Egg Diameter Research Articles

Perkembangan gonad, fekunditas dan diameter telur Hemisilurus heterorhynchus, Bleeker 1854 di sungai paparan banjir, Desa Mentulik, Kampar Kiri, Riau

Floodplain river is one of the freshwatercharacteristics of Riau Province. Selais humped fish (Hemisilurus heterorhynchus) is a demersal freshwater fish. and usually lives in tropical areas with rivers that are flood-prone. H. heterorhynchus is often caught regardless of size so that fish that are immature or have immature gonads are also caught. If this condition continues, it is likely that H. heterorhynchus will experience a population decline. Therefore it is necessary to conduct research on the reproductive biology of H. heterorhynchus to find out, gonadal development, gonado somaticindex (GSI), egg diameter, fecundity, the relationship between fecundity and body length and weight, spawning season and fish spawning patterns so that it can be used as a basis for conservation and cultivation of H. heterorhynchus. This research was conducted from October to March on the Kampar Kiri river. Gonad mature male and female fish were mostly found at the beginning of the rainy season in October and November. The highest male GSI was obtained in October (0.24%) and female in November (2.80%). Fecundity of H. heterorhynchus ranged from 6444-20654 eggs. The spawning pattern of H. heterorhynchus fish is once a year (total spawner).

Spawning interactions between hatchery‐reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high‐altitude tropical streams, Kenya

AbstractRainbow trout (Oncorhynchus mykiss) is among the most widely translocated fish species in the world. The current study evaluated the spawning interactions between naturalized and wild rainbow trout from two high‐altitude second‐order streams, in Kenya. Data on total length, weight, condition factor, fecundity, fertilization, egg diameter and fry survival were collected on spawning rainbow trout between March and December 2021. Length–weight relationship showed parabolic equations as W = 0.0144L2.900, W = 0.0069L3.0285 and W = 0.00027L3.175 for wild fish stock, hatchery‐reared and wild × hatchery‐reared rainbow trout, respectively. Total fecundity differed significantly among the hatchery‐reared, wild fish and the cross of the two (p < 0.05). The fertilization rate showed significant differences (p < 0.05), with no discernable difference observed between the hatchery‐reared and crossed (wild × hatchery‐reared). There was a positive correlation among the total fecundity to female egg weight, female body weight, fertilization rate and eyed egg survival in all the populations. Relative fecundity was significantly different among the three groups of fish (p < 0.05), but the differences between the hatchery and the crossed (wild × hatchery‐reared) fish showed no significant differences. We recommend the use of crossed (wild × hatchery‐reared) populations for fry production for use in aquaculture as they presented the highest fecundity and gave the best outcome of fry with high survival.

Efficiency of temperature and storage duration on some morphological measurements and reproductive capacity of the entomopathogenic nematode Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae)’s Turkish HBH hybrid strain

Entomopathogenic nematodes (EPNs) are successfully used in the biological control of agricultural insect pests. This study aims to determine the body length of hermaphrodite individuals, egg diameter and reproductive capacity obtained from Infective Juveniles (IJs) stored at different temperatures and durations. Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae)’s Hybrid Strain HBH was used in the study. IJs stored at 15, 25 and 35°C for 7, 14 and 21 days were inoculated onto Galleria mellonella L., 1758 (Lepidoptera: Pyralidae) last instar larvae at a dose of 100 IJs. On the 2nd day of infection, hermaphrodite individuals and eggs were obtained by dissecting the larvae. The reproductive capacity was determined 10-12 days after infection. The study was conducted in Bursa Uludağ University, Faculty of Agriculture, Plant Protection Department, Nematology Laboratory in 2023. In conclusion, the longest hermaphrodite individuals and egg diameter were obtained as 6207.22 µm and 55.65 µm, respectively from the IJs stored for 7 days at 15°C. The highest reproductive capacity was also observed as 167.500 IJs per G. mellonella larva in IJs stored under the same conditions with respect to temperature and time. This study is important for assessing the morphological effects of different temperature values and storage durations on EPNs.

Morphological characteristics, molecular species validation and spatio-temporal distribution of myctophid eggs off the Pacific coast of northeastern Japan

Myctophids in the world's oceans have a huge biomass and act as an important link between secondary producers and upper trophic levels through their extensive diel vertical migrations from the epipelagic to mesopelagic layers. Dominance of myctophid larvae in oceanic ichthyoplankton has been reported from various parts of the major oceans; however, there are few records concerning their eggs. We established species-specific morphological characteristics for identifying myctophid eggs which were then validated by sequence analysis of mitochondrial 12S rRNA and cytochrome b genes using representative subsamples of the morphotypes, and then used the criteria to determine the species composition and spatio-temporal distribution of myctophid eggs. Samples were collected monthly in the epipelagic layer off the Pacific coast of northeastern Japan, resulting in 664 net tows that yielded a total of 10,172 myctophid eggs, defined by a smooth and delicate chorion, segmented yolk, and single oil globule. Subsamples of 160 small, 34 intermediate, and 20 large-sized eggs were sequenced, resulting in their classification as Diaphus theta, Diaphus garmani, and Myctophum asperum, respectively. Mean egg diameter was smallest in D. theta (0.75 mm), intermediate in D. garmani (1.06 mm), and largest in M. asperum (1.31 mm). Eggs of D. theta had a markedly narrower perivitelline space (0.17 mm) than D. garmani and M. asperum (0.49 and 0.71 mm, respectively). Based on morphology, the myctophid eggs were dominated by D. theta (86.0%), followed by D. garmani (12.6%) and M. asperum (1.4%). Abundances of early-stage eggs of D. theta and D. garmani were high during the daytime to dusk but low at night and dawn, indicating that spawning would not be active in the epipelagic layer at night. Spawning can be considered to occur in the mesopelagic layer during the early night, and then the eggs rise to reach the epipelagic layer in the daytime. High abundances of D. theta and D. garmani eggs were observed in the slope region from spring to summer, corresponding with the larval distribution reported for the study area.

Reproductive biology of endemic sailfin silversides fish Telmatherina antoniae Kottelat, 1991 in Matano Lake, South Sulawesi

Sailfin silversides (Telmatherina antoniae) is an endemic species from Matano Lake, South Sulawesi. This study aims to learn about sailfin silversides’ reproductive aspects including sex ratio, length at first maturity, gonad maturity stage, gonad maturity index, fecundity, and egg diameter. Fish samples were taken using multifilament nets from March 2018 until February 2019. A total of 1,792 individuals fish comprises 922 males and 870 females were captured during the study period. The sex ratio was found in a balanced condition with 1.06:1. Length at first maturity for males and females were 48.08-57.73 mm and 56.78-68.55 mm, respectively. Based on sailfin silversides’ gonad maturity stage and maturity index are thought to be year-round spawning with a peak spawning season around March. The reproductive potential of sailfin silversides fish is estimated to be 179–1,690 eggs. Based on the egg diameter distribution, the sailfin silversides fish is classified as a partial spawner.

Life cycle exposure to 2-phenylbenzimidazole-5-sulfonic acid disrupts reproductive endocrine system and induces transgenerational adverse effects in zebrafish

Global attention has been focused on organic UV filters due to their ubiquity and potential damage to aquatic environment, yet the effects of their life cycle exposure on fish reproduction remain unknown. In the present study, the influence of 2-phenylbenzimidazole-5-sulfonic acid (PBSA) exposure on the reproductive endocrine system of zebrafish was examined, from 6 hours post fertilization (hpf) until 150 days, at levels that near-environmentally relevant (0 to 20 μg/L). Our results showed that exposure to PBSA at 20 μg/L caused a slight decrease in the Gonadosomatic Index (GSI) of female zebrafish in the F0 generation. Furthermore, this exposure had a negatively effect on reproduction, accompanied by delayed oocyte maturation, reduced cumulative egg production and decreased fertilization rate. Additionally, offspring embryos displayed reduced egg diameter at 0.75 hpf, delayed cumulative hatching rate at 60 hpf, and increased deformities rate at 72 hpf, indicating an adverse transgenerational effect. Moreover, PBSA exposure was associated with decreased plasma levels of sex hormones of 17β-estradiol (E2) and 11-ketotestosterone (11-KT), as well as altered the transcriptional profiles of certain genes in the HPG (hypothalamic–pituitary–gonadal) and liver axis. Molecular docking (MD) simulations revealed that specific amino acid residues of PBSA interact with zebrafish estrogen receptors, confirming its xenoestrogenic properties. Therefore, exposure to PBSA during its life cycle can disturb fish reproduction through endocrine disruption, thus necessitating strict environmental regulations for the disposal of UV filters to protect ecological and public health.

Growth, reproduction, fatty acid profiles and offspring performance of broodstock yellow catfish Pelteobagrus fulvidraco fed diets with different lipid levels

Parental nutrition plays important roles in reproductive performance and offspring health of broodstock yellow catfish. However, there is a lack of relevant knowledge concerning the broodstocks of many fish species. This study investigated the influence of dietary lipid levels on growth, spawning performance, tissue fatty acid profiles, sex hormone secretion, and offspring health status of yellow catfish (Pelteobagrus fulvidraco). Five experimental diets were designed containing a 7:3 ratio of fish oil and corn oil blends with graded lipid levels (6.3%, 8.2%, 10.8%, 12.2%, and 14.4% by dry weight) and were fed to female broodstock yellow catfish for 8 weeks. The results showed that weight gain, egg diameter, fertilization ratio, and hatching ratio increased initially and then decreased with increasing dietary lipid levels, reaching optimal peaks in the L10.8 group. Broodstock fed a diet with 10.8% lipid obtained the highest 17-β estradiol concentration. The deposition of highly unsaturated fatty acids in tissues increased initially and then decreased with the increase in dietary lipids, reaching a peak in the 10.8% group. Plasma superoxide dismutase activity and total glutathione content were lowest in fish fed a diet with a 6.3% lipid level, while the contents of malondialdehyde and cortisol in larvae 3 days post-hatching showed an opposite trend, indicating that a low-fat diet reduced the antioxidant capacity of broodstock and induced a stress response that had negative effects on offspring health. Broodstock fed a diet with an appropriate lipid level could increase the expression of antioxidant enzymes by activating the nrf2 signaling pathway. Based on the regression of dietary lipid level and weight gain, reproductive performance, and egg quality of fish, the optimal dietary lipid level was 10.1–11.7% for broodstock yellow catfish.

Individual Growth And Gonad Development Of Female Tilapia (Oreochromis Sp.) With Addition Of Velvet Bean (Mucuna Pruriens) Seed Extract

Tilapia is one of the fish that is widely cultivated in Indonesia. The obstacle to tilapia cultivation is high reproduction, which inhibits growth. An alternative to increase growth is by inhibiting gonad growth, so that feed energy is focused on somatic development. The aim of this research was to analyse the effect of velvet bean extract concentration on individual growth and gonad development of female tilapia fish and to determine the optimum concentration of velvet bean extract to increase growth and reduce reproductive activity in female tilapia fish. This study used a Completely Randomized Design (CRD) with the addition of various velvet bean extracts and compared with the control (without velvet bean extract). The use of velvet bean extract had a significant effect (p<0.05) on growth parameters such as length, weight, fecundity and egg diameter. The best treatment was found in treatment 3 (velvet bean extract 5 ml.kg-1 ) which resulted in growth in individual length of 16.1 cm, individual weight of 89.43 g, fecundity of 2206 and egg diameter of 1.11 mm. In addition, the dose in this treatment may reduce the reproductive activity of tilapia.

Ca2+ addition facilitates the shell repair with eggs production of Pomacea canaliculata through biomineralization and food intaking regulation

Pomacea canaliculata was by far one of the most harmful invasive organisms in the world, causing serious harm to aquatic crops and ecosystem. Calcium carbonate is a common component of aquatic environment, which is important for the growth of Pomacea canaliculata. Therefore, the objective of this study was to investigate the response characteristics of P. canaliculata suffered shell breakage to the addition of calcium carbonate in water environment. In this experiment, we explored the effects of calcium carbonate addition on the P. canaliculata shell repair rate, food intake, egg production, shell strength, and calcium content through breaking the snails shell and the addition of calcium carbonate treatment. The results showed that snail broken-shell repaired mostly within 21 days. The snails experienced a significant increase in shell repair rates during earlier days of the treatment, especially for female snails. Food intake of snails exhibited different patterns when their shells were broken and calcium carbonate was added. Shell breakage treatment combined with calcium carbonate addition significantly increased the diameter of snail eggs compared with the control and the calcium carbonate addition treatment without shell-broken snail group. There was no significant difference in shell strength or calcium content of male snails between the treatments. The study suggests that P. canaliculata exhibits a sex-dependent response pattern when subjected to shell damage and calcium carbonate addition. The findings can provide some references to better understand the invasion mechanism and survival strategy of the P. canaliculata.

Isa Brown yumurtlayan tavuklarda yumurta kalitesi özelliklerinin analizi ve yumurta ağırlığının tahmini

Objective: The objective of this study was to determine the best-fitted regression model for estimating egg weight of Isa Brown laying chickens using external and internal egg parameters. Materials and Method: Data collected include: egg weight (EWT), egg length (EL), egg diameter (ED), shell thickness (ST), shell weight (SW), albumen height (AH), albumen weight (AW), yolk height (YH), yolk weight (YW) and yolk length (YL). Data were subjected to statistical analysis procedures of SPSS (version 23.0.0). Egg weight was regressed on external and internal egg parameters using forward, backward and full model regression procedures, to determine the combinations of egg parameters that explain variation in the dependent variable. Results: Results showed that the mean (±SE) of EWT, EL, ED, ST, SW, AH, AW, YH, YW and YL were 60.49±0.47, 4.23±0.03, 2.94±0.02, 1.37±0.01, 6.04±0.05, 1.20±0.01, 36.30±0.39, 1.22±0.02, 15.29±0.15 and 2.32±0.02 respectively. The models of EWT = 30.638+0.582AW+0.571YW and EWT = -14.991+8.779EL+5.493ED+3.686SW are the best fitted regression models for predicting egg weight of Isa Brown laying chickens. Conclusion: Conclusively, egg weight of Isa Brown laying chickens can be improved through selection for EL, ED, ST and SW trait

Reproduction of Carijoa riisei (Cnidaria: Octocorallia) in the Panamanian tropical eastern Pacific

Octocorals are the main component of rocky walls in the Panamanian tropical eastern Pacific (TEP), providing shelter and substrate for diverse marine invertebrates and demersal fishes. Despite their ecological importance, many essential biological traits of these corals remain undescribed. Like some cnidarians, octocorals may be related to bioinvasion. One emerging risk is the rise of the Indo-Pacific invasive octocoral Carijoa riisei, which overgrows other soft corals, competing for food and space and promoting the emergence of diseases. Considering the potential risk to native octocorals, we investigated the reproductive seasonality of C. riisei at 15 m depth every month for one year in the Gulf of Panama (Las Perlas Archipelago), an octocoral diversity hotspot with seasonal upwelling. Carijoa riisei showed an average fecundity (percentage of polyps with eggs sampled throughout the year from only female colonies) of 53% (SE 0.03%) with no seasonality. Carijoa riisei produced eggs continuously with overlapping generations, with an average of 23 (1–107; SE 0.75) eggs per fertile polyp and an average egg diameter of 0.12 (0.10–0.64; SE 0.0008) mm. The number of eggs inside the gastrovascular cavity was higher during the upwelling. However, the size and proportion of large eggs were greater towards the end of the upwelling season, with a drastic decrease from 30% to 2% at its end. Our results over a one-year sampling period show that in the Panamanian TEP, C. riisei reproduces continuously, seemingly energized by higher nutrient levels present during upwelling. This, along with its rapid growth rate, makes this species a formidable competitor for native species. Thus, we encourage future monitoring of these populations.

Reproductive characteristics of the hermaphroditic four-finger threadfin, Eleutheronema tetradactylum (Shaw, 1804), in tropical coastal waters

This study investigated the reproductive traits of the hermaphroditic four-finger threadfin, Eleutheronema tetradactylum, along the coasts of Thailand during January to December 2021. Fish samples were collected from Pattani Bay, Thailand to assess the sex ratio, gonadosomatic index (GSI), maturity stage and fecundity. Additional fish samples were also collected from other areas to evaluate the length and weight at first sex change (Ls50 and Ws50) and length at first maturity (Lm50). The overall sex ratio for male and female was 1:0.69 with male being predominant throughout the year. Threadfin fish spawn the whole year round with peaks during moderate rainy and heavy rainy seasons. Histological examination confirmed its protandrous hermaphrodite posing multiple spawning habits. The average fecundity was 1.85 × 105 ± 1.05 × 105 eggs and positively related with standard length, body weight, gonad weight, and egg diameter (p < 0.05). The Ls50 and Ws50 were 27.58 cm and 419.39 g, and 29.71 cm and 457.28 g, for fish from Pattani Bay and Samut Prakan province, respectively. The Lm50 of male from Pattani Bay and Samut Prakan province were 25.78 cm and 25.56 cm, respectively, which were larger than those from Satun and Nakhon Sri Thammarat provinces. The Lm50 of females from Pattani Bay was smaller than that from Samut Prakan province. This study provided fundamental information on the reproductive characteristics of E. tetradactylum, which can be implemented to support management of natural fish stock and aquaculture development.

Acceleration of gonadal maturity of female striped catfish, Pangasianodon hypophthalmus (Pisces, Pangasiidae) by irradiation to low-power soft-laser

This study was aimed to investigate the effects of red photodiode soft-laser irradiation on gonadal maturity and egg quality of female striped catfish, Pangasianodon hypophthalmus. Four female striped catfish (weighing 700–800 g) at stage I of gonadal maturation (for all treatments) were exposed four times (once a week) to different doses (0.2, 0.4, 0.6, and 0.8 J/cm2) of red photodiode soft-laser in the reproductive acupoint. Doses of 500 IU and 0.5 mL per kg body weight of human chorionic gonadotropin (hCG) and Ovaprim™, respectively were injected intramuscularly at week 4 (positive control), and no treatment (negative control). Finally, gonadal maturation stage (GMS), gonadosomatic index (GSI), hepatosomatic index (HSI), fecundity, and egg diameter were measured at week 5. The results showed that red photodiode soft-laser irradiation of 0.4 J/cm2 dose accelerated GMS IV at early week 3 (100 %) and increases GSI (3.42 %), HSI (1.26 %), fecundity (67,665 eggs/body weight), and egg diameter (1.01 mm) compared to the other treatments. Treatments of 0.2, 0.6, and 0.8 J/cm2 doses, and positive and negative controls only reached GMS III (75 %), III (25 %), I (100 %), II (25 %), and I (100 %), respectively. GSI values were 2.20 %, 1.47 %, 0.93 %, 0.44 %, and 0.42 %, respectively and HSI values were 1.07 %, 0.85 %, 0.7 7%, 0.66 %, and 0.53 %, respectively. Females irradiated with doses of 0.2 and 0.6 J/cm2 had fecundities of 38,822 and 29,530 eggs/body weight, respectively, and egg diameters of 0.88 and 0.29 mm, respectively. These results suggest that a red photodiode soft-laser irradiation accelerates gonadal maturity and improves egg quality in female striped catfish.

Early embryonic development of green crucian carp Carassius auratus indigentiaus subsp. nov.

The early embryonic development of the green crucian carp (Carassius auratus indigentiaus subsp. nov.) was observed to study its timing and characteristics. The fertilized eggs are round, slightly yellow, and viscous demersal. The egg diameter after water swelling was 1.47 ± 0.04 mm. Embryonic development can be divided into eight stages according to its major characteristics: blastoderm formation, mitotic, blastula, gastrula, neurula, blastopore closure, organogenetic and hatching stages. Under a water temperature of 24 ± 1 °C, salinity of 35 ± 1, and pH of 7.4 ± 0.5, the blastoderm began to form 35 min after fertilization. It entered the mitotic stage at 55 min, blastula stage at 220 min, gastrula stage at 460 min, neurula stage at 675 min, blastopore closure stage at 700 min, organogenetic stage at 900 min and hatching stage at 3390 min. The total length of newly hatched larvae was 4.07 ± 0.35 mm. Regression models of growth characteristics were obtained. The full-length growth rate was fastest from 15 to 26 days, with an average of 0.396 mm/day. Compared with other cyprinid fishes, green crucian carp exhibited some distinct characteristics in certain stages of embryonic development. The eye primordium developed before the sarcomere, and the heart rate was relatively high before the member stage. Yolk fluctuation was observed during the multi-cell phase of embryonic development. The sarcomere formed after the eye primordium. The heart rate in the hatching phase was 136 beats/min. This study provides a reference for embryonic development in green crucian carp, which will assist its large-scale cultivation.

The Fecundity Characteristics and Spawning Strategy of Uroteuthis edulis in the East China Sea.

The fecundity characteristics and spawning strategy of Uroteuthis edulis in the East China Sea were investigated by observing the potential fecundity (PF), relative fecundity by dorsal mantle length (PFML) and relative fecundity by body weight (PFBW). The relationship between fecundity and a single biological indicator was measured, and generalized additive models (GAMs) were fit by adding environmental variables to help better understand this comprehensive relationship. The long diameter and short diameter of the ovarian oocytes ranged from 0.72 mm to 4.74 mm and from 0.46 mm to 3.67 mm, respectively. The long and short diameters of oviducal eggs ranged from 0.61 mm to 5.12 mm and from 0.39 mm to 3.81 mm, respectively. The egg diameter had a unimodal distribution. The PF, PFML and PFBW ranged from 540 to 13,743 cells, 5 to 86 cells/mm and 6 to 53 cells/g, respectively. Three fecundity indicators were unimodally distributed, and the PFBW was more stable than the PFML (δ2PFBW < δ2PFML). The fecundity and single biological indicators were fitted, and it was found that the PF and PFML were positively correlated with dorsal mantle length (ML) and body weight (BW). The generalized additive model (GAM) fitting showed that when considering the interaction between dorsal mantle length and sea surface height (M13), the deviation explanation rate of the PF and PFML was the highest. Studies have shown that the ovary oocytes of U. edulis mature in batches, and then the eggs are laid in batches. The dorsal mantle length (ML), water temperature at 25 m depth (T25) and sea surface height (SSH) are important indicators to measure the fecundity of U. edulis. These findings allow for a deeper understanding of the U. edulis population dynamics for the future management of this economically and ecologically important species.

Laying performance and egg characteristics of Japanese quail fed rations containing different levels of Maxigrain as a feed additive

The performance, egg characteristics and lipid profile of Japanese quail (Coturnix japonica) fed diets containing different levels of Maxigrain as a feed additive were investigated. A total of 225 (7 weeks) old Japanese quails weighing 235-248 g at the point of lay were allotted to 5 dietary treatments in a completely randomized experimental design with 5 replicates of 9 birds each. Dietary treatments for the entire 56 of days the feeding trial included: T1: 0 g of Maxigrain kg-1 diet, T2: 0.5 g Maxigrain kg-1 diet, T3: 1 g Maxigrain kg-1 diet, T4: 1.5 g Maxigrain kg-1 diet and T5: 2 g Maxigrain kg-1 diet. The results of the study showed that values for average daily feed intake, egg length, egg diameter, egg shape index, cholesterol, high density lipoprotein, low density lipoprotein, triglyceride, albumen weight, albumen height and yolk height were not affected by the treatment (P &gt; 0.05), while dietary treatment significantly (P &lt; 0.05) affected the values for the average daily weight gain, egg weight, egg mass, egg yolk weight and shell thickness among the treatments with T4 and T5 having the highest values of the above variables. It was concluded that T4 and T5 treatment could be safely included in the diet for improved performance in laying quail.

Population structure and reproductive dynamics of the ridged swimming crab Charybdis natator in the southern Taiwan Strait of China: significant changes within 25 years

The ridged swimming crab Charybdis natator (Portunidae) is a commercially important crustacean species in China. The purpose of this study is to compare its population structure and reproductive pattern within the same fishing area (the southern Taiwan Strait) from two datasets over 25 years; one from 1994−1996 (the early years of the C. natator fishery) and the other from 2019. The overall sex ratio (male:female) changed from a male bias (1:0.76, p &amp;lt; 0.01) in 1994−1996 to a female bias (1:1.38, p &amp;lt; 0.01) in 2019. Male body sizes (carapace width, CW) were significantly larger than those of females in both datasets (p &amp;lt; 0.05). The average CW and body weight (BW) of males and females in 2019 were significantly smaller (p &amp;lt; 0.01) and lighter (p &amp;lt; 0.01) than those in 1994−1996. The maximum body size and the proportion of large-sized individuals (CW &amp;gt; 10 cm) decreased dramatically over 25 years. One spawning peak season was identified from each dataset, i.e., March−August 1994−1996 and February−April 2019, revealing a 1-month shift. The minimum body sizes for female maturation (carrying eggs) were 6.9 cm CW in 1994−1996 and 6.1 cm CW in 2019, an 11.6% reduction over 25 years. For the first time, the CW at 50% female maturation, the relationship between female absolute fecundity and CW, and egg diameters were obtained from the 2019 dataset, which can be applied in the future comparisons. Recent studies have revealed a consistent spawning peak in February–April for several commercially important crabs in the southern Taiwan Strait. These findings should be considered in crab fishery management. Furthermore, both fishery- and environment-associated factors influencing crustacean population structure and reproductive dynamics merit further investigation.

Population parameters of the non-indigenous invasive shrimp Palaemon macrodactylus Rathbun, 1902 (Caridea: Palaemonidae) from the southeastern Caspian Sea, with implications for range expansions, threats and conservation

Knowledge on invasive species is critical for the conservation. This study is the first documentation on population parameters of oriental shrimp (Palaemon macrodactylus) in the southern Caspian Sea, where the occurrence of invasive species is of great importance. The samples were collected using a small beach seine (35 m long and 2.5 m height) monthly from April 2019 to March 2020, and a total of 1643 specimens of P. macrodactylus were sampled. The growth form of the males was negative and that of females positive allometric nature. From the size-frequency distributions, the shrimp's lifespan was estimated to be about 2 years for both sexes. High recruitment can take place over nearly all months of late summer and autumn. The VBGF parameters were L∞ = 65.00 mm, K = 0.82 y−1, and t0 = −0.80 for males, and TL∞ = 71.00 mm, K = 0.51 y−1 and t0 = −0.59 for females. The estimated Z was 3.65 and 3.10 year−1 for males and females, respectively. The total sex ratio was significantly biased toward females in the population. Length group analysis showed a clear pattern of female dominance in lengths larger than 29 mm. Based on the occurrence of ovigerous females, the reproductive period lasts for seven months (April–October). Fecundity, as the number of both eyed and non-eyed eggs per clutch of females, varied from 71 to 2308 eggs shrimp−1 with a mean of 1074 ± 553.8 (±SD) eggs shrimp−1. The estimated relative number of eggs in a clutch of ovigerous females varies between 1208.8 and 1714, with a mean value of 889.1 eggs. female−1. The egg diameter averaged 0.675 ± 0.063 mm (±SD), ranging from 0.512 to 0.812 mm. The relationships of the total and relative number of eggs in a clutch of ovigerous females with their size were statistically significant, while the egg diameter in ovigerous females was independent of shrimp size (length and weight). P. macrodactylus underwent a life-history strategy including high abundance, short life span, high mortality rate, long reproductive season, and female dominance that showed characteristics of r-strategist species, promoting the invasion of this shrimp in the Caspian Sea as a new area of introduction. We are convinced that P. macrodactylus established in the Caspian Sea it is in the last stage of invasion (impact on the ecosystem).

Natural spawning of the leopard grouper (Mycteroperca rosacea) in captivity in La Paz, Mexico

Natural spawning of the leopard grouper (Mycteroperca rosacea) was studied in captivity from 2004 to 2008 under natural photoperiod conditions. Fish spawned naturally in 2006, but only 90,000 unfertilized eggs were collected. A total of 43 and 27 spawning days were observed in 2007 and 2008, respectively. Spawning season began in March and lasted until May–June and was related to an increase in water temperature from 21.1 to 23.8 °C. The mean (SE) number of eggs released each day was 101,705 (13,876) in 2007 and 40,510 (7,874) in 2008, and the total number of eggs collected in 2007 and 2008 was 4.37 × 106 and 1.07 × 106, respectively. The number of eggs collected per month was not significantly different within each year (P &gt; 0.05), although a significant difference was observed between 2007 and 2008 (P &lt; 0.05). The annual relative number of eggs released was 288,750 eggs·kg–1 in 2007 and 72,919 eggs·kg–1 in 2008, and viable egg production was 184,800 eggs kg–1 in 2007 and 25,375 eggs kg–1 in 2008. The fertilization rate (%) of the eggs collected daily differed significantly throughout the spawning season of 2007 (P &lt; 0.05). The fertilization rate also differed (P &lt; 0.05) between 2007 (61.10%) and 2008 (32.30%). Statistical analysis of the 2 consecutive spawning seasons indicated no correlation between the fertilization rate and fecundity. The effect of the moon phase on spawning was also considered. The fish spawned at dusk before total darkness. Mean (SD) egg diameter was 864.0 ± 22.0 μm.

Kuluçkahane Kökenli F5 ve F6 Nesil Karadeniz Somonu Anaçlarının (Salmo labrax PALLAS, 1811) Üreme Performansları

In this study, reproductive performances of F5 and F6 generation hatchery-originated female Black Sea salmon (Salmo labrax) were evaluated to determine the effects of the ongoing selective breeding program. The study was conducted in freshwater pools and marine cage systems between 2018 and 2021. For the study, 53 specimens from F5 generation females with an average length of 52.71±7.08 cm and weight of 1561.29±639.76 gr, and also 56 broodstıcks specimens from F6 generation females with an average length of 51.92±5.35 cm and weight of 1506.12±417.28 gr were used. Gonad maturity controls and spawning studies were carried out in the 2018-2019, 2019-2020 and 2020-2021 breeding periods along the entire season, lasting from November to January. The number of ovulating females, their fecundity, egg diameters and fertilisation rates of eggs were recorded. In all seasons, 36.17% of F5 females ovulated in November, and the remaining females (63.83%) ovulated in December. Ovulation time in F6 females also showed a similar pattern of 1/3 of females (37.40%) ovulating in November and the remaining majority (62.60%) ovulating in December. According to the results, total egg yields as 4439.31±1675.69 and 4112.08±1041.16 egg/broodstock, relative egg yields as 2313.44±278.48 and 2345.76±516.30 egg/kg, egg diameters as 5.08±0.19 and 5.21±0.17 mm, and fertilisation rates as 96.78±3.24% and 96.63±3.73% were determined for F5 and F6 generations, respectively. In both generations, as the size of the broodstock increases, the total egg production increases (F5: r=0.9169, F6: r=0.74254), while the relative egg production (F5: r=-0.2526, F6: r=-0.3486) decreases. When the total egg yields and fertilisation rates were compared, the difference between the F5 and F6 groups was insignificant (p≤0.05). The condition factors of the two generations were found to be statistically similar (p≤0.05).