Gonadal Maturation Research Articles

Morphological and Genetic Assessment of Sympatric Lenok Species (Brachymystax spp.) in the Onon River, Mongolia

The genus Brachymystax is represented by three putative species that disjointedly inhabit the major river basins of central and northeast Eurasia. Brachymystax lenok and B. tumensis have been regularly misidentified throughout their range, including across sympatric populations in the upper Onon River of Mongolia. This research has focused on Mongolia’s understudied lenok populations by conducting detailed morphometric measurements and genetic analyses to confirm key metrics for accurately distinguishing between these cryptic species. While there are slight differences in colouration and patterns including size and density of their defining black spots, four key metrics were found to be significantly different between the species including gill rakers counts, snout length, lateral line scale counts and body depth. Brachymystax tumensis was also typically heavier than B. lenok at the same length. These results were supported by genetic analyses which clustered the two species into separate clades and displayed unique haplotypes for the Mongolian populations. Initial investigations of diets and gonad maturation indicated an ecological and spatial separation of these sympatric species. The current study is important for these recreationally targeted species which require further research and species-specific management measures to ensure their threatened populations are conserved in Mongolia for the future.

Shell morphology and size distribution of Turbo spp in Sepanjang Beach by shell collecting: An Initial Survey

Turbo spp. in Sepanjang Beach, Gunung Kidul, Indonesia, are at risk of depletion due to their popularity for consumption and decoration. Protecting this species demands sustainable management practices. This initial survey aimed to examine the shell morphology, size distribution, and shell growth patterns of Turbo spp. at Sepanjang Beach, Indonesia, to establish baseline data for future research. A total of 233 shells were collected randomly and analyzed for morphological parameters. Shell dimensions exhibited variations in size, shape, color, and whorl features. Shells ranged from 7.59 to 60.96 mm in length and 7.47 to 52.43 mm in width. Operculum dimensions varied from 3.14 to 29.75 mm in length and 3 to 22 mm in width. Size frequency distributions highlighted a peak at 30-35 mm shell length. The right-skewed size distribution indicated a prevalence of smaller individuals, possibly influenced by the environmental and genetic factors. Positive correlations between shell and operculum dimensions suggested an isometric growth pattern, implying symmetrical shell development. These insights are crucial for developing effective conservation strategies for Sepanjang Beach. Further research, including species genetics, size at first gonadal maturity, and environmental influences, is recommended for a comprehensive understanding of Turbo spp. sustainability in the region.

Reproductive ecology of the Argus brief squid Lolliguncula argus in the coast off Oaxaca, southern Mexican Pacific

Abstract Lolliguncula argus is a squid species endemic to the Tropical Eastern Pacific and caught incidentally by the artisanal fishery around Puerto Angel, Oaxaca (Mexico). Due to the low abundance of Argus brief squid, basic aspects of the species’ reproductive biology have not been adequately studied. Therefore, in this study, we assess size at maturity (L50), gonad maturation, ovarian development and spawning pattern by means of both histological and oocyte size–frequency analyses. Our results are based on 581 squid specimens: 534 females (11.9–82.4 mm dorsal mantle length, DML) and 47 males (16.0–68.2 mm DML) caught by artisanal fishery from May 2017 to April 2018. The L50 was 58.0 mm DML for females and 55.4 mm DML for males. The ovulation pattern in L. argus is asynchronous, with multiple-batch spawning in a relatively short period of time (intermittent spawning). Lolliguncula argus breed in the coastal waters off Puerto Angel, in the western margin of the Gulf of Tehuantepec, and exhibit gregarious behaviour during spawning events, which is associated with the regional oceanographic conditions. Based on these results, we determine that the opportunistic reproductive strategy of L. argus occurs in response to suitable regional environmental conditions.

Reproductive biology of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816) in the southern waters of West Java (FMA 573)

Indian mackerel is a small pelagic fish with important economic value in Java Island. This study aims to analyze the reproductive characteristics and determine management recommendations for the Indian mackerel in the southern waters of West Java. Fish monthly sampling collection was conducted at three fish landing ports: PPI Ciwaru, PPN Palabuhanratu, and PPI Binuangeun from July to December 2022. A total of 1,038 fish samples, comprised of 582 males and 456 females, were examined. The sex ratio was unbalanced, with a value of 1:0.79. Gonadosomatic indexes ranged from 0.19-0.95 and 0.45-3.41 for males and females, respectively. The fish fecundity ranged from 27,027 to 87,837 eggs. The Indian mackerel is predicted to spawn every month, with a peak season in August, and performs a total spawner pattern. The Indian mackerel reached the size of the first maturity gonad at 198.5 mm and 197 mm for males and females, respectively. Management strategies for Indian mackerel in the southern waters of West Java include setting the catch size above the first mature gonad size (197 mm), the mesh size of gillnets above 1.5 inches, and limiting fishing activities during the spawning season (July, August, and September).

Analysis of Molecular Genetic, Morphometric and Sexual Characteristics of the Beluga (Huso huso L., 1758) Grown in the Aquaculture of the Republic of Belarus

The subject of the study was genetic and phenotypic characteristics of Beluga (Huso huso (Linnaeus, 1758)) grown in the warm and cold-waters aquaculture at the “Selets” fish farm (the Republic of Belarus). Molecular-genetic analysis was performed using STR-markers and species-specific PCR revealed the absence of hybrid individuals in analyzed broodstock of (Huso huso L.). Affiliation of individuals to the Caspian population was established based on the sequence analysis of the 367 bp region of mitochondrial D-loop. Using six STR loci, the population structure was analysed. The population structure and gene pool of the only broodstock of (Huso huso L.) in Belarus was compared with domesticated (H. huso L.) from the Russian Federation. The analysis showed a lack of genetic variation and the heterozygote excess in Beluga from the Belarusian farm. Analysis of morphometric indicators revealed that the conditions in which the Beluga broodstock is kept at the fish farm “Selets” should be improved. Using ultrasound scanning, the following stages of gonad maturity were established: stages II, III and IV in males; II, II semi-fatty, II fatty, III and IV in females. The Beluga broodstock at the fish farm “Selets” is mainly represented by females (the females exceeded the males by 1.6 times in terms of their number).

BIOMETRIA E CRESCIMENTO RELATIVO DO BIVALVEAmusium papyraceum (Gabb, 1873) COLETADO NA COSTA NORTE DO BRASIL

The present study aims to characterize the biometry and relative growth of Amusium papyraceum (Gabb, 1873) collected as by-catch of shrimp fisheries on the North Coast of Brazil. For that, morphometric relationships were performed between the external measures of the shell (length, width and height) and the wet biomass of 51 individuals collected in October 2015. The results indicate that the morphometric and biomorphometric relationships of the mollusk are classified as “extremely strong and positive”. Relationships involving A. papyraceum shell width were classified by negative allometry, which indicates that this morphometric measure grows at a higher rate than the others. It is noteworthy that the density index of A. papyraceum increases proportionally with the growth of the species. This difference in yield probably comes from the gonadal maturation of the individuals, which causes the gonads to increase in size. The information presented here will subsidize further research involving the population dynamics of the species.

Growth performances and gonadal development of golden rabbitfish, Siganus guttatus fed with two types of floating diets in sea cages

A feeding trial was designed to evaluate the effects of utilizing floating pellets on the growth performances, feed utilization and gonadal maturation of the golden rabbitfish, Siganus guttatus. The treatments were two kinds of commercial floating pellet containing different crude protein (CP) levels which were 26% (FD1) and 33% (FD2). The tested diets were fed to golden rabbitfish. Golden rabbitfish with initial body weight of 239.7±4.8 g were stocked into six sea cages with size of 2x2x2 m3 with density of 50 fishes/cage. The feeding trial lasted for 120 days with results showed that the growth performances of weight gain and specific growth rate were significantly higher (P<0.05) in fish fed FD2 diet (55.0±3.7% and 0.37±0.02 %/d) compared to those fed with FD1 diet (41.7±1.6 and 0.29±0.01%/d), respectively. Both female and male fishes had developed gonad at the end of feeding trial. The gonadosomatic index (GSI) for spermatid significantly higher (<0.05) in fish fed FD2 (4.8±0.6%) than FD1 group (3.4±0.3%). Similarly, the GSI for oocyte of fish fed FD2 diet (8.9±1.0%) was significantly higher than the group fed FD1 diet (4.2±0.5%). The FD2 diet produced higher protein content in the whole body and fillet. In contrast, lipid content of whole body and fillet of fish fed FD1 diet was higher than FD2 diet. As conclusion, better growth performances and gonadal development was found in fish fed FD2 diet, a floating diet containing approximately 33% CP.

Aspects of Population Dynamics of Shortfin Scad Fish (Decapterus Macrosoma) in the Flores Sea, Bulukumba, South Sulawesi, Indonesia

Shortfin Scad (Decapterus macrosoma), is a pelagic fish that plays a role in the economic sector of fishermen in South Sulawesi waters. Apart from being consumed by the public, Shortfin Scad is also used as bait for tuna and is exported frozen. Shortfin Scad is a type of small pelagic fish that is dominantly caught and has high economic value, especially for areas with more oceanic waters such as in eastern Indonesian waters. The aim of the study was to determine the population dynamics of the Shortfin Scad (D, macrosoma) in Bululumba waters. The research was conducted in the waters of the Flores Sea, Bulukumba, South Sulawesi. Sampling of fish to measure fork length and to observe gonadal maturity was carried out randomly every month. Information on population parameters obtained in this study is group age, Yield Per Recruitment, Growth, Mortality and level of exploitation. The results showed that there were 3 groups of Shortfin Scad (D. macrosoma), the female fish had a long mode range: 18.4 – 22.08 cm; 21.16cm – 25.8cm; 20.24 – 26.7 cm and in male fish it has a long mode: 17.3 cm – 22.3 cm; 21.05 cm – 24.8 cm,; 24.8cm – 28.6cm. The asymptote length is 33,293 cm for female fish and 27,023 cm for male fish. The estimated Y/R for female fish was 1.96 gram/recruit and male fish was 2.91 gram/recruit. The threshold value (E) of female fish is 12.60 per year and male fish is 17.84 per year. in the female and male fish that exceeds the optimum limit. The value of the rift rate of Shortfin Scad (D. macrosoma) in the waters of Bulukumba Regency experienced over fishing.

Fishing impact of blue swimming crab (Portunus pelagicus) fishery on target in Lamongan Water, Northern Coast of Eastern Java Province

Blue swimming crab (Portunus pelagicus) is a high-value export commodity of fisheries to the international market. Thus, it promotes overfishing, reducing target stocks, and ecological impact on non-target biota. Fishers in Lamongan Regency use traps, trammel nets, and mini trawl (arad) to target the crabs. The fishing gears have different levels of selectivity. This study aims to evaluate the impact of crab fishing on target (P. pelagicus), particularly in the study area. The samples of blue swimming crab (BSC) were collected using the quota sampling method. The parameters of the crab catch (Portunus pelagicus) collected included carapace width, weight, sex, and gonad maturity stage (GMS). 1424 fishing vessels and 3598 fishers targeted the BSC in the Lamongan water. The result of this study showed that 93% of BSC catch was higher than the legal size from traps, 66% (arad), 89 % (trammel nets). The growth parameter of L∞ = 156.95 mm (for female) and L∞ = 182.22 mm (male), while K = 1.4 per year (for female) and K = 1.4 per year (male). The relationship between carapace width and weight of the male and female crabs was positive allometric growth. The LB-SPR parameter value was 23% which indicated that the crab resource stock in Lamongan waters was a ‘fully-moderately’ status, while the selectivity level indicated an ‘over-exploitation’ base on the E value = 0.69 (for female crab) and E = 0.72 (for male). This study proposes urgently reducing the fishing effort targeting BSC, particularly by the mini trawl (arad) and implementing a rebuilding stock program for the BSC.

Distribusi Ukuran dan Tingkat Kematangan Gonad Ikan Julung-Julung Hemiramphus lutkei (Valenciennes, 1847) yang diperdagangkan di Kabupaten Manokwari Papua Barat

This study aims to determine the distribution of length to weight, sex ratio, gonad maturity level of julung fish (Hemiramphus lutkei) traded in Sanggeng and Borobudur Manokwari fish markets, West Papua. Research data collection was carried out for ± 1 month, namely February - March 2021, using a descriptive method. The number of fish samples collected was 542 fish. The results of the analysis of the size distribution of julung-julung fish during sampling for body length ranged from 219 – 355 mm for males and 215 -380 mm for females, with a body weight range of 27-53 grams for males and 30-65 grams. The sex ratio analysis of julung julung fish was obtained for males (321 fish) and females (221 fish) significantly different, which means this ratio deviated from the ideal value of 1:1. Based on the results of the analysis show that the value of X2 -count > X2 -table, then H0 is rejected, which means the sex ratio of male and female fish is not balanced from TKG I-VII for males and TKG II-VII for females and mostly found in TKG III conditions. The size of the male julung fish when the gonads first mature was estimated at a length of about 230-260 mm and the female at a size of 250-280 mm. The average Gonad Somatic Index (GSI) of female julung fish was 0.0876 and the standard error was 0.0061 with a GSI range of 0.0092 – 0.7574. The relation- ship between TKG and GSI shows that the increasing stage of fish gonad maturity will be followed by an increase in the value of the fish gonadal index.

Bioecological Aspects of Snakeskin Gourami (Trichopodus pectoralis) in the Flooded Swamp Waters of Bilah River, Labuhanbatu Regency

Background: The potential fish resources of snakeskin gourami (Trichopodus pectoralis) in the flooded swamp waters of Bilah river, Labuhanbatu Regency, are pretty high. Thus, this is one of the essential resources and has economic value. This study aimed to inform the bioecological aspects of snakeskin gourami fish (T. pectoralis). Methods: The determination of 3 sampling points was done using the purposive random sampling method. The sampling of T. pectoralis was carried out using the trap. The data analysis presented information on the abundance of Gonad Maturity Level, growth pattern, the Fulton (K) factor condition, and the Pearson correlation among environment parameters to the T. pectoralis population, which was presented quantitatively. Results: The results showed the length-weight relationship of T. pectoralis in the allometric category. The average relative weight (Wr) for male T. pectoralis was 100.46 ± 8.37, and for females was 99.83 ± 2.30. The mean value of the Fulton’s (K) factor condition in male T. pectoralis (8.94 ± 0.54) and female T. pectoralis (9.27 ± 0.67). Conclusions: T. pectoralis showed an allometric category and domination of the first gonadal maturity level. It describes that the female is abundant in optimum condition and ensures for future generations, and Pearson’s correlation result informs that increasing the value of environmental parameters will affect the optimization of T. pectoralis life.

Lipid and fatty acid composition of muscle, liver, ovary, and peritoneal fat in wild flathead grey mullet (Mugil cephalus) according to ovarian development

Wild adult females of a low trophic omnivore teleost species, the flathead grey mullet (Mugil cephalus), caught in the western Mediterranean were sampled. The lipid and fatty acid composition of ovaries, liver, muscle, and peritoneal fat were analysed at previtellogenesis, early-vitellogenesis —first observed at mid-summer (early August)—, late-vitellogenesis, and the post-spawning period —from mid-September to mid-October—. During ovarian development, the lipid content of muscle was low and constant (3.85%–4.92%), indicating that the muscle was not used to store lipids for gonadal growth. Although constant, lipid content in the liver was higher (18.46%–22.62%) than in the muscle, and HSI% increased during gonad development, suggesting a dynamism in the mobilization of the hepatic lipids. Total lipids in the gonads significantly increased with maturation (from 4.90% to 34.59%) in parallel with the GSI (from 0.8% to 15.5%) to decrease after spawning. Peritoneal fat was probably transitional fat that could be rapidly metabolized or transferred to other tissues but no specific function could be assigned because its presence in previtellogenic and early-vitellogenic females varied greatly. One of the main sources of lipids accumulated in the ovary was most likely diet. The total percentage of ΣMUFA, mainly 17:1 —previously not identified in high quantities in teleost vitellogenic ovaries and likely of bacterial origin— and 16:1, strongly increased in the ovaries with maturation. The 16:1 might be an important source of lipids for embryo development. High percentages of DHA, EPA, and ARA were found in the ovary during previtellogenesis available to be used during gonadal maturation. Understanding lipid and fatty acid changes in broodstock tissues can increase our knowledge of the nutritional requirements of the fish used in aquaculture breeding programs.

Рибогосподарська оцінка плідників сибірського осетра (Acipenser baerii Brandt, 1869), вирощених у плавучих садках за природної температури води Лісостепу України

Purpose. To determine and evaluate the main fishery parameters in the process of artificial production of mature eggs from brood Siberian sturgeon grown in floating cages at natural water temperature of the Forest-Steppe of Ukraine. Methodology. The material for the study was 121 specimens of Siberian sturgeon females of various ages with body weights from 3.80 to 16.84 kg, which were cultivated in industrial-type farming conditions in a water body with a natural temperature regime for the Forest-Steppe zone Ukraine with the use of floating cage systems. Experiments on obtaining mature eggs were carried out under controlled water temperature during the period from January to April under the conditions of a recirculation aquaculture system. Hormonal stimulation for the maturation of sturgeon gonads was performed using natural cyprinid pituitary preparations. Determination of fishery indicators and study of environmental abiotic factors were carried out according to methods generally accepted in fish farming and hydrochemistry. Findings. The efficiency of maturation in brood fish of different groups varied between 57–100% at a water temperature of 14.0–15.5°C after the injection of a gonadotropic drug with a total dose from 2.5 to 4.5 mg/kg per fish weight. A total dose of the gonadotropic drug of 3.5 mg/kg per fish weight was found to be sufficient for the high efficiency of gonad maturation. The weight of mature eggs obtained from brood fish aged 8+ to 17+ varied on average from 0.54 to 2.12 kg. The average working fecundity and relative fecundity in females of different ages varied, respectively, within the range of 33.60-108.21 thousand eggs and 6.62-7.95 thousand eggss/kg of fish weight, with average values of the gonadosomatic index of 10.71-15.81%. Originality. The peculiarities of obtaining ovulated eggs and the main fishery parameters of brood Siberian sturgeon cultivated using the technology of intensive sturgeon aquaculture, which is not common in Ukraine, were studied. Practical value. The study results can be used for the development of modern methods of sturgeon aquaculture in the industrial farms conditions. Keywords: brood Siberian sturgeon, industrial fish farming, fishery parameters, ovulated eggs, combined aquaculture technology.

Reproduction of the Caramote prawn, Melicertus kerathurus (Forskål, 1775) (Decapoda, Penaeidae) in Boka Kotorska bay, Montenegro (South-eastern Adriatic)

The aim of this study was to investigate for the first time some aspects of the reproductive activity of the Caramote prawn, Melicertus kerathurus, in Montenegrin waters. This species is considered a target species in the small-scale fishery in Boka Kotorska Bay, being a species of high commercial value. Sampling was carried out on a monthly basis from April 2019 to December 2019 by trammel nets. The spawning season was estimated based on monthly changes in the gonadosomatic index, condition factor and gonadal maturity stages. The main spawning season for females extends from April-May to September, with a clear peak in June. The total sex ratio (males/females) was 1:1. Sexual differences related to the length-weight relationship were noted.

Where have all the beads gone? Fate of microplastics in a closed exposure system and their effects on clearance rates in Mytilus spp.

The fate of microplastic particles (MP) in exposure experiments is mostly unclear. We measured the recovery of polystyrene (PS) microbeads, which were applied in various concentrations from 0.07 to 47.47 beads/ml, from the different compartments of an experimental system with mussels (Mytilus spp.). At the end of the experiment, we detected a significant loss of MP indicating that the mussels were exposed to less particles than intended. If such a discrepancy remains un-recognized by the experimenter, observed effects are related to an inaccurate particle concentration. Additionally, we observed reduced clearance rates of the mussels in the presence of MP and the effect size increased with increasing particle concentration. This effect was more pronounced in mussels that had recently spawned than in mussels that still had mature gonads. This is a hint that effects of MP may depend on the reproductive status of an organism.

The biological characteristics of the Nile tilapia (Oreochromis niloticus) in the Weija Reservoir, Ghana

Abstract. Kpelly DK, Blay Jr.J, Yankson K. 2022. The biological characteristics of the Nile tilapia (Oreochromis niloticus) in the Weija Reservoir, Ghana. Intl J Bonorowo Wetlands 12: 41-54. Studies on the biological characteristics of the Nile tilapia (Oreochromis niloticus L.) were undertaken in a manufactured lake, the Weija Reservoir, in Ghana from September 2007 to August 2008. From commercial landings, a sum of 657 specimens of O. niloticus was examined, of which 357 were males and 300 were females (sex ratio of 1: 0.84; P < 0.05). GSI was highest in March and May 2008 and low in December 2007 and August 2008, which suggested that O. niloticus spawned throughout the year, but major spawning occurred in March. The length at first sexual maturity (L50) was 16.33 cm for males and 13.49 cm for females. Observations on the frequency distribution of ovum size measured between 1.2 to 3.1 mm showed two distinct peaks that were not completely separated, which were probably shedding eggs in batches, indicating protracted spawning in the population. Fecundity ranged from 563 to 1542 ova for fish of total length 15.6-21.5 cm with a mean of 851 ± 13.2 eggs. The relationships between fecundity and body weight (BW) and fecundity (F) and total length (TL) were: F = 0.519 BW + 785.4 and F = 12.36 TL + 628.5. Furthermore, based on studies on monthly fluctuations in the GSI and the occurrence of the ripe gonad, the major reproductive activity of O. niloticus in the reservoir coincided with months with increasing total alkalinity, reduced water temperature, and dissolved oxygen. The regression coefficient of 3.1 for the length-weight relationship (for both females and males) was not significantly different from the expected value of (P > 0.05), indicating isometric growth of the population. Therefore, collection of the species as seed for stocking or brood stock or by fish farmers is recommended in March-April. Moreover, appropriate management policies with periodic studies of the fishery and the limnology of the reservoir are essential to sustain fishery production.

Length-Weight Relationship and Condition Factor of Yellowfin Tuna (Thunnus albacares) from Demta Coast, Jayapura Regency, Papua

The population of Thunnus albacares yellowfin tuna from the Scombridae family is very abundant in North Papua Waters (WPP 717). This study aims to analyze the parameters of population dynamics based on the long-weight relationship and condition factors on Thunnus albacares in Demta Coastal Waters, Jayapura Regency. Fish data collection uses passive and active fishing methods using gill nets, handlines, and long line fishing through fishing activities by traditional fishermen during April - June 2022. Data analysis uses analysis length-weight relationship and condition factor. The results of this study found that the population structure of yellowfin tuna (T. albaceras) was very diverse in the waters of North Papua, with a negative allometric growth pattern (b < 3), i.e. the growth of body length was faster than weight. The condition factor averaged 1.1302 with a maximum of 1.4718 and a minimum of 0.7028. Where in the gonadal maturity period morphometric adaptation occurs, weight growth becomes faster and body length becomes slower.

Predicting Sex-Related Transcripts in the Chinese Giant Salamander (Andrias davidianus): A Transcriptomics Study, Selection Gender for Preservation, Breeding and Reintroduction

The Chinese giant salamander (Andrias davidianus) is the biggest extant and endangered amphibian, which has an incongruous sex ratio during the artificial breeding process and is sex indistinguishable in appearance. The sex development mechanism of this rare species thus needs to be explored. We therefore conducted this study to explore the molecular mechanisms of sex hallmarks or gonad maintenance genes for CGS. In this study, we sequenced and analyzed the sexually mature male and female gonads of Chinese giant salamanders (CGSs) using RNA-seq technology and found a total of 15,063 differentially expressed genes (DEGs) in the testicular and ovarian tissues, of which 7973 (52.93%) were expressed in testicular and 7090 (47.07%) in ovarian tissues. Thirteen gonad DEGs were selected based on gene expression abundance and quantified in the muscle and skin tissues of both male and female CGSs. The results showed that these 13 DEGS, out of the 20 analyzed DEGs, were expressed in both the muscle and skin tissues and only two of them (Bmp15 and ZP3) were consistent in the muscle and skin compared to the gonads of CGSs of the two sexes. Overall, our study should provide an important reference for the sex-characteristics-related genes in this type of species, shedding new light on future research on this topic.

Reproductive Biodynamics of Short Mackerel (Rastreliger brachyoma Bleeker, 1851) in the Northern Waters Makassar Strait, Indonesia

Short mackerel are caught with high intensity by the fisherman and using various fishing gear. It is feared that this activity could change the reproduction habits of short mackerel in ther habitat. This study aims to analyze the bio-dynamics reproduction of short mackerel, including sex ratio, maturity stage, length at first maturity, length at first spawning, and fecundity. The survey method obtained the sample collection from the fish landing sites. Samples were collected in 1320 samples consisting of 651 females (13.0-16.5 cm) and 669 males (13.3-17.4 cm). The results showed that the sex ratio was balanced (1.00:1.02), the stage of gonad maturity showed from immature gonad to spawning (I to V), and the highest gonad maturity index for males and females were found in July (1.609 and 1.794). The length at first maturity of males and females had occurred when they were 16.51 cm and 16.63 cm, and the length at first spawning for males and females was 17.12 cm and 17.03 cm in size. The fecundity of female mackerel ranges from 30.106 to 58.439 in the northern waters of Makassar Strait. Capturing fish is suggested with a length above the spawned fish (>17 cm), considering that the fish only spawn at least once from their life cycle. The fecundity of short mackerel is relatively high as an indicator of high reproductive potential.

Some Aspects of the Reproductive of Japanese Threadfin Bream (Nemipterus japonicus Bloch, 1791) Caught in the Area Around the Artificial Reef In the Pitu Sunggu Waters of the Makassar Strait

Japanese Threadfin Bream is a demersal fish commonly found around artificial reefs. Food availability in the artificial reef ecosystem is essential for the sustainability of this species. Hence, this research aimed to determine several aspects of bio-reproduction of Japanese Threadfin Bream caught in the artificial reef (bioreeftek). Samples were taken using handline fishing, twice a month (April-July 2020) in Pitu Sunggu Waters, Makassar Strait. The samples were observed for its reproduction aspects. The result showed that the Japanese Threadfin Bream fish caught have a balanced sex ratio between males and females, 1:1.03. The analysis of the gonad maturity stage obtained was II-IV, and the gonado somatic index ranged from 0.541-0.940 for males and 1.156-2.358 for females. The first mature Japanese Threadfin Bream size was 18.29 cm for males and 16.99 cm for females. The Japanese Threadfin Bream fish fecundity ranged between 35.042-42.061 eggs.