International Journal of Aquatic Research and Environmental Studies
Volume:3 Issue: 2, Summer-Autumn 2023

The polyculture system was used to increase the productivity of extensive brackishwater ponds to produce optimal agar with varying densities of three commodities: milkfish, Vannamei shrimp, and Gracilaria verrucosa. This study aims to obtain the optimal density of the three commodities in extensive brackishwater ponds with polyculture systems to produce the best agar quality for G. verrucosa. The research was conducted in the expanse of the Polyculture System Extensive brackishwater Pond in Lamongan Regency. The study used a Completely Randomized Design (CRD) with 3 density treatments (milkfish m-2 : Vannamei shrimp m-2 : G. verrucosa g m-2) and 3 replicates: A (10:10:250), B (20:20:500), and C (30:30:1000). Statistical analysis uses one way ANOVA (Analysis of Variance), while Tukey's HSD (Honestly Significant Difference) and Path Analysis use Pearson Correlation. The results showed that the best density obtained in treatment A gave a significant difference from treatments B and C in producing Specific Growth Rate, Absolute Weight, Absolute Length, Carbon Content, and quality of agar rendementing the best of seaweed G. verrucosa. From the path analysis, CNP nutrients and the growth of G. verrucosa seaweed have a strong and very strong influence to improve the quality of agar rendementing G. verrucosa seaweed.

Two Omobranchus punctatus (Valenciennes,1836) and one Omobranchus ferox (Herre, 1927) were collected for the first time from the oyster bed ecosystem of Vellar estuary, Tamilnadu. Omobranchus ferox is well distinguished by the presence of a vertical crest posterior of the eye, also Omobranchus punctatus is easily recognized by the presence of horizontal stripes from the posterior operculum to the caudal peduncle; the head region has no cirri or spikes and dorsal fins base with yellow spots. The two species were confirmed at a molecular level by the DNA barcoding technique.

An 8-week feeding trial was conducted to study the effects of dietary protein-energy level on the survival, growth, and body composition of tinfoil barb, Barbonymus schwanenfeldii fry. Fry (0.70±0.02 g) were randomly stocked in 60 L glass aquaria at 25 fish per aquarium. Six test diets were formulated to contain 40, 45, and 50 % protein with 17 and 18 kJ g-1 gross energy. Each diet was randomly assigned to three replicate aquaria, and fish were fed twice a day until satiation. Fish survival was not affected by the dietary protein, energy level, and their interaction. The results showed that higher dietary energy did not have significant effects on weight gain, specific growth rate, and feed efficiency of tinfoil barb. However, dietary protein had significant effects on fish growth and feed efficiency, while its interaction with energy had significant effect on growth. All dietary fed groups did not have histopathological changes in the liver and intestine. Fish fed 50% protein and 17 kJ g-1 gross energy showed significantly highest (p<0.05) specific growth rate compared to fish fed with 40% protein and 17-18 kJ g-1 gross energy.

The bottleneck of the oyster industry worldwide is imposed by the limitation in oyster seed supply and long culture cycles. In developing technology seed production for hatchery seed production to the commercial plant scale, the main challenge lies not only in getting the D- hinged larvae to the settling stage (eyed larvae) but also in growth and survival rates of the juvenile oysters to economically viable levels. Subsequently, efforts are concentrated on research designed at defining optimal conditions for growth and survival of the juvenile oysters cultured using different intensive rearing systems. The nursery systems used in this project are modified and refined technologies used by most hatcheries in the world. Attention is focused on developing oyster seeds or juvenile oysters with good growth and survival rate. Different systems of intensive nursery systems to obtain juveniles with regular shape and size were used. The systems applied in this project were the down-welling system, up-welling system, the rain-down system and the “coke-bottle” system. All these four systems produced cultchless spat, which grew into single oysters. The results of the survival of juveniles (from 1 week to 4 weeks) using different nursery systems showed that the best survival and highest growth rate was observed in the up-welling system (89.3±7.3%), followed by the rain-down system (76.5±4.1%) and coke-bottle system (72.2±12.0%). The down-welling system showed the lowest survival rate. This may be due to the down-flowing water of the system that made it difficult for the water to flow efficiently in the system, with the juveniles blocking the nitex screen. In general, there are no significant differences in the up-welling system, rain-down system and coke-bottle system for culturing the smaller juveniles. The survival of juveniles (from 4 weeks to 2 months) using different nursery systems showed the best survival, and the highest growth was observed in the Coke-bottle system (93.2 ± 9.1%), followed by the up- welling system (85.6± 7.4%). The down-welling system showed the lowest survival rate. The coke-bottle system showed the highest survival rate because of its flow of water moving upwards in a narrower diameter (compared to the up-welling system), which enables the juveniles to be rotated regularly in the system and the food to be distributed evenly in the system.

The present study was aimed at studying the growth and age structure in the Caspian trout (Salmo Caspius). The back calculation and biometrical parameters including body length and weight, and age were, respectively determined in 43 and 101 individuals captured from Cheshmehkileh River, Tonekabon, Iran. The fish were with minimum and maximum age of 4 and 7 years, respectively, while the 5 year-old fish were the most frequent. The mean length and weight of cathead individuals were measured to be 69.2±6.2 cm and 3323±677 g, respectively. According to the back calculation method in 2014, the mean length of 1-, 2- and 3-year-old fish were 18.98±3.5, 30.5±7.24 and 41.7±9.1 cm, respectively that were below maturity age, and thus did migrate to the coastal area for spawning. The males showed larger size, however greater prevalence and frequency were occurred in females. Growth parameters including growth coefficient (K) and L∞ were measured to be 0.18, 104 cm, respectively, and growth performance index (Ø’) was calculated 3.289 indicating an allometric negative growth. Calculated L∞ and K were in an acceptable range. Here, we provide back-calculated size-at-age estimates based on otoliths from individuals belonging to native fish from the Cheshmekileh River while male possessed larger size however the greater prevalence and frequency occurred in female fish.

Three types of hormonal stimulation were tried using HCG, PG extract and Ovaprim to induce egg production and accelerate thermal accumulation period (TAP). Results showed that there is a direct relationship between the type of hormones and TAP. Fish receiving PG-extract had the shortest TAP which was significantly different than those receiving HCG and Ovaprim treatments. Values ranged between 258.97, 344.67 and 322.78 (C -hour) in fish injected with PG extract, HCG and Ovaprim respectively. Results also showed noticeable variation in egg production in fish receiving various hormones with clear superiority for fish injected with PG-extract compared with those receiving HCG and Ovaprim. The lowest weight of extracted eggs (7.3 g/kg) was in fish injected with HCG and the highest (139.7 g/kg) in fish receiving the PG hormonal extract.

The Chilean crayfishes belong to family Parastacidae, and it included the genus Parastacus (P. pugnax and P. nicoletti), Samastacus (S. spinifrons), and Virilastacus (V. araucanius, V. jarai, V. retamali, and V. rucapihuelensis). This family is widespread from Central Chile to central southern Chile (33-46°S) specifically P. pugnax and S. spinifrons, whereas the other species are restricted between 38-40° S. It remarks that Parastacidae family is restricted to south of Chile and south of Brazil in subtropical latitudes. All species inhabits of Parastacus and Virilastacus in flooded plains in underground galleries, whereas S. spinifrons live in rivers. The species are endemic and endangered due habitats reduction and human exploitation as food in rural zones. The ecology of these species indicated that they fed mainly on vegetal matter, whereas their predators are mainly aquatic birds. There are not parasites reported, whereas it was reported the presence of ectocomensals, such as peritriches ciliates and temnocephalids. Within the reported species, only P. pugnax and S. spinifrons are important as human food in rural zones nevertheless there are not regulations for their extractions, and it was done initial studies for this aquaculture in southern Chile.

The last distribution map of different Artemia populations in Iran dates back to 2006, which reported the identification of Artemia from 17 different geographical areas. Iran climate changes and Artemia compatibility to new environments, reinforce the importance of the study of its new habitats. In this study, in addition to introducing three new habitats for Artemia, scientific information on the species and population characteristics of Artemia found from these new habitats was presented. Moreover, cyst samples were recorded and stored in the cyst bank of National Artemia Research Center, Urmia, Iran. Cyst samples collected from three new areas of Iran including Qazvin, Behshahr and Khoy were transferred to the laboratory for general biometric study of cysts, molecular studies and species differentiation by examining the nucleotide diversity of the COI-mtDNA region and the marker of the Na/K ATPase pump. The results showed that the identified Artemia were all bisexual and in terms of species, the Artemia found in Behshahr region was Artemia sinica and those found in Qazvin-Abyek and Khoy-Qotur were A. urmiana. The mean diameter (mean ± standard deviation) of the Artemia cyst in Behshahr region was significantly different from that of the other two regions (p<0.05). The largest cyst diameter was related to A. sinica from Behshahr region (280.53±19.64 µm) and the smallest cyst diameter was related to Artemia in Khoy-Qotur region (255.15±5.51 µm). For the first time, the isolation and identification of A. sinica in Behshahr and A. urmiana in Qazvin and Khoy were reported in Iran. The reason for the presence of Artemia in these areas seems to be the presence of nearby fish farms, which may have used Artemia as a live food for larvae, from which Artemia cysts spread out and became a permanent habitat of the reported areas in recent years.

This research was carried out to determine the abundance, distribution, and marketing channels of Botia dario in several areas of Bangladesh through a questionnaire survey. Survey information was collected from the fishermen, aratdar, faria, retailer, consumer, wholesaler and aquarium fish keeper. The quantity of B. dario gathered overall from the four districts of Mymensingh, Kishoregonj, Sunamgonj, and Sylhet and calculated the abundance of this species. B. dario was discovered in considerably larger quantities at Dekhar Haor in south Sunamgonj and Bhramhaputra River in Mymensingh than other locations. This species started to appear in local markets in August, although it was more common from September to October and becomes scarce after November.  In the marketing channel, fishermen directly sold B. dario to the consumer (22.6%), to the retailers (19%), to the aratdar (50%), and to the wholesaler of the ornamental fish market (5%) and a little portion (3.4%) was consumed by them. There were two species of Botia available in the ornamental central fish market of Katabon, Dhaka. Among the shopkeeper in this market, 2% were stocked B. dario and 16% stocked B. lohachata. In each month, average 30 pieces of live B. dario are sold by a shopkeeper in the ornamental fish market where an average price was 40 BDT per pair. Price ranges for dead B. dario in the food fish market vary greatly, from 450 to 700 BDT per kg. Lower price of live B. dario was observed in the sunamganj’s fish market compared to the other fish market. In the ornamental fish market, 57% of shopkeeper reported that has medium demand and 43% has low demand. But in the edible fish market, 35% of respondents reported strong demand and has medium demand by the 65% responder. Due to its enormous potential in the fisheries sector and the demand it has in both markets, conservation and culture are essential to prevent the extinction of this species.

Gaveh-rood and Gheshlagh Rivers are the main branches of the Sirvan River. Zhaveh dam was built on this river, with the purpose of use in agriculture and industry. Determine the water quality and water pollution in the Sirvan River and predicting the trophic conditions of the Zhaveh Dam reservoir are important goals of this study before the operation phase of the dam. Sampling was done at 5 selected stations of surface water in the branches of the Gheshlagh and Gaveh-rood Rivers, as well as the reservoir of Zhaveh Dam location. In this study, 27 water quality parameters (such as physical variables, hardness, alkalinity, nutrient, and sulfate) were investigated. Comparing the data of the current research with different standards showed that only the nitrate was within the permissible limit, but other parameters from one to several times (especially organic nitrogen) exceeded the permissible limit, which indicates that the water is polluted and has bad quality in different stations (especially in stations 2 and 3 in Gheshlagh branch). Based on the classification of the Iran water quality index (IRWQI) and the Comprehensive Water Pollution Index (CPI), all sampling stations (except the upstream of Gheshlagh River, Station 1) were classified in the “very bad” group (class V) and severely polluted (CPI=2.01) classes, respectively. Based on the values of TN and TP, the area was classified as a hypertrophic condition. Therefore, it is recommended to improve the water quality of the river to reduce adverse effects and promote sustainable use of water sources.