Gonadal Maturation Research Articles

Identification of sex-specific markers using genome re-sequencing in the blunt snout bream (Megalobrama amblycephala)

BackgroundThe blunt snout bream (Megalobrama amblycephala) is an important economic freshwater fish in China with tender flesh and high nutritional value. With the cultivation of superior new varieties and the expansion of breeding scale, it becomes imperative to employ sex-control technology to cultivate monosexual populations of M. amblycephala, thereby preventing the deterioration of desirable traits. The development of specific markers capable of accurately identifying the sex of M. amblycephala would facilitate the determination of the genetic sex of the breeding population before gonad maturation, thereby expediting the processes of sex-controlled breeding of M. amblycephala.ResultsA whole-genome re-sequencing was performed for 116 females and 141 males M. amblycephala collected from nine populations. Seven candidate male-specific sequences were identified through comparative analysis of male and female genomes, which were further compared with the sequencing data of 257 individuals, and finally three male-specific sequences were generated. These three sequences were further validated by PCR amplification in 32 males and 32 females to confirm their potential as male-specific molecular markers for M. amblycephala. One of these markers showed potential applicability in M. pellegrini as well, enabling males to be identified using this specific molecular marker.ConclusionsThe study provides a high-efficiency and cost-effective approach for the genetic sex identification in two species of Megalobrama. The developed markers in this study have great potential in facilitating sex-controlled breeding of M. amblycephala and M. pellegrini, while also contributing valuable insights into the underlying mechanisms of fish sex determination.

Poly(A)-Specific Ribonuclease Deficiency Leads to Deregulated Expression of Genes Involved in Sex Determination and Gonadal Maturation in Zebrafish

Abstract Background Deadenylation, the process of removal of poly (A) tail of messenger ribonucleic acids (mRNAs), is a rate-limiting step in mRNA stability, and poly(A)-specific ribonuclease (PARN) is the most important exonuclease involved in this process. Besides mRNA stability, PARN is also involved in several other processes including telomere maintenance, noncoding RNA maturation, ribosome biogenesis, and TP53 function. Previously, we have shown that zebrafish PARN null mutants are viable and fertile but turn out to only develop into males, indicating a role in oogenesis. The present study was focused on analyzing the expression of genes involved in sex determination and gonadal development in PARN mutant zebrafish. Materials and Methods Total RNA was extracted and quantitative real-time polymerase chain reaction was performed to determine the expression level of genes involved in gonad development in PARN mutant embryos (4 days postfertilization [dpf]) and adults (120 dpf) in comparison to their wild-type siblings. The expression levels were estimated by the ΔΔCT relative quantification method. Results At 4 dpf, the expression of germ cell-specific genes did not show any significant difference in the null mutants compared to the heterozygous and their wild-type siblings, suggesting no effect on germ cell differentiation due to the loss of PARN. However, the majority of the ovary-associated genes analyzed showed an increased expression in PARN null and heterozygous mutants compared to the wild-type siblings. Intriguingly, the expression of testis-associated genes showed decreased expression in the mutants compared to their wild-type siblings at 4 dpf. In adult stages, as expected, the expression of genes that jointly regulate the proper formation and function of ovaries and testes showed decreased expression in PARN null mutants. Interestingly, the expression of genes involved in the differentiation of testes, despite showing a decreased expression in the mutants, was comparable between the null and heterozygous mutants. Conclusion Taken together, these results suggest that the loss of PARN does not affect germ cell differentiation but affects the sexual differentiation that happens at later stages of development, particularly the process of oogenesis, in zebrafish.

Половая структура поселений двустворчатого моллюска Macoma calcarea (Gmelin, 1791) в районах с разным гидрологическим режимом

The influence of changes in environmental conditions on the reproductive cycles of benthic organisms (sexual structure, size of puberty, stages of gonad maturity, oocyte size) of the bivalve mollusk Macoma calcarea in the western part of the Spitsbergen archipelago (Grenfjord Bay) and the eastern part of the Barents Sea (coastal archipelago) was studied New Earth). In a settlement of M. calcarea in the warmer waters of Grenfjord, intensive reproductive processes were observed. In this area, females reach sexual maturity with a shorter shell length than males and individuals from other areas of the Barents Sea; In terms of sex ratio, females dominate over males, and a large number of juveniles are noted. Females at the spawning stage were found only near Novaya Zemlya. The diameter of the oocytes varied from 30 to 200 µm depending on the stage of maturity. In the mollusks M. calcarea, the breeding season is extended in time in both study areas.

Seasonal dimorphism as an expression of sexual dimorphism: Influence of gonad maturity on the body shape of a rocky intertidal polyplacophoran

Seasonal dimorphism in the body shape of marine invertebrates has been poorly explored compared to vertebrates. We aim to investigate through traditional (body length/width ratio, dorsal elevation ratio and angle of elevation) and geometric (centroid size and shape geometric configurations) morphometrics the effect of gonad maturity (via the gonadosomatic index [GSI] and gonad development stages [GDS]) on changes in body shape in males and females of two latitudinally different populations of the broadcast-spawning intertidal mollusc Chiton articulatus. We confirmed that C. articulatus does not present external sexual dimorphism since sex does not have a significant effect on body shape (1%); instead, dimorphism was seasonal and related to the reproductive season, and varied across populations, probably because in the subtropical zone additional energy is invested in shell (scleritome) bending at the same time as the gonad matures, which is opposite of what occurs in the tropical zone. C. articulatus shows a narrower body shape (i.e., diminished body width) during its gonad maturity compared to the rest of the GDS and is corroborated by a body length/width ratio that contributes the greatest variation in the geometric shape descriptors (18%), just below the centroid size (24%). The expression of centroid size differences shows a correspondence with the change in body dimensions expressed by the three morphometric ratios during gonad maturity. The use of traditional body ratios over time may be useful in polyplacophoran molluscs as a proxy tool to estimate gonad maturity and to provide a reliable indication of the reproductive season.

Reproductive effort affects cellular response in the mantle of Nodipecten subnodosus scallops exposed to acute hyperthermia

In marine ecosystems, temperature regulates the energy metabolism of animals. In the last decades, the temperature increase was related to mass mortality events of marine ectotherms, particularly during high-energy investment for reproduction. In scallops, the mantle has been poorly investigated while this tissue covers more than 40 % of the body mass, contributing to the perception of surrounding environmental stimuli. Our aim was to assess the cellular and molecular responses linked to energy metabolism in the mantle of adult N. subnodosus facing acute hyperthermia during reproductive effort. Scallops collected in spring (late gametogenesis) and summer (ripe gonads) were exposed to a control temperature (22 °C) or acute hyperthermia (30 °C) for 24 h. In spring, increased arginine kinase (AK) activity together with increased pyruvate kinase/citrate synthase ratio (PK/CS) suggested an enhanced carbohydrate, pyruvate, and arginine metabolism to maintain the adenylate energy charge (AEC) in the mantle of scallops coping with acute thermal increase. In summer, animals decreased their AEC (5 %) and arginine phosphate pool (40 %) and increased their anaerobic metabolism as shown by enhanced activities of lactate-dehydrogenase (LDH) and octopine dehydrogenase (ODH), respectively. The abundance of twenty proteins involved in energy metabolism (isocitrate dehydrogenase, ATP synthase subunit β), protein protection (cognates heat shock protein 70), and cytoskeleton (actins and tubulins) were affected only by season. These results underlie the role of the mantle of N. subnodosus in the seasonal responses of this tissue to thermal fluctuations during reproductive effort with possible implications for the physiological performance of scallops under heat waves in wild or harvest conditions.

Stock exploitation status of silver croaker (Pennahia argentata) from the East China Sea

Silver croaker (Pennahia argentata) is an important economic species in the East China Sea (ECS); however, its population has been declining, and studies on its status are scarce. This study collected biological data, including length, weight, and gonadal maturity of silver croaker from the southern coastal waters of Zhejiang Province between 2015 and 2021, to evaluate its life history and assess stock status. Methods from the TropFishR package were employed to estimate population growth and natural mortality parameters. Two widely used length-based data-limited models, length-based bayesian biomass estimation method (LBB) and length-based spawning potential ratio method (LBSPR), were applied to assess the stock status of silver croaker in the ECS. The results indicated that with a maximum age (Amax) of 4 years, the asymptotic length (Linf) was 23.80 cm, growth rate (K) was 0.74/year, and natural mortality coefficient (M) ranged from 1.068 to 1.376. Under the assumption of Amax = 5 years, Linf was 26.77 cm, K was 0.63/year, and M ranged from 0.818 to 1.193. The LBB and LBSPR models showed that, except for scenarios with L∞ = 23.8 cm, M/K = 1.46, and L∞ = 26.77 cm, M/K = 1.30, 1.38, or 1.48, the selectivity at length parameters L50SandL95S for silver croaker exhibited an increasing trend over the years. In the LBB model, L50S for different years consistently fell below the optimum length (Lc_opt), indicating that most individuals did not reach the size at first sexual maturity or optimal catch length. Moreover, under high fishing pressure, the Spawning Potential Ratio (SPR) and the unfished biomass ratio (B/B0) for silver croaker showed a decreasing trend, despite some stability or recovery in recent years. However, in all scenarios, SPR values were below 0.2, and B/B0 values were below 0.5, suggesting a significant risk of population collapse for silver croaker in the ECS due to intense fishing pressure. Therefore, it is recommended to reduce the current fishing pressure and increase the minimum catch size of this species for effective conservation and management in this region.

Comparative effects of curcumin, nano curcumin and their combination on reproductive traits and spawning performance of red tilapia (Oreochromis Niloticus X O. Mossambicus)

Curcumin, the main polyphenol component of turmeric powder, has garnered increasing attention as an effective supplement in fish diets. A comparative trial was conducted to evaluate the impacts of dietary supplementation with different forms of curcumin (free, in combination, or nanoparticles) on hemato-biochemical parameters, reproductive capacity, and related gene expressions of red tilapia (Oreochromis niloticus x O. mossambicus) broodstock. Fish (n = 168) were fed an isonitrogenous (30% CP), isocaloric (18.72 MJ kg − 1) diet containing basal diet (Control), 60 mg kg-1 of either free curcumin (Cur), curcumin/nano-curcumin blend (Cur/NCur), or nano-curcumin (NCur) for 56 days. Red tilapia broodstock (155 ± 5.65 g) were stocked at a male: female ratio of 1:3. Blood samples and gonads were collected to assess hemato-biochemical parameters, reproductive capacity, and related gene expression at the end of the feeding trial. The results indicated that the values of hematological parameters (RBCs, WBCs, hemoglobin), total protein, albumin values, and reproductive hormones (T, LH, and FSH) were significantly increased, while liver function enzymes were decreased in the NCur group (P < 0.05). Reproductive performances (GSI, gonad maturation, total number of fry per female) were significantly improved in the NCur group compared with those in other groups (p < 0.05). The expression of reproductive genes (CYP19A1A, FSHR, LHR, FOXL2A, ESR1, ESR2A, and PGR) were significantly up‐regulated in the gonads of fish fed NCur. Collectively, feeding red tilapia diets containing NCur led to noticeably better results followed by Cur/NCur blend, then free Cur compared to the control diet. These results indicate the superiority of NCur over its free or blended form, suggesting that a diet containing about 60 mg/kg of NCur is beneficial for enhancing hemato-biochemical parameters, improving reproductive performance, and enhancing the gonadal architecture of red tilapia.

Elucidating maternal provisioning for bivalve larvae under ocean acidity extreme events

Ocean acidity extreme (OAX) events, triggered by climate change and anthropogenic activities, are projected to become more intense and frequent in coastal ecosystems, devastating marine bivalves and ecosystems they support. Maternal effects adaptively modulate offspring performance in response to climatic stressors, but whether and to what extent they can confer offspring resistance to OAX remain largely unknown. Here, we investigated impacts of OAX on the parental and larval lipidomes of Manila clams (Ruditapes philippinarum) to add further insights into the energetic nature of maternal effects. A total of 177 significantly down-regulated lipid components (categorized into glycerolipids mainly) were shown in OAX-stressed adults compared with those reared under ambient conditions, and following parental conditioning, larvae also exhibited a further decreasing down-regulation of the glycerolipid components. Triacylglycerols were identified as the predominant composition of glycerolipids and the primary sources of energy for gonadal maturation and larvae development. Yet, larvae spawn from adults exposed to OAX had significantly lower contents of triacylglycerols than those without a prior history of parental conditioning, with the carbon chain length and unsaturation degree of the triacylglycerol components being significantly affected. The latter was also in line with significant increases in the production of triacylglycerol byproducts (diacylglycerols). Overall, our findings suggest that when OAX prevailed during reproductive seasons of Manila clams, maternal effects could be maladaptive by depressing the energetic deposition of larvae, and may not be a potential adaptive modulator of marine bivalves to cope with unprecedented environmental change.

Participation of the insulin-like growth factor system in the early maturity in juvenile male European sea bass

It is known that the insulin-like growth factor (Igf) system is involved in gonadal development and, in turn, reproduction in vertebrates. In this study, the circulating levels of Igf-1 and follicle-stimulating hormone (Fsh) were assessed as physiological signals related to gonadal maturation stage in juvenile male European sea bass at 1 year of age. The seasonal profiles of Igf-1 and Fsh were analyzed in non-precocious (NP) and precocious (PR) fish during the early onset of puberty. Subsequently, gonadal expression patterns of the three igf genes and their two receptors, igf-1r and igf-2r, were studied during their first year of life. The analysis was continued to evaluate the mRNA expression profiles of three genes (sox17, scf, nf2) mediating spermatogenesis progression. Collectively, these results demonstrated that PR males have higher circulating levels of Igf-1 as compared to NP fish before and during the putative gonadal development period (PGD). Plasma Fsh levels were significantly higher in PR males as compared to NP fish before the start of the PGD period, although this was followed by a decrease in Fsh levels and a subsequent recovery, coinciding with the reproductive season (February). Results showed that the total variance associated with the appearance of precocity may be explained by the contribution of factors such as body size and plasma levels of Igf-1, Fsh and sex steroids in male sea bass. Expression of igfs was high during stage I, and this was significantly correlated with the expression of genes related to cell cycle progression, including sox17, scf and nf2. Finally, the decreased expression of all these gonadal factors in precocious animals suggests their potential involvement in regulating the proliferative growth of spermatogonia and supporting cells during the early stages of spermatogenesis, thus evoking the onset of puberty in male sea bass.

Effects of dietary cholesterol on ovary development and reproductive capacity in Pacific white shrimp broodstock, Litopenaeus vannamei

Cholesterol is an important component of fresh biological baits and essential precursor to synthesize steroid hormones for crustacean. However, the cholesterol demand in Pacific white shrimp broodstock and its roles on ovary development and reproductive capacity are unknown. In the present study, female Pacific white shrimp broodstock (initial weight 51.3 ± 0.5 g) were fed with three diets contained 0.5 %, 1 % or 1.5 % cholesterol for 45 days. The results found that dietary cholesterol levels did not affect survival rate, weight gain, egg-laying number, vitellogenin content and vitellogenin receptor gene expression in the hepatopancreas. However, the hepatosomatic index, gonadosomatic index, egg diameter, vitellogenin level in the ovary and fertilized egg, C22:6n-3 (DHA) level in the fertilized egg, total protein, triglyceride and cholesterol contents were all increased in the 1.0 % and 1.5 % cholesterol groups than those in the 0.5 % cholesterol group. Moreover, compared with the 0.5 % and 1.0 % cholesterol groups, the 1.5 % cholesterol group had significantly higher gonad maturation number, mating rate, estradiol level in the hemolymph, steroid hormones synthesis related genes (HMGCR, StAR, 17βHSD and 1vMFBP) expression in the ovary and hepatopancreas. In conclusion, dietary 1.5 % cholesterol could promote ovary development and reproductive capacity in female Litopenaeus vannamei broodstock by improving nutrients accumulation and steroid hormones synthesis pathway. Our results provide guidance for design of artificial compound feed and healthy development of shrimp broodstock farm.

TEKNIK PEMBENIHAN ABALONE (HALIOTIS SQUAMATA) DI BALAI PERIKANAN BUDIDAYA LAUT LOMBOK

The aim of this research is to describe the abalone (Haliotis squamata) hatchery technique at the Lombok Marine Aquaculture Center (BPBL). This research is participatory research, researchers took part in all activities at the Lombok Marine Aquaculture Center (BPBL). Data collection methods are by observation and documentation. The data obtained was analyzed using descriptive statistics. The data collected is related to abalone hatching techniques. The results of research regarding abalone hatchery techniques at the Lombok Marine Cultivation Fisheries Center went through several stages, namely container preparation, gonad maturity selection, stimulation, spawning, abalone stocking, feeding, water quality management and harvesting

Study of Life Feed in Cantang Grouper Hatcheries (Epinephelus fuscoguttatus x Epinephelus lanceolatus)

Abstract Cantang grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus) is a cross between female tiger grouper (Epinephelus lanceolatus) and male tiger grouper (Epinephelus fuscoguttatus), according to statistical data from the Ministry of Maritime Affairs and Fisheries (KKP) it has a production value of 4,406 tons in 2022 and experienced an increase in growth of 33.92%. Fulfilling this need can be done by maximizing the hatchery process, the key to which is natural food, namely for broodstock (flying fish, tuna and squid) and larvae (chlorella, artemia, rotifers, rebon shrimp). The aim of this article is to study natural feed in the hatchery of cantang grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus). This study was conducted at the Pecaron Brackish Water Aquaculture Fisheries Center (BPBAP), Situbondo, East Java on 19 June - 19 August 2023. The work method used was a descriptive method with primary and secondary data collection. The study results showed that the Hatching Rate (HR) was 73.25%, the Survival Rate (SR) was 15.98%, the Specific Grow Rate (SGR) was 0.24 g/day. Water quality measured is temperature ranging from 28-30°C, pH between 7.78-8.44, salinity between 31-32 ppt, dissolved oxygen (DO) between 5.72-6.20 mg/L, ammonia between 0.001-0.031 mg/L, nitrite is 0.001 mg/L. Natural feed has complete amino acids, fatty acids, enzymes and minerals which function in the maturation of the parent gonads and larval growth.

Gonad development of female tilapia (Oreochromis niloticus) exposed to acid red 88 textile dye

Abstract Textile dyes are artificial dyes that are widely used by the textile industry because they have many types of colors and are cheap. The azo dye used can be an aromatic compound that has stable properties, so if it is in water, it can be more toxic than the azo dye itself. This study aims to determine the effect of exposure to acid red 88 dye and a minimum dose of acid red 88 dye on the level of gonad maturity and gonadosomal index (GSI) of parent tilapia fish. This research was an experimental study; tilapia fish were kept for 7 days with 5 treatments and 4 repetitions. Data collection was carried out by looking at the TKG of tilapia fish in morphology and histology, and then the GSI of tilapia fish was analyzed using the ANOVA test. The results of this research show that acid red 88 is said to be an endocrine-disrupting chemical and produces excess reproductive hormones, which can affect fish health. Then there was damage to the histology of the TKG of the tilapia. The conclusion of this research is that exposure and dose of acid red 88 dye have an influence on the morphology and histology of TKG and the GSI value of tilapia.

Evaluation of Indian white shrimp (Penaeus indicus) rearing technique at Balai Besar Perikanan Budidaya Air Payau (BBPBAP) Jepara

Abstract Indian white shrimp is one of the important fishery commodities with high economic value after banana prawns (Penaeus merguiensis) in the northern coastal waters of Central Java Province. This shrimp needs to be more developed since its aquaculture technique was not quite as well-known as in other shrimps such as P. vannamei or P. monodon. This study aimed to unveil the techniques for rearing white shrimp and its influencing factors. The method in this research used active participation and descriptive methods. The data collection method used was from primary and secondary data. Both primary data were FCR (Feed Conversion Rate), ABW (Average Body Weight), ADG (Average Daily Growth), and water quality parameters while the secondary data were literature review and staff information. The results showed that the FCR values in the three pools were high (1: 5.5, 2: 24.57, 3: 10.36). For growth parameters, the ABW values for the three ponds were 29.57, 20.00, and 23.91 while the final ADG values were 0.53, 0.14, and 0.52 respectively. It can be concluded that the enlargement activity of Indian white shrimp needs to be improved due to high FCR value and fluctuating water quality. Higher FCR value would reduce the feed efficiency so that a lot of feed was given to the shrimps but their growth is less than optimal. The Enlargement activities at Jepara should use feed with a minimum protein content of 33% by the protein requirements of Indian white shrimp so that it can support gonad maturity. Additionally, it is necessary to rearrange the pond size to conform to the standard size (2000-5000 m2), as well as manage water quality through daily siphoning so that the water quality remains optimal.

Life History Parameters and Spawning Potential Ratio of Upeneus vittatus (Forsskål, 1775) in the Coastal Waters of Lebak and Sukabumi, Indonesia

Abstract It is necessary to obtain information regarding the life history and stock status of the yellow-striped goatfish (Upeneus vittatus) in the coastal waters of Lebak and Sukabumi, Indonesia. This study aims to determine the stock status of U. vittatus in the coastal waters of Lebak and Sukabumi based on their life history parameters and length-based spawning potential ratio (LB-SPR). Eight hundred seventy-four samples were collected from Binuangeun, Palabuhanratu Nusantara, and Ciwaru Fishing Ports. The monthly length frequency data were obtained from July to December 2022. The results show that the Von Bertalanffy growth parameter was Lt=254(1-e−(0.58(t+0.154)) for males, Lt=239(1-e−(0.42(t+0.221)) for females, and Lt = 258(1-e−(0.37(t+0.246)) for both. The mature gonads of U. vittatus were mostly obtained from October to December. The length of first maturity L50 and L95 were 158 mm and 236 mm for males and 149 mm and 229 mm for females, respectively. The exploitation rate (E) on male, female, and combined U. vittatus revealed that E values exceed 0.5 or are overexploitation. The estimated SPR of U. vittatus was 23%, lower than the target reference point of 40%. Therefore, U. vittatus was fully exploited in the coastal waters of Lebak and Sukabumi.

Induced sexual reproduction ex situ reveals bidirectional sex change of the coral Montastraea cavernosa

Induction of gonad maturation and synchronized spawning of corals ex situ has been mostly used to propagate corals for restoration, but it also provides a unique opportunity to study the reproductive biology of species. We present, for the first time, the induction of gonad maturation and synchronous spawning of the coral Montastraea cavernosa in a laboratory. This was achieved by mimicking the annual temperature, sun and moon cycles experienced in the northern portion of Florida’s Coral Reef. Similarly to field observations, peak spawning of M. cavernosa colonies in the laboratory occurred 5–10 nights after the full moons of July, August, and/or September, 75–125 min after sunset. This coral species was known as gonochoric, meaning colonies are either females (release eggs) or males (release sperm). Yet, three consecutive years observing the same colonies ex situ revealed that these corals are capable of changing sexes annually, and they can do so in both directions. Spawning observations and histology showed corals shifting from male to female, others shifting from female to male, and several changing sex one year and reverting to their original sex in the following year. The sex change was not related to size, nor likely socially driven. A greater number of colonies was observed to shift from female to male when food provision was reduced. Further studies are required to determine if food availability drives sex change in this species.

Development of Reliable Male-Specific Molecular Markers for Genetic Sex Identification in Sea Cucumber Apostichopus japonicus.

Apostichopus japonicus is an important marine aquaculture species in China, with high nutritional and economic value. In A. japonicus, there is no obvious sexual dimorphism in external appearance, and sex differentiation primarily relies on the observation of mature gonads after dissection, which leads to difficulties in sex identification. The confusion in sex identification greatly reduces breeding efficiency in the sea cucumber industry. Therefore, developing a reliable sex-specific marker is crucial. In this study, we identified 586 male-specific sequences through whole-genome assembly and sequence alignment, but did not identify any female-specific sequences, inferring an XY-type sex determination system in sea cucumbers. We developed a set of male-specific molecular markers to establish an accurate, stable, and widely adaptable genetic sex identification technique for A. japonicus. The male-specific molecular markers were validated with 100% accuracy in sea cucumber populations from six different geographical regions in China. In conclusion, this study provides further evidence for the XY-type sex determination system in A. japonicus and establishes an effective genetic sex identification method for multi-geographic populations, which benefits future study on reproductive biology and has significant implications in sea cucumber aquaculture industry.

Reproductive ecology of the sand crab (Ovalipes punctatus) population in the Yellow Sea of Korea

AbstractUnderstanding the reproductive ecology of crustaceans is important for developing appropriate resource management policies. Because the demand for sand crabs (Ovalipes punctatus) as a food resource has recently surged in Korea, their reproductive ecological characteristics should be comprehensively described. In this study, the reproductive ecological characteristics—sex ratio, female gonad maturity, abdominal width (AW), condition factor (K), and gonadosomatic index (GSI)—of individuals of O. punctatus collected from the Yellow Sea in Korea (35°15′00″N, 125°15′00″E) from January to December 2021 were examined. Based on the sex ratio (1:1.61, females:males), we determined that males were more abundant than females. The monthly K for both the males and females reached its maximum in April. The monthly GSI revealed that the males were most numerous in December, whereas the females were most abundant in May. The GSI graph indicates that the main spawning season of O. punctatus is from May to July. The AW and GSI of the females increased as their gonads matured; based on this correlation, the maturity of female individuals can be determined by examining the abdominal flap morphology. The results of histological analysis indicated that females of O. punctatus exhibit synchronous development, by which oocytes develop simultaneously. Furthermore, the size at maturity, at which more than half of the individuals participated in spawning, was 75.6 mm. The findings of this study contribute to the development of policies for the sustainable fisheries of O. punctatus.

PERTUMBUHAN DAN KEMATANGAN GONAD IKAN WAKONG MERAH (Caesio chrysozona) DI KEPULAUAN BANDA

The fusilier fish (Caesio chrysozona) is an abundant fish resource that contributes to the economy of the Banda Islands community. This study aims to examine the growth, gonad maturity level (GML), and gonad maturity index (GMI) of the red fusilier fish landed on the coast of Kampung Baru Village, Banda District, Central Maluku. The study was conducted from July to August 2023. A total of 40 fish were collected, measured for their total length, and weighed for their body weight. After that, the fish were dissected for gonad observation, which was then weighed and determined for gonad maturity levels. The results showed that out of 40 fish, there were 14 male and 26 female fish. The length of the fish ranged from 18 to 24 cm, with body weights for females between 83 and 220 grams, and for males between 79 and 171 grams. The length-weight relationship analysis showed a (b) value for female fish of 3.664 with an ( R2) value of 0.834, while male fish had a (b) value of 1.446 with an (R2) value of 0.273. The length-weight relationship equations for female fish is (W=0.0018 L{3.664}), and for male fish (W=1.7876 L{1.446}). The gonad maturity level (GML) was dominated by GML II for both genders. The gonad maturity index (GMI) varied each month during the study, with the highest GMI for males reaching 3.10% and the lowest at 0.25%, while the highest GMI for females was 2.562% and the lowest was 0.091%.

BIOLOGI REPRODUKSI IKAN BALOBO (Hyporhamphus quoyi) HASIL TANGKAPAN JARING BALOBO DI PERAIRAN DESA APARA KABUPATEN KEPULAUAN ARU

Garfish is a small pelagic species that has long been used as a raw material for dry fish production from Maluku called balobo dried fish. Many species of Garfish have been exploited but the species Hyporhamphus quoyi has not much been informed. This study aims to understand the reproductive aspects of Garfish consisting of measuring the sex ratio, changes in the gonad maturity stages (GMS) and counting the size of the first size gonad maturity. Located at the waters of Apara village, Aru Archipelago Regency, this study was conducted using a balobo net from November to December 2023. The catches were identified, measured its fork length (FL cm) and dissected to examine its reproductive organ. The Chi-squire heterogeneity test was occupied to measure sex ratio at different sizes. GMS was accessed based on the morphology of testis and ovary. First size maturity was calculated using Spearman-Karber method. The target fish captured by the balobo net consists of the Hemirhamphus far and Hyporhamphus quoyi. The ratio of male and female Hyporhamphus quoyi is unbalanced (c2=8.36; df=1; P=0.0038) but the sex ratio based on the length distribution of fish is not significantly different ( c2=6.92; df=6; P =0.328). Changes in GMS during the observation period indicate the occurrence of spawning in November. Balobo fish reach gonad maturity at FL = 24.9cm for females and FL = 26.8cm for males. Since the optimum size of the fish Hyporhamphus quoyi caught by balobo net is 27cm, this net produced legal sized of fishes.