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This article discusses the observation of the critically endangered soupfin shark in the Changing Salish Sea. The study confirms the presence of soupfin sharks in Hammersley Inlet through fishing efforts and sampling. The findings suggest that the presence of soupfin sharks may have implications for trophic dynamics and fisheries management in the region. The article also provides a list of references for further research on marine ecosystems in the Salish Sea and surrounding areas. [Extracted from the article]

To understand the reproductive biology of Hemitripterus villosus in the Bohai Strait, and fill the key knowledge gap in verifying reproductive seasonality and documenting gonadotropin dependent reproductive cycle of this species, a year-round detail study was conducted for the first time. In total, 263 individuals were randomly sampled off the coasts of the Bohai Strait. Results show that and the overall female-to-male ratio (1.35:1) did not differ significantly from the 1:1 sex ratio. The length and weight relationship for females and males were regressed, depicting an isometric growth for both sexes. Four reproductive phases of the complete gonadotropin dependent reproductive cycle in both sexes were identified. The monthly variations in the gonadosomatic and hepatosomatic indexes for both sexes further indicated that this species spawns a single batch of eggs per year and the peak spawning period is from October to December. The average diameter of eggs ranged from 2.10 to 3.57 mm. The length at first sexual maturity was 224.87 mm for females and 241.26 mm for males. Significant positive relationships between absolute fecundity and fish size, and also gonadal weight were observed. H. villosus from the Bohai Strait exhibited smaller body size, smaller egg diameter, lower gonadosomatic index, lower absolute fecundity, and higher population extinction risk than the other populations' studied previously. Our findings contribute to understanding the status of this isolated westernmost population, and we emphasize that more efficient protection measures for the species and control measures are urgently required to improve the coastal environment in the Bohai Strait. [ABSTRACT FROM AUTHOR]

Egyptian fisheries including the aquaculture represent an important sector in the national economy, and it is a source of employment. All studies dealing with the stock assessment and fisheries management in Egypt confirmed the overexploitation situation for most commercial stocks leading to a serious decrease in domestic fish production from natural resources. This situation made the fisheries managers in Egypt explore new fishing areas to enhance fish production in Egypt. The present work was undertaken as a part of NIOF scientific plan about the Gulf of Aqaba fisheries and how rationally it can be exploited. Fish biology and population dynamics are fundamental for fish stock assessment and its management. Some biological and dynamical parameters of Lethrinus variegatus from the Gulf of Aqaba, Egypt were investigated to assess its exploitation status. Comparisons of age and growth characteristics recorded no significant differences (P> 0.05) between the sexes. The von Bertalanffy growth parameters for pooled data were K= 0.51/year, L8= 25.79cm TL and t0= -0.387 year. The mean size at which the fish attained sexual maturity for L. variegatus was 16.33cm TL. The mean size at first capture was 17.31cm, which was greater than the size at first sexual maturity, indicating the healthy status of L. variegatus stock in the Gulf of Aqaba. The fishing mortality rate for L. variegatus (0.80/yr) was substantially greater than the target Fopt (0.51/yr) and limit Flimit (0.67/yr) estimates. The slender emperor stock was in its optimum situation as the current exploitation rate was 0.44/yr. The results of the study are important to fisheries management authorities in the region since they will contribute to planning the regional fishery management policies in Egypt. [ABSTRACT FROM AUTHOR]

Understanding the reproductive characteristics of a species is of crucial for accurate stock assessment and management plans to ensure sustainable fisheries. In this study, the size at 50% sexual maturity (L50) parameters in different bio-ecological provinces were estimated for bigeye tuna, Thunnus obesus, sampled from the Eastern Pacific Ocean tuna fisheries-dependent survey from 2013 to 2019. The overall sex ratio of the catch during the sampling differed significantly from 1:1. Bigeye tuna exhibit sexual dimorphism in the growth of males and females, with a clear shift in predominance from female to male with increasing sizes. In the North Pacific Subtropical Gyre (east) (NPST-east), North Pacific Tropical Gyre (NPTG), Pacific North Equatorial Countercurrent (PNEC), and Pacific Equatorial Divergence (PEQD), females (meals) reached sexual maturity round 102 cm (106 cm), 106 cm (100 cm), 125 cm (110 cm), and 113 cm (110 cm), respectively, the estimated L50 of bigeye tuna was 124.08 cm, 121.97 cm, 139.92 cm and 132.45 cm, respectively. The degree of populations mixing between equatorial (PNEC and PEQD) and high-latitude regions (NPST-east and NPTG) is extremely small, but it is reasonably high between the NPST-east and NPTG or PNEC and PEQD. These parameters were significantly different, suggesting the occurrence of a spatial difference in the size-at-maturity of bigeye tuna between these bio-ecological provinces. The findings of this study provide the key information for understanding the life history of bigeye tuna in the Eastern Pacific Ocean and will contribute to the conservation and sustainable yield of this species. [ABSTRACT FROM AUTHOR]

The size selectivity and catch pattern of Trichiurus lepturus in 40 mm diamond and square mesh codends were investigated in this study. A 34 m high opening trawl was used, which is a common design used by fishermen operating along the northwest coast of India, and the cover codend method was employed to determine codend selectivity. Along with the changes in the length at 50% retention rate for Trichiurus lepturus with the usage of the square and diamond mesh codends, indicators to understand the exploitation pattern of this species in the fishery were assessed based on the total number of individuals and on total weight of the catch. The mean selection length increased and discard fraction is reduced when 40 mm square mesh codends are used in place of diamond meshes, however, it is observed that individuals at commercial length are also lost. The results demonstrate that mandatory use of legal mesh sizes alone will be insufficient to aid in the sustainable harvest of this species, given its estimated length at first sexual maturity of 61.2 cm. This is the first study to compare the size selection of this species in 40 mm diamond and square mesh codends along Northwest coast of India. Results of the study will help as a baseline for gear-based regulations in the region. [ABSTRACT FROM AUTHOR]

Dogtooth tuna, Gymnosarda unicolor were sampled off the east coast of Australia (southwest Pacific Ocean) from 2007 to 2012. Ages were determined by examining thin transverse sections of their sagittal otoliths and were based on counts of alternating opaque and translucent zones (annual growth increments). Growth was rapid during the first year of life, after which growth in length was much reduced. Parameters of the constrained von Bertalanffy growth function (fork length-at-age) were L∞ = 1164.77 (mm, FL) and K = 0.44 year-1. Preliminary estimates of longevity indicate a maximum observed age of at least 20 years. There was a high degree of variation in the observed length and age of sexual maturity for G. unicolor. Despite this variation, the size at 50% maturity for female G. unicolor estimated in this study was 713 mm FL (<2 years of age). The diet of G. unicolor is very broad and covers a range of fish species. The life history characteristics of G. unicolor overall, indicate that this species may be somewhat resilient to fishing. However, reports of localised depletions, in association with heavy targeting by sports fishers, low effective population sizes and patchy recruitment indicate that this species is particularly vulnerable to overfishing. [ABSTRACT FROM AUTHOR]

This study was performed to obtain information on the sex ratio, spawning period, and size at sexual maturity for fishery management of the largehead hairtail Trichiurus japonicus in Korean waters. The overall sex ratio (female, F; male, M) was 1:0.46 (n = 1274 females:589 males, 68.4% female) and as fish increased in length, the proportion of females increased. The oocyte development pattern was group-synchronous development, for which oocyte groups at different stages can be identified within the same ovary. The average gonadosomatic index (GSI) showed two peaks in June (3.03) and August (3.10) in females and in May (1.81) and September (2.24) in males. The median value of GSI showed two peaks in May (2.65F, 1.78M) and September (2.55F, 1.87M) for both females and males. As a result of analyzing the GSI and the monthly gonadal developmental stages, the main spawning season was estimated to be bi-annual (May–June and September–October). The anal length of fish at 50% sexual maturity was analyzed using a logistic regression model and was determined to be 16.38 cm (female) and 18.31 cm (male). [ABSTRACT FROM AUTHOR]

The concentrations of thyroid and sex steroid hormones in the blood of immature and precocious brown trout Salmo trutta at the final stage (age 1+, 2+) of the formation of early maturing fishes in the population were determined. The formation period of precocious males varied in different years in the Alatsoya River (Karelia); fish reached sexual maturity at ages 1+ or 2+. Immature and precocious fish at ages 1+ and 2+ do not differ in the concentrations of free and total triiodothyronine, of free thyroxine. Immature females and males at ages 1+ and 2+ also do not differ in the concentrations of sex steroid hormones. In contrast to immature brown trout, precocious males at age 2+ were characterized by an increased concentration of testosterone and decreased level of estradiol-17β in the blood. It has been established that the final stage in the formation of precocious fish in the population was characterized by the poor involvement of the thyroid gland in the maturation process of males and a significant decrease (by four times) in the rate of conversion of testosterone to estradiol-17β. This transformation in all studied females and males of brown trout was associated with their body length: the rate of conversion of estradiol-17β was increased with body length growth. [ABSTRACT FROM AUTHOR]

Simple Summary: The healthy management of fishery resources requires the evaluation of a series of population attributes, such as mortality, fecundity, spawning biomass, recruitment and the age at which fish reach sexual maturity. All these attributes depend on the age of fish. Then, the adequate administration and management of these resources require estimators of fish age. Age is estimated by ring counts in the otoliths, which are hard and calcified structures responsible for the balance of fish; however, this is an expensive and time-consuming methodology. An alternative is the use of otolith weight due to its expected relationship with fish age. Yellowtail king fish is a valuable resource, which arrives at the Chilean northern coast in the summer (southern hemisphere). Many aspects of the biology of this fish, such as age and growth, remain unknown. In this study, we estimated the age and growth using otolith weight, which was measured from fish with a known age, and we calculated parameters explaining growth using four different models. The best model was the seasonalized von Bertalanffy growth function, which takes into account that fish do not grow at the same rate year round. The age and growth of fish populations is a critical issue for stock assessment, population dynamics and fishery management. Spawner biomass, mortality, growth, recruitment and age at maturity can be misconstrued if the age estimator is inaccurate. Age can be estimated by annuli count, but this requires expertise and is expensive. Otolith weight (OW) is a good indicator of how long a fish has lived, because OW increases during an individual's life. Seriola lalandi is a migratory fish and is an important resource for local fishermen in northern Chile. Aspects of its biology, i.e., age and growth, remain unknown, at least for the population annually arriving in northern Chile. Fish of a known age (n = 105; from 5.5 to 25.7 cm in FL) from yellowtail aquaculture facilities at Universidad de Antofagasta allowed us to estimate the growth rate of OW, and fish obtained from local fishermen (n = 71; from 37.9 to 109 cm in FL) allowed us to estimate the age and growth of S. lalandi from the analysis of OW, without the need for calibration. The following four models were fitted with the known ages and fork lengths: the von Bertalanffy growth function, the Gompertz and logistic models and the seasonalized von Bertalanffy growth function. The latter model showed the best adjustment (according to the Akaike information criterion) with the following parameters: L∞, 98.58 cm.; K, 0.59; t0, 0.07; ts, 0.84; and C, 0.97. [ABSTRACT FROM AUTHOR]

European perch undergoes several ontogenetic dietary shifts during its lifetime. The present study focused on the variability in otolith shape caused by ontogenetic dietary changes in this species. A total of 172 specimens (7.5 to 27.5 cm TL) were caught by local fishermen in Lake Ladik from April to November 2019. Shape indices (SIs) and elliptic Fourier coefficients (EFCs) were calculated for each otolith. To detect ontogenetic changes in otolith shape, SIs and EFCs were compared among the three defined size classes (I, II, and III). Size-related groups were distinguished by both SIs and EFCs. Otolith shape analysis was more effective than morphometric analysis in distinguishing ontogenetic groups. Simultaneous use of both methods improved the classification success of each method alone. This study demonstrated that otolith shape of European perch is influenced by ontogenetic changes in diet. However, sexual maturity of the fish is also responsible for these variations in otolith shape. European perch undergoes several ontogenetic dietary shifts during its lifetime. The present study focused on the variability in otolith shape caused by ontogenetic dietary changes in this species. A total of 172 specimens (7.5 to 27.5 cm TL) were caught by local fishermen in Lake Ladik from April to November 2019. Shape indices (SIs) and elliptic Fourier coefficients (EFCs) were calculated for each otolith. To detect ontogenetic changes in otolith shape, SIs and EFCs were compared among the three defined size classes (I, II, and III). Size-related groups were distinguished by both SIs and EFCs. Otolith shape analysis was more effective than morphometric analysis in distinguishing ontogenetic groups. Simultaneous use of both methods improved the classification success of each method alone. This study demonstrated that otolith shape of European perch is influenced by ontogenetic changes in diet. However, sexual maturity of the fish is also responsible for these variations in otolith shape. [ABSTRACT FROM AUTHOR]

Background: Teleost fish are known to respond to environmental manipulation, which makes them an ideal model animal for testing relationships between the environment and behavior. The Siamese fighting fish, Betta splendens, is a solitary, highly territorial fish that displays fierce stereotyped aggressive behavior toward conspecifics or members of other species. Adult fish, especially males, are generally housed in isolation in captivity. Here we report evidence that an enriched rearing environment can decrease the level of aggression in bettas and enable adults to be housed in groups. Results: B. splendens individuals were hatched in our laboratory and raised in groups in an enriched environment. At the juvenile or subadult stage, some individuals were relocated to a poor environment and kept in isolation. To evaluate aggression, a mirror-image test was conducted at the juvenile, subadult, and adult stages for each fish, and body parameters as well as plasma concentrations of 11-ketotestosterone, estradiol, and cortisol were evaluated. Male and female adult bettas raised in a group showed lower levels of aggression than other adult fish. The magnitude of threatening behavior was greater in adult bettas isolated as subadults, whereas the magnitude of fighting behavior was grater in adult bettas isolated as juveniles. The influence of rearing conditions on behavior was greater in females than in males. Plasma cortisol concentrations of adult bettas isolated as subadults after the mirror-image test were higher than those in other experimental groups. Adult males isolated as subadults had significantly higher plasma concentrations of 11-ketotestosterone than males raised in a group and isolated as juveniles. Females isolated as subadults had a higher gonadosomatic index than females raised in a group and females isolated as juveniles. Conclusions: These results indicate that bettas can be kept in a group under enriched environments and that the timing of isolation influences the aggression and sexual maturity of bettas. Female and male bettas responded differently to environmental manipulation. Judging from their level of sexual maturity, bettas isolated as subadults show proper development. [ABSTRACT FROM AUTHOR]

Over the last century anthropogenic activities have rapidly increased the influx of metals and metalloids entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects on target organisms, having broad implications for human seafood consumers. We provide the first assessment of metal (Cd, Pb, Cr, Mn, Co, Cu, Zn, As, Ag, and THg) and metalloid (As) concentrations in the muscle tissue of coastal sharks from The Bahamas. A total of 36 individual sharks from six species were evaluated, spanning two regions/study areas, with a focus on the Caribbean reef shark (Carcharhinus perezi), and to a lesser extent the tiger shark (Galeocerdo cuvier). This is due their high relative abundance and ecological significance throughout coastal Bahamian and regional ecosystems. Caribbean reef sharks exhibited some of the highest metal concentrations compared to five other species, and peaks in the concentrations of Pb, Cr, Cu were observed as individuals reached sexual maturity. Observations were attributed to foraging on larger, more piscivorous prey, high longevity, as well a potential slowing rate of growth. We observed correlations between some metals, which are challenging to interpret but may be attributed to trophic level and ambient metal conditions. Our results provide the first account of metal concentrations in Bahamian sharks, suggesting individuals exhibit high concentrations which may potentially cause sublethal effects. Finally, these findings underscore the potential toxicity of shark meat and have significant implications for human consumers. [ABSTRACT FROM AUTHOR]

A wide range of classification schemes has been developed to describe reproductive development and stages in teleosts. These have been rationalised for clarity in recent years by Brown‐Peterson et al. (Marine and Coastal Fisheries, 2011, 3, 52–70) and the WKASMSF (ICES, Report of the workshop for advancing sexual maturity staging in fish (WKASMSF), 2018) working groups. These have largely benchmarked classification schemes with examples from seawater fishes but have not been routinely applied to freshwater species. In addition, classification schemes developed to assess maturation of fish ovaries are either macroscopic and can be used in the field or histological for laboratory‐based studies, and the two have rarely been coupled in the same classification scale or study. The present study reviews published maturation classifications for application to a freshwater teleost, ruffe Gymnocephalus cernuus L., sampled monthly over three annual cycles in Loch Lomond at locations in the extreme north and south ends of the loch. The gonado‐somatic index and size frequency distribution of oocytes were used to verify the annual reproductive cycle and spawning of several egg batches. The study showed that a paired modified Percid scale (Treasurer & Holliday, Journal of Fish Biology, 1981, 18, 359–376) and the Rinchard scale (Rinchard & Kestemont, Journal of Fish Biology, 1996, 49, 883–894) gave an improved macroscopic and histological description of maturation compared with and benchmarked against previous ovarian developmental classifications for G. cernuus. The attributes of these various classifications are benchmarked and compared with the Brown‐Peterson and WKMATCH scales, and the merits of these new notations are examined. [ABSTRACT FROM AUTHOR]

Effective fisheries management depend on having an exact assessment of biological parameters, including growth parameters, reproduction, size at sexual maturity (Lm), and stock assessment. The purpose of this research was to estimate the size at sexual maturity (Lm) for 20 fish species belongs to 14 families from a wetland (Gajner Beel) ecosystem in the north-western (NW) Bangladesh through multi-models such as length (Lmax) based empirical model, gonadosomatic index (GSI)-based model, and logistic model using commercial catches from January to December 2018. Also, we assessed the Lm in other water-bodies worldwide. Specimens' total length (TL) was noted up to 0.1 cm using measuring board body weight (BW) and gonad weight (GW) weighed by digital electronic balance with 0.01 g accuracy. To assess the Lm, maximum body length (Lmax) based empirical model; the relation between TL (total length in cm) vs. GSI (gonadosomatic index in %); and a logistic model were considered. The minimum Lm was 4.64, 3.90, and 4.15 cm for Chanda nama Hamilton, 1822 and the maximum was 25.33, 24.50, and 24.70 cm for Channa striata (Bloch, 1793) through Lmax, GSI, and logistic-based models, respectively. From these three models, the minimum mean Lm was 4.23 cm for C. nama and the maximum was 24.84 cm for C. striata. The Lm with 50.0% species was in 8.80 cm TL. We also calculated the Lm from different bodies of water based on Lmax. This study was generated data of 17 new Lm among 20 species, which are globally absent. Therefore, the study will help develop sustainable management strategies, conservation through the implementation of mesh size based on the size at sexual maturity (Lm). [ABSTRACT FROM AUTHOR]

Scale circuli yield valuable information about the life history, age, and growth of a fish. However, because circuli formation is influenced by somatic growth, the rate at which circuli are formed and the factors influencing these rates must be taken into account for the given life stage of the study species. Scales were collected from Atlantic salmon raised in marine net pens off of the coast of Maine in order to characterize the formation of scale circuli and the growth of scales during the ocean phase, and to relate circulus deposition and scale growth rate to water temperature. Fish were sampled 13 times over a period of 25 months. Neither circulus deposition rate nor growth rate were constant through time and the same trend held when circulus deposition and growth were related to thermal experience. Both rates decreased over the course of the study, presumably related to the fish reaching sexual maturity. The results of this study indicate that the pattern of circulus deposition and scale growth of Atlantic salmon vary greatly during the early marine phase, and this dynamic should be taken into account when assessing growth, especially over short time periods. [ABSTRACT FROM AUTHOR]

The size and age at which individuals mature is rapidly changing due to plastic and evolved responses to fisheries harvest and global warming. Understanding the nature of these changes is essential because maturity schedules are critical in determining population demography and ultimately, the economic value and viability of fisheries. Detecting maturity changes is, however, practically difficult and costly. A recently proposed biphasic growth modelling likelihood profiling method offers great potential as it can statistically estimate age-at-maturity from population-level size-at-age data, using the change-point in growth that occurs at maturity. Yet, the performance of the method on typical marine fisheries datasets remains untested. Here, we assessed the suitability of 12 North Sea and Australian species' datasets for the likelihood profiling approach. The majority of the fisheries datasets were unsuitable as they had too small sample sizes or too large size-at-age variation. Further, datasets that did satisfy data requirements generally showed no correlation between empirical and model-derived maturity estimates. To understand why the biphasic approach had low performance we explored its sensitivity using simulated datasets. We found that method performance for marine fisheries datasets is likely to be low because of: (1) truncated age structures due to intensive fishing, (2) an under-representation of young individuals in datasets due to common fisheries-sampling protocols, and (3) large intrapopulation variability in growth curves. To improve our ability to detect maturation changes from population level size-at-age data we need to improve data collection protocols for fisheries monitoring. [ABSTRACT FROM AUTHOR]

Length at first maturity (L50) is an important tool for the management and conservation of fish populations. Traditional approaches based on macroscopic and microscopic maturity staging exhibit high accuracy and precision, while alternative approaches (e.g., Ig‐based staging, stanza changing point) are less resource‐demanding. Herein, we compare four approaches to estimate L50 in a population of the heptapterid Rhamdioglanis transfasciatus from Atlantic Forest streams. Fish were sampled monthly during a year by using electrofishing. We measured the length (cm), mass (g), and gonad mass (g) of each specimen, then classified their maturity status macroscopically and microscopically. Alternative approaches were strongly discordant from traditional ones. Logistic curves considering mature individuals as those displaying at least 1% of the maximum Ig in the sample greatly underestimated L50 for females and overestimated L50 for males. The stanza changing point derived from the polyphasic growth model underestimated L50 in both cases. Despite the increasing development of less onerous approaches, it seems that they are not suitable for all fish populations and the requirements to use such approaches demand further investigation. [ABSTRACT FROM AUTHOR]

We outline a new flexible method for estimating maturity that incorporates skip spawning, which can lead to non-asymptotic behavior in the population maturity schedule. This new approach aids fisheries managers who seek to understand marine species' responses to changing oceans. In an effort to assess shifts in maturity and spawning behavior of west coast groundfish, we used this new method to evaluate spatio-temporal trends in length at maturity, the annual reproductive cycle, and spawning behavior of aurora rockfish (Sebastes aurora). We estimated biological (presence of physiological maturity markers) and functional (potential spawners in a given year) maturity using a standard logistic and the new flexible spline model. The range in lengths at 50% maturity (biological and functional) slightly varied between the two methods (23.66–23.93 and 25.34–25.57 cm). We also investigated spatial trends in maturity and found ~ 2 cm difference in functional maturity between fish sampled north and south of Cape Mendocino, CA (26.22–26.48 and 24.38–24.74 cm). We demonstrate model sensitivity by updating the maturity estimates in the 2013 aurora rockfish stock assessment. Absolute, but not relative, spawning output, was sensitive to model choice, spatial resolution, and the updated data. This new flexible spline model can account for skip spawning, capturing potential spawners in a given year, and thus provides accurate measurements for spawning output models. [ABSTRACT FROM AUTHOR]

Neolissochilus hexagonolepis (McClelland, 1839) is one among the notable species in snow-fed torrential rivers of Nepal. The present study attempts to investigate some reproductive traits of N. hexagonolepis, including the length at first maturity, fecundity and its relationships with biometric variables like lengths (TL, SL, and FL) and weights (TW and OW) of the fish in the mi dreaches of Tamor River, Nepal. A total of 109 fish samples were collected from the river. For each individual, total length (TL), standard length (SL) and fork length (FL) were measured in a fully stretched condition to the nearest 1mm using a measuring tape and graduated ruler, while total weight (TW) and ovary weight (OW) was measured using a digital balance with the precision of 0.01 g. The mean absolute fecundity (F) was 8356.44 ± 4612.59 and ranged from 2398.6 to 20160. SL was more significantly correlated with absolute fecundity (R2=0.59; p<0.001) than other body metrics. The results showed that female individuals of N. hexagonolepis attained the first sexual maturity at TL 32.9 cm. N. hexagonolepis exhibited a protracted breeding period with its ovaries passing through six different stages of maturation. The finding of the present study may serve as a protocol for fishery biologists and managers to promulgate adequate regulations for continual fishery management in the River Tamor, Nepal. [ABSTRACT FROM AUTHOR]

In order to provide biological evidence of the real impact of mosquito seine nets in southwestern Madagascar, an efficient procedure for determining the size at maturity of small‐sized tropical fishes was developed. The fishes caught by two small‐scale fishermen were studied between October 2017 and April 2018. One catch per day was analyzed three days per month during the full‐moon period. In the laboratory, fishes were all sorted by morphospecies, photographed and measured. One individual per morphospecies was selected for being identified using CO1 DNA barcoding. A total of 34,051 individual fishes belonging to 144 DNA bacoded species from 48 families was obtained from 42 samples, 467 individuals from 22 morphospecies that had not been successfully barcoded were excluded from the analyses. The macroscopic observations of 8,143 individuals between 0.7 and 10 cm SL indicated the proportion of individuals with clearly observable gonads was 15% only.Among the 144 species identified via DNA barcoding, 83 consisted of individuals that were all without clearly observable gonads, seven of individuals that were all with clearly observable gonads and 54 included of individuals with and without clearly observable gonads. As the determination of L50 using logistic general linear models failed for most species, the minimum size at maturity was retained to determine the proportion of juveniles and adults for these 54 species. Compared to the data available in FishBase, the minimum size at maturity appears more adequate to discrimine juvenile from adult fish of small‐sized tropical species. [ABSTRACT FROM AUTHOR]

Placental maturity grading (PMG) is quite essential to assess fetal growth and maternal health. To this date, PMG has mostly relied on the subjective judgment of the clinician, which is time-consuming and may cause wrong estimation due to redundancy and repeatability of the process. To tackle it, we propose an automatic method to stage placental maturity via deep hybrid descriptors based on B-mode ultrasound (BUS) and color Doppler energy (CDE) images. Specifically, convolutional descriptors extracted from multiple deep convolutional neural networks (DCNNs) and hand-crafted features are integrated to get the hybrid descriptors for grading performance boosting. First, different models with various feature layers are combined to obtain hybrid descriptors from images. Second, the transfer learning strategy is also utilized to enhance the grading performance via the deeply represented features. Third, extracted descriptors are encoded by Fisher vector (FV). Finally, we use support vector machine (SVM) as the classifier to grade placental maturity. The experimental results demonstrate that our proposed method could achieve good performance in PMG. [ABSTRACT FROM AUTHOR]

Inadequate ambient temperature along with short photoperiod, during five winter months (November to March) is one of the major hindrances in development of aquaculture sector in the NE region of India, which besides hampering in growth and production of fish also cause mismatching in between culture period and availability of stocking material, leading to poor performance of the available culture resources. To address this issue, a study on the impact of artificially enhanced temperature and photoperiod during winter months on sexual maturation and breeding of cultivable fish species was undertaken at Fisheries Research Centre, AAU, Assam, NE India, by taking a minor carp Labeo gonius (Ham) as the test fish. The water temperature of the experimental pond was maintained at 26±2°C during winter months (normal average temperature 14.8±8°C), by using Polyhouse made of UV stabilized LDPE film over a concrete pond and water heating system. The photoperiod was increased by 2.0±0.5 hours per day inside the polyhouse by artificial illumination. The results indicated that optimum water temperature (26.0±2°C) and enhanced photoperiod during the winter months had significant positive impact by way of rapid gonadal development and early sexual maturity of the test fish. Successful induced breeding in advance (70±6 days ahead of the normal breeding period) could be achieved in the experimental pond with 90.0±10% spawning success, 85.0±5% fertilization & 90.0±5% hatching rate. The results of the study pave the way for developing a protocol for advance breeding of different carp species by artificially enhancing temperature and photoperiod, thereby addressing the issue of non availability of stocking material at proper time of stocking in the region. [ABSTRACT FROM AUTHOR]

The gonadal maturation of the pleasure oyster Crassostrea corteziensis during four cultivation cycles (November 2004-June 2005, N4J5; August 2014-February 2016, A14F16; September 2015-December 2016, S15D16; September 2016-August 2017, S16A17) was studied in the southeastern Gulf of California, Mexico. Although C. corteziensis exhibited the typical reproductive phases (undifferentiated or resting, initial gametogenesis, advanced gametogenesis, maturity, spawning and post-spawning), the intensity of reproduction and the timing of the onset of the different phases of gonadal development varied in each cultivation cycle. Reproductive peaks were observed in different months (N4J5 in May, A14F16 in July, S15D16 in May and S16A17 in June) during spring and summer. Spawning correlated with temperature in the N4J5 and A14F16 cultivation cycles but it showed no correlation with chlorophyll-a concentration in any of the cultivation cycles. C. corteziensis presented an opportunistic continuous reproductive strategy with spawning occurring during several months of the year. The modification of the species' reproduction pattern could contribute to the natural settlement of larvae, increasing the natural production of this native oyster resource in the southeast of the Gulf of California, where it has been fished intensively. [ABSTRACT FROM AUTHOR]

Grass carp Ctenopharyngodon idella have been widely introduced in aquatic ecosystems to combat outbreaks of problem aquatic plants. However, the extent to which introduced carp stray from intended habitats and ecosystems is frequently unevaluated. Grass carp were stocked into a temperate riverine and montane reservoir (Claytor Lake, VA USA) to control a rapidly spreading Hydrilla verticillata infestation. Fish introductions sparked concern that grass carp might exit the reservoir and impact adjacent river ecosystems and native plants. We conducted a 2-y telemetry study concurrent with annual grass carp stockings in Claytor Lake to investigate migration potential, habitat use, and annual survival of recently introduced grass carp. We radio-tagged 34 and 45 juvenile grass carp in 2011 and 2012, respectively. In both years, grass carp movements were highest during the first month post-stocking and declined dramatically thereafter, presumably due to carp settling in areas with high hydrilla biomass. Only 3% of radio-tagged grass carp exited the reservoir upriver over the study period. Statistical modeling indicated grass carp movements were driven largely by temperature, while other climatic (e.g., wind speed and barometric pressure) and habitat variables (depth, vegetation coverage) were occasionally also important. Year-1 survival of grass carp was 44% for the 2011 cohort, and 25% for the 2012 cohort. Even though young grass carp did not express an inclination for out-reservoir migrations during the study, these patterns may change as fish approach sexual maturity, hydrilla coverage declines, and divergent climate variations occur. We recommend managers continue monitoring grass carp movements alongside changes to the spatial and temporal dynamics of hydrilla in the reservoir over time. [ABSTRACT FROM AUTHOR]

We assessed the effects of sexual maturity on space use in Atlantic salmon (Salmo salar) parr as facultative early maturation enables us to work on individuals belonging to the same cohort. We monitored the space use of 40 1‐year‐old males in natura throughout a breeding season. First, mature individuals covered longer distances (absolute and upstream) and located within broader home ranges than immature parr. Second, sexual maturity also generated a higher interindividual variability in space use. Finally, mature individuals exhibited a higher probability of association with likely breeding sites on average. However, some mature individuals experienced a lower probability than immature individuals, suggesting that the space use of some mature individuals may not be optimal. Moreover, mature parr exploiting a broader home range or covering longer upstream distances had a higher probability of association with likely breeding sites. Covering longer upstream distances may therefore increase the reproductive success of mature parr, while involving higher energetic costs and a greater risk of predation. [ABSTRACT FROM AUTHOR]

The age of sexual maturity of the Atlantic bluefin tuna (Thunnus thynnus; ABFT) is a reference point for stock assessment and management. The International Commission for the Conservation of Atlantic Tunas (ICCAT) recognizes a western and an eastern Atlantic ABFT stock, based on the assumptions of separate, exclusive spawning grounds, i.e., the northern Gulf of Mexico and the Mediterranean Sea, with different ages of sexual maturity, 8–12 years vs 3–5 years, respectively. Multiple line of evidences indicate that spawning is not restricted to the Gulf of Mexico and the Mediterranean Sea, and reconsideration of historical documents, as well as results from recent studies, indicate that sexual maturation schedules of the two proposed stocks are similar (3–5 years). The present review of classical and recent literature suggests that ABFT have more complex reproductive behavior than previously considered: on eastern spawning grounds 50% of ABFT females reproduce at 3 years of age and 100% are sexually mature at 5 years of age. In the western management area, younger adults (age ≥ 5 years) and some larger adults apparently spawn in the northwest Atlantic Ocean across the Slope and Caribbean Seas, whereas the Gulf of Mexico spawners are mostly large adults (age ≥ 8 years). [ABSTRACT FROM AUTHOR]

The muscle and textural parameters were analyzed in four myotome zones (epaxial upper, hipoaxial upper, epaxial bottom, and hipoaxial bottom) in seven diploids (D) and seven triploids (T) turbot specimens. Diploid specimens showed the highest values of the size and number of white fibers in the epaxial zones, being such values higher in female than male specimens. In triploid specimens, the highest fibers sizes were found in the upper zones (epaxial and hipoaxial), whereas the lowest number and density of fibers were found in the epaxial upper zone. In this latter group (T), the lowest fibers sizes were found in female specimens, whereas the rest of the parameters were usually higher in female than male specimens. When comparing both groups, the hypertrophy was higher in T than D in all zones. In both ploidy groups, the highest textural values were usually observed in the upper epaxial fillet, being slightly higher in female than male specimens. The values of standard length, total weight, gonad weight, gonadosomatic index and gutted weight were higher in female than male specimens in both groups (D and T). [ABSTRACT FROM AUTHOR]

Background: Understanding genetic architecture is essential for determining how traits will change in response to evolutionary processes such as selection, genetic drift and/or gene flow. In Atlantic salmon, age at maturity is an important life history trait that affects factors such as survival, reproductive success, and growth. Furthermore, age at maturity can seriously impact aquaculture production. Therefore, characterizing the genetic architecture that underlies variation in age at maturity is of key interest. Results: Here, we refine our understanding of the genetic architecture for age at maturity of male Atlantic salmon using a genome-wide association study of 11,166 males from a single aquaculture strain, using imputed genotypes at 512,397 single nucleotide polymorphisms (SNPs). All individuals were genotyped with a 50K SNP array and imputed to higher density using parents genotyped with a 930K SNP array and pedigree information. We found significant association signals on 28 of 29 chromosomes (P-values: 8.7 × 10−133–9.8 × 10−8), including two very strong signals spanning the six6 and vgll3 gene regions on chromosomes 9 and 25, respectively. Furthermore, we identified 116 independent signals that tagged 120 candidate genes with varying effect sizes. Five of the candidate genes found here were previously associated with age at maturity in other vertebrates, including humans. Discussion: These results reveal a mixed architecture of large-effect loci and a polygenic component that consists of multiple smaller-effect loci, suggesting a more complex genetic architecture of Atlantic salmon age at maturity than previously thought. This more complex architecture will have implications for selection on this key trait in aquaculture and for management of wild salmon populations. [ABSTRACT FROM AUTHOR]

Effective stock assessment relies on the evaluation of the reproductive potential of a population, but this is often achieved using fast, inexpensive, and inaccurate macroscopic indicators of gonadal maturity. Indeed, this approach suffers from high error rates as a result of misclassification and operator errors. Although histology is considered the gold standard to assign reproductive stages, it represents a time‐consuming and expensive method. Therefore, cost‐effective approaches are currently needed to assess the species‐specific reproductive potential and define the correct size at first maturity (L50).In the present study a histology‐calibrated method based on the gonadal index (GI) was developed to assign maturity stages to the overfished Mediterranean swordfish (Xiphias gladius), supported by histological classification of gonadal development, an estimation of L50, and an analysis of the reproductive output of this species.The performance of this new method had an overall agreement of 90% with histological data, and the L50 calculated by the GI‐based method compared with histology analysis was not statistically different (p > 0.05). Moreover, in order to apply this method without bias, a thorough validation of the relationship between length and gonad weight was carried out and the suitability of the GI to compare individuals of different size and maturity stages was confirmed.The present findings provide a comprehensive picture of the patterns characterizing Mediterranean swordfish reproduction and a promising method to assign maturity stages based on a macroscopic indicator. This method has the potential to be extensively applied during routine fish sampling activities in the field because of its simple requirements. [ABSTRACT FROM AUTHOR]

Growth studies on Anomura, especially hermit crabs, are relatively limited, due to the complexity in constructing generalized growth models as well as the heterogeneity of the group. Despite Diogenes alias being one of the most abundant species in the study area, there is a lack of information regarding its sexual dimorphism and maturity. The present study aims to evaluate its ontogenic allometry, using Jolicoeur's multivariate allometric coefficient. The specimens were collected biweekly from trawl fishing grounds off the Mumbai coast for one year. Sexual dimorphism was patent at the larger cheliped width in males and the wider shield width in females, which was attributed to the differential energy allocation by both male and female. The size of morphological sexual maturity was established at 7.6 mm shield length for males, and at 6.2 mm in females. [ABSTRACT FROM AUTHOR]

This study investigates how age at first maturity of two tropical amphidromous species Sicyopterus lagocephalus (Pallas, 1770) and Cotylopus acutipinnis (Guichenot, 1863) varies in relation to their larval and juvenile life history. Reproductive stage was estimated based on histological observation of ovaries of more than 200 females of each species caught monthly over 1 year. The age of fish was estimated by interpreting the daily increments deposited on otoliths during the oceanic larval phase, and the juvenile phase in the river. The age at first maturity was approximately 9 months for S. lagocephalus and 7 months for C. acutipinnis, corresponding to approximately 70–130 and 90–130 days after they returned to freshwater respectively. For both species, the time spent in freshwater before maturity was significantly influenced by the duration of the pelagic larval stage at sea (PLD) and the season of return in freshwater. Individuals with a long PLD, or returning in freshwater during the warmer season, maturated faster once in freshwater. This reproductive advantage may minimise the risk of extirpation due to catastrophic events at each generation and thus probably benefits amphidromous species living in very unpredictable tropical rivers. [ABSTRACT FROM AUTHOR]

Specific impacts of somatic growth, sexual maturation, and spawning events on otolith zone formation in Atlantic cod (Gadus morhua) were assessed in a 33-month tank experiment, using Barents Sea cod and Norwegian coastal cod. High and low feeding ration combinations were used to mimic environmental stressors in the field. For both stocks, apparent macrostructural "spawning zones" in otoliths are registered in statutory stock monitoring programs to estimate age at maturity, thus adding key information to stock biomass assessments. We found that substantial energy investments in reproduction caused reductions in otolith growth and altered proportional width between translucent and opaque zones. These effects, however, were only statistically significant among individuals with high reproductive investments, while otoliths from individuals with low investments did not differ from the otoliths for immatures. Reproduction may thus not necessarily induce spawning zones, and alternatively, spawning zones may not necessarily reflect reproduction. Altogether, this suggests that the individual energy level, as a premise for metabolic activity, plays a key role in the formation of such zones and thus is related to environmental conditions. [ABSTRACT FROM AUTHOR]

The live-bearing genus Sebastes is renowned for its outstanding species richness and color diversity, and its speciation has been a point of interest. This study investigated the age, growth, reproductive biology, color pattern and ontogenetic divergence of a pair of closely related rockfishes from the coasts of the Shandong Peninsula, namely, Sebastes koreanus (n=879) and S. nudus (n=257). Marginal increment analysis of sectioned otoliths showed that annulus formation occurred once a year between June and July in both species. The sex-pooled growth curves of S. nudus and 3 populations of S. koreanus differed significantly from each other. No apparent latitudinal cline in growth parameters was found in S. koreanus. For both species, the peak parturition periods were from April to May, and the peak copulation periods were from November to December. S. nudus has a highly variable and conspicuous color pattern while S. koreanus has a stable and dull color pattern. This difference, together with the overlapping distribution and the close relationship, make S. koreanus and S. nudus an ideal model to investigate the color-driven speciation of the Sebastes. We confirmed that S. nudus changes its body color with age and season and fully expresses the carotenoid-based nuptial coloration when the fish reaches first maturity. Moreover, our comparisons of morphological traits that are likely related to survival and quality of these fishes suggested that S. nudus may suffer higher predation risk and foraging difficulty beginning at age 3. In light of the ontogenetic development of the color pattern in S. nudus, we suggested that the full expression of nuptial coloration most likely triggers the strong selective pressure to enhance swimming performance, anti-predator defense and foraging capacity of S. nudus through predator-prey interactions. By understanding all these details, we further inferred a hypothesis that both color pattern and bathymetric segregation play key roles in facilitating the speciation of demersal rockfishes. [ABSTRACT FROM AUTHOR]

The shrimp Potimirim brasiliana plays an important role in streams along the Brazilian coast as it feeds on the organic debris from the surrounding ecosystem. We determined the morphological sexual maturity of P. brasiliana by means of relative growth. Monthly throughout a year, we used sieves (2 mm mesh diameter) to collect the specimens in a coastal stream. A total of 3,521 specimens had their carapace length (CL) measured, as well as their second pleura length (PL) and the length (AML) and width (AMW) of the appendix masculina. The studied relationships were the following: CL vs. PL; CL vs. AML and CL vs. AMW, with the data adjusted to a logistic equation. All the relationships tested among the demographic groups differed statistically. The CL50 of females measured 3.45 mm, while the CL50 of males measured 2.75 mm. Two adult morphological groups were set apart for each sex. The CL vs. AMW relationship is the best at demonstrating the separation of the morphological groups for males. This fact is an intriguint issue as it suggests the presence of morphotypes in males, probably, playing different roles in the reproductive process. [ABSTRACT FROM AUTHOR]

The present study investigated a non‐invasive method based on macroscopic morphological features of male Clarias gariepinus for the assessment of sexual maturity stage. As African catfish cannot be stripped for semen as in most other fish species; they have to be killed to obtain semen from the testes. This method could be used to ensure that males used to obtain sperm are sexually mature to increase the concentration and quality of mature sperm for egg fertilization in the production of C. gariepinus. Morphological features including the length and width of the urogenital papillae (UGP), an external secondary sexual characteristic of C. gariepinus (n = 89) were measured and calculated as a percentage of total body length. The urogenital papillae length (LUGP) and width (WUGP) index of each fish were used and compared with the macroscopic and microscopic maturity stage of the testes. The results revealed that although positive, a significant correlation does not exist between the LUGP or WUGP and maturity stage of the testes. Therefore, although this procedure would be valuable as an initial non‐invasive assessment of maturity, it does not provide an accurate or reliable indication of the maturity stage of the fish. [ABSTRACT FROM AUTHOR]

Small-bodied coastal sharks are often caught as by-catch in fishing operations. Life-history information for these sharks is needed to ascertain the level at which these populations are potentially affected by fishing. This study determined the age, growth and maturity of Carcharhinus coatesi captured by prawn trawlers in the Gulf of Papua. Using vertebral aging and an information-theoretic multimodel approach, the von Bertalanffy growth model fit the data best; parameters were L0 = 40.6 cm ± 0.8, L∞ = 74.8 cm ± 2.1, k = 0.33 year−1 ± 0.06. Length-at-maturity analysis indicated that males reach maturity at L50 = 66.3 cm (CI: 63.8, 71.4) and L95 = 71.6 (CI: 64.6, 74.2) cm while females matured at L50 = 71.4 cm (CI: 61.5, 72.01) and L95 = 72.5 cm (CI: 62.7, 74.0). Age-at-maturity estimates showed that both males (A50 = 5.1 years (CI: 4.6, 7.1), A95 = 6.4 years (CI: 5.1, 7.2)) and females (A50 = 5.3 years (CI: 3.5, 8.7), A95 = 7.4 years (CI: 3.6, 8.8)) reach maturity at about the same age. This study addresses the need for specific life-history information for a data-deficient species in a region that has remained relatively under-researched but in need of ongoing improvements to fisheries management. This study addresses the need for region-specific life-history data to improve fisheries management. The Australian blackspot shark is commonly caught as by-catch in the Gulf of Papua prawn trawl fishery. We found that this shark species is relatively fast growing and reaches maturity at approximately five years of age in this region of Papua New Guinea. [ABSTRACT FROM AUTHOR]

Alligator Gars Atractosteus spatula are being cultured to restore populations in areas of their historical occurrence or abundance. This phylogenetically ancient species can be long‐lived and reach a large body size. Broodfish development has been considered an obstacle for aquaculture because of the species' advanced age at maturity and unpredictable volitional spawning, requiring large animals to be injected with spawning‐inducing hormones. This species has been the focus of a collaborative conservation program involving universities in the southeastern United States and Mexico. Alligator Gars from eggs fertilized in Louisiana on May 2, 2013, were brought to Florida, where they matured, spawned without hormone induction, and produced viable larvae before April 25, 2017. A rapid change in osmotic environment directly preceded this spawning event. Data on Alligator Gar life history are limited, and this fundamental observation provides novel information on the age of sexual maturity. Ovarian development indicating sexual maturity in similar‐aged fish previously has been described from dissections of otolith‐aged specimens, but this article describes the earliest reported spawning of known‐age fish. [ABSTRACT FROM AUTHOR]

The present study express the biometry, including length-weight relationships (LWRs) using 12 equations, length-length relationships (LLRs) using 15 equations, condition factors (allometric, KA; Fulton's, KF; relative, KR; and relative weight, WR), form factor (a3.0), first sexual maturity (Lm), natural mortality (MW) and fecundity (FT) of Dermogenys pusilla from the Ganges River, northwestern Bangladesh. A sum of 75 individuals was hardly collected using cast net and gill net during July 2013 to June 2014. In our study total length ranged from 6.6-16.1 cm for male and 7.5-15.6 cm for female and fin formula was- dorsal, D. 12 (4/8); pectoral, P1. 11 (2/9); pelvic, P2. 6 (1/5); anal, A. 13-14 (2-3/11-12) and caudal C. 18-20 (4/14-16). All LWRs were highly significant (P < 0.001) and based on highest value of r2, BW vs. FL was the best fitted model among 12 equations for both sexes. The analysis of covariance (ANCOVA) revealed significant differences between males and females for LWRs (P < 0.001). Also, all LLRs were highly correlated (P < 0.001) with r2 values = 0.940. According to highest value of r2, LLR by TL vs. FL was the best suited model among 15 equations for both genders. Based on Pearson correlation values, KF was highly correlated with BW and TL; thus KF can be used for the wellbeing of this species in the Ganges River. The a3.0 was 0.0025 for male and 0.0024 for female. The Lm was 9.70 cm TL for male and 9.40 cm TL for female. Also, the MW was 1.13, 1.41 year-1 for males and females respectively, and the fecundity was ranged from 620-1544 (mean ± SD = 1125 ± 248). Therefore, the findings of this study would be very effective for sustainable conservation of this endangered species in the Ganges River and surrounding ecosystem. [ABSTRACT FROM AUTHOR]

The study of otolith morphometry is a tool widely used in numerous studies of fish populations (fish stocks, taxonomic, ecological, ontogeny, among others). The aim of this study was to detect ontogenetic variations in the otolith of Odontesthes argentinensis through the application of traditional and geometric morphometry and the association of these variations with ecological and trophic habits of the species. Fish (52 to 360 mm TL) were collected seasonally between years 2013–2016 in the southwest coast of the Atlantic Ocean (36°39'30.96"S - 56°40'40.09"W). Otolith shape indices (circularity, rectangularity, aspect ratio and surface occupied by sulcus) and Fourier descriptors were measured and compared through ontogenetic stages (I, II and III). The three stages analysed in the present study were differentiated by both traditional and geometric morphometry. The four analysed indices showed significant differences between stages (ANOVA Kruskal Wallis test, P < 0.001) and a simultaneous analysis of the morphometric variables also showed significant differences (Hotelling's T2 < 0.001). The quadratic discriminant analysis performed on the Fourier descriptors showed a clear separation for each defined group. Therefore, the use of both methodologies simultaneously could be considered robust to evaluate the ontogenetic variations in this species. The observed changes could be associated to changes in the habitat throughout its development, to the sexual maturity of fish and to dietary shifting of these organisms. [ABSTRACT FROM AUTHOR]

Arctic char, Salvelinus alpinus L. is a promising candidate for aquaculture expansion in Northern Europe, Canada, and the United States because of its excellent growth at low temperature, tolerance to high rearing density, high fillet yield, and superior flesh texture and flavor. To support this industry, several breeding programs in these regions currently focus on selection for growth and delayed maturation. While the growth potential of existing strains has been improved, preharvest sexual maturation remains a problem in this industry. This article describes current knowledge on the control of preharvest maturation in Arctic char at the hatchery level through the production of single‐sex and triploid populations and during the grow‐out phase through the manipulation of photoperiod and feed intake. Research perspectives on the subject are also suggested in order to complement the efforts of ongoing breeding programs. [ABSTRACT FROM AUTHOR]

College websites are websites that are used as media and means of campus information. Since the website is widely accessible, the level of security on the website must always be maintained. To see the level of web security, it can be done by testing the security vulnerability of the web. The test results using the tools Nessus and Skipfish, on the websites of several universities in Jakarta, show that there are still several vulnerabilities. This vulnerability will affect the maturity level of the web site security. The results of vulnerability testing show that as many as 60% of the total 33 web sites have a maturity level below number 3. This indicates that the level of vulnerability on the web site is still high. [ABSTRACT FROM AUTHOR]

There is growing evidence across taxa for a mortality-growth rate tradeoff, however the extent to which individuals experience selection both for and against growing faster in the wild can be difficult to assess. We used otoliths to assess growth rates in the wild for Xiphophorus multilineatus, a species of swordtail fish with genetically influenced male alternative reproductive tactics. The ARTs are thought to be maintained due to a trade-off between a higher probability of reaching sexual maturity (smaller sneaker males) and maturing later as a large male with higher mating success (larger courter males). We show that the early juvenile growth rates of the subadult courter males were faster as compared to the other juveniles, potentially suggesting selection for growing faster to increase the probability of reaching sexual maturity. However, variance in the early juvenile growth rates of adult courter males was reduced (truncating high values) as compared to the subadult courter males and overall growth rates were faster in the subadult courter males than the adult courter males. These results support a cost of growing faster as juveniles: reduced longevity as an adult. We also detected a negative relationship between the early growth rates of females and their age, further supporting a longevity cost to growing faster. While both male ARTs are likely to experience stabilizing selection on growth rates, the differences between the morphs in how they optimize this tradeoff in relation to overall fitness (courters optimize growing faster to increase probability of reaching sexual maturity, sneakers optimize longevity as adults) has the potential to lead to disruptive selection between the ARTs on growth rates. We show that the data collected here is consistent with the "growth-mortality optimization" hypothesis and highlight some of the challenges that stabilizing selection presents for examining adaptive variation of growth rates in a natural environment. [ABSTRACT FROM AUTHOR]

Male reproductive biology is described for the Southern Hemisphere long-finned pilot whale (Globicephala melas edwardii), a subspecies that regularly mass strands along the New Zealand coastline. Ten mass stranding events sampled over a 7-year period enabled assessments of key life history parameters. Sexual maturation in immature, maturing, and mature males was assessed using morphological data and histological examination of testicular tissue. Variation was observed in the age (11–15 years) and length (450–490 cm) at which individuals attained sexual maturity. Using Bayesian cumulative logit regression models, we estimated the average age and length at the attainment of sexual maturity to be 13.5 years and 472 cm, respectively. Combined testes weight, combined testes length, an index of testicular development (combined testes weight/combined testes length), and mean seminiferous tubule diameter were all good indicators of sexual maturity status. Combined testes length was the best nonhistological indicator, and all testicular measures were found to be better indicators of sexual maturation for G. m. edwardii than age or total body length. Sexual maturity was attained before physical maturity (> 40 years and 570 cm), and at a younger age and smaller body length than previously reported for Globicephala melas melas in the North Atlantic. Given the ease of collection, minimal processing, and applicability to suboptimal material collected from stranding events, future studies should assess the value of testicular size as an indicator of sexual maturity in pilot whales and other cetacean species. Estimates of the average age and length at sexual maturity for G. m. edwardii provided in this study may be used to inform population models required for conservation management of the subspecies, which is subject to high levels of stranding-related mortality. [ABSTRACT FROM AUTHOR]

The horse mackerel is a pelagic marine species of commercial interest at the Romanian Black Sea coast. The present study presents the analysis of the age of horse mackerels at the first sexual maturıty. For the determination of age, the method used was the interpretation of the otoliths, these are bone structures located in the inner ear. Age of sexual maturity of horse mackerel is 1-2 years. As a general rule, a fish population is considered to be in a good condition when the age at first sexual maturation exceeds 30% of the individuals present in the catch. The analyzed periods were 2012-2015 and 2016-2017. In the period 2012-2015, the percentage of the age of the first sexual maturation exceeded the 30% threshold compared to the 2016-2017 period when a decrease was recorded. The reduction is mostly due to fishing pressure on these species. In conclusion, it can be said that the horse mackerel population on the Romanian Black Sea coast is not in good condition status, and measures are needed to conserve the population. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the reproductive dynamics of the Litopenaeus schmitti through macroscopic and microscopic analyses. Specimens were collected monthly from December 2016 to November 2017 through artisanal beach seine fishery in the municipality of Lucena, state of Paraíba, Brazil. A total of 1710 shrimp were caught and the proportion of males was significantly lower than that of females (43.51% and 56.49%). The ovarian maturation stages were classified as immature, initial development, advanced development, mature and spent. These classification criteria added an additional stage than those previously reported for this species on the Brazilian coast. The proportion of ovarian maturation stages per month suggest a seasonal reproductive cycle that extends from September to June, with no reproductive activity occurring in July and August. The reproductive activity was directly related to the precipitation and salinity in the area of the present study. Mean cephalothorax length at first gonad maturity for females (2.20 cm) was larger than values reported 13 years ago for this species in the same area. This finding may indicate that the prohibition of motorized trawler fishing in the area since 1990 is contributing to the more sustainable exploitation of this resource. [ABSTRACT FROM AUTHOR]

Mate choice in most organisms is not random, but determined by a suite of interacting traits and environmental factors. While the selective pressures underlying differences in mate choice between species, populations, individuals and even within individuals has been gaining interest, there still remains unexplained variation in mate preferences especially in non-model systems. Despite being of social, environmental and economic importance there is comparatively little known about how salmonids and other tetraploids make mate choice decisions in the wild and the resultant reproductive success (i.e. the number of offspring which survive to sexual maturity). Resolving questions related to salmonid mate choice is of particular importance given that humans have been supplementing salmon populations through aquaculture for decades. Despite these efforts, hatchery produced fish have lower reproductive success relative to their wild counterparts and salmon populations are declining. Most studies on mate choice and reproductive success in salmonids focus on body size and major histocompatibility complex based choice. However, mate choice can also be affected by other factors including other genetic factors, predation risk and social environment. Here, we (a) synthesize what is presently known about mate choice and reproductive success in salmonids, (b) identify gaps in knowledge and areas where there is a lack of consensus in results, and (c) suggest interdisciplinary ways of advancing our understanding of mate choice in salmonids and other polyploids. [ABSTRACT FROM AUTHOR]

The average size at first |maturity (L50) is among the most important parameters for fisheries management and conservation. This paper aims to compare three different methods for its estimation. Considering a classical approach, a logistic model was used (a) by determining the gonadal stage macroscopically; and (b) by using the GSI as proxy of sexual maturity; and finally; (c) by using the length–weight relationship (LWR) in a theoretical approach. The proposed methods were applied using data of a detritivorous fish, Cyphocharax abramoides, monthly sampled using gill nets. Captured individuals were measured, weighed, sexed and the gonadal stage was classified macroscopically and weighed. Estimated L50 values using the macroscopic identification, GSI approach and LWR were not different from each other considering confidence intervals. Between the three different techniques, we concluded that the analysis of the LWR in fishes with polyphasic growth presented promising results as it only requires length and weight data to be performed and estimate a L50 within the range of both classical logistic models analysed. [ABSTRACT FROM AUTHOR]

Co‐inheritance in life‐history traits may result in unpredictable evolutionary trajectories if not accounted for in life‐history models. Iteroparity (the reproductive strategy of reproducing more than once) in Atlantic salmon (Salmo salar) is a fitness trait with substantial variation within and among populations. In the Teno River in northern Europe, iteroparous individuals constitute an important component of many populations and have experienced a sharp increase in abundance in the last 20 years, partly overlapping with a general decrease in age structure. The physiological basis of iteroparity bears similarities to that of age at first maturity, another life‐history trait with substantial fitness effects in salmon. Sea age at maturity in Atlantic salmon is controlled by a major locus around the vgll3 gene, and we used this opportunity demonstrate that these two traits are co‐inherited around this genome region. The odds ratio of survival until second reproduction was up to 2.4 (1.8–3.5 90% CI) times higher for fish with the early‐maturing vgll3 genotype (EE) compared to fish with the late‐maturing genotype (LL). The L allele was dominant in individuals remaining only one year at sea before maturation, but the dominance was reversed, with the E allele being dominant in individuals maturing after two or more years at sea. Post hoc analysis indicated that iteroparous fish with the EE genotype had accelerated growth prior to first reproduction compared to first‐time spawners, across all age groups, whereas this effect was not detected in fish with the LL genotype. These results broaden the functional link around the vgll3 genome region and help us understand constraints in the evolution of life‐history variation in salmon. Our results further highlight the need to account for genetic correlations between fitness traits when predicting demographic changes in changing environments. [ABSTRACT FROM AUTHOR]