in prey diversity (PERMANOVA: p = 0.010). These findings highlight that S. bacaila are primarily plankton feeders, with shifts in prey diversity driven by environmental factors in the Dhepa River. This research enhances our understanding of ecological dynamics and the relationship between S. bacaila and their prey in riverine ecosystems.

Effects of Streptococcus agalactiae infection and oral florfenicol administration on the hemato-biochemistry, erythrocyte morphology and histopathology of Oreochromis niloticus

Joshi Sharon — 2025-04-17

Streptococcosis is considered one of the most important diseases affecting farmed tilapia, causing severe economic losses. Antimicrobial therapy is the principal control measure applied during outbreaks. This research assessed the efficacy of florfenicol (FFC) when fed at 15 mg kg biomass^–1 day^–1 for 10 days against Streptococcus agalactiae infection in Oreochromis niloticus in terms of survival, changes in hemato-biochemistry, erythro-morphology, and histoarchitecture of the vital organs. Streptococcus agalactiae was moderately virulent to O. niloticus with a lethal dose (LD₅₀) of 1.26×10⁸ cells fish^–1 and sensitive to FFC with a minimal inhibitory concentration of 0.78 μg mL^–1. It caused systemic infection in tilapia. FFC therapy reduced bacterium-induced mortality and physiological stress. The histopathological findings indicated significant improvement in the kidney and liver tissues of fish. The erythrocyte morphological alterations noted in the challenged fish were irregularly shaped, elongated, crenated, and teardrop cells, hypochromic erythrocytes, ragged cytoplasmic membranes, hypertrophied nuclei, eccentric nuclei, and vacuolation, all of which were mitigated with FFC therapy. Eventually, FFC therapy improved wound healing, normalized plasma biochemistry, and aided recovery from bacterial infection. This study revealed that the therapeutic dose of FFC was effective against S. agalactiae infection in O. niloticus and lessened the physiological stress.