Experience-dependent learning of behavioral laterality in the scale-eating cichlid Perissodus microlepis occurs during the early developmental stage

Behavioral laterality—typically represented by human handedness—is widely observed among animals. However, how laterality is acquired during development remains largely unknown. Here, we examined the effect of behavioral experience on the acquisition of lateralized predation at different developmental stages of the scale-eating cichlid fish Perissodus microlepis. Naïve juvenile fish without previous scale-eating experience showed motivated attacks on prey goldfish and an innate attack side preference. Following short-term predation experience, naïve juveniles learned a pronounced lateralized attack using their slightly skewed mouth morphology, and improved the velocity and amplitude of body flexion to succeed in foraging scales during dominant-side attack. Naïve young fish, however, did not improve the dynamics of flexion movement, but progressively developed attack side preference and speed to approach the prey through predation experience. Thus, the cichlid learns different aspects of predation behavior at different developmental stages. In contrast, naïve adults lost the inherent laterality, and they neither developed the lateralized motions nor increased their success rate of predation, indicating that they missed appropriate learning opportunities for scale-eating skills. Therefore, we conclude that behavioral laterality of the cichlid fish requires the integration of genetic basis and behavioral experiences during early developmental stages, immediately after they start scale-eating.

Sinop İli Su Ürünleri Üretiminin Mevcut Durumu ve Türkiye Su Ürünleri Üretimindeki Yeri

In the present study, the production amount in the last five years (2015-2019) of Sinop province, which is located in the Black Sea Region and a significant part of fisheries production is carried out, was evaluated. For this purpose; Sinop Provincial Directorate of Agriculture and Forestry and TUIK (Turkish Statistical Institute) data were used. There are 2.326 commercial fishermen and 444 fishing boats in Sinop province. In the sea area of Sinop, 5 enterprises still produce culture fish in cages. The 2 potential marine culture areas identified in Sinop have an annual production capacity of 32.430 tons (31 enterprises). In addition, 5 bivalves (4.940 tons/year) and 1.000.000 number/year capacity juvenile fish production facilities are at the project stage. The total fisheries production of Sinop Province in 2019 was 34.620,9 tons, and 1.505 tons were obtained from aquaculture. In addition to these, 3.924 tons of fish processing facilities per year, and 35 tons of fish meal and oil processing facilities per year are operated. 66% of sea fish caught in Sinop are anchovy (Engraulis encrasicolus ponticus), 16% sprat (Sprattus sprattus phalericus), 13% horse mackerel (Trachurus trachurus), 3% bluefish (Pomatomus saltatrix) and 2% consists of other species. The most preferred marine fish by the consumers are anchovy (Engraulis encrasicolus ponticus), horse mackerel (Trachurus trachurus), whiting (Merlangus merlangus), red mullet (Mullus barbatus), bluefish (Pomatomus saltatrix), turbot (Psetta maxima) and bonito (Sarda sarda) and sea bream (Sparus aurata), sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhyncus mykiss) are the culture fish species offered for sale throughout the year.

Development of production technology for extruded starter compound feedsfor juvenile fish

The article presents the results of developing recipes for domestic extruded starter compound feeds for zander, tilapia and Clary catfish. Technological modes of their production, as well as physical-chemical, mechanical and technological indicators of the developed compound feeds are established. The developed compound feeds are well-loose grains of dark and light brown colors, with sizes from 0,2 to 2,0 mm. Indicators of water resistance were at least 2,5 hours, crumbling no more than 1,5 %, swelling of granules 10-15 minutes, volume mass below 1000 kg/m3. The data obtained show that the developed feed meets the regulatory requirements for starting fish feeds. The introduction of the developed technology for the production of starter compound feeds at domestic enterprises of the feed industry will reduce the dependence of industrial fish farms on the import of compound feeds and thereby increase the profitability of the industry.

PENILAIAN STATUS DOMAIN SUMBER DAYA IKAN LEMURU DENGAN PENDEKATAN EKOSISTEM YANG DIDARATKAN DI PPI KEDONGANAN, BALI

PPI Kedonganan is a fish landing base located in Kedonganan Village, Kuta District, Badung Regency. One of the fish commodities that landed at PPI Kedonganan is Lemuru Fish (Sardinella lemuru). The high rate of catching Lemuru must be balanced with proper management so that Lemuru Fish Resources remain sustainable. This study was conducted to determine the status of the utilization of Lemuru fish resources. The study was conducted from January 2021 to March 2021. Data collection was carried out by observation and interviews. Data analysis of each indicator was carried out using a multi-criteria analysis approach with composite index assessment and visualization by flag model. Indicators were observed the trends of fish size, the proportion of juvenile fish were caught, the species composition, range collapse of fish resources, Endangered, Threatened, and Protected species. The status assessment of the Lemuru resource domain which landed at PPI Kedonganan is in the good category with a composite value of 66.7. Results of the trend indicators of fish size is relatively fixed, the proportion of fish juvenile caught about 90%, the composition of species caught was 100% of the target fish i.e, lemuru that caught by using gill net, range collapse of fish resources as much as 57% of fishermen expressed relatively fixed in looking for fishing grounds, and ETP species not found. Keywords: EAFM; Lemuru Fish; Fisheries Management; PPI Kedonganan.

An experimental evaluation of the effect of escape gaps on the quantity, diversity, and size of fish caught in traps in Montserrat

Coral reef fisheries are vital to the livelihoods of millions of people worldwide but are challenging to manage due to the high diversity of fish species that are harvested and the multiple types of fishing gear that are used. Fish traps are a commonly used gear in reef fisheries in the Caribbean and other regions, but they have poor selectivity and frequently capture juvenile fish, impacting the sustainability of the fishery. One option for managing trap fisheries is the addition of escape gaps, which allow small fish to escape. We compared catches of traps with and without two 2.5 cm (1 inch) escape gaps on the Caribbean island of Montserrat. No significant differences were found in the mean fish length, total fish biomass, number of fish, fish species richness, and Shannon diversity index between hauls of the two trap designs, though traps with escape gaps did catch larger proportions of wider-bodied fish and smaller proportions of narrow-bodied fish. Furthermore, traps with gaps caught a smaller proportion of small-sized fish and fewer immature fish (though differences were not statistically significant). Linear mixed effect models predict that soak time (the length of time between trap hauls) increases the mean catch length, total catch biomass and total number of species in the catch. The relatively modest evidence for the effect of the gaps on catch may be explained by the long soak times used, which could have allowed most smaller-sized fish to escape or be consumed by larger individuals before hauling in both traps with and without escape gaps. Despite the small differences detected in this study, escape gaps may still offer one of the best options for improving sustainability of catches from fish traps, but larger escape gaps should be tested with varying soak times to determine optimum escape gap size.

Determination of Median Lethal Concentration (LC50) for Endosulfan, Heptachlor and Dieldrin Pesticides to African Catfish, Clarias gariepinus and Their Impact on Its Behavioral Patterns and Histopathological Responses

Pesticides such as endosulfan, heptachlor and dieldrin persist in aquatic environments as a result of their resistance to biodegradation. However, there is no adequate information about the toxicity of endosulfan, heptachlor and dieldrin to the aquatic organism, African catfish (Clarias gariepinus)—a high valued widely distributed commercially interesting species. The current experiment was performed with the aim to determine the median lethal concentration (LC50) of endosulfan, heptachlor and dieldrin to African catfish (Clarias gariepinus); their behavioral abnormalities and histopathological alterations in several vital organs. A total of 324 juvenile fish were exposed for 96 h to six concentrations of endosulfan and dieldrin at 0, 0.001, 0.002, 0.004, 0.008 and 0.016 ppm, and to heptachlor at concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.32 ppm for dose-response tests. The study demonstrated that the species is highly susceptible to those contaminants showing a number of behavioral abnormalities and histopathological changes in gill, liver and muscle. The 96-h LC50 value of endosulfan, dieldrin and heptachlor for the African catfish was found as 0.004 (0.001−0.01) mg/L, 0.006 mg/L and 0.056 (0.006−0.144) mg/L, respectively. Abnormal behaviors such as erratic jerky swimming, frequent surfacing movement with gulping of air, secretion of mucus on the body and gills were observed in response to the increasing exposure concentrations. Histopathological alterations of liver, gill and muscle tissues were demonstrated as vacuolization in hepatocytes, congestion of red blood cells (RBCs) in hepatic portal vein; deformed secondary lamellae and disintegrated myotomes with disintegrated epidermis, respectively. These findings are important to monitor and responsibly manage pesticide use in and around C. gariepinus aquacultural areas.

The recirculated aquaculture system (RAS) development with nanobubble application to improve growth performance of grouper fish fry culture

One of the aquaculture commodities with high economic value is grouper fish (Epinephelus sp.). RAS is known as one of superior and suitable aquaculture systems in juvenile fish culture. RAS installed with NBs is expected to increase the stocking density and production of hybrid brown-marbled grouper. This study aimed to analyze the system performance of grouper fish juvenile culture in high stocking density with water exchange system, RAS, and combination of RAS and NBs. This study used a factorial design with two factors, namely different stocking densities and cultivation systems. The densities were 500, 600 and 700 fish/m3, while the treatment systems were RAS without NBs, RAS installed with NBs, and control treatment with 200% water change. Each treatment was replicated three times. The total aquaria used for this study were 27 as each size was 1.5 m × 0.5 m × 0.5 m. The study results showed that the RAS installed with NBs and a stocking density of 600 fish/m2 showed the best results on fish production performance. Keywords: density, growth, grouper, nanobubble, RAS ABSTRAK Pendederan ikan kerapu meripakan salah satu segmen dalam usaha budidaya ikan kerapu (Epinephelus sp.). Salah satu sistem akuakultur yang cocok yang dapat digunakan dalam pendederan ikan kerapu ini adalah sistem recirculated aquaculture system (RAS). RAS dengan instalasi nanobubble (NBs) ini diharapkan bisa meningkatkan padat tebar dan kinerja produksi benih ikan kerapu. Penelitian ini bertujuan untuk menganalisis kinerja sistem pendederan ikan kerapu dengan padat tebar tinggi berbasis sistem pergantian air, RAS, dan perpaduan antara RAS dan NBs. Rancangan percobaan yang digunakan dalam penelitian ini adalah faktorial dengan dua faktor, yaitu padat tebar dan sistem budidaya berbeda. Padat tebar yang digunakan adalah 500, 600, dan 700 ekor/m3, sedangkan sistem budidaya terdiri dari RAS tanpa NBs, RAS dengan NBs dan kontrol (sistem pergantian air 200%), setiap perlakuan terdiri dari atas tiga ulangan. Hasil penelitian menunjukkan bahwa pendederan menggunakan RAS dengan NBs dengan padat tebar 600 ekor/m2 menunjukkan kinerja produksi ikan kerapu yang terbaik. Kata kunci: ikan kerapu, kepadatan, nanobubble, pertumbuhan, RAS

Nutrient metabolism in the liver and muscle of juvenile blunt snout bream (Megalobrama amblycephala) in response to dietary methionine levels

A 75-day rearing trial was designed to study the response of juvenile Megalobrama amblycephala to dietary methionine (Met) levels. Three practical diets with graded Met levels (0.40%, 0.84% and 1.28% dry matter) were prepared to feed the juvenile fish. The results showed that the 0.84% Met diet significantly improved the growth compared with 0.40% diets. Compared with 0.84% and 1.28% Met, 0.40% Met significantly increased the hepatic lipid content, while decreasing the muscular lipid and glycogen contents. 0.40% Met decreased the protein levels of phospho-Eukaryotic initiation factor 4E binding protein-1 (p-4e-bp1), 4e-bp1 and Ribosomal protein S6 kinase 1 in the liver, compared with 0.84% diet, while an increasing trend was observed in the muscle. Met supplementation tended to decrease and increase lipid synthesis in the liver and muscle, respectively, via changing mRNA levels of sterol regulatory element-binding protein 1, fatty acid synthetase and acetyl-CoA carboxylase. 1.28% dietary Met promoted fatty acid β-oxidation and lipolysis in both the liver and muscle by increasing carnitine palmitoyl transferase 1, peroxisome proliferator activated receptor alpha, lipoprotein lipase and lipase mRNA levels. Compared with 0.40% and 0.84% dietary Met, 1.28% Met enhanced the mRNA levels of hepatic gluconeogenesis related genes phosphoenolpyruvate carboxykinase (pepck), and glucose-6-phosphatase, and muscular glycolysis related genes phosphofructokinase (pfk), and pyruvate kinase (pk). The mRNA levels of hepatic pfk, pk and glucokinase were markedly downregulated by 1.28% Met compared with 0.84% level. Muscular pepck, glycogen synthase, and hepatic glucose transporters 2 mRNA levels were induced by 1.28% Met. Generally, deficient Met level decreased the growth of juvenile Megalobrama amblycephala, and the different nutrient metabolism responses to dietary Met were revealed in the liver and muscle.