Spawning Performance and Sex Steroid Levels in Female Pikeperch Sander lucioperca Treated with Poly(lactic-co-glycolic acid) Microparticles

Pikeperch Sander lucioperca is a piscivorous species considered a promising candidate for the diversification of intensive aquaculture. This study aimed to determine the effect of a sustained-release delivery system incorporating mammalian gonadotropin-releasing hormone agonist (mGnRHa) into poly(lactic-co-glycolic acid) (PLGA) microparticles on the sex steroid levels and aspects of artificial reproduction of pikeperch. Fish were divided into four groups and injected with 20 µg mGnRHa/kg, 5-day release microparticles encapsulated with 5 µg GnRHa/kg BW (PLGA 5), 20 µg GnRHa/kg (PLGA 20), or 1 mL/kg 0.9% NaCl (control). Cumulative percentage ovulation was 100% in the PLGA 5 group, significantly higher than in other tested groups. No differences among groups were observed in latency or fecundity. The level of 11-ketotestosterone (11-KT) peaked at 40 h post-injection, and was sustained during ovulation, in all treated groups. The 17β-estradiol (E2) concentration increased in the mGnRHa-only group immediately after hormone injection, while both PLGA groups showed a reduction in E2 after injection, continuing to decrease until ovulation. A low dose of mGnRHa in PLGA microparticles significantly improves induction of ovulation and results in acceptable reproductive performance, which may positively affect pikeperch production under controlled conditions.

Prospects of fish supply-demand and its implications for food and nutrition security in Egypt

Aquaculture plays an increasingly important role in meeting the rising global demand for fish fuelled by economic and demographic growth. However, in many middle income countries, the growth of aquaculture is constrained by rising labor costs, limited input supply, environmental concerns, and infectious diseases. In this paper, we developed a multi species, multi sector equilibrium model and applied it to the fishery sector of Egypt, a leading aquaculture producer in Africa, to examine these barriers. Projection results show that rising wage rates would slow down the growth of labour-intensive aquaculture compared to those that use relatively less labour. The demand for feed, seed inputs and water use for aquaculture would substantially increase. The results also show that disease outbreaks would possibly affect production sectors via output reduction and also consumers via increases in fish price. Our findings suggest that stabilising the prices of feed and seed, investments in disease control and input use efficiency improvement technologies, including water use, are important while the overall effectiveness of tax instruments is modest. Though calibrated to Egypt, our approach can be applied to other middle size national aquaculture industries.

Occurrence, Profile, and Potential Risks of Novel and Legacy Polyfluoroalkyl Substances in Bullfrogs: Pilot Study in an Intensive Aquaculture Region, China

Per- and polyfluoroalkyl substances (PFASs) have captured worldwide attention due to their persistent and bioaccumulative characteristics. The bullfrog is a highly nutritious and edible aquatic product, but the PFAS accumulation characteristics of bullfrogs had not been paid attention. The present study analyzed the PFAS concentrations in different tissues of cultured bullfrogs and relevant water and sediments collected from the aquaculture region in the coastal area of South China. Results showed that total PFAS concentrations were 50.26–364.25 ng/L in water, with a mean of 135.58 ng/L; concentrations in effluent water were significantly higher than those in influent water, which means bullfrog farming could increase contaminants into the surroundings. The total PFAS concentrations varied from 2.89 to 162.26 ng/g·dw in sediment. The distribution profile of PFASs in sediment was similar to that of water, with short chain playing a significant role. Total PFASs in bullfrog tissues were 3.36–84.07 ng/g·dw, with the highest values in the digestive system (intestines and stomach). As for one novel PFAS alternative, chlorinated polyfluorinated ether sulfonate (F-53B) was found at high detectable levels in all habitat samples and had a higher value of logarithmic bioaccumulation factors. The estimated dietary intake (EDI) for residents in the study area was generally higher than that in other regions; however, the hazard ratios (HRs) for most detected PFASs were far below the safety threshold value “1.” These results suggest that frequent consumption of these bullfrogs would basically not cause severe health effects on local residents in terms of PFASs.

Optimization of Paddle Wheel Aeration, a preliminary study of Integrated Smart Aquaculture System

The paddlewheel aerator is one of the supporting facilities in the intensive aquaculture pond system. Assuming all the land uses an intensive cultivation system, more than two million paddlewheels worth more than 10 trillion will be needed by 2024. Currently, all paddlewheels are produced abroad or imported. This is very unfortunate considering the vast market potential. This paper discussed a preliminary study of developing paddlewheel aeration for shrimp ponds using an integrated intelligent aquaculture system to support intensification. Two paddlewheel aerators with modifications in the gearbox have been successfully installed. Based on the observation and user’s testimony, the newly installed paddlewheel was quite good, the sound of the motor was smooth, then the flow range was longer, the coverage area was more expansive than the existing waterwheel. This research would be a foundation for intelligent paddlewheel aeration design that can be developed domestically to support local industry in Indonesia.

Application of Vermicompost Fertilizer in Aquaculture Nutrition: Review

Semi-intensive aquaculture using ponds is among the most common practices of fish production, whose output depends highly on the ponds’ natural primary productivity. With the increased sustainability and health concerns with artificial fish feeds and chemical fertilizers, organic manure has been credited as a cheap, safe and sustainable alternative source of aquaculture nutrition. Apart from supplying nutrients to the phytoplankton, organic manures supply food directly to zooplankton and fish, provide substrate for microbes and improve water and pond sediment quality. Vermicompost fertilizer (excrete of earthworms) has been recognized as a potential pond fertilizer because it has superior nutritional quality (of up to five times), contains microbes, and is in ready-for-uptake form. Besides, the vermicompost contains humic acid, which has antibiotic properties, and promotes fish gut health, stress management, and immune systems. Nonetheless, the application of vermicompost fertilizer in aquaculture is still not a common practice. Therefore, this study reviews the concept of vermiculture vis-à-vis pond fertilization and the various utilizations of the vermicompost in fish farming. This is to enable fish farmers to make an informed decision on identifying and selecting proper biofertilizer, which can increase yields and cut costs of production, thus maximizing profits and improving resource utilization.

An Experiment on Growth Performance, Specific Growth Rate (SGR) and Feed Conversion Ratio (FCR) of Rohu (Labeo rohita) and Tilapia (Oreochromis niloticus) in Tank Based Intensive Aquaculture System

The growth and survival are considered as the crucial factors that should be taken into consideration in any aquaculture system. The experiment was aimed to evaluate the growth performance and subsequent survival rate of the rohu (Labeo rohita) and tilapia (Oreochromis niloticus). It is important to evaluate the growth responses in relation to Feed Conversion Ratio (FCR) and assessment of the total production of the culture unit. As per the recommended stocking density of 320 fishes/decimal in intensive aquaculture system 8 fry per tank was released to assess the growth performance, survival and production of both rohu (T1) and tilapia (T2). During experimental period, there were three replications for each treatment and feed was supplied at the rate of 12%, 8%, and 4% of the body weight of rohu and 20%, 15%, and 10% of the body weight of tilapia in 1st, 2nd and 3rd month for T1 and T2, respectively. The initial weight of individual tilapia was 7.52±1.81 gm and 14.75±0.19 gm for T1 and T2, respectively. The mean final weight was 44.01±4.03 g for T1 and 139.94±1.29 for T2. The weight gains of fish were 36.49±4.09 gm and 125.19±1.29 gm for T1 and T2, respectively. The mean percent weight gain of tilapia was higher in T2 (1715.05±0.00) than T1 (485.23±0.00). The Specific Growth Rates (SGR) of T1 and T2 were found 4.98±2.28 and 6.26 ±3.83, respectively. There was significant difference (p>0.05) in term of SGR between the treatments. Feed Conversion Ratio (FCR) in T1 and T2 were 2.86±0.14 and 2.23±0.18, respectively. Higher total production was obtained in T2 (1119.52 gm) than T1 (278.19 gm) with 100% survival in both the treatments. The water quality parameters for both of the species were within the suitable range. This study reveals a promising arena for fish culture in tank-based intensive aquaculture system as an efficient way of overcoming the scarcity of water and land. This culture system may be an excellent way of producing fish in a small parcel of land with securing the propitious production and expected outcomes within a limited period of time.

Effects of Epibiotic Diatoms on the Productivity of the Calanoid Copepod Acartia tonsa (Dana) in Intensive Aquaculture Systems

We evaluated here the effects of the epibiotic diatom Tabularia sp. on the productivity of the calanoid copepod Acartia tonsa (Dana) for assessing their risk on copepod intensive aquaculture industry for the provision of live feed. In the first experiment, uninfested and intensively infested females were cultivated individually for the assessment of egg production. Intensively infested females appeared to have a significantly lower egg production (5.0–9.0 eggs/female/d) than uninfested females (22.0–26.0 eggs/female/d) during 5 consecutive days. In the second experiment, effects of culture densities on diatom epibiosis were investigated in 9 L cultures at three different densities (200, 400, and 600 ind. L–1). Another culture at higher volume (250 L) and lowest density (200 ind. L–1) was also carried out to test the effect of culture volume on diatom epibiosis. The infestation rate (%), infestation intensity (ratio of surface diatom coverage levels, classified as levels 0–3) and daily egg harvest rate (number of harvested eggs per day per liter) were evaluated among the four culture populations. The copepods had higher infestation rate (53.69–60.14%) and intensity rate (high ratios at level 2 and 3) when the densities were increased from 200 ind./L to 400 and 600 ind./L. Although egg harvest increased with increasing culture density, it seemed that the diatom-infested A. tonsa population reach a saturated egg production when the density was higher than 400 ind./L. Nevertheless, the differences of culture volumes (250 and 9 L) appeared to be not to have any effect when the copepods were cultivated at the same density (200 ind./L). This study reveals for the first time that the epibiosis of the diatom Tabularia sp. reduces the individual egg production, and egg harvest rate in high-density culture of the copepod A. tonsa. Our findings implicate that diatom epibiosis should be avoid in copepod intensive culture systems.

Automatic Monitoring of Relevant Behaviors for Crustacean Production in Aquaculture: A Review

Crustacean farming is a fast-growing sector and has contributed to improving incomes. Many studies have focused on how to improve crustacean production. Information about crustacean behavior is important in this respect. Manual methods of detecting crustacean behavior are usually infectible, time-consuming, and imprecise. Therefore, automatic growth situation monitoring according to changes in behavior has gained more attention, including acoustic technology, machine vision, and sensors. This article reviews the development of these automatic behavior monitoring methods over the past three decades and summarizes their domains of application, as well as their advantages and disadvantages. Furthermore, the challenges of individual sensitivity and aquaculture environment for future research on the behavior of crustaceans are also highlighted. Studies show that feeding behavior, movement rhythms, and reproduction behavior are the three most important behaviors of crustaceans, and the applications of information technology such as advanced machine vision technology have great significance to accelerate the development of new means and techniques for more effective automatic monitoring. However, the accuracy and intelligence still need to be improved to meet intensive aquaculture requirements. Our purpose is to provide researchers and practitioners with a better understanding of the state of the art of automatic monitoring of crustacean behaviors, pursuant of supporting the implementation of smart crustacean farming applications.

Sinking Feed Efficiency in Growth Performance, Feed Conversion Ratio (FCR) and Yield of Tilapia (Oreochromis niloticus) at Different Stocking Densities

The efficiency of feed is considered as one of the most crucial factors that affects the growth performance, feed conversion ratio and yield as well. The study was aimed to compare the growth parameters of tilapia at different stocking densities to detect the efficiency of sinking feed assessing the growth trends at various sampling stages. To evaluate the comparative yield, the study was carried out in twelve concrete tanks under an outdoor laboratory shed. Tilapia (Oreochromis niloticus) fry was released at the rate of 8 fry per tank as per the recommended stocking density of 320 fishes/decimal and 4 fry per tank equivalent to the stocking density of 160 fishes/decimal in intensive and semi-intensive aquaculture system, respectively. To evaluate the growth trends sinking feed was used for feeding the fish during the experimental period for T1 (Intensive) and T2 (Semi-intensive), respectively. The feed was supplied in each with three replications at the rate of 20%, 15%, and 10% of the body weight of fish, respectively. The daily ration of feed was delivered to fish dividing into two parts daily. Aeration facilities using air stone aerator were installed for 24 hours. To assume the consecutive growth trends, weight of fish was recorded in 3 days interval to have better understanding on the yield performance in relation to the feed conversion ratio (FCR). Water quality parameters i.e., temperature and dissolved oxygen (DO) were recorded two times daily. The final weight gains of fish were 133.77±5.65 gm and 50.70±2.40 gm for T1 and T2, respectively. The mean percent weight gain of tilapia was higher in T1 (1127.25±0.00) than T2 (518.51±0.00 gm). Feed conversion ratio (FCR) in T1 and T2 were 1.97±0.11 and 1.70±0.07, respectively. The specific growth rates (SGR) of tilapia in T1 4.90±3.03 and 4.78±3.83 considering the data at the beginning and the end of the production cycle, respectively. Higher total production was obtained in T1 (1070.19 gm) than T2 (610.00 gm) with 100% survival in both the treatments. The present study reveals that, the efficiency of sinking feed was higher in T1 than T2 and farmers might be suggested to practice tank-based intensive aquaculture system to get higher production in a short period of time.