Gonadal Maturation Research Articles

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

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

Molecular Characterization, Expression and In Situ Hybridization Analysis of a Pedal Peptide/Orcokinin-type Neuropeptide in Cuttlefish Sepiella japonica.

Neuropeptide pedal peptide (PP) and orcokinin (OK), which are structurally related active peptides, have been widely discovered in invertebrates and constitute the PP/OK neuropeptide family. They have complex structures and play myriad roles in physiological processes. To date, there have been no related reports of PP/OK-type neuropeptide in cephalopods, which possess a highly differentiated multi-lobular brain. Rapid Amplification of cDNA Ends (RACE) was employed to obtain the open reading frame (ORF) of PP/OK-type neuropeptide in Sepiella japonica (termed as Sj-PP/OK). Various software were used for sequence analysis. Semi-quantitative PCR was applied to analyze the tissue distribution profile, quantitative real-time PCR (qRT-PCR) was used to study spatio-temporal expression throughout the entire growth and development period, and in situ hybridization (ISH) was employed to observe the tissue location of Sj-PP/OK. in the present study, we identified the ORF of Sj-PP/OK. The putative precursor of Sj-PP/ OK encodes 22 mature peptides, of which only tridecapeptides could undergo post-translationally amidated at C-terminus. Each of these tridecapeptides possesses the most conserved and frequent N-terminus Asp-Ser-Ile (DSI). Sequence analysis revealed that Sj-PP/OK shared comparatively low identity with other invertebrates PP or OK. The tissue distribution profile showed differences in the expression level of Sj-PP/OK between male and female. qRT-PCR data demonstrated that Sj-PP/OK was widely distributed in various tissues, with its expression level increasing continuously in the brain, optic lobe, liver, and nidamental gland throughout the entire growth and development stages until gonad maturation. ISH detected that Sj-PP/OK positive signals existed in almost all regions of the optic lobe except the plexiform zone, the outer edge of all functional lobes in the brain, epithelial cells and the outer membrane layer of the accessory nidamental gland. These findings suggest that Sj-PP/OK might play a role in the regulation of reproduction, such as vitellogenin synthesis, restoration, and ova encapsulation. The study indicated that Sj-PP/OK may be involved in the neuroendocrine regulation in cephalopods, providing primary theoretical basis for further studies of its regulation role in reproduction.

Decoding the effect of photoperiodic cues in transducing kisspeptin-melatonin circuit during the pubertal onset in common carp.

This study unravels the intricate interplay between photoperiod, melatonin, and kisspeptin to orchestrate the pubertal onset of Common carp. Female fingerlings exposed to long days (LD) exhibited a hormonal crescendo, with upregulated hypothalamic-pituitary-ovarian (HPO) axis genes (kiss1, kiss1r, kiss2, gnrh2, gnrh3) and their downstream targets (lhr, fshr, ar1, esr1). However, the expression of the melatonin receptor (mtnr1a) diminished in LD, suggesting a potential inhibitory role. This hormonal symphony was further amplified by increased activity of key transcriptional regulators (gata1, gata2, cdx1, sp1, n-myc, hoxc8, plc, tac3, tacr3) and decreased expression of delayed puberty genes (mkrn1, dlk1). In contrast, short days (SD) muted this hormonal chorus, with decreased gnrh gene and regulator expression, elevated mtnr1a, and suppressed gonadal development. In in-vitro, estradiol mimicked the LD effect, boosting gnrh and regulator genes while dampening mtnr1a and melatonin-responsive genes. Conversely, melatonin acted as a conductor, downregulating gnrh and regulator genes and amplifying mtnr1a. Our findings illuminate the crucial roles of melatonin and kisspeptin as opposing forces in regulating pubertal timing. LD-induced melatonin suppression allows the kisspeptin symphony to flourish, triggering GnRH release and, ultimately, gonadal maturation. This delicate dance between photoperiod, melatonin, and kisspeptin orchestrates common carp's transition from juvenile to reproductive life.

Application of ultrasonography in abalone gonadal evaluation

The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding. However, traditional methods are damaging to the animals, causing the waste of a quality parent. Ultrasound imaging as a noninvasive technique is a candidate substitute. This study aimed to verify the application of ultrasonography to the assessment of abalone gonad condition. Pacific abalones (n = 20) were randomly selected for ultrasonography, another six abalones in different gonad maturation stages (mature, between mature and immature, and immature) were also subjected to the same detection and histological analysis. Abalones (n = 10) were induced to spawn, and the changes in the gonad index and the types of germ cells were determined before and after spawning. Thirty-six female abalones were selected and divided into a high-gonad index group (HGI) and a low-gonad index group (LGI) according to the gonad index determined by ultrasonography, and their reproductive performance was compared during the entire breeding process. There was no significant difference in gonad index or gonad relative average thickness (GRAT) obtained from ultrasonography and histological methods. The gonad index and GRAT measured by ultrasound images significantly decreased after spawning. After spawning, a minimal quantity of mature gametes remained in gonad tissue as reflected in histology images. In a reproductive trial, the HGI group showed comprehensive and overwhelming reproductive advantages compared to the LGI group in total fecundity, relative fecundity, fertilization rate, hatching rate, abnormality rate, and attachment rate. Ultrasonography was demonstrated to be useful as a noninvasive method to evaluate abalone gonad condition. The ultimate goal is to achieve tracing and monitoring the abalone reproductive cycle through the ultrasound technique.

Induction of maturation of gold fish (Carassius auratus) using sesame seed extract (Sesamum indicum L. ) on feed as phytoestrogens

Gonad maturity in fish is essential in fish farming because it is related to seed production. Sesame oil is one of the ingredients as a feed supplement to stimulate fish gonad maturation. The research aimed to obtain the best dose of sesame seed extract (Sesamum indicum L.) in feed to increase the gonad maturity of comet fish (Carassius auratus). This research had four treatment levels and three repetitions. The treatment levels in this study were: P0 Without giving sesame seed extract (Control), P1 Giving sesame seed extract 5 mL/kg feed, P2 giving sesame seed extract 10 mL/kg feed, P3 Giving sesame seed extract 15 mL/kg. The results of the six-week study showed that at the beginning of maintenance, they were in TKG I, in the 3rd week, they entered TKG III, and in the 6th week, P1, P2, and P3 entered TKG IV while P0 were still in TKG III. The highest gonad maturity index at each observation time occurred in treatment P2 with feed containing 10 mL/kg of sesame seed extract. In the 1st week, the highest gonad maturity index occurred at P2 at 7.80. In the 3rd week, the highest gonad maturity index occurred in P2 at 9.26%. In the 6th week, the highest gonad maturity index occurred in P2 at 11.17%. Fecundity at week 6 showed the highest result of P2 4,290. The level of gonad maturity with treatment given sesame extract was faster, with a maintenance time of 6 weeks. The results of this study illustrate that sesame extract can be used as a supplement to increase comet fish gonad maturity.

De Novo Assembly, Characterization, and Comparative Transcriptome Analysis of Mature Male and Female Gonads of Rabbitfish (Siganus oramin) (Bloch & Schneider, 1801).

The rabbitfish, Siganus oramin, is a commercially important table fish in southeastern China. However, there have been few studies on its gonad development and reproduction regulation. Comparative transcriptome analysis was first performed on adult male and female gonads of S. oramin. In total, 47,070 unigenes were successfully assembled and 22,737 unigenes were successfully annotated. Through comparative transcriptome analysis of male and female gonads, a total of 6722 differentially expressed genes were successfully identified, with 3528 upregulated genes and 3154 downregulated genes in the testes. In addition, 39 differentially expressed reproduction-related genes were identified. Finally, quantitative real-time PCR was used to validate the expression levels of several differentially expressed genes. These results provide important data for further studying the function of reproduction-related genes and the molecular mechanism regulating gonad development and reproduction in S. oramin.

Status of pink ear emperor (Lethrinus lentjan) fishery in the Sinjai and Bone waters, South Sulawesi, Indonesia

The pink ear emperor (Lethrinus lentjan) is a type of coral fish belonging to the Lethrinidae family, they usually eat mainly at night, namely benthic invertebrates or fish. L. lentcan included in the main family of food coral fish that live in coral reef ecosystems and in sandy bottom coastal waters. Good management of fisheries resources is by utilizing fish populations without having to deplete fishery resources. If fishing is carried out continuously without taking into account the ability to renew, over exploitation will occur. The research was conducted from March to May, 2023, in Sinjai and Bone waters, south sulawesi Indonesia which focused on fishing ports with L. lentjan landing potential. The highest class length was obtained in Sinjai Regency and in Bone regency which was negative allometric. Lc in Sinjai regency uses basic gillnet, and in Bone regency 21.9 uses basic longline. Gender comparison between L. lentjan males and females in Sinjai regency is 45% : 55%. Meanwhile for Bone regency it is 41% : 59%. L. lentjan males and females have a ratio of 1: 1.43 with the results of the chi square test tcount < ttable, this condition shows that H0 accepted, there is no real difference between the number of male and female biota. gonad maturity level L. lentjan in Sinjai regency it is 24 cm with a length range of 23 – 25 cm, and in Bone regency it is 24.6 cm with a length range of 24-25 cm.

Effectiveness of different photoperiods on gonad maturity and reproductive performance of freshwater crayfish (Cherax quadricarinatus)

This study aimed to determine the effectiveness of different photoperiod on gonad maturity and reproductive performance of freshwater crayfish. The study was conducted on July 22th - August 22th in the Green House Samudra University. Test fish used is seed of cherax quadricarinatus measuring 4-5 inches. The methods used in this study was Completely Randomized Design (CRD)with 4 treatments and 3 replications. The treatments in this study were P1 (8 hours light, 16 hours dark), P2 (10 hours light, 14 hours dark), P3 (12 jam hours light, 12 hours dark), and P4 (14 hours light, 10 hours dark). Seeds of fish was put in a containing 8 liters of water volume with a stocking density of of 1 tails male and female each container. The frequency of feeding is done 3 times a day at 08.00 am, 16.00 pm and 20.00 pm. The results showed that different natural feeding teratments had a very significant effect on the absolute weight, gonad maturity level (TKG), gonad maturity indexs (IKG), fecundity, and egg diameter. The best treatment in this study was P1 treatment (8 hours light, 16 hours dark) because it had a high-performance value compared to other treatments.Keywords: Absolute weight; Cherax quadricarinatus; Fecundity; Gonad; Photoperiod.

Different dosages effectiveness of Ovaprim on the maturation of freshwater lobster (Cherax quadricarinatus)

Freshwater lobsters have been developed as a commodity for consumption since 2003. The need for this commodity is increasing but production is still very low, so the price of freshwater lobsters is quite high and expensive. Therefore, it is necessary to carry out reproduction to carry out the seeding process for Freshwater Lobsters (LAT) using an injection technique in the form of the Ovaprim Hormone to accelerate the maturity of the LAT gonads. This study aims to examine the administration of different doses of the ovaprim hormone on the maturation of freshwater lobster broodstock. The research was conducted for 60 days. The method used was a Randomized Block Design (RAK) with 4 treatments and 3 replications. The treatments in this study were P0 (control), P1 (0,3 ml), P2 (0,5 ml) and P3 (0,7 ml). The parameters observed in this study were Gonad Maturity Index (IKG), Egg Diameter and Pleopode Fecundity. The results of the observations showed that giving different doses of ovaprim to the maturation of freshwater crayfish was not significantly different (P<0.05) to the Gonad Maturity Index IKG), Egg Diameter and Pleopode Fecundity but was significantly different to the P0 (control) treatment. The best treatment in this study was treatment P3 (0.5 ,l) because it had the highest performance between the other treatments.Keywords: egg diameter; fecundity; freshwater lobster; maturation; ovaprim

Development of gonad and brood pouch and expression profiles of cgα, fshβ and lhβ transcripts and plasma 17β-E2 and 11-KT during the first reproductive cycle of farmed big-belly seahorse (Hippocampus abdominalis)

Limited data are available regarding the gonadal development of farmed seahorse along with the physiological role of gonadotropins and sex steroids during gonadal maturation. In the present study, we conducted an examination of the developmental stages of gonad and brood pouch during the initial reproductive cycle of the farmed big-belly seahorse (Hippocampus abdominalis), and our results showed that males sexually matured half of a month later than females, and the brood pouch emerged at 3.5-month old and then reached the late-stage at 5.5-month old. Meanwhile, the open reading frame (ORF) of gonadotropin subunits (cgα, fshβ and lhβ) of the big-belly seahorse were cloned and characterized, and tissue distribution profiles of their transcripts were analyzed, revealing their detectability across various tissues, with a notable presence observed in the brain tissues. Furthermore, expression profiles of cgα, fshβ and lhβ transcripts and the plasma levels of 17β-estradiol (E2) and 11-ketotestosterone (KT) in farmed big-belly seahorse during the first reproductive cycle were also investigated. The findings indicated that cgα, fshβ and lhβ transcripts exhibited low expressions at the initial development of ovary or testis, raised continuously and reached their peak levels at the period of spawning or spermation, and they kept gradually increasing accompany with brood pouch growth. It is noteworthy that variation of mRNA levels of fshβ were slightly higher than those of lhβ. Besides, the results showed that plasma 11-KT levels presented an increasing trend during testicular development, peaking in fish with III and IV-stage testis and early-stage brood pouch, and plasma 17β-E2 levels were higher in vitellogenic stage of fish with II-stage ovary and early III-stage ovary. Taken together, these data reveal that gonadotropins and sex steroids likely play a role in the regulation of gonad and brood pouch growth in seahorse. These observations not only contribute to clarifying function of reproductive hormones on growth of gonad and brood pouch of seahorse, but also providing an important theoretical foundation for the artificial breeding of seahorses.

Changes in Behavior and Diel Melatonin Secretion Toward Estivation in Western Sand Lance, Ammodytes japonicus (Uranoscopiformes, Ammodytidae).

Western sand lance, Ammodytes japonicus, is known to have an estivation period, in which they cease feeding and stay in the sand from early summer to late autumn, followed by gonadal maturation. During the feeding period prior to estivation, they swim in daytime and spend the night in the sand. Before they start swimming, they show a typical behavior of head-exposing from the sand, which is likely to be related to foraging and predation avoidance. Our previous study revealed that melatonin regulates such diel behavior of this species. To elucidate the mechanisms of behavioral regulation throughout the life cycle of this sand lance, the present study examined the changes in behavior and melatonin secretion toward the estivation period. Both head-exposing and swimming behaviors were frequently observed at the transition period toward estivation. On the other hand, occurrence of these behaviors was suppressed just before entering estivation. Subsequently, it was found that plasma melatonin concentration was about three times higher at night than in daytime in the non-estivation period, while it was retained at high levels throughout the day in the estivation period. These results indicate that diurnal swimming behavior of sand lance from the feeding to estivation periods is associated with the daily cycle of melatonin secretion.

Food and feeding strategies of the green tiger shrimp, Penaeus semisulcatus, in southeastern India

Abstract Observations and analysis of the food and feeding habits of penaeid shrimp are decisive for understanding food webs and ecological processes. Published information on the feeding habits of the green shrimp, Penaeus semisulcatusDe Haan, 1844, from Indian waters, however, dates back four decades, despite the fact that green tiger shrimp is one of the important shrimp species that forms a unique fishery in Palk Bay, on the southeastern India. Hence, its dietary preferences were analysed concerning sex, season, gonad maturity, and size. The species preyed on were composed of diversified components, with mollusc remains being the most common food item in females, followed by crustacean remains, whereas in males, the crustacean remains were the most common food items followed by mollusc remains. There was no significant difference in the gastrosomatic index of females and gonadal maturity stages among seasons, but a significant difference among size groups. In males, there was no significant difference among seasons, gonadal maturity, and size groups. Females were more active feeders than males, and the difference could be seen in their size groups. Larger groups fed more actively than smaller groups. Feeding was more active in the post-monsoon and summer monsoon seasons. Penaeus semisulcatus dominates the ecosystem among the shrimp species due to its carnivorous behaviour. The observations made in this study form key inputs for trophic modelling and ecosystem-based studies, which could help develop suitable strategies for managing the shrimp resource in Palk Bay.

The distinctive morphology of caudal neurosecretory system and its impact on Pampus argenteus throughout the breeding season

The caudal neurosecretory system (CNSS) of teleost is intricately linked to reproduction. This study sought to explore the association between the CNSS and the reproductive cycle of Pampus argenteus. Utilizing microscopy and transmission electron microscopy, we observed the morphological alterations within the CNSS. Furthermore, we quantified the levels of urotensin-I (U-I), urotensin-II (U-II), cortisol, and corticotropin-releasing hormone (CRH) throughout the reproductive process. Findings revealed that Dahlgren cells, distributed along the spinal cord adjacent to the terminal 6 vertebrae of the silver pomfret’s tail, were primarily concentrated within the final 3 vertebrae. The neurohypophysis was characterized by an elongated oval form when viewed laterally and an almost spherical configuration in ventral perspective. Post-breeding season, the average diameters of Type I and Type II Dahlgren cells decreased by 21.8% and 15.44%, respectively (P < 0.05), accompanied by a reduction in neurosecretory granules to merely 60% of their initial pre-reproductive state (P < 0.05). Variations in the serum and gonadal concentrations of U-I, U-II, cortisol, and CRH indicated a significant correlation with gonadal maturation. In summary, the CNSS plays a crucial role in gonadal development, directly or indirectly influencing and modulating the reproductive activities of P. argenteus.

Morphological characteristics of sex dimorphism in Gobiopterus sp. (Gobiiformes: Oxudercidae) from Ranu Grati Lake, Pasuruan District, East Java, Indonesia

Abstract. Anitasari S, Arfiati D, Susilo, Marhendra APW. 2024. Morphological characteristics of sex dimorphism in Gobiopterus sp. (Gobiiformes: Oxudercidae) from Ranu Grati Lake, Pasuruan District, East Java, Indonesia. Biodiversitas 25: 1214-1222. Ranu Grati is a volcanic lake located in Pasuruan, East Java, Indonesia which has high ecological value as a habitat for a unique endemic fish found only in this lake, namely the Lempuk fish (Gobiopterus sp.). The aim of this research is to determine the morphological characters based on sexual dimorphism of Lempuk fish. in Ranu Grati Lake. The result showed the body color of male and female Lempuk fish is transparent. Lempuk fish do not have sexual dichromatism or their sex cannot be distinguished based on their body color. Lempuk fish have vomer teeth and canine teeth. Types of male and female ctenoid scales have a comb-like shape. The position of the mouth of the Lempuk Fish is located near the top or head of the fish but not precisely at the tip. There are variations in the superior subterminal mouth type between male and female fish, especially in terms of anatomical details and mouth structure. Based on meristic observations of the Lempuk fish, it can be explained that this fish has a fusiform body shape, this shows that gobies generally have a small fusiform body and also has pectoral fins, pelvic fins, dorsal fins, tail fins and anal fins. In this study, we found from histological observations of the Lempuk fish, mature oocytes and spermatids were found in one histological tissue sample at male fish with gonad maturity level II. This change from female to male occurs at the size of the fish with fish size of 21.21-30.58 ± 2.14mm. It indicates that is Lempuk fish is a species hermaphrodite protogyn.

Gonadal maturation in turn with ovulatory stimulation response to dietary inclusion of diverse seaweeds classes for strombus cornis

Gonadal maturation in turn with ovulatory stimulation response to dietary inclusion of diverse seaweeds classes for strombus cornis

FSH, bone, belly and brain.

The pituitary gland orchestrates multiple endocrine organs by secreting tropic hormones, and therefore plays a significant role in a myriad of physiological processes, including skeletal modeling and remodeling, fat and glucose metabolism, and cognition. Expression of receptors for each pituitary hormone and the hormone itself in the skeleton, fat, immune cells, and the brain suggest that their role is much broader than the traditionally attributed functions. FSH, believed solely to regulate gonadal function is also involved in fat and bone metabolism, as well as in cognition. Our emerging understanding of nonreproductive functions of FSH, thus, opens potential therapeutic opportunities to address detrimental health consequences during and after menopause, namely, osteoporosis, obesity, and dementia. In this review, we outline current understanding of the cross-talk between the pituitary, bone, adipose tissue, and brain through FSH. Preclinical evidence from genetic and pharmacologic interventions in rodent models, and human data from population-based observations, genetic studies, and a small number of interventional studies provide compelling evidence for independent functions of FSH in bone loss, fat gain, and congnitive impairment.

Gonadal Maturation and Spawning of Barred Loach (Nemacheilus fasciatus) Induced by Topical Gill Hormone Application

Barred loach Nemacheilus fasciatus are unable to reproduce naturally in captivity due to the lack of environmental cues and gonadal maturation occurs slower than in the wild. To optimize breeding procedures for this fish species, we determined whether hormone application via the gills was an effective process and assessed hormone dosage treatments. Oodev™ was used to induce gonadal maturation and Ovaprim™ was used to induce spawning via a topical gill approach. Multiple maturation parameters such as gonadal-somatic index (GSI) and hepatosomatic index (HSI), fecundity, and egg diameter; and spawning parameters such as latency period, egg produce, fertilization rate (FR), hatching rate (HR), survival rate (SR) were recorded and compared between the hormone dosage treatments and control treatment. Both the Oodev™ gonadal maturation induction and Ovaprim™ spawning induction were effectively applied to barred loach via topical gill application. Gonadal maturation parameters were positively correlated with dosage and all were significantly different. Fry survival rate was not different between doses. The optimal dose of Oodev™ (0.75 µL/g fish) resulted in male GSI of 5.334 ± 0.320%, female GSI of 15.501 ± 0.675%, male HSI of 0.416 ± 0.023%, female HSI of 1.670 ± 0.104%, egg fecundity 4584.20 ± 493.216 eggs, egg diameter 0.964 ± 0.0151 mm. Ovaprim™ optimal dosage (3.00 µL/g female and 1.50 µL/g male) was resulted latency period 11.05 ± 0.52 hours, egg produced 3504.83 ± 358.57, FR 96.77 ± 0.88%, HR 83.62 ± 3.78%, and SR 91.44 ± 2.53%.

Effect of Pregnant Mare Serum Gonadotropin and Antidopamine on the gonads of female bileh fish (Rasbora maninjau)

Bileh fish (Rasbora maninjau) still have difficulty spawning in a controlled manner in aquaculture containers because the maturation of female fish gonads is slow and takes a long time. Internal factors, including the hormonal system, strongly influence the maturation of fish gonads. This study aims to determine the effect of Pregnant Mare Serum Gonadotropin (PMSG) and antidopamine on female gonads of bileh fish. The research used an experiment with a CRD (Completely Randomized Design) experimental design. The experiment consisted of four treatments and three repetitions. The treatments were the administration of PMSG and antidopamine hormones at different doses through feed, namely: 0 ml/kg feed (P1), 0.5 ml/kg feed (P2), 1 ml/kg feed (P3) and 2 ml/kg feed (P4). The research procedures included container and fish preparation, hormone, and feed preparation, fish rearing, and data collection. The test parameters evaluated were weight gain (Wg), gonadosomatic index (GSI), and gonadal maturity level (GML). Data on test parameters were analyzed with statistics (Anova). The research results showed that the administration of PMSG hormones and antidopamine through feed had a significant effect on weight gain, gonadosomatic index and gonad maturity level of bileh fish (P<0.05). Effective and best treatment at P3 (1 ml/kg feed) with Wg 0.22grams, GSI 8.58%, and GML IV 60%.

Triploid brown trout, Salmo trutta, develop functional gonads with age and are able to interbreed with diploid counterparts.

The study investigated if gonad maturation in triploid brown trout, Salmo trutta, was entirely suppressed or only delayed, and if triploids could interbreed with diploid counterparts. Ten percent of the total number of 3-year-old triploid S. trutta, 15% of 4-year-old fish, and 17% of 5-year-old fish produced semen. Three and 4 years old triploid fish did not produce eggs, but 15% of the 5-year-old fish did so. The quantity and sperm motility of triploid semen did not differ from diploids, but the sperm concentration was significantly lower. When diploid eggs were fertilized with triploid semen (3n × 2n crosses), the percentage of eyed stage embryos, of hatched larvae, and of normal-shaped larvae did not differ from the diploid controls. Circa 90% of 3n × 2n crosses had a ploidy level of 2.4n. In the remaining percentage of 3n × 2n crosses, the ploidy level was ≥2n and <2.4n. In sperm competition experiments where diploid eggs were fertilized with a mixture of diploid and triploid semen, 52% of the originating larvae had a ploidy level of 2n, 43% of 2.4n, and 5% of the fish were not exactly classified. From the start of feeding to an age of 248 days, the mortality rate of 3n × 2n interploid crosses and of 2n × 2n controls was similar. The growth of interploid crosses was significantly higher than that of controls. In triploid mature females, the egg mass per kilogram of body weight was significantly lower than in diploids. The mass of the non-hardened eggs and the percentile weight increase during hardening did not differ from diploid eggs. When triploid eggs were fertilized with diploid semen (2n × 3n crosses), the development rate to normal hatched larvae was less than 10%. All originating larvae had a ploidy level of 3n. From the start of feeding to an age of 248 days, 2n × 3n crosses had a higher mortality rate (15%) than diploid controls (<5%). Growth of this type of interploid crosses was reduced in comparison to controls. Therefore, triploids introduced into natural waters for recreational fisheries or escaping from farms may interbreed with diploid counterparts. This not only alters the genotypes of local populations but also changes the ploidy levels.

Biological patterns of reproduction of the Brazilian sardine Sardinella brasiliensis in the purse seine fishery of Southwest Atlantic Ocean: A long-term assessment

Recent estimates of the size at first maturity (L50) of Sardinella brasiliensis showed contradictory results with a decreasing in the fish stock biomass encompassed by increasing values of L50. The methodological approach used hereby allowed to separate sardines classified in the virginal maturity stage from those categorized in the recovery stage, and ready for one next spawning event. This study evaluated the hypothesis of the existence of separated stocks experiencing distinct environmental conditions and fishing pressures which may have altered L50 estimates using a robust dataset based on biological samples collected along the entire species distribution area in the southeast-south Brazilian coast [Rio de Janeiro (RJ), São Paulo (SP), Paraná (PR), Santa Catarina (SC) and Rio Grande do Sul (RS)] between 2000 and 2018. A reclassification of the gonadal maturity stages provided a more realistic estimate of L50. Combining biological, reproductive, fishing data and the mean temperature of the catch (MTC), the leave-one-out classification correctly re-assigned individuals with an overall accuracy of 85% [100% (RJ), 45% (SP), 99% (PR), 99% (SC) and 82% (RS)]. The connectivity between the local populations of S. brasiliensis off RJ (23°S) and the southern populations is limited, contrasting to spatial structured semi-discrete population-units found between SP and RS (24°S-30°S). The northern extreme population-unit (RJ, 22°S-23°S) showed an expressive reduction of L50, and a negative correlation was detected between the increasing MTC values and the abundance of early maturing individuals and recruits of the species. Stock specific L50 estimates seemed to act as indicators of long term environmental fluctuations.