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Quantifying demographic parameters and variable vital rates, such as somatic growth rates, time to maturity, and reproductive longevity, is important for effective management of threatened and endangered populations such as sea turtles (Cheloniidae). To address these knowledge gaps, we applied skeletochronology to analyze and compare somatic growth rates and variation in life-history traits such as age and size at sexual maturity for 65 green turtles (Chelonia mydas) in the eastern Pacific Ocean (EP), along the west coast of the United States; turtles belonged to ≥2 nesting subpopulations that differed in body size (mean nesting size). Green turtles in the EP spend approximately 5 years in the oceanic stage before recruiting to nearshore habitats, males may be smaller and younger than females at maturation (x̅ = 17.7 ± 5.5 yr vs. 28.0 ± 8.2 yr), and younger age at sexual maturity was associated with smaller size at sexual maturity, suggesting that mean nesting body size may be reflective of maturation timing for subpopulations. Smaller body sizes for females nesting at Michoacán, Mexico (continental) rookeries, yielded a younger predicted age at sexual maturity (x̅ = ~17 yr) compared to females from Revillagigedo Islands, Mexico rookeries, which displayed larger body sizes and older age at sexual maturity (x̅ = ~30 yr). We consider possible mechanisms driving the observed divergence in life-history traits, including the possibility that earlier maturation (reduced generation length) for turtles in the Michoacán nesting subpopulation may be a response to intense harvesting in the past 50 years, and consideration of such anthropogenic impacts is warranted by population managers. Finally, our results indicate green turtles moved into nearshore neritic habitats at a young age (4–6 yr), emphasize the importance of protecting neritic habitats along the southwestern United States and northwestern Mexican coasts, and encourage the incorporation of variable maturation time in population recovery assessments.

Abstract The aim of this study was to estimate the size at first sexual maturity (Lm) for 36 species belonging to 24 families from the marine habitat of Balochistan and Sindh in Arabian Sea, Pakistan through maximum length based an empirical and logistic model using commercial catch during June 2020 to May 2021. Individual total length (TL) was noted up to 0.1 cm using measuring broad. The Lm was calculated using two formulae; (i) log (Lm) = - 0.1246 + 0.9924 * log (Lmax) for Elasmobranchs and (ii) log (Lm) = -0.1189 + 0.9157* log (Lmax) for ray-finned fishes. The minimum Lm was recorded as 10.27 cm TL for Caranx malabaricus and 108.38 cm TL for Isurus oxyrinchus, respectively. Around Lm with 58.33% species were ranges from 19.00 cm to 25.00 cm TL. This study was estimated 16 newly Lm which is globally absent and rest 20 Lm are absent in the Arabian Sea (Pakistan coastal habitats). Therefore, the results will be helpful for the sustainable management and conservation of these marine fishes through the establishment of mesh size of trawl nets based on the size at sexual maturity (Lm). Resumo O objetivo deste estudo foi estimar o tamanho na primeira maturidade sexual (Lm) para 36 espécies pertencentes a 24 famílias do hábitat marinho do Baluchistão e Sindh, no Mar Arábico, Paquistão, por meio de modelo empírico e logístico com base no comprimento máximo usando captura comercial, durante junho de 2020 e maio de 2021. O comprimento total individual (TL) foi anotado até 0,1 cm usando medição ampla. O Lm foi calculado por duas fórmulas; (i) log (Lm) = - 0,1246 + 0,9924 * log (Lmax) para elasmobrânquios; e (ii) log (Lm) = - 0,1189 + 0,9157* log (Lmax) para peixes com nadadeiras raiadas. O Lm mínimo foi de 10,27 cm de TL para Caranx malabaricus, e o máximo, de 108,38 cm de TL para Isurus oxyrinchus. Em 58,33% das espécies com Lm foram encontradas faixas de 19,00 cm a 25,00 cm de TL. Este estudo estimou que 16 espécies com Lm estão globalmente ausentes e as 20 espécies restantes com Lm estão ausentes no Mar Arábico (hábitats costeiros do Paquistão). Portanto, os resultados serão úteis para o manejo sustentável e a conservação desses peixes marinhos por meio do estabelecimento da malhagem das redes de arrasto com base no tamanho na primeira maturidade sexual (Lm).

Traditionally, growth can be either determinate, ceasing during the natural lifespan of individuals, or indeterminate, persisting throughout life. Although indeterminate growth is a widely accepted strategy and believed to be ubiquitous among long-lived species, it may not be as common as previously thought. Sea turtles are believed to be indeterminate growers despite the paucity of long-term studies into post-maturity growth. In this study, we provide the first temporal analysis of post-maturity growth rates in wild living sea turtles, using 26 yr of data on individual measurements of females nesting in Cyprus. We used generalised additive/linear mixed models to incorporate multiple growth measurements for each female and model post-maturity growth over time. We found post-maturity growth to persist in green Chelonia mydas and loggerhead Caretta caretta turtles, with growth decreasing for approximately 14 yr before plateauing around zero for a further decade solely in green turtles. We also found growth to be independent of size at sexual maturity in both species. Additionally, although annual growth and compound annual growth rates were higher in green turtles than in loggerhead turtles, this difference was not statistically significant. While indeterminate growth is believed to be a key life-history trait of ectothermic vertebrates, here, we provide evidence of determinate growth in green and loggerhead turtles and suggest that determinate growth is a life-history trait shared by cheloniid species. Our results highlight the need for long-term studies to refine life-history models and further our understanding of ageing and longevity of wild sea turtles for conservation and management.

Appropriate management systems for the protection of fishes are mostly relying on the information of size at sexual maturity and optimum catchable length. The purpose of this research was to estimate the size at sexual maturity ( L m ) and optimum catchable length ( L opt ) of 10 marine fish species from the Bay of Bengal (Bangladesh) through multi-models using commercial catches from October 2019 to September 2020. Also, we calculated the L m and L opt of these species from worldwide water bodies based on maximum length ( L max ). A total of 2967 specimens of 10 fish species were evaluated in the current study and total length (TL) was noted up to 0.1 cm using a measuring board, while body weight (BW) and gonad weight (GW) are weighed by digital electronic balance with 0.01 g accuracy. To assess the L m , three different models such as (i) empirical model based on L max , (ii) the relationship between TL (total length in cm) vs. GSI (gonadosomatic index in %), and (iii) logistic model were considered and L opt was assessed based on L ∞ . The estimated lowest L m was 11.8 cm ( L max - based), 12.8 cm (TL vs. GSI), and 13.7 cm (logistic model) for Thryssa setirostris and highest L m was 23.3, 20.5, and 22.0 cm for Priacanthus macracanthus through L max , TL vs. GSI, and logistic-based models, respectively. From these three models, the lowest mean value of L m was obtained for T. setirostris (12.7 cm) and highest was recorded for P. macracanthus (21.9 cm). Fifty percent of mature marine species was in 14.9 cm TL and 90% species was in 19.5 cm TL. The smallest L opt was obtained as 13.4 cm TL for T. setirostris and largest was 28.2 cm TL for P. macracanthus . This study was generated data on L m and L opt for 10 newly marine species, which are globally absent. Therefore, this study will be helpful for developing sustainable management strategies and conservation of marine fishes through the implementation of mesh size based on the size at sexual maturity ( L m ) and optimum catchable length ( L opt ).

The lesser spiny eel, Macrognathus aculeatus (Bloch, 1786), holds substantial economic importance as a food fish in South Asia, due to its exceptional nutritional value. This study was conducted to investigate the reproductive ecology of M. aculeatus within the Gajner beel wetland ecosystem in northwestern Bangladesh, with a specific focus on size at sexual maturity, spawning season, and fecundity in relation to eco-climatic variables. A total of 649 M . aculeatus female individuals were randomly collected from January to December 2018, with 440 mature selected for this study. The findings of this study revealed that the female’s total length (TL) exhibited a range from 10.5 to 28.0 cm. Multiple methods, including maximum length ( L max ), TL vs. gonadosomatic index (GSI), TL-standard length (SL) regression, and logistic model estimated the size at sexual maturity ( L m ) at approximately 15.02 cm, 14.0 cm, 14.4 cm, and 14.0 cm, respectively. The spawning season was observed between May and August, with a peak in June–July. The Fulton’s condition factor ( K F ) proved to be the most reliable indicator ( p  < 0.0001), with 50% and 90% of fish spawning at K F values of 0.38 and 0.42, respectively. Relative weight ( W R ) for females showed no significant deviation from 100 ( p  = 0.143), indicating a well-balanced M. aculeatus population. Fecundity varied from 600 to 7000 with TL and body weight (BW) that ranged from 10.5–28.0 cm, to 3.33–87.05 g, respectively. Fecundity was highly correlated with TL ( p  < 0.0001) and BW ( p  < 0.0001). The study also observed significant relationships between GSI and environmental factors, including temperature ( p  = 0.0016), dissolved oxygen (DO) ( p  < 0.0001), pH ( p  < 0.0001), alkalinity ( p  < 0.001), and climatic variable such as air temperature ( p  < 0.001) and rainfall ( p  < 0.001). The optimal range of DO, pH, and temperature for M. aculeatus spawning was found to be 5.82–6.10 mg/l, 7.65–7.85, and 28.55–31.0 °C, respectively. Additionally, our observation highlighted a robust correlation between GSI and rainfall. Moreover, data for 47 years (1971–2018) indicated a gradual increase in average air temperature by 0.029 °C per year and a decrease in annual rainfall by 2.96 mm per year. These trends could potentially lead to a shift in the spawning season of M. aculeatus in the next 15–20 years. This information holds significance for the conservation and sustainable management strategies of wild M. aculeatus stocks in the Gajner beel and its adjacent ecosystems, helping to address potential impacts of climate change.

Jack-knife shrimp Haliporoides sibogae is a target species for boat seine fishery in the waters off south-western Kyushu, Japan. Reproduction, including ovarian maturation, size at sexual maturity, and spawning season of this species were studied using females collected from Kagoshima Bay, southern Japan. The present study also explored an alternative maturity index by conducting a microscopic examination of oocytes. Histological analysis of the ovaries validated six oocyte developmental stages. Ovarian development was asynchronous, indicating multiple spawning throughout a reproductive season. On the basis of the developmental stage of the most advanced oocytes, ovarian maturity was categorized into three stages: immature, maturing and mature. Females containing oocytes exhibiting cortical crypts were defined as mature. The gonadosomatic index (GSI) significantly increased as ovarian maturation progressed, and all females with a GSI of ≥ 6% were determined to be mature. The minimum size at sexual maturity was estimated to be 24.0 mm in carapace length. The spawning season extended from November to May, with February being the peak. Moreover, microscopically, the oocytes with spherical bodies on the periphery all had cortical crypts. Therefore, observation of oocytes using a microscope was considered an effective method to easily identify mature females.

The striped snakehead, Channa striata , is commercially and nutritionally important due to its medicinal properties, such as wound healing and antimicrobial abilities. This study investigated the reproductive biology of C. striata in relation to hydro-climatic changes using a fuzzy logic approach for long-term management in the wetland ecosystem (Gajner beel ), Bangladesh. A total of 1200 C. striata individuals were collected monthly during January to December 2019 using various fishing methods. Measurements of total length (TL), body weight (BW), and gonad weight (GW) were taken with a precision of 0.01 cm and 0.01 g, respectively. The GSI (gonadosomatic index in %), MGSI (modified gonadosomatic index in %), and DI (Dobriyal index) were used to determine size at sexual maturity ( L m ) and the spawning season. Results revealed a wide range of TL, ranging from 12.7 to 46 cm. The L m was estimated between 21.7 and 25.33 cm based on various model as TL vs. GSI, MGSI, and DI; TL-fork length (FL) regressions; and maximum length ( L max ) for this species. The spawning period was observed from April to July, peaking in May, indicated by higher GSI, MGSI, and DI values. Eco-climatic factors showed a significant relationship with GSI, except for total dissolved solids (TDS). Rising temperatures and declining rainfall could delay spawning of C. striata . A fuzzy logic approach was employed to predict future GSI changes over extended periods (e.g., 50 or 60 years), enabling anticipation of shifts in the timing and duration of the spawning season. Finally, the findings of our research might be effective to carry out specific conservation efforts of C. striata in response to climate variability in sub-tropical water.

The intergenerational effects from chronic low-dose exposure are matters of concern. It is thus important to elucidate the radiation-induced effects of germ cell maturation, fertilization and embryonic development. It is well known that DNA methylation levels in CpG sites in gametes are reprogrammed in stages during their maturity. Furthermore, the binding of Izumo on the surface of sperm and Juno on the surface of oocytes is essential for fertilization. Thus, there is a possibility that these genes are useful indicators to evaluate fertility in mice after irradiation exposure. Therefore, in this study, we analyzed global DNA methylation patterns in the testes and gene expression of Izumo1 and Izumo1r (Juno) in the gonads of mice after neonatal acute high-dose ionizing radiation (HDR) and chronic low-dose ionizing radiation (LDR). One-week-old male and female mice were irradiated with a total dose of 4 Gy, with acute HDR at 7 days at a dose rate of 30 Gy/h and LDR continuously at a dose rate of 6 mGy/h from 7 to 35 days. Their gonads were subsequently analyzed. The results of global DNA methylation patterns in the testes showed that methylation level increased with age in the control group, the LDR group maintained its DNA methylation level, and the HDR group showed decreased DNA methylation levels with age. In the control group, the gene expression level of Izumo1 in the testis did not show age-related changes, although there was high expression at 100 days of age. However, in the LDR group, the expression level recovered after the end of irradiation, while it remained low regardless of age in the HDR group. Conversely, gene expression of Izumo1r (Izumo1 receptor) in the ovary decreased with age in the control group. Although the gene expression of Izumo1r decreased with age in the LDR group, it remained low in the HDR group. Our results indicate that LDR can induce different DNA methylation patterns, and both high- and low-dose radiation before sexual maturity might affect gametogenesis and fertility.

 This study utilized 100 local Iraqi laying hens, aged 67 days, which were individually housed in numbered cages (1 to 100) for the duration of the experiment, conducted from October 26, 2021, to March 5, 2022. The results revealed highly significant differences (P ≤ 0.01) in the number and frequency of the LEI0234 marker among the different alleles, with the A1 allele showing superior performance compared to the other alleles. The A1 allele appeared in various genotypic forms, with a frequency of 27.00%. No significant differences were observed among the alleles in terms of body weight, age at sexual maturity, egg mass, or feed conversion efficiency. However, significant differences (P ≤ 0.05) were recorded during the 84-day period. Egg weight showed significant differences (P ≤ 0.05) during the production periods of 14 and 28 days. However, no significant differences were observed during the subsequent periods of 42, 56, 70, 84, 98, and 100 days. In contrast, feed consumption exhibited significant differences (P ≤ 0.05) during the production periods of 14, 28, 42, 56, 98, and 100 days.

This study was carried out to identify the effect of the quantitative trait loci (QTL) region on some productive and physiological traits of Iraqi chickens. One hundred five and ten-week-old laying hens were used and bred in individual sages from sexual maturity to 100 days of production. Blood samples were collected from the brachial vein for DNA extraction and serum isolation, and then polymerase chain reaction (PCR) was done to determine the target region of the QTL. Two groups were obtained: the first had a PCR product with band 294 bp denoted (P) and the second had no PCR product denoted (NP). The P group had a significant (p < 0.05) effect on egg weight at the second stage of the study amounted 48.23 gm. and a significant (p < 0.05) effect was observed in egg shell weight amounted 6.97 gm. No significant effects were found in all productive, physiological, or qualitative traits.In conclusion, the presence and absence of QTL regions significantly affect egg weight and egg shell weight, which is suitable for selection programs to improve the genetic makeup of Iraqi chicken.