Fish Hatchery Research Articles

Feasibility of snakehead fish hatchery (Channa striata) using a round pond in Labuan Amas Selatan district, Hulu Sungai Tengah regency, Kalimantan Selatan province, Indonesia

<p>This study aims to determine the technicalities and analyze the feasibility of <em>snakehead fish</em> (<em>Chana striata</em>) hatchery using round ponds in Labuan Amas Selatan District. The data collection methods used are observation, interviews, and documentation. The data analysis used is a qualitative descriptive analysis to determine the technical aspects of the fish hatchery, financial analysis to determine the feasibility of the business with profit analysis, Payback Period (PP), Break Event Point (BEP), Net Present Value (NPV), Net Benefit Cost (Net B/C), and Internal Rate of Return (IRR). The study results show that <em>snakehead fish</em> hatchery using round ponds produces <em>snakehead fish</em> seed in 7 cycles in one year; in each cycle, 6–10 pairs of <em>snakehead fish</em> are used, which can be spawned with an average nursery time of 1.5 months. <em>Snakehead fish</em> cultivation techniques include broodstock maintenance, broodstock selection, spawning, larval transfer and maintenance, nursery, harvesting, and marketing. The results of the business feasibility analysis obtained a profit value of IDR 63,465,000/year with a speedy return on investment for 1.64 years, the BEP value of production = 20,742 seed < the production value = 56,000 seed, and the BEP price of IDR 667/seed < the current price = IDR 1,800/seed. The NPV value at the hatchery reached IDR 366,007,925, meaning NPV > 0, Net B/C > 1 value of 4.62, and IRR value of 62.81%, which means it is greater than the current interest rate of 6%. Based on various financial analyses, the <em>snakehead fish</em> hatchery business using round ponds is profitable and feasible.<strong></strong></p>

Unveiling Emerging Opportunistic Fish Pathogens in Aquaculture: A Comprehensive Seasonal Study of Microbial Composition in Mediterranean Fish Hatcheries

The importance of microbial communities in fish hatcheries for fish health and welfare has been recognized, with several studies mapping these communities during healthy rearing conditions and disease outbreaks. In this study, we analyzed the bacteriome of the live feeds, such as microalgae, rotifers, and Artemia, used in fish hatcheries that produce Mediterranean species. Our goal was to provide baseline information about their structure, emphasizing in environmental putative fish pathogenic bacteria. We conducted 16S rRNA amplicon Novaseq sequencing for our analysis, and we inferred 46,745 taxonomically annotated ASVs. Results showed that incoming environmental water plays a significant role in the presence of important taxa that constitute presumptive pathogens. Bio-statistical analyses revealed a relatively stable bacteriome among seasonal samplings for every hatchery but a diverse bacteriome between sampling stations and a distinct core bacteriome for each hatchery. Analysis of putative opportunistic fish pathogenic genera revealed some co-occurrence correlation events and a high average relative abundance of Vibrio, Tenacibaculum, and Photobacterium genera in live feeds, reaching a grand mean average of up to 7.3% for the hatchery of the Hellenic Center of Marine Research (HCMR), 12% for Hatchery A, and 11.5% for Hatchery B. Mapping the bacteriome in live feeds is pivotal for understanding the marine environment and distinct aquaculture practices and can guide improvements in hatchery management, enhancing fish health and sustainability in the Mediterranean region.

The Effect of Parasitization by Trichodinid Ciliates on the Mortality of Cultured Pacific Fat Sleeper larvae (Dormitator latifrons).

Trichodinidae, a prevalent group of protozoan ectoparasites in aquaculture, cause rapid mortality in fish hatcheries. Despite their significance, knowledge about these parasites in farmed fish in South America, especially in native species that are currently being domesticated for aquaculture, remains limited. This study morphologically characterized the Trichodinid species that are infecting Pacific fat sleeper (Dormitator latifrons) larvae and evaluated their impact on larval rearing. Four pairs of broodstock were induced with GnRHA implants and placed in tanks containing 200 L of freshwater, with a water temperature of 28 ± 1.0 °C and a dissolved oxygen level of 4.00 ± 1.23 mg L-1, with partial water exchanges being performed daily. The larvae hatched 7 to 8 h after fertilization and were transferred to tanks containing water with the same quality parameters. Twelve hours post-hatching, the presence of Trichodina was observed. Every 24 h, 60 larvae per tank (n = 180 per treatment) were sedated, and larval wet mounts were prepared, air-dried at room temperature, and impregnated with silver nitrate. Infection parameters and daily mortality were calculated. Trichodina was observed to parasitize the pelvic fins, caudal fins, and heads of fish larvae, which showed lethargy and erratic swimming movements. The Trichodina species showed a daily increase in the infection parameters, and a 58% rate of larval mortality was observed at the fourth day post-hatching (dph) in the infected tanks. In captivity, D. latifrons larvae typically survive up to 7 days post-hatching (dph) before reaching their point of no return due to the lack of adequate diet and feeding regimes. However, our study indicates that Trichodina infestation accelerates mortality, causing infected larvae to die more quickly than uninfected ones.

Distribution and environmental preferences of Saprolegnia and Leptolegnia (Oomycota) species in fish hatcheries in Hungary

We studied for the first time the abundance and species distribution of water molds (Oomycota, Saprolegniales) in fish hatcheries in Hungary, with a focus on Saprolegnia and Leptolegnia spp. A total of 182 water mold isolates were obtained from different developmental stages of fish (eggs, fry, and adults) and water samples collected during the spawning season of cyprinids and salmonids. Of the ten water mold species identified based on their ITS–rDNA sequences, S. parasitica, S. ferax, and S. australis were the most abundant. Statistical analyses of species proportions in relation to the sample source and host preference revealed that S. parasitica was significantly more abundant in the host than in water samples, whereas the opposite trend was observed for S. ferax and S. australis. In addition, our results confirmed previous findings that S. australis and S. ferax prefer warm water (+21–24 °C) and that S. parasitica has a wide temperature tolerance (+3–24 °C). The DNA sequence identity analysis showed that the species demarcation criterion for Saprolegnia spp. was approximately 98 % identity, based on ITS–rDNA sequences. Furthermore, our phylogenetic analyses suggest that taxonomic revision of Leptolegnia spp. is necessary.

Conditions for reproduction of juvenile salmon fish in Sakhalin fish hatcheries: oxygen, temperature regimes and sanitary state of factory water sources

Conditions for reproduction of juvenile salmon fish in Sakhalin fish hatcheries: oxygen, temperature regimes and sanitary state of factory water sources

Biochemical analysis and fertilization success of Cirrhinus mrigala ova during induced spawning

Fish egg quality is very crucial in aquaculture sector for production of healthy seed. Egg yolk is an energy reservoir for growth and development of embryo. This study evaluated the biochemical composition and quality of Cirrhinus mrigala eggs at three different hatchery sites of Pakistan, (Site 1= Fish Seed Hatchery, District Pakpattan; Site 2= Sidhuwan Hatchery, Head Balloki, District Kasur; Site 3= Chenab Fish Hatchery, Rangpur, District Muzaffargarh) during induced breeding. For this, a total of 36 (18 males and 18 females) fish brooders, 12 (06 males and 06 females) from each site were utilized. Fatty acids analysis revealed significant differences among three different sites. Saturated fatty acids i.e., palmitic acid (C16:0) and stearic acids (C18:0) were higher at site 2 compared to the others sites. Monounsaturated fatty acids i.e., Oleic acid (C18:1) and polyunsaturated fatty acids i.e., Docosahexaenoic acid (DHA) (C22:6) exhibited considerably greater values at site 2 than those of other two sites. Egg mineral contents unveiled remarkable differences, particularly at site 2 indicating significantly higher mineral contents except copper (Cu) in comparison to the other sites. Significant variation exists in fertilization and hatching rates during induced spawning, with the highest values recorded at site 2. It is concluded that biochemical composition of egg especially fatty acid profile and mineral content greatly influences the embryonic development and hatching success of farm reared Cirrhinus mrigala.

Effect of water pollution by nickel on hepatic enzymes and oxidative enzymes in Cyprinus carpio (common carp)

Nickel (Ni) is considered a toxic heavy metal that causes serious diseases in humans and animals. Therefore, this study was conducted on common carp, which is considered an essential food item for humans. This study was designed to investigate the effect of nickel on the hepatic and antioxidant enzymes of Cyprinus carpio after 3 and 6 weeks of exposure to water contaminated with Ni. C. carpio fingerlings were purchased from a neighboring fish hatchery. The morphometric characteristics of the experimental fish were documented. All fish were stocked, regardless of gender. The fish were exposed to different concentrations (20, 40, 60, 80, and 100 mg/L) to obtain the LC50 for Ni during 96 hours, and the median lethal concentration of Ni was 80 mg/L through 96 hours. The fish were exposed to two safe concentrations, 1 ppm and 5 ppm. The results after 3 and 6 weeks were as follows: When compared to the control groups, all treated groups had significantly higher levels of liver function parameters (ALT and AST). Malondialdehyde (MDA) and catalase activity measurement (CAT) enzyme levels were considerably higher in all treated groups after 3 and 6 weeks as compared to control groups. These changes are trustworthy indications of the cellular and humoral immune responses in C. carpio.

Special Features of Chum Salmon Oncorhynchus keta (Salmonidae) Stock Formation in the South-Western Sakhalin Fish Hatcheries as Identified Using the Otolith Marking Method

Special Features of Chum Salmon Oncorhynchus keta (Salmonidae) Stock Formation in the South-Western Sakhalin Fish Hatcheries as Identified Using the Otolith Marking Method

Long life spans can mitigate the genetic effects of strays from temporary conservation hatchery programs.

While conservation fish hatchery programs can be a valuable tool providing demographic support, they can also cause domestication, risking unintended fitness consequences to both target and connected populations. When conservation hatcheries are used over a fixed amount of time, the interaction between program duration and species life history might determine the scale of fitness effects and the effectiveness of mitigation measures. We develop a mathematical model to quantify the effectiveness of approaches to mitigate unintended fitness consequences in such temporary conservation hatchery programs. We parameterize our model to represent a conservation aquaculture-based recovery program for white sturgeon (Acipenser transmontatus) in the Nechako River (British Columbia), which might impose genetic risks on the adjacent populations within the Fraser River. We find that, over a period spanning 50-200 years of hatchery operation, the life history characteristics of white sturgeon, particularly late age of maturity and longevity, reduce the genetic risks of conservation hatcheries when compared to shorter-lived species. The genetic impacts of the hatchery accumulate slowly providing increasing the potential for adaptive management in this system.

CARP HATCHERY MANAGEMENT (Cyprinus carpio L.) NATURALLY AT THE PUNTEN AQUACULTURE INSTALLATION (IPB), BATU CITY, EAST JAVA

The large market demand for consumption fish makes some farming communities interested in farming, especially consumption fish farming. Fish hatchery business is the first step to the success of fish farming, because for each growing season the aquaculture business requires a supply of seeds from the hatchery business. Goldfish hatcheries are relatively easy because carp can spawn naturally or artificially. Goldfish have a relatively high fecundity or number of eggs, which ranges from 84,000-110,000 eggs per kilogram of brood. The implementation of carp hatchery techniques includes several processes, namely pond preparation, brood selection, kakaban installation, brood release, spawning, hatching eggs, larval care, checking water quality, seeding, pest and disease control. calculation of fecundity, fertilization rate (FR), hatching rate (HR), and survival rate (SR). The data collection method used in this street vendor is primary data. Primary data include active participation, observation, interviews, and documentation. The carp hatchery technique (Cyprinus carpio L.) at IPB Punten, Batu City is carried out naturally, the carp mother used comes from Punten using a ratio of male to female parents of 1: 3. The feeding method, namely Blind Feeding, obtained an F value of 40,000 eggs, FR 84%, HR 84.5% and SR 90.2%.

Saprolegniosis in aquaculture and how to control it?

AbstractSaprolegniosis, also called water mould, induces a cotton or wool‐like white growth on fish skin. It can kill fish at all stages of life, from eggs to adults. It is caused by oomycetes from the genus Saprolegnia and causes fish mortality and huge financial losses to fish farms and hatcheries. Saprolegnia species are endemic and ubiquitous in all freshwater habitats around the world. The exposing factors for saprolegniosis are still largely unknown, but stressors such as temperature shocks, poor water quality, handling and high fish density have been associated with outbreaks. For decades, malachite green was the most effective treatment against Saprolegnia infection, but it has been banned due to its carcinogenic and toxic effects. This has forced farmers to use alternative disinfection methods against Saprolegnia infection, such as hydrogen peroxide, formalin, Bronopol, NaCl, acetic acid and ozone, although many may have safety concerns or are impractical to use. This has led to the investigation of plant‐based compounds with antifungal and antibacterial properties against saprolegniosis. These include extracts of certain herbs, onion, garlic, extracts of the plant Chrysanthemum, essential oils of Eryngium campestre, Mentha piperita, Cuminum cyminum and Thymus linearis, which include a variety of phenolic compounds and fatty acids with antifungal properties. This review combines the current knowledge regarding the predisposing factors to Saprolegnia infections and current methods to prevent and treat them, including those under further research. Thus far, many compounds have been tested and studied, but an effective, suitable and safe compound to treat Saprolegnia infection remains to be found.

Biosecurity protocols and fish health management in Kenyan fish hatcheries: a key to sustainable production of quality fish seed

Aquaculture, or aquafarming, is increasingly becoming a vital farming activity globally to meet exponentially high demand for fish and reduce pressure on global capture fisheries. In Kenya, aquaculture growth has led to concerns over the supply of quality fish seed, with farmers often reporting involving fingerling adulteration and mislabelling where frog tadpoles are packed and supplied as Clarias gariepinus fingerlings and mixed-sex Oreochromis niloticus fingerlings are falsely sold to fish farmers as sex-reversed monosex Nile tilapia. This study aims to identify strategies to enhance the quality of fish seed production in the country. Primary data were collected via questionnaires and interviews using the Kobo toolbox. Respondents were selected through purposive and random sampling. The SPSS software was used for the analysis. Findings showed moderate reliance on specific reporting offices for fish disease cases and significant variation in disease types and bio security measures. Fish disease treatment and management practices were more engaged by hatchery operators than disease reporting. No significant differences were found between disease treatment and management, type of fish diseases encountered at the hatchery, and the nature of fingerlings produced (p > 0.05). However, there was a significant difference between the source of broodstock, biosecurity measures, type of fish diseases encountered, and the Disease Case Reporting Office (p < 0.05). No significant difference was found between biosecurity measures and the period when the hatchery was established (p > 0.05). Lack of financial support, inexperienced workforce, and a lack of knowledge in fish disease identification and treatment were the major problems affecting the sustainability of hatchery operations in the country. Aquaculture policymakers should establish financial support for hatcheries, implement disease management training, promote research collaborations for disease surveillance, and incentivize biosecurity measures among hatchery managers and farmers to improve aquaculture sustainability in Kenya. Further research should explore treatment methods and long-term sustainability to mitigate disease risks.

Impact of organic and nanoparticle-selenium fortified larval weaning diet on survival, growth, gastrointestinal, and (GPx) activity of European Sea Bass (Dicentrarchus labrax) Larvae

The study involved three groups of six broodstock with a 1:1 male-to-female ratio. They were injected with 13 µg/kg LHRHa to stimulate spawning. We fed the broodstock three diets: a control diet without selenium, a diet containing 0.3 mg of nano-selenium /kg (N-Se), and a diet containing 4 mg of organic selenium /kg (O-Se). The broodstock diet consisted of equal parts of dry feed (45% protein), sardines, and squid. After being laid, the eggs were obtained from the collection ponds at the General Authority for Fisheries Development's fish hatchery and incubated until hatching. The larvae were given a micro diet containing 51.7% crude protein and live food (Rotifer and Artemia). Rotifer density increased from 5/ml to 15/ml by day 22 dph, Artemia nauplii increased from 0.2 to 4 ind./ml, from 7 to 35 dph then decreased to 0 at 55 dph, and micro-diets increased from 100-200 µ at 16 dph to 200-400 µ at 23-40 dph to 300-500 µ at 55 dph, and 500-1000 µ until the experiment ended. Three different diets in three replicates were tested: A micro diet free of selenium as a control diet (C), A micro diet with 0.3 mg of nano selenium (N-Se) kg-1, and A micro diet supplemented with organic selenium 4 mg (O-Se). Each group was taken from the three Broodstock groups respectively. Sixteen days after hatching, the three experimental micro diets were introduced to the larvae and continued for 76 days post-hatch. Larvae (260,000 per tank) were placed in fiberglass tanks with 4 m3 of water at a temperature of 19±2°C for optimal conditions. The larvae fed the N-Se diet had significantly better survival rates (75.0 ± 1.2 %), final body weight (240.0 ± 5.8 mg), weight gain (239.00 ± 5.8 mg), average daily gain (3.98±0.1mg), total length (39.0±0.06 mm), specific growth rate (9.133±0.04 %/day), feed intake (471.67±0.01 mg), and better feed conversion ratio (1.97±0.01) than the other groups (P < 0.05). The group provided with N-Se also had the highest levels of glutathione peroxidase enzyme (GPx) content in the whole larval body, whereas the control diet without Se supplementation recorded the lowest value of (14.8 ± 0.1 U/mg protein). The number and length of folds in the stomach and esophagus of sea bass post-larvae fed on diets fortified with selenium in both forms, nanoparticles or organic, showed a significant (P < 0.05) enhancement on the larval gastrointestinal (GI) tract. Moreover, selenium has an anti-inflammatory action in sea bass post-larvae. This study concluded that using N-Se as an antioxidant supports the growth and survival of European seabass D. labrax, gastrointestinal development and antioxidant efficacy during critical weaning.

Implementing Zonal Aquaculture Innovation Platforms in Uganda: Key Lessons Learned

Uganda’s aquaculture sub-sector is rapidly developing, contributing up to 22% of all fish produced in the country. However, the sub-sector still faces challenges related to limited access to extension services, production inputs, post-harvest handling facilities, disease incidences, value-addition skills and weak market linkages. Although there have been isolated interventions at different aquaculture value-chain nodes, the registered challenges continue to recur. To address prioritized issues in Uganda’s aquaculture sub-sector, nine zonal aquaculture innovation platforms were established based on the country’s nine agro-ecological zones. These platforms brought together different stakeholders to identify solutions to common problems in each aquaculture value-chain node. Each innovation platform consisted of fish farmers, hatchery operators, traders, extension workers, researchers, input dealers, local leaders, and financial institutions. During a series of zonal workshops, participants identified constraints to the aquaculture sub-sector in their respective zones. From the findings, there are technical knowledge gaps across the entire aquaculture value chain mainly affecting hatchery operators, input suppliers, and farmers. Therefore, there is need for coordinated interventions to enhance access to production technologies, innovations, knowledge, and skill transfer to promote gender-centered aquaculture development.

Innovative structure to mount demand feeders to concrete raceways at a production fish hatchery

AbstractObjectiveAs a type of automatic feeder, demand feeders reduce labor costs and can improve fish‐rearing efficiencies. However, mounting demand feeders can be problematic because of the variety of nonstandardized fish‐rearing units. This article describes an innovative, simple, sturdy, and durable demand feeder mount for rectangular, concrete raceways.MethodsThe feeder mount was made from aluminum and sits flat on a raceway wall or walkway. A horizontal base plate, secured to the wall by vertical plates, holds a vertical riser of aluminum tubing. Attached to this tubing is a rod that secures the demand feeder.ResultThis feeder mount design has proven durable over several years of actual use. Over this time, it has needed no maintenance other than occasional cleaning with water to remove spilled fish food. The feeder can be easily and quickly removed from the mount by simply pulling a pin and sliding the feeder off of the tubing. The mount is constructed to dramatically reduce tripping hazards and occupational safety and health risks.ConclusionThis simple, inexpensive (~US$50 to construct), and no‐maintenance mount is a viable solution to the typically difficult problem of mounting demand feeders to concrete raceways used for trout production.

INVERTEBRATE DIVERSITY FROM DEEP WELLS OF THE SOUTHERN BOUNDARY OF THE EDWARDS AQUIFER OF SOUTH-CENTRAL TEXAS

Abstract This study examined the invertebrate fauna from three deep wells located at the Uvalde National Fish Hatchery in south-central Texas. These wells provide a water source from geological strata of the southern boundary of the Edwards Aquifer ranging in age from Lower Cretaceous to Recent. Forty-seven collections, sampled on a continuous basis from November 2020 to January 2022, produced a total of 738 specimens comprising 15 different species. These collections reveal a diverse crustacean assemblage along with dominant numbers of the stygobiotic snail Balconorbis uvaldensis. This study provides a preliminary survey for future investigations of unidentified crustacean species as well as revealing seasonal variations in the reproductive life cycle of Balconorbis uvaldensis.

Feasibility of Haruan Snakehead Fish Breeding Units for Recipients of Non-Cash Government Assistance Revitalization of People's Seedling Units (UPR) in Hulu Sungai Tengah District, South Kalimantan Province

Haruan snakehead fish, as one of Indonesia's fisheries germplasm wealth, has an important role as a source of animal protein and buffers the stability of inflation rates in the Kalimantan region. The feasibility factor is expected to make a significant contribution to the development of the local fisheries sector and related government policies at the regional level. The research aims to analyze the feasibility of the local haruan fish hatchery business for recipients of government assistance in the form of revitalizing the People's Hatchery Unit (UPR) in Hulu Sungai Tengah Regency, South Kalimantan Province. Research activities take place in the Mufakat Group, Mahang Baru Village, South Labuan Amas District, Hulu Sungai Tengah Regency - Province South Kalimantan. Sampling was carried out using the proportional sampling method, namely samples were taken deliberately from Haruan snakehead fish cultivators who received grant assistance. The total number of respondents was 1 Cultivator Group. Feasibility of the Haruan snakehead fish hatchery unit for recipients of non-cash government assistance for revitalizing people's hatchery units (UPR) in Hulu Sungai Tengah Regency, South Kalimantan Province Hulu Sungai Tengah, South Kalimantan Province, with different discount rates, the present value (NPV) snakehead fish cultivation business obtained a value of Rp. 189,533,025, which shows that this project can provide financial benefits. The Internal Rate of Return (IRR) value of 56% indicates a fairly high rate of return, exceeding the interest rate generally available on the market. The payback period (PP) is 1.76 years Keywords: Haruan Snakehead Fish, Feasibility, Revitalization, HST

Baía dos Tigres - The dynamic of the process

Baía dos Tigres is a well-known sandbank in Angola, referred to since the 15th century when the Portuguese navigators passed there in 1488, on the voyage that allowed them to round the Cape of Good Hope, in southern Africa. It is a phenomenon of a sedimentary nature and therefore it is linked to the availability of solid flow carried by the drift current coming from the South. However, several changes in its condition have been recorded over the centuries. It has shifted from being a sandbank (restinga) and an island, this latter occurring when the isthmus that connects it to the mainland broke, becoming a restinga again when it reestablisheb itself. In March 1962, a huge storm at sea destroyed the fragile structure connecting the land to the coast and since then, precisely 60 years ago, Baía dos Tigres became an island, being separated from the coast in a way that seemed definitive. The observation and analysis of the satellite images used in this work seem to suggest that a setback is beginning to appear, since Baía dos Tigres may be starting to reconnect to the mainland. If this occurs, there is the possibility for Angola to have again a true fish hatchery where countless varieties of fishes and molluscs find unique conditions for spawning. Those partially closed conditions, with waters sufficiently oxygenated to generate excellent biological environment for spawning, are of great importance for the future of fish industry in the country. If those conditions are restored, the zone will be protected from the direct action of storms and the speed of currents, covering an area of more than 250 km2. This article makes an up-date of the situation, based on the analysis of satellite images currently available.

Variation in resting respiration rate of Brook Trout among source populations: Implications for bioenergetic models

AbstractObjectiveOur objective was to compare wild and hatchery sourced Brook Trout Salvelinus fontinalis to determine the importance of source population on routine respiration rate (RRR), the major cost term in bioenergetic models.MethodsWe evaluated intraspecific variation in RRRs of one hatchery and four wild Brook Trout populations. Hatchery fish were obtained from the Bowden State Fish Hatchery in Elkins, West Virginia, and were the basis for the previously published bioenergetics model for the species. Wild fish were obtained from four headwater streams in West Virginia. Using intermittent respirometry, we measured and analyzed RRRs sequentially at 20, 16, and 12°C. Measures on hatchery fish were censored to restrict the dataset to similar sizes and temperatures as used with the wild populations. We used a suite of mixed effects models and one linear model to compare RRRs of hatchery fish with wild fish, as well as to determine whether wild populations differed.ResultWe found that the RRR of hatchery fish was double that of wild fish over the range of 12–20°C. Within the wild populations, the RRR of the Potomac drainage fish was lower than two of the three Ohio drainage populations despite all steams falling within 55 km of each other.ConclusionOur findings suggest that selective pressures at the hatchery, as well as factors that influence thermal regimes in wild populations, likely influence RRR in Brook Trout. More research is needed to identify correlates related to intraspecific variation in fish respiration rates. Most fish bioenergetics models are not based on, or calibrated to, the specific population to which they are applied. Therefore, we encourage greater efforts be expended to calibrate and validate such models in the future.

The development and usability test of an automated fish counting system based on CNN and contrast limited histogram equalization

The aquaculture industry has rapidly grown over the year. One pertinent aspect is the ability of the aquaculture farm management to accurately count the fish populations to provide effective feeding and the control of breeding density. The current practice of counting the fish manually increased the hatchery workers workload and led to inefficiency. The presented work proposed an intelligent, web-based fish counting system to assist hatchery workers in counting fish from images. The methodology consists of two phases. First, an intelligent fish counting engine is developed. The captured image was first enhanced using the contrast limited adaptive histogram equalization. A deep learning architecture in the form of you only look once (YOLO)v5 is used to generate a model to identify and count fish on the image. Second, a web-based application is developed to implement the developed fish counting engine. When applied to the test data, the developed engine recorded a precision of 98.7% and a recall of 65.5%. The system is also evaluated by hatchery workers in the University Malaysia Sabah fish hatchery. The results of the usability and functionality evaluations indicate that the system is acceptable, with some future work suggested based on the feedback received.