Fish Research Articles

The impact of climate change on the reproductive biology and population dynamics of fishes: Implications for fisheries and food security

The purpose of this paper is to review and evaluate published literature on the impact of climate change on the reproductive biology and population dynamics of fishes. A systematic method was utilized to access published literature on “Impacts of Climate Change on fishes and fisheries”. A total of fifty-two (52) research papers published between the years 1973 to 2024 were accumulated and used for this review. A subjective approach was used to select the topics: impact of climate change and fishes and fisheries. The physical and biological impacts of climate change on fisheries were evaluated. In addition, the role of fisheries in food security to combat the global hunger index of human beings was assessed in this review paper. Strategies to be implemented by fisheries to mitigate the effect of climate change was also presented in this review. The literature accessed revealed that fish is an important resource to the economies of many countries and a source of natural protein. As the average per capita food supply from fish and fisheries products continue to rise in developing nations, it is falling in underdeveloped nations. The published works of literature established that the global fisheries and fish population dynamics, reproductive biology, abundance and distribution are all affected by climate change. This review highlights the fact that more extensive studies on the impact of climate change on fishes and fisheries should be done in neotropical countries since there are gaps of such information on research and published data in these biodiversity rich regions.

Growth, development and commercial traits of sturgeon fish species under industrial fi sh farming conditions when use the feed additive Abiotonic

Artificial fish farming including commercial sturgeon farming using highly nutritious balanced feeds is nothing less than a strategically important area in Russian agriculture. In recent years, methods for increasing animal productivity using highly biologically active additives both natural and artifi cial, which have a growth-stimulating, protective and immune-modulating eff ect on the body of animals at various stages of development, have found wide application. These include the feed additive Abiotonic. In the literature studied by us, we found no information on the eff ect of the feed additive Abiotonic on the growth, development and livability of sturgeon fi sh, as well as on the quality indicators of the resulting fi sh products. In this regard, studies aimed at studying the eff ect of the vitamin-microelement growth immunostimulant Abiotonic on the productivity of sturgeon fi sh are relevant. The purpose of the research was to study the growth, development and commercial traits of sturgeon fi sh species under industrial fi sh farming conditions using the feed additive Abiotonic. The research established the optimal amount of the feed additive Abiotonic for use in the diets of the hybrid Russian and Siberian sturgeon inder industrial fi sh farming conditions. Thus, when rearing sturgeon fi sh with high productive and commercial traits, as well as with low feed costs per unit of fi sh weight gain and the cost of fi sh products under industrial conditions, we recommend that fish farms use the feed additive Abiotonic in the diets of sturgeon fi sh in the mount of 1.0 ml per 1.0 kg of fi sh body weight.

A Critical Assessment of the Process and Logic Behind Fish Production in Marine Recirculating Aquaculture Systems

A recirculating aquaculture system (RAS) represents a forward-looking form of aquaculture. A RAS consists of fish tanks and water treatment processes in a closed loop to sustain the environmental conditions for fish production. However, the rapid industrialization of the technology is fraught with transfer problems. This review justifies a RAS process chain based on fish biology. The underlying concept has been evaluated by the author in experimental and commercial RAS projects. The core idea is that the fish must be considered as a technical subcomponent in a RAS, determining the technology. Fish, when considered as small biological machines, are still a black box in many ways. However, their basic biology and physiology provide all the knowledge to implement them in a technical setting. The information required to understand this concept is presented and discussed based on current scientific knowledge. The conclusion is that the technology is available but needs to be rigorously implemented. If this were carried out, fish production in RASs would be ecologically sustainable, which is already claimed for RASs but is not always the reality in commercial applications.

Deep Dive Into Noninvasive Biometrics: A Pilot Journey Using Stereo-Video in a Public Aquarium.

Accurate collection of biometric data is important for understanding the biology and conservation of marine organisms, including elasmobranch and teleost fish, both in nature and controlled environments where monitoring marine specimens' health is mandatory. Traditional methods involving specimen capture and handling are invasive, stressful, and disruptive. Some techniques like underwater visual census or laser photogrammetry have been used for noninvasive data collection, but they have limitations and biases. The application of stereo-video photogrammetry through the use of diver-operated stereo-video systems (stereo-DOV) is a noninvasive method that overcomes these challenges, providing highly accurate measurements. It has become popular for species monitoring, studying anthropogenic impacts, and assessing length distributions. However, this technique is still uncommon and barely reported in aquarium settings. This study describes an innovative pilot study targeting multiple species carried out in a Public Aquarium, using a low-cost house-made device. The results revealed that measuring more than 100 individuals in approximately 1 day's work is possible. Total and fork lengths were estimated using specific software for 31 teleost and 16 elasmobranch species and compared with real measurements for the available species. Despite technical limitations that must be reviewed for application in future studies that resulted in high root mean square (RMS) values (> 20 mm), differences between methodological approaches revealed a minimal discrepancy (1.37%-5% in large sharks and rays and 1.8%-5.5% in teleost fish). This technique has time and cost requirements, but might represent a major advance in husbandry and in the contribution to conservation that ex situ studies can provide.

A novel approach for rapidly determining the reproductive status of walleye pollock (Gadus chalcogrammus) using Raman spectroscopy

Knowledge of the reproductive biology of fishes is essential for effective fisheries management. Information derived from an understanding of fish reproduction, such as size and age at maturity, is used in models to assess fish stocks and can affect estimates of important ecological processes such as recruitment, abundance, and trophic interactions. Common practices for determining the reproductive status of teleost fishes include macroscopic evaluation of gonads as well as histological analysis. However, macroscopic evaluation can be biased and histological analysis is time-consuming, resulting in limitations to spatial and temporal data availability. Here, we explore Raman spectroscopy of ovaries as a novel approach to rapidly determine the reproductive status of walleye pollock (Gadus chalcogrammus), a commercially and ecologically important species in the North Pacific. We used a two-stage partial least-squares (PLS) regression analysis followed by a linear discriminant analysis (LDA) to classify walleye pollock ovary samples as physiologically mature or immature and to subsequently predict their histologically-determined reproductive stage based on the Raman spectra. Biologically mature samples with visible yolk differentiated from mature and immature samples (non-yolked; 99% accuracy). Non-yolked ovaries that were physiologically mature (either mature non-developing or previously spawned) were further differentiated from physiologically immature ovaries (93% accuracy). In addition, detailed, histologically-determined reproductive stages of yolked samples also differentiated via Raman spectroscopy, but with reduced accuracy (79% - 86% accuracy). Our results indicate that accurate identification of maturity status and the reproductive staging of oocytes of walleye pollock based on spectral data from ovaries is possible. This can provide a fast and efficient way to increase the availability of a key component of reproductive data to inform fisheries research and management.

Calibrating acceleration transmitters to quantify the seasonal energetic costs of activity in lake trout.

Bioenergetics models are powerful tools used to address a range of questions in fish biology. However, these models are rarely informed by free-swimming activity data, introducing error. To quantify the costs of activity in free-swimming fish, calibrations produced from standardized laboratory trials can be applied to estimate energy expenditure from sensor data for specific tags and species. Using swim tunnel respirometry, we calibrated acceleration sensor-equipped transmitting tags to estimate the aerobic metabolic rates (ṀO2) of lake trout (Salvelinus namaycush) at three environmentally relevant temperatures. Aerobic and swim performance were also assessed. Like other calibrations, we found strong relationships between ṀO2 and acceleration or swimming speed, and jackknife validations and data simulations suggest that our models accurately predict metabolic costs of activity in adult lake trout (~5% algebraic error and ~20% absolute error). Aerobic and swim performance metrics were similar to those reported in other studies, but their critical swimming speed was lower than expected. Additionally, lake trout exhibited a wide aerobic scope, suggesting that the avoidance of waters ≥15°C may be related to selection for optimal growing temperatures. The ability to quantify the free-swimming energetic costs of activity will advance our understanding of lake trout ecology and may yield improvements to bioenergetics model.

Effects of temporal hydrologic shifts on the population biology of an endangered freshwater fish in a dryland river ecosystem

AbstractSpecies occupying dryland river ecosystems often experience “boom‐and‐bust” demographic cycles that coincide with shifts in habitat availability. Knowing whether declines are within natural thresholds versus those caused by acute human disturbance is critical for managing protected species. We investigated temporal shifts in abundance and habitat use of an endangered population of the threespine stickleback Gasterosteus aculeatus in southern California, where a Mediterranean climate leads to ephemeral habitat in one of the regions' least hydrologically modified rivers, the Santa Clara River. We conducted population surveys over a period of below‐average rainfall in the upper watershed in Soledad Canyon, with predefined reaches surveyed multiple times per year to capture different hydrologic conditions. Abundances were stable across years but varied significantly depending on location, with some reaches remaining dry and others drying seasonally to varying degrees. Occupancy models showed that the presence of stable perennial reaches, drying regime, and other site‐specific factors were important predictors of habitat use, and that certain reaches may be key to ensuring source‐sink dynamics as flow dissipates over the dry season. Low occupancy in two sections was driven by different predominant mechanisms, one by diel cycles of evapotranspiration and the other by cattails (Typha spp.), with both having greater effects during the hotter, drier parts of the year. As dryland river ecosystems are vulnerable to the effects of anthropogenic‐induced climate change, this study demonstrates how temporal monitoring can delimit dry‐state benchmarks for improving management interventions (i.e., translocation and habitat restoration) for protected species under conditions that are predicted to worsen in the coming years.

Comparative analysis of blood protein fractions in two mediterranean farmed fish: Dicentrarchus labrax and Sparus aurata

Total protein levels in fish are widely used in health and welfare studies, providing a simple and accessible measure. However, the multifaceted role of blood proteins makes it sometimes challenging to link total protein content to specific health issues, while specific protein fractions may offer more precise insights into fish biology and health, particularly in farmed fish species where such data is often lacking. Data were gathered from two experiments involving Dicentrarchus labrax and Sparus aurata, key species in European marine aquaculture. The aim was (1) to assess how different globulin fractions contribute to total protein content in blood and (2) how these contributions vary across different sampling times in healthy animals. In D. labrax, the beta1 globulin fraction emerged as the major contributor (34.16%), followed by albumin and alpha2 globulins (18.24% and 16.41%, respectively). In contrast, pre-albumins and alpha1 fractions had the least contribution (5.49% and 7.71%). S. aurata exhibited albumin as the primary contributor (23.39%), followed by beta1 and alpha2 globulins (19.71% and 19.15%, respectively), with gamma and alpha1 fractions contributing the least (5.34% and 8.63%). Notably, the study revealed relatively stable contributions of globulin fractions to total proteins within both species, albeit with minor variations over time, potentially linked to environmental and individual factors. Furthermore, larger fish displayed higher total protein levels. This research underscores the need for further investigation into the diverse factors influencing globulin contributions to total proteins, ultimately enhancing health and welfare monitoring for farmed fish species.

GONAD MATURITY LEVELS OF LEMPUK FISH (Gobiopterus sp) IN RANU GRATI, PASURUAN, EAST JAVA

Pasuruan Regency in East Java Province boasts a natural lake, Ranu Grati, formed by volcanic activity, covering about 50 hectares and home to endemic species like the Lempuk fish (Gobiopterus sp.). These fish play a crucial role in Ranu Grati's trophic structure, serving as primary consumers and key planktonic organisms supporting higher trophic levels. The Lempuk fish population faces sustainability challenges due to high demand for this traditional food, leading to overexploitation and decreased reproductive capabilities. Understanding the reproductive biology, particularly gonad maturity levels, is vital for effective resource management. This study, conducted from June to August 2023, aimed to investigate the reproductive biology and gonad maturity levels of Lempuk fish in Ranu Grati. Analysis revealed a male-biased sex ratio, with significant fluctuations in gonad maturity levels across months. In June, the sex ratio was 1.05, in July 1.17, and in August 1.39, indicating a higher population of males. Histological observations showed asynchronous egg development, likely influenced by environmental factors and the fish's reproductive strategy

Environmental endocrine disrupting chemical 4-tert-butylphenol induced calcium overload and subsequent autophagy impairment via miRNA-363/CACNA1D Axis in epithelioma papulosum cyprini cells

Environmental endocrine disrupting chemical 4-tert-butylphenol (4-tBP), a widely-utilized surfactant in various industries, poses potential risks to aquatic organisms. Our previous sequencing results suggested that 4-tBP-induced common carp liver injury might be associated with Ca2+ signaling and autophagy. However, the intricate involvement of these pathways in 4-tBP-induced cytotoxic mechanisms remained unexplored. To bridge these knowledge gaps, this study focused on epithelioma papulosum cyprini (EPC) cells, a significant cell type in fish biology. Initial observations showed that 4-tBP induced a dose-dependent perturbation in Ca2+ levels. Further investigations, with siRNA and L-type Ca2+ channel agonist (BAYK8644), identified L-type calcium channel gene CACNA1D as a critical regulator of 4-tBP-induced Ca2+ overload. Predictive analysis using miRanda platform suggested a potential interaction between miR-363 and CACNA1D, which was subsequently verified through dual-luciferase reporter gene assays. We then established miR-363 mimic/inhibitor models, along with miR-363 and CACNA1D co-suppression models in EPC cells. Through TEM observation, immunofluorescence assay, Ca2+ staining, and qRT-PCR analysis, we evaluated the role of miR-363/CACNA1D axis in modulating the effects of 4-tBP on Ca2+ signaling and autophagy. Results showed that miR-363 inhibitor exacerbated 4-tBP-induced increase in CALM2, CAMKII, Calpain2, and p62 expression and also led to decrease in ATG5, ATG7, and LC3b expression. In contrast, miR-363 mimic notably alleviated these changes. Notably, siRNA CACNA1D effectively modulating miR-363 inhibitor's effect. Our study revealed that 4-tBP induced Ca2+ overload and subsequent autophagy impairment via miR-363/CACNA1D axis. These findings illuminated a profound understanding of molecular mechanisms underlying 4-tBP-induced cytotoxicity and spotlighted a potential therapeutic target.

Targeted metabolomics revealed the seasonal plasticity of skin color and pigment metabolites in ornamental koi carp

The koi carp is an ornamental fish that was obtained through artificial selection from the common carp (Cyprinus carpio L.). The most economically important traits of koi are their beautiful skin patterns in bright colors. As seasonality is an important factor in the biology and ecology of fish, we thus assumed that seasonal changes are involved in regulating the formation of skin color and patterns of koi carp. The white, red, cyan, and black skin colors from four varieties of scaleless koi carp (Doitsu Shiromuji (W), Doitsu Kohaku (WR), Doitsu Showa Sanke (WRI), and Kumonryu (WI)) were evaluated using the CIELab color space (lightness, redness, and yellowness) in different seasons. Compared to winter, the yellowness of the white color in all koi varieties decreased in summer and autumn. The black skin color areas in WRI and WI koi increased in summer and autumn compared to winter. The yellowness of the red color decreased only in WRI koi, while no changes were observed in WR koi. Targeted metabolomics analysis revealed that the levels of the structural pigment guanine of all koi varieties showed significant seasonal variation. Of seven detected carotenoids, the zeaxanthin and tunaxanthin contents in W, WI, and WRI koi changed with the seasons, while none of the carotenoids in WR koi were altered. Of the seven potential regulatory metabolites, epinephrine, melatonin, and cyclic adenosine monophosphate (cAMP) in all four koi varieties showed the highest levels in winter. A correlation analysis suggested that the seasonal changes in white skin color occurred through the epinephrine-cAMP pathway; melanin-dependent and carotenoid-dependent skin color changes occurred through melatonin in koi carp. This study demonstrated the seasonal plasticity of skin color in koi carp regulated by melatonin and epinephrine, associating with variety and color specificity.

Environmental influence on the Atlantic salmon transcriptome and methylome during sea lice infestations

The fish's immune response is affected by different factors, including a wide range of environmental conditions that can also disrupt or promote changes in the host-pathogen interactions. How environmental conditions modulate the salmon genome during parasitism is poorly understood here. This study aimed to explore the environmental influence on the Salmo salar transcriptome and methylome infected with the sea louse Caligus rogercresseyi. Atlantic salmon were experimentally infected with lice at two temperatures (8 and 16 °C) and salinity conditions (32 and 26PSU). Fish tissues were collected from the infected Atlantic salmon for reduced representation bisulfite sequencing (RRBS) and whole transcriptome sequencing (RNA-seq) analysis. The parasitic load was highly divergent in the evaluated environmental conditions, where the lowest lice abundance was observed in fish infected at 8 °C/26PSU. Notably, transcriptome profile differences were statistically associated with the number of alternative splicing events in fish exposed to low temperature/salinity conditions. Furthermore, the temperature significantly affected the methylation level, where high values of differential methylation regions were observed at 16 °C. Also, the association between expression levels of spliced transcripts and their methylation levels was determined, revealing significant correlations with Ferroptosis and TLR KEEG pathways. This study supports the relevance of the environmental conditions during host-parasite interactions in marine ecosystems. The discovery of alternative splicing transcripts associated with DMRs is also discussed as a novel player in fish biology.

Fishers' ecological knowledge points to fishing-induced changes in the Peruvian Amazon.

Scientists increasingly draw on fishers' ecological knowledge (FEK) to gain a better understanding of fish biology and ecology,and inform options for fisheries management. We report on a study of FEK among fishers along the Lower Ucayali River in Peru, a region of exceptional productivity and diversity, which is also a major supplier of fish to the largest city in the Peruvian Amazon. Given a lack of available scientific information on stock status, we sought to identify temporal changes in the composition and size of exploited species by interviewing fishers from 18 communities who vary in years of fishing experience since the mid-1950s. We develop four FEK-based indicators to assess changes in the fish assemblage and compare findings with landings data. We find an intensification of fishing gear deployed over time and spatiotemporal shifts in the fish assemblage and reported declines in species weight, which point to a fishing-down process with declines across multiple species. This finding is reflected in a shifting baseline among our participants, whereby younger generations of fishers have different expectations regarding the distribution and size of species. Our study points to the importance of spillover effects from the nearby Pacaya-Samira National Reserve and community initiatives to support the regional fishery. Reference to fishers' knowledge also suggests that species decline is likely underreported in aggregated landings data. Despite the dynamism and diversity of Amazonian floodplain fisheries, simple FEK-based indicators can provide useful information for understanding fishing-induced changes in the fish assemblage. Fishers hold valuable knowledge for fishery management and conservation initiatives in the region.

Study of the influence of fish feeding on the example of carp (Cyprinus carpio L.) under conditions of chemical pollution of the aquatic environment

The study of the influence of chemicals in the aquatic environment on the nutrition of fish, which lead to gradual pollution of the aquatic environment and violation of living conditions, and the development of methods for improving the nutritional properties of fish, which is an important branch of science that combines fish biology, in-depth study of nutrition and rational management, has been established fish resources and environmental sustainability. In recent years, a significant amount of research has been conducted aimed at understanding the relationships between fish nutrition, their development and the quality of fish products, the influence of chemicals on these processes in today's conditions using the example of carp (Cyprinus carpio L.). Analyzing the data, it was found that the quality of fish nutrition depends on the quality and composition of water, which affects the growth, development and health of fish. Considering the requirements of nutrients such as proteins, fats, vitamins and minerals, good nutrition can improve the quality of fish production. Special attention is paid to the role of proteins in the metabolism of fish using the example of cyprinus carp (Cyprinus carpio L.), growth and development, as well as adaptation to the interesting study of the composition of tissue proteins of carp during cadmium and lead intoxication. This year's carp (Cyprinus carpio L.), which is a widespread object of pond culture in Ukraine, was used for the experiment. A detailed analysis indicates that taking into account the effect of toxic substances on fish nutrition is necessary to ensure their health and optimal fish production. The development of new feeding strategies and the use of special additives is becoming a key aspect not only for improving the quality of products, but also for ensuring compliance with safety standards and environmental sustainability in the field of aquaculture and fisheries. Such research identifies new ways to create sustainable and healthy fish populations, contributing to the coordinated development of the agro-industrial sector and the preservation of aquatic ecosystems.

Estimating maximum oxygen uptake of fishes during swimming and following exhaustive chase - different results, biological bases and applications.

The maximum rate at which animals take up oxygen from their environment (ṀO2,max) is a crucial aspect of their physiology and ecology. In fishes, ṀO2,max is commonly quantified by measuring oxygen uptake either during incremental swimming tests or during recovery from an exhaustive chase. In this Commentary, we compile recent studies that apply both techniques to the same fish and show that the two methods typically yield different mean estimates of ṀO2,max for a group of individuals. Furthermore, within a group of fish, estimates of ṀO2,max determined during swimming are poorly correlated with estimates determined during recovery from chasing (i.e. an individual's ṀO2,max is not repeatable across methods). One explanation for the lack of agreement is that these methods measure different physiological states, each with their own behavioural, anatomical and biochemical determinants. We propose that these methods are not directly interchangeable but, rather, each is suited to address different questions in fish biology. We suggest that researchers select the method that reflects the biological contexts of their study, and we advocate for the use of accurate terminology that acknowledges the technique used to elevate ṀO2(e.g. peak ṀO2,swim or peak ṀO2,recovery). If the study's objective is to estimate the 'true' ṀO2,max of an individual or species, we recommend that pilot studies compare methods, preferably using repeated-measures designs. We hope that these recommendations contribute new insights into the causes and consequences of variation in ṀO2,max within and among fish species.

Bioecology of Electric Fish (Actinopterygii: Gymnotiformes)

The poraquê has an elongated and cylindrical body, with just one anal fin, which extends across almost the entire abdomen it resembles the shape of an eel. Its head is flat and its mouth is equipped with a row of sharp, conical teeth. The color of this animal is always very dark, but the ventral part of the body is yellowish and they have poor vision. This group of fish is known for their ability to generate and detect electrical fields in the environment in which they occur, and these characteristics are used in communication, prey detection, defense, reproduction and even to help these animals move in the absence of light. This manuscript aims to describe the biology, ecology, morphology, geographic distribution, life cycle, habitat, and therapeutic use of electric fish (Chordata: Actinopterygii: Gymnotiformes). Concerned with establishing a public profile of quality research in the area, we sought to answer these questions based on a literature review in the main journals (national and international) classified by the Coordination for the Improvement of Higher Education Personnel (CAPES). Complement this analysis with other documents such as books, theses, dissertations, scientific journals, documents, and digital platforms.

Puzzling parrotfishes: Radiocarbon age validation and updated longevity estimates for western Atlantic species in support of sustainable fisheries management

For management efforts to succeed in Caribbean fisheries, local fishers must support and be willing to comply with fishing regulations. This is more likely when fishers are included in a stock assessment process that utilizes robust scientific evidence, collected in collaboration with fishers, to evaluate the health of fish stocks. Caribbean parrotfishes are important contributors to coral reef ecosystem health while also contributing to local fisheries. Scientifically robust stock assessments require regional species-specific information on age-based key life history parameters, derived from fish age estimates. Evaluation of the accuracy of age estimation methods for fish species is a critical initial step in managing species for long-term sustainable harvest. The current study resulted from a collaborative research program between fish biologists and local fishers investigating age, growth, and reproductive biology of the seven parrotfish species landed in U.S. Caribbean fisheries; specifically, we validated age estimation for stoplight parrotfish Sparisoma viride and queen parrotfish Scarus vetula. This is the first study to directly validate age estimation for any parrotfish species through analysis of Δ14C from eye lens cores. Our age estimation validation results show that enumeration of opaque zones from thin sections of sagittal otoliths for a Sparisoma and a Scarus species provides accurate age estimates. The oldest stoplight parrotfish and queen parrotfish in the Δ14C age estimation validation series were 14 y and 16 y; while the oldest stoplight parrotfish and queen parrotfish we aged to-date using the Δ14C validated age estimation method were 20 y and 21 y, respectively. Fish longevity (maximum age attained/life span) is a key life history parameter used for estimation of natural mortality, survivorship, and lifetime reproductive output. Past reviews on parrotfishes from the Pacific and Atlantic concluded that most Caribbean/western Atlantic parrotfish species are relatively short-lived with estimated maximum ages ranging from 3–9 y. However, information from our collaborative research in the U.S. Caribbean combined with recently published age estimates for Brazilian parrotfish species indicate that many western Atlantic parrotfishes are relatively long-lived with several species attaining maximum ages in excess of 20 y.

Reproduction biology of mullet fish (Mugil dussumieri) found in Bandar Khalipah Waters Serdang Berdagai Regency, North Sumatera Province

The Mullet fish (Mugil dussumieri) is one of the types of marine fish that is caught in waters Bandar Khalifah. This limited information reproductive aspects of Mugil dussumieri, such as sex ratio, gonad maturity level, gonad maturity index, fecundity, egg diameter, and gonad histology, that can be used as a guideline for the management of mullet resources to ensure sustainable utilization. This study was conducted from January to March 2023, and method used in this research was random purposive sampling. Fish samples were taken in 3 station is estuary, Pandang River and the coastal waters of Bandar Khalifah District, Serdang Berdagai Regency, North Sumatera Province, which was divided into 3 stations using a census sampling method. The total catch was sampled once a month for 3 months. The fishing gear used was a Gillnet with a mesh size of 1.5 cm. The data analysis included measurements of the samples, gonad maturity level, fecundity, and gonad histology. The reproductive results showed an unbalanced sex ratio of 1:3. The gonad maturity level of the mullet fish ranged from gonad maturity level I to gonad maturity level IV. The egg fecundity ranged from 963 to 129,311 eggs, and based on the egg diameter, the Mullet fish is classified as a partial spawner. These studies are crucial for obtaining information that can be used as a guideline for the management of Mugil dussumieri resources to ensure sustainable utilization.

The Relationship between Length and Weight and Condition Factors of Lompa Fish (Thryssa baelama) in Kabauw Village Waters

The biology of the Lompa fish (Thryssa baelama, Forskall, 1975) in the waters of Kabauw Beach, Central Maluku is not yet known. This research aims to analyze fish size, the relationship between length weight and condition factors of Lompa fish. A total of 628 fish samples were collected using cast net fishing gear, from October – November 2023. The results showed that the total length of the fish ranged from 6 – 6.5 cm and body weight ranged from 1,703 – 13,072 grams. The relationship model for the length and weight of male fish W = 0.0102L2.8294 and female fish W = 0.0119L2.7501, and the combination of male and female W = 0.0111L2.7885. The condition factor (K) of male Lompa fish (Thryssa baelama) ranges between 0.695 – 1.3728 (0.993 ± 0.0779) and for females ranges between 0.7912 – 1.3783 (1.0056 ± 0.0807).

Dried storage of sperm at supra-zero temperatures: An alternative for flow cytometric analysis under field conditions

In biotechnological processes such as chromosomal manipulation studies, semen has become a reference in the ploidy verification of the evaluated material. However, the use of fresh samples is limited to the use at field conditions because the analysis is performed under laboratory conditions. Thus, this study aimed to develop a simpler procedure for storing dry semen at 28 °C to reduce cold storage costs. For this, semen samples were evaluated according to established quality semen parameters, a protocol for dry, and 3 sterilization treatments of dry semen were applied to the store. The integrity of the DNA was evaluated every two months, using fresh semen, dry semen (untreated), and particles 3C to compare the peaks by flow cytometry. The results indicated that all samples evaluated before and after drying showed no significant difference in the DNA content. UV-treated semen showed a 1C peak in the histogram up to 180 days of storage and a non-significant difference (P > 0.05) from fresh control in the number of DNA particles up to 120 days and untreated only showed a 1C peak up to 120 days. The developed method may become an interesting procedure to serve as a reference peak for practical flow cytometric analysis, not only in the field of fish biology but also in biomedical and agricultural sciences. Furthermore, dried semen can become a tool for the preservation of genetic material and is a promising low-cost storage technique for biobanking.