Iranian Journal of Fisheries Sciences
Volume:24 Issue: 1, Jan 2025

An investigative field survey was performed from October to November 2023 at nine villages within five districts in four selected regions, aimed to assess the status, challenges, and future perspectives of coastal mariculture development along the coastline in Mainland Tanzania. During this study, both purposive and snowball sampling techniques were used. A structured questionnaire forms were used as an assessment tool to gather fish farmers’s information, followed by a focussed group discussion and key informants’ interviews with government officials. A total of 162 fish farmers, government officials and animal feed sellers were assessed. Demographic data indicated that most farmers were male accounting for 67.9% and females (32.5), aged between between 20 and 40 years old (56.8%), with primary education level, accounted for 82.7%. On the other hand, milkfish were mostly stocked at 2-3 fish/m2 in an earthen pond system, and under monoculture were mostly fed local feed ingredients (88%). The study showed that three major income-generating activities: Milkfish (85%), crab fattening (12%), tilapia (2%), and sea cucumber (1%) were practiced along the coast to support blue economy initiatives. Additionally, the results indicated that government subsidies (89), farm inputs (81%), and capital investment were the major challenges that constrained milkfish development along the coastline of mainland Tanzania. Further, current data indicated that milkfish farming is solely practiced at the subsistence level and needs a scale-up to sustain the blue economy. The present study highlighted the status, challenges, and plan for the future development of coastal mariculture in Tanzania.

Caspian Sea have significantly declined due to overfishing and inadequate sustainable management practices. This research aims to assess assessment of the restoration trend of Sturgeon stock by using SWOT model. The data was collected through questionnaires, which provided both quantitative and qualitative insights into various aspects of the phenomena. The findings were then generalized to identify the strengths, weaknesses, opportunities, and threats related to the restoration process of sturgeon stocks in these waters. The reliability of the questionnaire was confirmed using the internal consistency method (Cronbach's alpha), In this research, the Cronbach's alpha coefficient was 0.94, as well as the reliability of each of the strengths (0.89), weaknesses (0.83), opportunities (0.92) and threats (0.88). Key reasons for the decline in sturgeon stocks and catches include lack of effective management and sustainable exploitation of fish stocks, insufficient revival and protection measures for stocks, socio-economic issues, particularly unemployment in coastal communities, inadequate policy-making and investment in the fisheries sector, habitat destruction and obstruction of migration routes for spawning due to dam construction on major rivers, changes in food resources in spawning areas, and industrial pollution, urban, and agricultural activities.

This study examined the dietary impacts of essential oils from garlic (Allium sativum), black seed (Nigella sativa), and black caraway (Carum carvi) on the hematological and immunological parameters of rainbow trout (Oncorhynchus mykiss). A total of 200 fish, each with an average initial weight of 225 ± 10 g, were divided into five groups, each consisting of three replicates with 40 fish per group. The fish were fed for eight weeks with a diet supplemented with 0.2% of the herbal essential oils, while a control group received an unsupplemented diet. The hematological indices, including hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), the number of red blood cells (RBCs) and white blood cells (WBCs), and immune responses, including serum lysozyme and complement levels (C3 and C4), were studied. The analysis showed no significant differences in erythrocyte indices or leukocyte profiles between the control group and the groups receiving essential oils (p>0.05). The control group exhibited the highest values for RBC, Hb, MCV, MCH, MCHC, Hct, and WBC, while the highest percentages of lymphocytes and monocytes were found in the black seed and black caraway groups, respectively. On day 28 of the experiment, there were no significant differences in lysozyme activity among the control and treatments (p>0.05), while a significant difference was observed for black caraway essential oil on day 56 (p<0.05). A significant difference between the control group and all treatments was reported for C3 value on day 28 (p<0.05). Comparisons from days 28 to 56 indicated significant changes for the control versus mixed essential oil, garlic essential oil, and black caraway essential oil (p<0.05). C4 and plasma protein values showed no significant differences between the control group and treatments on both days (p>0.05), however, significant differences were noted when comparing values from days 28 and 56 for the control and treatments of mixed essential oil, black seed essential oil, and black caraway essential oil (p<0.05). The results of this study demonstrated that dietary garlic essential oil significantly enhanced immune functions and TNF-α expression levels in rainbow trout compared to black caraway or black seed essential oils (p<0.05). However, all essential oils boosted immune parameters like lysozyme activity and complement levels, but garlic essential oil showed the most promising results.

The consumption/Biomass (Q/B) ratio and aspect ratio are basic inputs to mass-balanced trophic structures that are frequently used by ECOPATH software program. Here, we listed Q/B ratio for 154 fish species of the Persian Gulf and the Gulf of Oman to contribute to mass-balanced trophic model parametrization. Samples were collected using a research vessel bottom trawl from the Persian Gulf and the Gulf of Oman (Hormozgan province) between May and December 2017. All species were classified into six ecological groups (demersal, benthopelagic, reef-associated, pelagic-neritic, pelagic-oceanic, and bathypelagic). The aspect ratio value for all species ranged from 0.59 for Plotosus lineatus to 5.16 for Megalaspis cordyla. On the other hand, the Q/B ratio varied from 3.94 for Epinephelus coioides to 29.47 for Pentaprion longimanus. The Q/B index quantifies the proportion of food consumed within the ecosystems of the Persian Gulf and Gulf of Oman, establishing a significant correlation with fish production. It serves as a fundamental parameter in ECOPATH modeling, which is essential for sustainable fishing practices and effective fisheries management.

The main obstacles to the artificial reproduction of sturgeon can be mentioned the long-term viability of sturgeon aquaculture and the significant mortality rate of fingerlings. Microalgae supplementation has been shown in numerous studies to have a positive effect on improving overall health and survival rates in a variety of fish species larvae. This study combines the findings of other studies with the results of experimental trials to try and elucidate the mechanisms underlying the beneficial benefits of Arthrospira platensis on Persian sturgeon fingerlings. It also seeks to provide helpful information on the optimal dosage and administration methods for A. platensis supplementation in sturgeon hatcheries. During a 12-week feeding trial, 600 A. persicus larvae (200.50± 0.07 g), were used in this study to evaluate the effects of dietary supplementation of A. platensis at different concentrations (2.5%, 5%, and 7.5%, compared to a 0% control) on the growth, survival, and hemo-biochemical indices. The 7.5% A. platensis-fed group showed significantly higher values of white blood cells, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration. The 7.5% S. platensis-fed group also showed a significant increase in hemoglobin levels, red blood cells, hematocrit, and mean corpuscular volume values. Regarding blood biochemical indices, a significant decrease was observed in cholesterol, triglyceride, low-density lipoprotein, lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase levels. In addition, compared to other groups, A. platensis at 7.5% resulted in greater serum glucose and HDL levels. In conclusion, Supplementing with A. platensis in a concentration of 7.5% of the diet improves the general health and stress tolerance of Persian sturgeon fingerlings, as well as their survival rates during artificial reproduction.

Rainbow trout (Oncorhynchus mykiss; Kamloops strain), were introduced to Khyber Pakhtunkhwa in 1928 and are now successfully farming in the Malakand and Hazara divisions due to the region's favorable cold-water conditions. Our study investigated the artificial breeding success, incubation period, and fecundity of rainbow trout at Jaghour trout hatchery in the district Chitral. A total of 4,311 eggs were harvested from four females with a combined body weight of 1.264 kg. The eggs were fertilized and incubated in spring water at temperatures ranging from 12.6 to 13.3°C. The survival and mortality rates from fertilization to hatching were approximately 79% and 21%, respectively. The eyed stage commenced at around 155±05 degree days (D°), with hatching occurring at approximately 305±05 D°. The incubation period spanned from 305±05 to 349±05 D°. Furthermore, the study explores female fecundity, revealing a range of 1.87 to 3.42 eggs per gram of body weight (n=15). The size of green ova increased by 1.02% to 8.60% during water hardening at 9°C for 1.5 h (n=46). Our study provides valuable insights into the incubation period of Rainbow trout, highlighting the survival and mortality rates of fertilized eggs in spring water. This information can assist local hatchery managers in estimating seed production from known brood stock.

This trial aimed to investigate the impact of dietary lemon pomace inclusion on growth, immune response, anti-oxidative capacity, intestinal health, and disease resistance against Edwardsiella tarda in the Nile tilapia. The fish weighted (20±5 g) were randomly allocated into three groups and fed diets containing varying amounts of dried lemon pomace powder (0[control], 1, and 2%) for 10 weeks. After this period, the fish were challenged with E. tarda. The bacterium was isolated from naturally infected fish from fish farms in the Kafr- Elsheikh governorate, Egypt with a rate of 14%, and its virulence genes (cds1, qse C, and pvsA) were detected using PCR. It was observed that 1 or 2% of lemon pomace dietary addition improved productive performance compared to control. Also, 1 or 2% of lemon pomace dietary addition reduced serum glucose, cortisol, triglycerides and cholesterol concentrations, while increasing the serum catalase and superoxide dismutase activities and improving phagocytic, lysozyme, and bactericidal activities in a dose-dependent manner compared to the control group. Moreover, 1 or 2% of lemon pomace dietary addition increased the length of intestinal villi and goblet cell number in a dose-dependent manner of different intestinal portions compared to the control group. The highest survival (80%) with the lowest mortality (20%), morbidity (56.6%), and re-isolation (30%) rates after E. tarda infection was observed in the group fed a diet containing 2.0% lemon pomace followed by 1.0% lemon pomace group, while the worst rates were recorded in the control fish.

An examination was carried out from spring 2020 (April) to winter 2021 (February) to determine the occurrence of endoparasitic helminth in European chub (Squalius cii) in the Susurluk basin from the Northwest region of Turkey. The infection levels of all identified endoparasitic helminths were also investigated in relation to host factors and seasons. In addition, the differences with their prevalence, mean intensity, and mean abundance were evaluated statistically. A total of 79 S. cii were examined, 33 fishes were found to be infected by one or more endoparasitic helminth specimens. Three species of endoparasitic helminth were identified on gill cavities and in the gastrointestinal tracts, respectively: Clinostomum complanatum (Rudolphi, 1814), Caryophyllaeides fennica (Schneider, 1902), and Rhabdochona denudata (Dujardin, 1845). R. denudata was the most common and most abundant species. The endohelminth infections were recorded in all seasons. C. fennica was recorded in spring and summer, while C. complanatum was encountered in spring and autumn, whereas it was not detected in summer and winter. The prevalences were higher in larger hosts based on body length in C. complanatum, C. fennica, and R. denudata, while a high mean intensity of C. complanatum and R. denudate was in smaller hosts. Male host fishes had higher prevalence levels of endoparasitic helminth infection. The present study provides the first record of the endoparasitic helminth of S. cii considered a valid species in Turkey and the first host record of three endohelminth species in S.cii.

For most marine organisms, including fish, species diversity is very high in the Indo-Pacific region, and it reflects how past and present environmental conditions shape a link between biodiversity and ecosystem function. The distribution of a taxon in the region is due to the establishment of morphological, genetic, behavioral, and physiological aspects of species. Despite extensive surveys in the Indo-Pacific region still, there are new species and new records especially in the case of small cryptic species such as blennies. The family Blenniidae including members of the genus Entomacrodus are mostly small fishes of less than 15 cm having an elongate and slender body with a worldwide distribution. Entomacrodus comprises herbivorous combtooth blennies with about 27 species, 7 of which occur in the western Indian Ocean. In this study, the presence, general morphology, otolith shape variation, osteology, distribution, and molecular phylogenetic affinity of the reef margin blenny Entomacrodus striatus have been documented/presented from the westernmost part of the Indo-Pacific region (the Jask Port, Oman Sea). The morphological and meristic characteristics of specimens were well fit with E. striatus. The vertebral column includes 10 abdominal and 23 caudal vertebrae, for a total vertebral count of 33. Corroborating the morphological results, DNA barcoding based on mitochondrial COI confirmed that the specimens collected from the Jask Port area are conspecific with E. striatus from other Indo-Pacific localities. Entomacrodus striatus from the Oman Sea and other Indo-Pacific regions show a distinct clade sister to a clade of E. epalzeocheilos, E. niuafoouensis, and E. randalli with a closest phylogenetic relationship to E. niuafoouensis (0.108 K2P genetic distance). The presence of E. striatus in the coastal area of the Oman Sea in the Jask coastal area represents the first record of this species for the westmost of the northern Indian Ocean and markedly expands its known geographical distribution range.

Recently, the contamination of microplastics (MPs) has emerged as a globally significant issue, raising concerns across all environmental matrices, particularly in marine environments. This study investigates the ingestion of MPs by Psettodes eromei, a commercially important demersal fish in the northern Oman Sea, Iran, with the aim of assessing the presence and characteristics of MPs in gills, guts, and skin. A total of 154 microplastic particles were identified across all tissues examined. These MPs were characterized based on their physical (size, shape, and color) and chemical (polymer types) attributes using a stereomicroscope and Raman spectroscopy respectively. The results showed that fibers were the most prevalent shape and blue and black being the dominant colors. MPs predominantly ranged in size from 50-200 µm. Polyethylene (PE) and polypropylene (PP) were the most common polymers detected. These findings highlight the pervasive nature of MP contamination in marine environments and raise concerns about potential health risks to humans consuming contaminated seafood. Hence, it can provide crucial baseline data on MP pollution in the Oman Sea. Moreover, contributes to our understanding of the environmental impacts of plastic waste on marine ecosystems and food webs.