Gonadal Maturation Research Articles

Reproductive Biology of Carp (Cyprinus carpio) in Batu Bulan Reservoir, Sumbawa, West Nusa Tenggara

Research about carp (Cyprinus carpio) reproductive biology in Batu Bulan Reservoir was conducted in April, May, July, and October 2016. This study aims to determine some biological aspects include the degree of gonad maturity, fecundity, spawning frequency and season, and length of the first gonad maturity. The results showed the sex ratio between male and female fish in April (1:5), May (1:3), July (1:3), and October (1:3), with an average of 1:3.5 with the Chi-Square test on the confidence interval. 95%, it turns out that the sex ratio does not follow the 1:1 pattern, or the sex ratio of the fish is not balanced. TKG II carp occurred every month of observation, while the ripe fish of TKG IV gonads were founded only in April, July, and October. The highest percentage of female fish ripe for TKG IV gonads was 45.32%, and males 67.40% were found in October. The size of the ripening female carp size in Batu Bulan Reservoir is 20.16 cm. Carp fecundity ranges from 1,439 to 40,281.

Notes on the Reproductive Traits of Holothuria fuscogilva Cherbonnier, 1980 from Laguindingan, Misamis Oriental, Philippines

Reproductive traits of white teatfish Holothuria fuscogilva from Laguindingan, Misamis Oriental were investigated from February to July 2020. Gonad samples from 62 adult individuals weighing 1,240g to 5,800g were collected and examined macroscopically and microscopically to determine gonad morphology, sex ratio, gonad maturity, and gonad index. Gonads were composed of numerous branched tubules of varying lengths and frequency of bifurcations arising from the gonad basis. There was no significant variation in the ratio of male to female white teatfish (x2=2.32, α=0.05) and were mostly mature in May (weighing 1,750g–4,000g in males and 2,600g-3,900g in females) with relatively high gonad output. Information on gonad maturation is useful in the development of a successful breeding technology for this economically important sea cucumber species.

Activin receptor type IIB in rohu (Labeo rohita): molecular characterization, tissue distribution and immunohistochemical localization during different stages of gonadal maturation.

Activin receptor type IIB (ActRIIB) is a transmembrane serine/threonine kinase receptor which plays a pivotal role in regulating the reproduction in vertebrates including teleost. Earlier studies have documented its importance in governing gonadal maturation in higher vertebrates. However, reports on the regulation of fish reproductive system by ActRIIB gene are still limited. Here, we report the identification and characterization of ActRIIB cDNA of Labeo rohita, a commercially important fish species of the Indian subcontinent. The full-length gene encoding rohu ActRIIB was cloned and found to be of 1674bp in length. Functional similarities were evident from evolutionary analysis across vertebrates. Real-time PCR to measure the expression of ActRIIB transcript in rohu revealed significant mRNA levels in gonads followed by non-reproductive tissues, including the brain, pituitary and muscle. With respect to different gonadal maturation stages, predominant expression of ActRIIB mRNA was observed during the pre-spawning phase of both sexes. To further delineate its role in rohu reproduction, a recombinant protein of the extracellular domain of ActRIIB (rECD-ActRIIB) was produced, and polyclonal antibody is raised against the protein for its immuno-localization studies during different gonadal maturation stages. Strong immunoreactivity was noticed in the pre-vitellogenic oocytes which decreased dramatically in the fully mature oocytes. Similarly, the strong and intense immunoreactivity was found in the spermatids and spermatocytes of the immature testis, and eventually the intensity reduced with the progression of the maturation stage. These results provide the first evidence of the presence of ActRIIB in rohu gonadal tissues. Taken together, our observations lay the groundwork for further understanding and investigating on the potential role of ActRIIB in fish reproduction system in the event of gonadal maturation.

Lipid metabolism of sea urchin Paracentrotus lividus in two contrasting natural habitats

Sea urchins Paracentrotus lividus were harvested monthly from April 2015 to March 2016 from two sites in Sardinia (Italy). The two sites, a Posidonia oceanica meadow and a rocky bottom habitat, were naturally characterized by different food sources and availability, being mainly populated by the sea grass Posidonia oceanica and the brown algae Halopteris scoparia, respectively. Total lipids showed a minimum during winter in mature gonads, and a maximum in the summer (recovery stage). Fatty acid (FA) profiles of gut contents and gonads differed from those of the most available food sources. Levels of C18:3 (n-3) (ALA) discriminated samples from the two sites. Despite the very low amounts of C20:5 (n-3) (EPA) and C20:4 (n-6) (ARA) in P. oceanica, the main FA in gonads and gut contents were EPA and ARA in both sites. Increase in green algae intake prior to gametogenesis, especially C. cylindracea, likely affected EPA and ARA levels in gonads. The results show that P. lividus is able to concentrate lipids in gut contents and also to selectively store EPA, ARA and their precursors ALA and 18:2 (n-6) (LA). Moreover, bioconversion of ALA to EPA and of LA to ARA in P. lividus is suggested.

Transcriptome analysis of five ovarian stages reveals gonad maturation in female Macrobrachium nipponense

BackgroundMacrobrachium nipponense is an economically important species of freshwater shrimp in China. Unlike other marine shrimps, the ovaries in adult female M. nipponense can mature rapidly and periodically during the reproductive period, but the resulting high stocking densities and environmental deterioration can negatively impact the harvest yield and economic benefits. To better understand ovary development in female M. nipponense, we performed systematic transcriptome sequencing of five different stages of ovarian maturation.ResultsWe obtained 255,966 Gb of high quality transcriptome data from 15 samples. Of the 105,082 unigenes that were selected, 30,878 were successfully annotated. From these unigenes, we identified 17 differentially expressed genes and identified three distinct gene expression patterns related to different biological processes. We found that cathepins, legumains, and cystatin were enriched in the lysosome pathway, and they are related to vitellogenin hydrolysis. Additionally, we found that myosin heavy chain 67 participated in oocyte excretion.ConclusionsWe provide the first detailed transcriptome data relating to the ovarian maturation cycle in M. nipponense. Our results provide important reference information about the genomics, molecular biology, physiology, and population genetics of M. nipponense and other crustaceans. It is conducive to further solve the problem of M. nipponense rapid ovarian maturation from the aspects of energy supply and cell division.

Lunar cycle and reproductive activity of Redbelly yellowtail fusilier, Caesio cuning in Karimunjawa National Park, Indonesia

Abstract. Ayodya FP, Wijayanti DP, Sabdono A. 2021. Lunar cycle and reproductive activity of Redbelly yellowtail fusilier, Caesio cuning in Karimunjawa National Park, Indonesia. Biodiversitas 22: 3075-3082. Redbelly yellowtail fusilier (Caesio cuning) is known as fish that has been widely distributed among Southeast Asian countries. Fishers in Indonesia especially target the species, causing the scarcity and depletion of the catch in many fisheries areas each year. One of the priority aspects in improving fisheries management in conservation areas is information regarding reproductive activities. Many reports suggested that the lunar cycle affects the reproductive activity of fishes. However, none of the studies reported on the effect of lunar cycle on the reproductive activity of C. cuning. This study aimed to explain the lunar cycle effect on the reproductive activity of C. cuning through gonadosomatic index (GSI), viscerosomatix index (VSI), and the observation of oocyte conditions. There were 374 individual fishes collected from Nyamuk Island, Karimunjawa from September to November 2020. Samples were taken in each phase and between major phase of the moon (new, first quarter, full, last quarter) during two lunar cycles. The results point out mature gonad (stage IV and V) was present around the new moon. The peak of female GSI occurred around the last quarter moon with figures 6.12 and 5.51% respectively. The condition of the mature oocyte and ovulation were present around the last quarter and the new moon. The condition indicates imminent spawning.

Characterization of Spatial and Temporal Variability of Crassostrea spp. Spat Settlement to Ascertain Allocable Sites for Spat Collection at Cox’s Bazar, Bangladesh

AbstractSpat settlement (spat density, recruitment, and mortality) of edible oysters Crassostrea spp. was estimated for three sites (Nunia Chara [NC], Chowfoldandy [CD], and Sonadia Island [SI]) located along the Cox’s Bazar coast of Bangladesh from February 2019 to January 2020 by deploying shellstrings. Field observations were made every 15 d to understand the monthly variation of oyster spat settlement more precisely. Environmental variables varied significantly with the study site × month interaction or across study sites and months. Gonadal maturation and spawning of oysters may depend on certain environmental conditions, which were greatly influenced by seasonality, especially the monsoon. Spat density, recruitment, and mortality rates were significantly different with the study site × month interaction. The NC site offered higher spat density and recruitment than CD and SI during most months; spat density was lower due to increased mortality during the monsoon (late May to mid‐October) at all sites. Spat density was positively related to salinity, pH, and total suspended solids but negatively related to temperature and high‐ and low‐tide water depths. Recruitment was positively related to salinity and negatively related to low‐tide water depth. Spat mortality was positively related to high‐tide water depth but negatively related to low‐tide water depth. Eight different groups of fouling organisms were observed during the study, which could affect spat settlement. Most interestingly, oyster drills at NC and SI and marine macrophytes and bushlike organisms at CD and SI could contribute to increased mortality during the monsoon. This study showed that none of the three sites would be potential locations for spat collection on shellstrings during the monsoon; however, if avoiding the monsoon, NC has a higher potentiality of allocation for spat collection both for commercial farming and oyster restoration efforts.

Use of periodically hCG hormones injection for the gonadal development of java barb (Puntius javanicus) as bioreproduction applied on aquaculture

Tawes fish or Java barb (Puntius javanicus Bleeker, 1855) as the one of the endogenous species in Indonesia has specific reproductive roles that its cycle still depends on local environment. It makes limited frequency of spawning in nature that has been decreasing seeds production either domestication or cultivation. As a seasonal spawner, it needs long time for gonadal development. Gonadal development of endogenous species broodstock by hormone is needed to improve bio-reproductive capacity and it will cause faster gonadal maturity of Java Barb. One of exogenous hormones that could trigger gonadotropin hormone (GtH) is the human chorionic gonadotropin (hCG) hormone and it will accelerate the maturity level of the gonad by periodically injection. The aim of research is to determine the effect and the best dosage of hCG hormone for the gonadal development of Java barb. This study used an experimental method with a completely randomized design, with 4 treatments and 3 repetitions in 30 days observed. 48 broodstock with 200 gram average weight were used and induced by hCG. The doses of hCG are 0, 100, 200 and 300 IU/kg. The parameters observed include the level of gonad maturity, gonado somatic index (GSI) and hepatosomatic index (HSI). After statistical analysis, result showed that dose of 200 IU could improve the best development of gonad in Java barb base on 3rd maturity level achieved, gonado somatic index (10.11 ± 0.74%) and the hepatosomatic index at (1.99 ± 0.06%) respectively. The observation which used hCG hormone can improve gonadal development and one step closer to reproduce domesticated and cultived of Java Barb.

Gonadal development in a landlocked population of pejerrey fish Odontesthes argentinensis during spawning season in relation to sex steroids and water temperature

ABSTRACT The relationship between water temperature and gonadal maturation of a landlocked ecophenotype of marine pejerrey (Odontesthes argentinensis) in La Salada de Pedro Luro lake was analysed during three spawning seasons. Mainly vitellogenic females were found in August (winter), some ovulating in October (mid-spring) and with atretic oocytes in December (end of spring). In accordance with this, gonadosomatic index (GSI) and estradiol plasma levels showed maximum values in October (7.6 ± 0.7%; 1631.7 ± 256.1 pg/mL) and minimum values in December (1.2 ± 0.3%; 230,33 ± 8,74 pg/mL). Spermiating males were found during the whole spawning season and only arrested in December. The highest GSI values were recorded in October (4.6 ± 0.2%) and for testosterone (T) in August (1113.2 ± 503.8 pg/mL). Meanwhile, in December the minimum GSI and T plasma values (1.3 ± 0.6%, 323.8 ± 5.3 pg/mL) were observed. According to the Fourier fitted models, temperature explains more than 70% of the observed variation in GSI in both sexes. Moreover, the total GSI variation range was positively related to the total temperature range variation experienced during the reproductive seasons demonstrating the influence of this environmental variable on maturation intensity and dynamics.

Reproductive aspects of greenback mullet Planiliza subviridis (Valenciennes, 1836) in Cengkok coastal waters, Banten Bay Indonesia

Greenback mullet (Planiliza subviridis) is one of commercially important fish species and widely caught in Cengkok Beach, Banten Bay. This study aims to examine some reproductive aspects of greenback mullet in Cengkok coastal waters of Banten Bay. The study was conducted from April to August 2019 at Cengkok Beach, Banten Bay. Fish sampling was performed by using gill net and cast net. Samples analysis were conducted including gonad maturity index, fecundity, relationship between body length with fecundity, and egg diameter. A total 223 individuals of mullet were captured, consisted of 113 males and 110 females. The total length and weight ranged from 56-263 mm and 2.3-182 g, respectively. The sex ratio of male and female fish was 1: 0.97 (balanced). Condition factor of male and female fish ranged from 0.99 to 1.02 and 0.96 to 1.03, respectively. Size at first maturity for male and female were 137.8 mm and 163.9 mm, respectively. It is very likely that the spawning season occurred from April to August with the peak season in July. Reproductive potential ranged from 17.284-101.670 eggs with a spawning type as total spawner.

Populasi Kepiting Bakau (Scylla serrata) di Perairan Muara Sungai Barumun Kabupaten Labuhanbatu Ditinjau dari Pola Pertumbuhan dan Faktor Kondisi

Mangrove crab (Scylla serrata) is one of the prima donna sources of protein caught by fishermen around mangrove forest waters in the waters of the Barumun River Estuary, Labuhanbatu Regency. This study aims to inform about condition factors, growth patterns of crab populations, and reproductive aspects in the form of abundance of Gonad Maturity Level (TKG). Determination of 3 sampling points is done by using purposive random sampling method. Scylla serrata sampling was carried out using Bubu. Data analysis presents information on the abundance of gonadal maturity level, growth pattern, and Fulton condition factor (K), which is presented quantitatively. The results showed that male and female Scylla serrata growth patterns were categorized as negative allometric b < 3, with carapace width growth being faster than weight gain. Fulton condition factor (K) values obtained ranged from 50.14-132.75 for male Scylla serrata, and female ranged from 80.34-123.94. The gonadal maturity level of Scylla serrata was dominated by TKG II crabs, and the lowest abundance of gonad maturity was in TKG IV crabs. This indicates that, in December-February, the condition of the Scylla serrata population around the mangrove forest waters of the Barumun river estuary, is predicted to be in the stage of adult dominance that is ready to reproduce and prepare to spawn.

ASPEK BIOLOGI PERIKANAN IKAN LAYANG (Decapterus Macrosoma) YANG TERTANGKAP DENGAN BAGAN RAMBO DI PERAIRAN PANTAI SUMPANG BINANGAE KABUPATEN BARRU

Flying fish is one of the dominant pelagic fish caught and has high economic value in Sumpang Binangae Waters. This fish is caught by many chart rambo fishing gear. The purpose of this study was to determine the biological aspects of flying fish especially those caught in the waters of Sumpang Binangae, Barru Regency. This research will be conducted for four months, from May 2020 to August 2020, which is located at the Sumpang binangae Fish Landing Base, Barru district. Identification of flying fish species is done visually by looking at the color and body shape and special characteristics based on the Guidelines for Practical Identification of Small Pelagic Fish Species in Figure, Suwarso, 2010, The composition of the type of catch is calculated based on the amount of catch (tonnes). Sex ratio, TKG, (Walpole 1993), Length of First-Time Gonads of Fish (Lm)The results showed that based on the composition of the types of fish caught, the percentage of the dominant catch was 27.41% mackerel (Rastrelliger kanagurta), 24.26% flying fish (Decapterus macrosoma), 23 anchovies (Stolephorus sp). 28%, squid (Loligo sp) by 2.24%, flying fish (Cypselurus sp) by 8.98% and tembang fish (Sardinella fimbriata) by 13%, while the type of flying fish caught was only one type, namely white-tailed flying fish. slightly yellowish (Decapterus macrosoma). Comparison of the number of male and female sex, it was found that the sex ratio of male and female Layang fish (D. macrosoma) was 52.83%: 47.17% or 1.12: 0.89, l. The size of the first maturity of male flying fish gonads in Barru waters is at the size of 15.68 cm or 156 mm and the female is at the size of 15.62 cm or 156 mm, while the male and female fish that are immature gonads are more than the fish that are mature gonads.

Bioekologi Udang Swallow (Penaeus merguiensis)

This study aims to examine the bioecological aspects of P. merguiensis around the estuary of the Berombang river in terms of growth patterns, the abundance of gonad maturity and condition factors. The method used in this research is purposive sampling. Shrimp sampling was carried out using arad nets which were stocked at low tide. The results showed that the composition of the abundance of the gonadal maturity level of P. merguiensis shrimp at three sampling stations was dominated by immature gonadal shrimp (BMG) to TKG 2. The growth pattern of P. merguiensis shrimp based on the length-body weight relationship in the Berombang river was classified as positive allometric. Fulton condition factor (K) ranged from 0.14 to 4.68, with an average total body length ranging from 2.35 to 13.70 cm. In conclusion, the condition factor of P. merguiensis shrimp in the Berombang river was classified as a plump category with shrimp weight gain being faster than body length growth, with female plumpness being greater than males.
 Keywords: Fulton Condition Factor, Gonad Maturity, Growth Pattern, P. merguiensis, Berombang River

Effects of Diethylstilbestrol on Zebrafish Gonad Development and Endocrine Disruption Mechanism.

Environmental estrogen is a substance that functions as an endocrine hormone in organisms and can cause endocrine system disruption. A typical environmental estrogen, diethylstilbestrol (DES), can affect normal sexual function and organism development. However, even though the effects of different exposure stages of DES on the endocrine system and gonadal development of zebrafish juveniles are unknown, sex determination is strongly influenced by endocrine-disrupting chemicals (EDCs). From 10–90 days post fertilization (dpf), juvenile zebrafish were exposed to DES (100 and 1000 ng/L) in three different stages (initial development stage (IDS), 10–25 dpf; gonadal differentiation stage (GDS), 25–45 dpf and gonadal maturity stage (GMS), 45–60 dpf). Compared with that of IDS and GMS, the growth indicators (body length, body weight, and others) decreased significantly at GDS, and the proportion of zebrafish females exposed to 100 ng/L DES was significantly higher (by 59.65%) than that of the control; in addition, the zebrafish were biased towards female differentiation. The GDS is a critical period for sex differentiation. Our results show that exposure to environmental estrogen during the critical gonadal differentiation period not only affects the development of zebrafish, but also affects the population development.

Testicular maturation of thin-lipped grey mullet during the annual reproductive cycle in captivity

ABSTRACTIntroduction: Continuous maintenance of mullet broodstock in captivity and the control of testicular development are important, particularly when linked to mass propagation of juveniles in the hatcheries, however, the complete description of testes maturation still lacking.Aim of the work: The main goal of our study to present a complete description for the testes and the obtaining of mature thin-lipped mullet, Liza ramada, males suitable for breeding in captivity.Material and methods: We performed morphological and histological techniques to describe the testicular cycle of developmental stages of male mullet reared in freshwater and captivity. Results: In general, the testes of L. ramada exhibit remarkable seasonal variations in shape, size, color and texture. Indeed, five developmental stages were characterized during testicular cycle in L. ramada in freshwater based on the histomorphology and gonadosomatic index. These stages include immature testis, stimulating spermatogenesis, rapid spermatogenesis, mature (ripe) testis and spawning (running) testis. Importantly, the testis development started when the day length and water temperature begun to decrease in September while the gradual decrease in both photoperiod and water temperatures ensure complete gonad maturation (September-December). However, induction of successful spawning in L. ramada occurs when photoperiod and water temperatures decline to their minimum values during December.Conclusion: The present study provides the morphological and histological description for testes of L. ramada during gonad maturaion in captivity and able to obtain a ripe mullet male suitable for hormonal induced reproduction in these species especially in captivity. In spite of attaining the ripe stage of L. ramada males in freshwater, the spawning can only possible with hormonal and environmental stimulation.

MATURASI LELE MUTIARA Clarias gariepinus BETINA MELALUI PENAMBAHAN HORMON OODEV DAN ESTRADIOL-17ß PADA PAKAN

The problem in Mutiara strain of North African catfish Clarias gariepinus culture is that the production of both larvae and seeds is still inhibited by the seasonal reproductive cycle where the catfish only spawn once during the spawning season. The purposes of this study were to evaluate the effect of administration of oodev and estradiol-17ß on the maturity process and to determine the best doses in accelerating the maturion of female Mutiara strain. This study used a Completely Randomized Design with 5 treatments and 3 individual replications. The treatments were combination between dose Oodev (PMSG and Anti-Dopamine) and dose Estradiol-17ß in feed (both doses in ml/kg feed):A(0+0), B(0.5+0), C(0+0.6), D(0.5+0,6), E(1+1). The results of this study showed that the administration of Oodev and Estradiol-17ß significant affect on gonadal maturity index about 82.21% compared to control and acclerating maturation of female mutiara strain with doses the best is the treatment E (oodev 1 ml/kg feed+estradiol-17ß 1 ml/kg feed).Key words: Clarias gariepinus, dose, estradiol-17ß, maturation, oodev

Thermal Stress Affects Gonadal Maturation by Regulating GnRH, GnRH Receptor, APGWamide, and Serotonin Receptor Gene Expression in Male Pacific Abalone, Haliotis discus hannai During Breeding Season

Temperature has crucial effects on gonadal development and reproduction of abalone. To understand the impact of thermal stress on molecular and physiological processes triggering the regulation of reproduction, changes in the mRNA expression of neuroendocrine genes encoding two abalone gonadotropin-releasing hormone (Hdh-GnRH, Hdh-GnRH-like peptide), GnRH receptor (Hdh-GnRH-R), Hdh-APGWamide, serotonin receptor (5-HThdh), and a heat shock protein HSP70 were examined in ganglia and testis of male Pacific abalone (Haliotis discus hannai). Abalone were exposed to low water temperature (LWT) and high water temperature (HWT) in early and peak breeding seasons for 7 days. Then, gonadosomatic index (GSI) was calculated, relative gene expression was measured by qRT-PCR, and levels of testosterone in hemolymph were also measured by ELISA during the peak breeding season. GSI did not show any significant changes during the early breeding season. However, it was significantly decreased in LWT- or HWT-exposed abalone compared to the normal water temperature (NWT) group during the peak breeding season. In the early breeding season, changes of mRNA expression of all five genes were significant between LWT and HWT groups on day-7. In the peak breeding season, compared to the NWT group, the mRNA expressions of different genes were significantly decreased in different tissues both in LWT and HWT groups of abalone, such as Hdh-GnRH-like peptide in the cerebral ganglion (CG) and testis; Hdh-GnRH in the pleuropedal ganglion (PPG) and branchial ganglion (BG); Hdh-GnRH-R in the CG, PPG, and testis; and Hdh-APGWamide in the PPG and testis. Interestingly, the expression of 5-HThdh was significantly increased in the HWT group but decreased in the LWT group. Expression of HSP70 was significantly increased in the testis after exposure to HWT. Hemolymph levels of testosterone were significantly decreased in the HWT group compared to those in the NWT group. Altogether, these results denote that thermal stress has a repressive effect on gonadal maturation and reproduction by regulating the expression of Hdh-GnRH-like peptide, Hdh-GnRH, Hdh-GnRH-R, Hdh-APGWamide, 5-HThdh, and HSP70 genes and levels of hemolymph testosterone.

Proteomic analysis of pikeperch seminal plasma provides novel insight into the testicular development of domesticated fish stocks

Control of the reproduction of domesticated stocks is considered a prerequisite for aquaculture development of pikeperch. However, knowledge about the physiology of the captive pikeperch male reproductive system and the biology of semen is very limited, especially regarding protein characteristics. The aims of our study were to characterize pikeperch sperm quantity and quality parameters and to analyze changes in the proteome of the same males spawned for the first and second times. Moreover, attempts were made to generate the first proteomic library of seminal plasma proteins. Semen collected during the first spawning season was characterized by lower sperm concentration and volume than for the second season. Using mass spectrometry-based label-free quantitative proteomics, we identified 850 proteins in the seminal plasma of pikeperch from both spawning seasons, and 65 seminal proteins were found to be differentially abundant between the first and second spawning seasons. The majority of differentially abundant proteins were involved in stress and immune responses, developmental processes, cofactor metabolic processes, proteolysis, cellular oxidant detoxification and organization of the extracellular matrix (ECM). In addition, several proteins unique to pikeperch seminal plasma were identified, including antifreeze proteins, hibernation-specific plasma proteins, lectins and vitellogenin. In summary, our results indicate that males that spawned for the first time were characterized by incompletely mature gonads and the expression of proteins associated with the early phase of spermatogenesis and ECM organization. On the other hand, males that spawned for the second time exhibited advanced gonadal maturation and expression of proteins related to the late stage of spermatogenesis and sperm maturation, including regulation of reactive oxygen species generation, bicarbonate production, sperm elongation and separation. The identification of a large number of seminal plasma proteins provides a valuable resource for understanding the functions of seminal plasma and the molecular mechanisms involved in testicular development and maturation in domesticated fish, which is a prerequisite for better control of reproduction in captivity.

A review of recent sightings and reports of the giant tiger shrimp <i>Penaeus monodon</i> (Decapoda: Penaeidae) on the Mexican coast of the Gulf of Mexico (2012-2019)

This work shows an update of the sightings and reports of tiger shrimp Penaeus monodon on the Mexican coast of the Gulf of Mexico recorded from 2012 to 2019 and reports the smallest specimen found in the western Atlantic. The results show an increase of almost 300% in sightings and reports since the first report. The zone with most sightings and reports was the coast of Campeche and Yucatán. The wide range of size and distribution of the captured specimens, including the smallest specimen found in the western Atlantic and the presence of females at an advanced stage of gonadal maturity, indicates that P. monodon has established itself in the area. The possible negative effects of such establishment make necessary the proposal of measures based on scientific evidence.

Determination of Some Biological Characteristics and Population Parameters of the Blotched Picarel (Spicara flexuosa Rafinesque, 1810) Distributed in the Eastern Black Sea (Rize - Hopa)

This study was carried out in order to determine some biological characteristics of the fish species of Spicara flexuosa, which is distributed on the Eastern Black Sea coast, and to contribute to the management of the picarel in all the seas of our country. Between October 2015 and September 2016, 599 fish samples were obtained and examined in the laboratory. It was determined that the examined individuals were distributed between the ages of I-VII which 31.22% of the population was male and 68.78% was female. The minimum-maximum total length values of the samples were between 8.7 and 21.8 cm; and the weight values ranged from 7.1 to 129.94 g. It has been determined that the mean total length of males is statistically different from that of females (P<0.05). Von Bertalanffy growth equilibrium was calculated as "L∞=22.71 cm TL, K=0.243 year-1, t0=-2.306 year-1; W∞=118.27 g" for females, "L∞=38.34 cm TL, K=0.063 year-1, t0 = -6.381 year-1; W∞=755.37 g" for males, and "L∞=33.42 cm TL, K=0.080 year-1, t0=-5.381 year-1; W∞=401.24 g" for all individuals. The length-weight relation of all individuals was found as W= 0.0118*L2.9727 (R2=0.9487). When the ratio of gonadosomatic index (GSI) data and gonadal maturity stages were examined over the year, it was determined that the reproduction of the picarel in the Black Sea occurred between June and September.