Search

The reproductive biology of the invasive blue crab Callinectes sapidus was studied in the Thermaikos Gulf (Northwest Aegean Sea, Eastern Mediterranean). In the two-year survey, 5698 (2897♂/2801♀) crabs were caught with the use of fyke nets. Total sex ratio (♂/♀) reached equality (1.03:1). The female blue crab exhibited a protracted reproductive period. Mature and ovigerous females exhibit short migratory movements from estuarine and inshore waters, where the population mostly congregates (0–3 m), and move to slightly deeper waters (1–3 m) up to 9 m for spawning. A total of 340 ovigerous females were caught. Their number varied both spatially and temporally; they were observed for a 7-month period (April to October) with a clear peak in July–August and at a 3 m depth gradient corresponding to ≈60% of the total number of ovigerous females caught in both years. Size at first sexual maturity (CW50) was estimated at 113.1 mm CW. Average fecundity was ≈790,000 eggs. Experimental trawling showed that inshore waters (<1 m) in the estuaries serve as nursery areas for juveniles. Defining the spatiotemporal and bathymetrical distribution of ovigerous females in any invaded coastal habitat could be considered key information for the implementation of a management policy for the species. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the growth parameters and age-length relationships of the sandbird octopus (Amphioctopus aegina) along the coast of Chao Samran Beach, Phetchaburi Province, Thailand. This included determining reproductive stages, the gonadosomatic index, and size at first maturity. A total of 1436 specimens comprising 782 males and 654 females were collected using octopus traps during January to December 2021. The mantle length and weight of each specimen were measured. Reproductive stages were assessed to determine the gonadosomatic index and size at first maturity, and growth parameters were estimated using the von Bertalanffy growth equation. Results showed that males exhibited a mantle length range of 3.1–7.5 cm (mean: 5.2 ± 0.7) and a weight range of 5.99–94.00 g (mean: 35.34 ± 11.24). Mantle length at first maturity for males was 4.2 cm, with full maturity at 7.0 cm. Females had a mantle length range of 2.8–9.4 cm (mean: 5.7 ± 0.9) and a weight range of 7.70–105.00 g (mean: 45.43 ± 17.00). Mantle length at first maturity for females was 5.9 cm, with full maturity at 7.5 cm. GSI values were highest in both sexes in February, April, May, June and November, suggesting reproduction occurred through much of the year, and females showed a large peak in May. GSI values were lowest in both sexes in September. The smallest recorded mantle length was 2.8 cm in May, and the largest was 9.4 cm in January. The specific values of t0 for males, females, and both combined sexes were −0.017719, −0.014519, and −0.00672, respectively. These findings provide valuable insights into the growth and reproductive biology of A. aegina, which can inform sustainable management and conservation efforts for this species.

The objective of the current study was to describe the female reproductive characteristics of populations of the non-indigenous shrimp Penaeus latisulcatus off the Egyptian Mediterranean coast. P. latisulcatus was sampled from the commercial catch of Boughaz El-Maadiyah's landing center off the Mediterranean coast between July 2020 and June 2021. This study focused on describing maturity stages, calculating the gonadosomatic index (GSI), determining the spawning season, and measuring the size at first maturity of female P. latisulcatus. The stages of ovarian development were divided into six stages; i.e., immature, early maturing, late maturing, nearly ripe, ripe, and spent. A prolonged spawning season was identified, extending from the summer season to autumn and showing a peak in August. The GSI followed the same pattern of ovarian maturation and confirmed the spawning season of P. latisulcatus. As revealed, 50% of female individuals attained maturity at a total length of 11.34 cm. Hence, this study provides fundamental and helpful information for understanding the reproductive dynamics of P. latisulcatus on the Egyptian Mediterranean coast as a new habitat for its propagation. This information also helps in providing the proper management of fisheries and conservation of this shrimp species, which can be useful for aquaculture processes as well.

Abstract 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

Horse mackerel is a semi-pelagic fish widely distributed in the eastern Atlantic, where it represents a species of interest for fisheries and is subject to intense exploitation, leading to its global classification as a vulnerable species by IUCN. In the Northwestern (NW) Mediterranean Sea, the knowledge of their distribution, abundance and main biological parameters is fundamental to achieve their sustainable exploitation and contribute to the ecosystem approach to fisheries management. The time series (2009–2020) data set analyzed in this study came from two geographical subareas (GSAs) defined by the General Fisheries Commission for the Mediterranean (GFCM), Northern Spain (GSA06) and Northern Alboran Sea (GSA01) sampled in July during the MEDiterranean International Acoustic Survey (MEDIAS). Our results suggest that in summer, a higher concentration and aggregation of fish exists in GSA01, with a density ten times greater than in GSA06. Possible life history changes can be inferred through the analysis of the biological parameters of Trachurus trachurus in the NW Mediterranean Sea. In both GSAs, the annual decline of the size at first maturity (L50) and condition factor (Kn) was prominent. Moreover, the population structure lacked adult modes that could guarantee a successful recuperation of future stocks. Nonetheless, fish inhabiting GSA01 seem to have a better adaptive response to the events responsible for these alterations. In comparison, GSA01 is under less fishing pressure and the upwelling occurring in this area contributes to a higher availability of food, in addition to reducing the increases in sea surface temperature due to climate change during the study period. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective of the current study was to describe the female reproductive characteristics of populations of the non-indigenous shrimp Penaeus latisulcatus off the Egyptian Mediterranean coast. P. latisulcatus was sampled from the commercial catch of Boughaz El-Maadiyah's landing center off the Mediterranean coast between July 2020 and June 2021. This study focused on describing maturity stages, calculating the gonadosomatic index (GSI), determining the spawning season, and measuring the size at first maturity of female P. latisulcatus. The stages of ovarian development were divided into six stages; i.e., immature, early maturing, late maturing, nearly ripe, ripe, and spent. A prolonged spawning season was identified, extending from the summer season to autumn and showing a peak in August. The GSI followed the same pattern of ovarian maturation and confirmed the spawning season of P. latisulcatus. As revealed, 50% of female individuals attained maturity at a total length of 11.34 cm. Hence, this study provides fundamental and helpful information for understanding the reproductive dynamics of P. latisulcatus on the Egyptian Mediterranean coast as a new habitat for its propagation. This information also helps in providing the proper management of fisheries and conservation of this shrimp species, which can be useful for aquaculture processes as well. [ABSTRACT FROM AUTHOR]

Gill surface area (S) and respiration (R) in juvenile and adult crustaceans scale with their body weight (W) such that S ∝ R ∝ Wd, with d ranging mostly between 0.6 and 0.9, but always <1, as in other water-breathing ectotherms (WBE). The growth of adult crustaceans therefore approaches an asymptote, whether or not seasonal growth oscillations are explicitly considered in the model used to describe that growth (e.g. von Bertalanffy growth function). On the other hand, the variation in asymptotic size (L∞ or W∞) among crustaceans is primarily determined by water temperature, which impacts on the oxygen requirements of WBE. Through multiple examples, this and related aspects of the Gill-Oxygen Limitation Theory (GOLT), first developed for fishes and later extended to other WBE, are shown to also apply to the growth of a wide range of crustacean taxa. The GOLT also explains certain aspects of crustacean reproduction, such as the relationship between size at first maturity and maximum size, and, possibly, the feature that female crustaceans hold their eggs outside of their bodies instead of internally. [ABSTRACT FROM AUTHOR]

This study supplies knowledge on the reproductive traits of Glossogobius aureus, one of the commercial fishes living in brackish water and freshwater. A collection of 742 G. aureus specimens was caught using gill nets from January to December 2020. The results of the gonadal breeding frequency and gonadosomatic indices showed that G. aureus spawned year-round, but with higher activity during four months, from August to October, of the wet season. Size at first maturity (Lm) of males was higher than that of females in all study sites. The batch fecundity (F) was 1044–27,349 eggs/female and increased with fish size, as shown by the high determination values (r2 > 0.6). The study results provide new references on the reproductive biology of the population of Glossogobius aureus which will help in the sustainable management of its fisheries in the studied areas.

Global warming affects the phenology of the Earth's flora and fauna, notably by advancing the date at which many plants and animals tend to reproduce. We use fish, where this reproductive acceleration is well-documented, to present a simple approach based on sine curves to predict, in spring spawning fish, the minimum number of days (Δdmin) that spawning is advanced as the result of a given increase in water temperature (Δ°C). We show, via comparison with field estimates, that our simple model's robust predictions correspond to observed values of Δdmin/Δ°C, and discuss both the potential uses and the limitations of the model. [ABSTRACT FROM AUTHOR]

This present study provides an overview of the reproductive traits, including ovarian development, spawning season, size at maturity (Lm), and fecundity of Acentrogobius viridipunctatus - a high economic value fish in the Vietnamese Mekong Delta (VMD). A total of 432 females were collected using trawl nets from January to December 2020 at four sites, including Long Huu-Tra Vinh (LHTV), Trung Binh-Soc Trang (TBST), Dien Hai-Bac Lieu (DHBL), and Tan Thuan-Ca Mau (TTCM). The ovarian diameter was seen to increase from 2.09 (stage I) to 6.57 mm (stage V). Histological analysis showed that the goby was a multi-spawner due to the different oocyte stages found in stages IV and V of ovaries. It can release eggs all year-round due to the monthly appearance of ovarian stages IV and V during the study period, with the main peak in the 2-4 months of the wet season noted with the highest value of gonadosomatic index at that time. The Lm increased from 6.6 cm at TBST to 9.4 cm at TTCM. This species displayed relatively high fecundity, ranging from 5,481 to 130,683 eggs/female. The average fecundity of this fish was 27,698 ± 7,983 eggs/female at LHTV, 46,592 ± 7,264 eggs/female at TBST, 23,271 ± 4,985 eggs/female at DHBL, and 31,408 ± 2,515 eggs/female at TTCM. Egg diameter ranged from 0.45 ± 0.01 at DHBL to 0.50 ± 0.01 at TBST. For sustainable exploitation, local governments should ask the fishers to avoid catching fish during the main spawning period, and the fish length at first capture should be >Lm. [ABSTRACT FROM AUTHOR]

In this study, some reproductive parameters of the non-native silver crucian carp ( Carassius gibelio) in Seyhan Dam Lake (Southeastern Mediterrenean) were investigated. Samplings were conducted monthly through trammel nets between June 2013 and May 2014. From a total of 540 individuals investigated, 10 (1.85%) were males and 530 (98.15%) of them were females. The length at first maturation was detected as 16.8 cm TL. According to maturation stages of female gonads, ripe females were found to be present between February-July. Intense spawning periods was inspected in spring months of March, April, and May. The biggest egg diameter was found as 1.32 mm in March and the highest number of eggs was found as 347550. Silver crucian carp displayed a great reproductive output in Seyhan Dam Lake and the given reservoirs have been completely invaded. [ABSTRACT FROM AUTHOR]

This study investigates the ovarian development, spawning patterns, maturity size and fecundity of the goby Glossogobius giuris –a commercial fish in the Vietnamese Mekong Delta–based on the data analysis of 659 individuals. Specimens were caught using trawl nets from four sites representing freshwater (Cai Rang, Can Tho) to salinized regions in the dry season (Long Phu, Soc Trang), and brackish water regions (Hoa Binh, Bac Lieu and Dam Doi, Ca Mau) over the 12 months of 2020. Histological analysis showed that it was a multi-spawner as different stages of oocytes appeared in mature ovaries. The fish could spawn throughout the year, with a peak in April at the freshwater region and in September at salinized and brackish areas as mature ovaries appeared monthly during the studied period and gonadosomatic index displayed the highest value in April and in September, respectively. This goby's primary egg releasing time tended to be regulated by salinity changes over the four sampling sites. Likewise, size at first maturity of this species could be related to the salinity variation as this value was the longest in freshwater (6.14 ± 0.17) and the shortest in the salinization region (4.82 ± 0.66). Batch fecundity is measured at 5,118–100,003 eggs/female and related to fish length and weight (r2 > 0.76). Findings can be useful for the development of fish conservation strategies and artificial reproducing studies. [ABSTRACT FROM AUTHOR]

The blue swimming crab (BSC) fishery in Tiworo Strait has been heavily exploited since two decades ago when its worldwide demand and price was very high. Study on population aspects of this organism in this waters is limited. The aim of present study was to investigate growth patterns, population stock status, and size at first gonad maturity of Portunus pelagicus. One of the main fishing ground of BSC around Tiworo Strait waters is at Bangko and Gala Islands. Samples of BSC were taken monthly using gillnet and collapsible trap. Each sample taken was identified its sex, measured its carapace width, and weighed. Data collected from fishing ground of BSC were analyzed to find out growth patterns, population stock status using spawning potential ratio (SPR) method, and the first gonad maturity (CW50). The results of study showed that growth patterns of BSC male and female following isometric growth patterns (b=0) (P 20%). The size at first gonad maturity (CW50) was attained at carapace width of 9.16 cm for male and 10.16 cm for female. Those imply that BSCs allowed to be caught should be >10 cm.

This study supplies knowledge on the reproductive traits of Glossogobius aureus , one of the commercial fishes living in brackish water and freshwater. A collection of 742 G. aureus specimens was caught using gill nets from January to December 2020. The results of the gonadal breeding frequency and gonadosomatic indices showed that G. aureus spawned year-round, but with higher activity during four months, from August to October, of the wet season. Size at first maturity (Lm) of males was higher than that of females in all study sites. The batch fecundity (F) was 1044–27,349 eggs/female and increased with fish size, as shown by the high determination values (r2 > 0.6). The study results provide new references on the reproductive biology of the population of Glossogobius aureus which will help in the sustainable management of its fisheries in the studied areas. [ABSTRACT FROM AUTHOR]

Understanding drivers of fish maturity is essential to predict the productivity, stability, and resiliency of exploited populations. Size at maturity for European sardine (Sardina pilchardus) in the Central Mediterranean Sea has never been published within rigorous peer review process. In the past, stock assessment working groups in the Mediterranean requested such information; however, the size at which 50% of the fish population reaches the sexual maturity (L50) often received weak estimates based on a single or few years of observation, which do not necessarily reflect the whole stock. To address this data gap for the Central Mediterranean Sea, the present research estimated size at maturity of European sardine in the Strait of Sicily. In the study period (2009–2017), sampled individuals exhibited significant differences in size range as well as in body condition and reproductive effort. Data also permitted a clear identification of the spawning season, starting in September–October and ending in March–April the following year. Along the analyzed period, the size at first maturity ranged from 108 to 124 mm (total length) for females and from 102 to 122 mm for males. Significant differences were recorded among genders and years. Moreover, a goodness-of-fit measure was proposed to assess the robustness and reliability of L50 estimates, and thus selecting those that minimize the fitting-associated errors. Finally, results suggested that the low proportion of immature individuals in the samples represents the main source of bias in L50 estimation and possible solution was also proposed.

The present study delves into the reproductive characteristics of Metapenaeopsis andamanensis , a commercially significant deep-water shrimp collected from Sakthikulangara, off Kollam, India (8°56′60.78″ N/76°32′34.27″ E) during September 2019 to May 2022. Despite its economic importance, the reproductive traits of this species remain elusive. This research comprehensively examines macroscopic and microscopic features associated with gonadal maturity stages, including determination of size at first maturity (CL 50), gonadosomatic index, and fecundity of M. andamanensis. Male-to-female sex ratio was noted as 1:1.03 using chi-square analysis. The smallest mature individuals were observed at 12 mm and 16 mm carapace length for males and females, respectively. Macroscopic observation categorized females into five groups based on gonadal coloration, while microscopic examination identified seven stages using histological characteristics. Notably, the absence of cortical crypts in the periphery of oocyte cytoplasm, a characteristic feature of the genus Metapenaeopsis , was observed in this species. Males were classified into two categories based on macroscopic and microscopic observation. The gonadosomatic index ranged from 4.25 to 10.13 for mature female individuals, exhibiting a significant increase until stage IV. Continuous spawning was observed, with a peak in May and November. The size at first maturity for females and males was determined as carapace length (CL) 23.05 mm and 17.53 mm, respectively. The average absolute fecundity was calculated as 53,889 with an average relative fecundity of 9934 oocytes. This investigation contributes valuable insights into the reproductive traits of the deep-water penaeid shrimp M. andamanensi s, facilitating the development of effective management strategies for sustainable fisheries. • First study to address the relative and absolute fecundity of a Metapenaeopsis species. • M. andamanensis is a continuous spawner with peaks in May and November. • Gonado-somatic index increases rapidly until stage IV and then decreases in stage V. • Determining the size at maturity helps formulating mesh size regulations. [ABSTRACT FROM AUTHOR]

The peppery furrow shell Scrobicularia plana is a commercial valuable bivalve in the east Atlantic and Mediterranean Sea. To ensure the sustainability of this resource and implement efficient management strategies, it is essential to understand the life history traits of the species, such as growth, reproduction, and size at first maturity. These features were investigated in the southern range of the species' European distribution, specifically in Ria de Aveiro (Portugal), and compared to other geographical areas. At Ria de Aveiro S. plana spawns from June to October, with a peak in August/September, aligning with the typical reproductive pattern of mid latitude European populations. The condition index is lowest in March and highest in May just before spawning. Sexual maturity (L 50 = 27 mm SL) is attained at approximately 1 year of age, enabling offspring to reproduce in the subsequent spawning season. In this study, the overall sex ratio did not differ significantly from 1:1. Hermaphroditism (ovotestis) was detected in one specimen, representing 0.3% of the total examined males. Shell rings are formed annually during growth cessation in fall/winter and become conspicuous when growth resumes in March. The growth equation parameters, estimated from surface shell ring analysis and internal shell microgrowth bands, were: Lt = 58.1[1 - e−0.46(t −0.09)]; Lt = 54.7[1 - e−0.53(t −0.30)], respectively. Values for K and L ∞ are among the highest recorded for the species, highlighting the growth performance of S. plana in the Ria de Aveiro and its potential for commercial exploitation. An analysis of morphometric relationships between shell length, height, and width was performed to optimize the harvesting process of S. plana. Management measures are proposed for the fishery of S. plana in Ria de Aveiro, based on the species' biological traits. [Display omitted] • Reproductive biology of Scrobicularia plana is described. • Condition index exhibited a seasonal pattern linked to the reproductive cycle. • Fast growth and rapid maturity allow first-year reproduction. • A minimum conservation reference size of 27 mm SL can enhance sustainable exploitation. • A closed fishing season between August and November should be enforced. [ABSTRACT FROM AUTHOR]

Recent estimates of the size at first maturity (L 50) of Sardinella brasiliensis showed contradictory results with a decreasing in the fish stock biomass encompassed by increasing values of L 50. The methodological approach used hereby allowed to separate sardines classified in the virginal maturity stage from those categorized in the recovery stage, and ready for one next spawning event. This study evaluated the hypothesis of the existence of separated stocks experiencing distinct environmental conditions and fishing pressures which may have altered L 50 estimates using a robust dataset based on biological samples collected along the entire species distribution area in the southeast-south Brazilian coast [Rio de Janeiro (RJ), São Paulo (SP), Paraná (PR), Santa Catarina (SC) and Rio Grande do Sul (RS)] between 2000 and 2018. A reclassification of the gonadal maturity stages provided a more realistic estimate of L 50. Combining biological, reproductive, fishing data and the mean temperature of the catch (MTC), the leave-one-out classification correctly re-assigned individuals with an overall accuracy of 85% [100% (RJ), 45% (SP), 99% (PR), 99% (SC) and 82% (RS)]. The connectivity between the local populations of S. brasiliensis off RJ (23°S) and the southern populations is limited, contrasting to spatial structured semi-discrete population-units found between SP and RS (24°S-30°S). The northern extreme population-unit (RJ, 22°S-23°S) showed an expressive reduction of L 50 , and a negative correlation was detected between the increasing MTC values and the abundance of early maturing individuals and recruits of the species. Stock specific L 50 estimates seemed to act as indicators of long term environmental fluctuations. • A long-term assessment of S. brasiliensis was conducted using a novel methodology • The study distinguishes 2 population-units: northern (22-23°S) and southern (24-30°S) • The northern population shown a notable reduction of the size at first maturity (L 50) • L 50 estimates correlated with increased mean temperature of the catch • Stock-specific L 50 may be used as indicator of long-term environmental fluctuations [ABSTRACT FROM AUTHOR]

The reproductive cycle and gonadal development of Donax striatus from a sandy beach in Ajuruteua, Amazon region, were studied. Monthly sampling took place from March 2015 to April 2016. Histological analysis was performed on 420 individuals, and the oocyte diameters were determined from histological sections and used to determine the reproductive period. The population showed a balanced sex ratio (1:1) with a size at first maturity of 10.9 mm in males and 8.9 mm in females. The population showed r-strategist characteristics and continuous spawning, and the reproductive cycle showed no seasonal variation or significant relation with any environmental parameter. The organic matter was significantly higher in the rainy season. According to the generalized linear model analysis (GLM), only the condition index (CI) had a significant relationship with the organic matter of the sediment. The type of reproductive strategy adopted by D. striatus corroborates the global breeding hypotheses for species of tropical environments. For conservation, it should be recommended to harvest this species at a shell length above 13 mm.

A total of 6265 Mediterranean green crabs Carcinus aestuarii were sampled from the Gediz Delta in the eastern Aegean Sea (Turkey) during 24 sampling surveys with a 15-day interval from November 2014 to October 2015. The overall ratio of males to females was 1.8:1. Males were predominant in all sampling surveys, except in September 2015. The ranges of total weight (W) and carapace width (CW) for all crabs were 0.19–45.74 g and 8–53 mm. Male crabs were, on average, larger and heavier than females. The W–CW relationships were W=0.0004×CW2.88 for females, and W=0.0003×CW2.96 for males. The estimated von Bertalanffy growth parameters for females were: CW∞=49 mm, K=0.82 year-1 and t0=-0.9 year, and for males CW∞=54 mm, K=0.92 year-1 and t0=- 0.96 year. The total mortality rates were 2.25 and 2.27 year-1 for females and males, respectively. The breeding season spans from mid fall to early spring peaking in winter. The recruitment of juveniles to the lagoon happens predominantly in summer. The median size at first maturity was 30.6 mm for females and 41.5 mm for males. The average potential fecundity estimate was 63565±36519 oocytes per female crab while the average realized fecundity was 42810±33310 eggs. [ABSTRACT FROM AUTHOR]

The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals. [ABSTRACT FROM AUTHOR]

The population ecology of luciferids has been scarcely studied. This study examined the distribution and population parameters of Belzebub faxoni and Lucifer typus in the western Gulf of Mexico. Samples were collected using a Bongo net at 82 sampling stations during three periods (July, January, and October–November). Abundance data of species were subjected to a regression tree analysis to determine the main factors affecting their distribution. In addition, total length data of individuals were fitted to a logistic equation to estimate the size at first maturity. Food availability was the key factor affecting the distribution of B. faxoni, which exhibited its highest abundance over the inner shelf. In contrast, L. typus avoided low salinity waters (B. faxoni was always biased towards females, but L. typus showed variable sex proportions. Several hypotheses attempting to explain these disparities are discussed. Size structure in B. faxoni favored small individuals in summer, the reproduction peak. In contrast, the L. typus population was always dominated by large individuals, probably transported by currents from the main hatching sites. Size at first maturity was higher in L. typus (females: 8.16 mm; males: 8.63 mm) than in B. faxoni (females: 6.53 mm; males: 6.74 mm). Information here provided may help to better understand the population dynamics of these species.

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carinotetraodon travancoricus, is endemic to rivers of Western Ghats of India and supports a lucrative export trade of live aquarium fishes from India. Aspects of its reproduction are studied from fishes collected from the Pampa River, South India. Among 966 fishes analyzed females predominated in March and males in May. However, the overall sex ratio was close to 1 : 1. Ripe gonads could be encountered in almost all months, but registered significantly higher preponderances during May to August. A total length of 18.33 mm is observed as the size at first maturity in males and 18.0 mm in females. Highest mean gonadosomatic index was recorded in August (1.4%) in males and in June in females (6.1%). Significant variation in oocyte diameter among different ovary maturity stages has been observed. Primary oocytes at the previtellogenic stages, oocytes with perinulceolar stage as well as with advanced vitellogenic stage were present in ripe ovaries, indicating asynchronous maturation. The absolute fecundity ranges from 139 (21 mm TL) to 480 (29 mm TL). The present results indicate that though fishes with ripe gonads occur throughout the year, the peak spawning period for C. travancoricus inhabiting the Pampa River extends from May to August concurring with South-West monsoon period. [ABSTRACT FROM AUTHOR]

During the period from April to September for the years 2014–2016, 998 swordfishes caught by the Moroccan artisanal longline fishery in the Strait of Gibraltar were sampled to study the reproduction of this species in this mixing area between the Mediterranean Sea and the North Atlantic. The results showed that the sex ratio is slightly in favour of males for sizes smaller than 130 cm LJFL (Lower jaw-fork length), whereas females are more numerous in sizes larger than 140 cm LJFL. Fifty per cent of females were estimated to be mature at 170 cm LJFL, while for males, the size at first maturity was estimated to be 95 cm LJFL. The swordfish spawn from June to September, probably in the Mediterranean Sea. The findings of this study suggest that the reproductive characteristics of swordfish caught in the Strait of Gibraltar are similar to those of the Mediterranean swordfish, and a high mixing rate between the Mediterranean and the North Atlantic stocks occurs in the study area. [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]

Here we report findings regarding the reproductive biology of swordfish Xiphias gladius in Corsican waters in the north-western Mediterranean Sea. We sampled 558 swordfish (72–216 cm; lower jaw to fork length, LJFL) caught from June to September in 2019 and 2020 off Corsica's western and eastern coasts. We assessed swordfish reproductive activity using macroscopic gonad characteristics, trends of gonadal indexes for both sexes, and histological investigation of oocyte developmental stages. Size at first maturity (L 50) was estimated at 139.2 ± 2.7 (95% CI) cm LJFL for females using histological techniques and 117 ± 1.7 cm (LJFL) for males using macroscopic criteria, corresponding to 3–4 and 2–3 year old-fish, respectively. Spawning occurred mainly from June to July, with a peak in July, characterized by a high gonadal index and histological and macroscopic evidence of reproductive activity. X. gladius spawning period is of relatively short duration, closely linked to SST, during which the females lay successive batches of eggs at a non-evaluated frequency. Batch fecundity (BF) and relative fecundity (RF) were estimated from five gravid females (135–209 cm LJFL) with unovulated, hydrated oocytes. BF was exponentially related to fish length with a mean BF of 1.94 ± 1.33 (mean ± SD) million hydrated oocytes in females. RF ranged from 22.29 to 37.24 (29.05 ± 5.97; mean ± SD) hydrated oocytes per gram of body weight. Our results improve knowledge regarding the sexual maturity, reproductive period, and spawning areas of swordfish in Corsican waters. These data are essential for the spatiotemporal management of Mediterranean swordfish stocks. We also provide an overview of the available information related to the reproductive biology and dynamics of Mediterranean swordfish and demonstrate the ubiquitous presence of swordfish spawning grounds throughout the Mediterranean Sea. • Female swordfish L 50 (histological estimate) is 139.2 cm LJFL, and male L 50 (macroscopic estimate) is 117 cm LJFL. • In Corsican waters, swordfish spawn mainly in June and July. • Swordfish batch fecundity ranges from 0.68 to 4.13 × 106. • Overview of available information on the reproductive biology of swordfish in Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Parapenaeopsis stylifera, a major commercial penaeid shrimp fishery resource in the Indian Ocean, has lacked adequate information on life history parameters for nearly two decades. In this study, growth and mortality parameters of P. stylifera from the southwest coast of India were estimated using length data and used to derive biological reference points for the species. The asymptotic length for females was L∞ = 131 mm; k = 1.1 y−1 and for males L∞ = 117 mm; k = 1.25 y−1. Mortality parameter estimates were Z = 4.42, M = 1.24, F = 3.18 y−1 and exploitation rate E = 0.72 for females; Z = 5.76, M = 1.39, F = 4.37 y−1 and E = 0.76 for males. Thomson and Bell yield biomass, Beverton and Holt yield per recruit, and relative yield per recruit models were applied to predict the stock status and length cohort analysis for estimating the stock size. The Beverton and Holt analysis gave Emax = 0.69 in females and 0.75 for males, which is below the Ecurrent values obtained for the sexes. The Thomson and Bell analysis indicated that if Fcurrent at which the yield is 121 460 t in females and in males 128 064 t is further increased, rise in yield will be modest. B/B0 and SB/SB0 at Fcurrent were 24% and 18% for females and 21% and 16% for males, respectively. Target reference point F0.1 and F0.5 at different levels of age at capture tc (0.5, 0.6, 0.7 and 0.8 yrs) was estimated by Beverton and Holt yield per recruit model. The outcome from these models forms integral inputs for multispecies/multigear tropical fisheries management. Parapenaeopsis stylifera is one of the inshore penaeid shrimp identified by the Marine Stewardship Council for certification from the region and, moreover, biological reference points are a prerequisite to assessment and management of tropical multispecies fisheries for ecosystem-based fisheries management.

The mutable nassa, Tritia mutabilis, a marine gastropod that is widely exploited on the Adriatic coast is an important source of income for small-scale fishermen in the Mediterranean Sea, particularly in the Gulf of Lion. However, the lack of knowledge on the ecology and biology of this species limits our capacities to propose and produce an effective management plan. As a result, stocks are currently declining, especially in Italy. In order to optimize a management plan for this fishery, we designed a study to better characterize the reproductive biology of T. mutabilis, using gonad histology and performing a regular monitoring of population size frequency. The average shell height of individuals during the breeding period was 24 ± 2.7 mm for males and 30 ± 3.7 mm for females. The presence of small females (10 mm) and large males (32 mm) in the whole sample challenged previous assumptions regarding protandry (sex change from male to female). The size at first maturity was estimated for males and females at 17.5 mm and 24.4 mm shell height, respectively. In Italy, current management measures include a minimum conservation reference size of 20 mm in shell height. Therefore, it is likely that many individuals that did not reproduce are being caught, which could partly explain the decline observed, despite conservation measures introduced more than ten years ago. Overall, our study provides some baseline information to establish, in consultation with fishermen, management measures for this small-scale fishery in France.

Abstract We studied the reproductive biology of Otocinclus vittatus in the southern Pantanal, Brazil. A total of 1066 fishes were analyzed (490 males, 488 females and 88 individuals of undetermined sex), sampled with a rectangular sieve and a seine net from February/2009 to January/2011. Variations in the sex ratio, seasonality in reproduction, fecundity, and size at first maturity were estimated. No variations were detected in the total sex ratio for the study period as a whole; although ratio has varied over time. The gonadosomatic index varied according to the river level, but not according to water temperature and rainfall. The mean fecundity was estimated at 84.1 oocytes, with a positive correlation with standard length. The size at first maturity (L50) estimated was 18.7 mm for females and 20.1 mm for males.

Abstract: This paper aimed to define the reproductive period and population parameters of Serrasalmus marginatus relative to local environmental features, such as day length, rainfall and mean river level. The study site was a floodplain in the Negro river, Pantanal, Brazil, and samples were collected bimonthly using gill nets and cast nets with meshes from 1.5 to 8 cm between adjacent knots. The reproduction period, as determined by gonadosomatic index (GSI) and percentage of gonad stages, varied significantly along the year (F4,116 = 77.5; p < 0.01), but it was well defined from October to December. Reproduction period was positively correlated with rainfall (rs = 0.97; p < 0.01) and photoperiod (rs = 0.92; p = 0.02), but not with the rise of river level (rs = 0.10; p = 0.86). Rainfall and photoperiod may act as predictive factors, providing cues to fish to begin reproduction in order to find the best conditions for offspring in the following months, during the flooding season, when the river level reaches its peak and extends to the plain. We have herein reported the first population parameters described for this species in the Brazilian Pantanal, including growth rate (k = 0.53/year), asymptotic length (L∞ = 32.74), lifespan (A0.95 = 5.65) and mortality (M = 1.11), showing that this population has better growth performance when compared to data reported for this same species in the Paraná river since the population in the Negro river is characterized by lower growth and mortality rates, and S. marginatus achieved longer lengths and lifespan. This latter parameter was compatible with six cohorts estimated by Electronic Length Frequency Analysis (ELEFAN). The size at first maturity (L50 = 18.26 cm A50 = 1.56 years) was also larger and later than the population in the Paraná river, likely a consequence of the the lower mortality and the maintenance of larger specimens in the Negro river. [ABSTRACT FROM AUTHOR]

Abstract Arenicola spp. are marine benthic polychaetes dug for bait by anglers. Without regulation, this activity can lead to the decrease of lugworms' population meanwhile affecting the physical characteristics of the beach and the biodiversity. Here, we identified through morphology and genetics two species of lugworms, Arenicola marina and A. defodiens, within a Marine Protected Area of the Eastern English Channel (France). For each species, abundance and spatial distribution were assessed using a stratified random sampling and interpolation at four studied sites, as well as some life-history traits. These data were compared to lugworms' collection data to estimate its sustainability and to provide potential management measures. At one site, A. marina was present in large numbers on the higher and middle shore, whereas A. defodiens occupied the lower shore. At the other sites, both species co-occurred on the lower shore, and A. marina individuals were less numerous and lacking recruits. Spawning periods for A. marina occurred in early autumn and in late autumn for A. defodiens. The size at first maturity of A. marina was at 3.8 cm of trunk length (between 1.5 and 2.5 years old). One site (Au) appeared in need for management when linking abundance data with bait collection, where harvest of both species represented ∼14% of the total amount of lugworms and was above the carrying capacity of the beach for A. marina. The retail value associated to lugworm harvesting within the MPA was estimated at the same level as the shrimp retail value. Our results highlight the need for some fishery regulations. Highlights • At Wimereux Arenicola defodiens and A. marina live separately (typical spatial distribution pattern). • At Le Touquet and Fort Mahon Arenicola defodiens and A. marina live in sympatry. • The size at first maturity of Arenicola marina is 3.8 cm of trunk length (between 1.5 and 2.5 years old). • At Ault, the harvest of Arenicola marina was above the carrying capacity of the beach. • The retail value associated to lugworm harvesting within the MPA was 232 447 €. [ABSTRACT FROM AUTHOR]

The leopard grouper Mycteroperca rosacea is endemic to northwestern Mexico. It has been classified as vulnerable by the IUCN since 2008. M. rosacea has high commercial value and is caught yearround in Baja California Sur (BCS). Biological information on this species, especially in its natural environment, is scarce, and the objective of this study was to analyze its reproductive biology in Santa Rosalía, BCS. A total of 345 specimens were collected from March 2014 to May 2015. The sex ratio was 2.0: 1.0 (females: males, P < 0.05). Population size at first maturity (L50) was estimated at 40.77 cm TL; 37.31 cm TL for males and 42.44 cm TL for females. Gonadic development was synchronous by group, with a reproductive period occurring from March to May in 2014 and 2015 (at 20-23°C). The gonadosomatic index achieved maximum values in May 2014 and March 2015, as did the highest frequencies of mature and spawning individuals, indicating that there was a clear seasonal pattern of reproduction, and a negative correlation with temperature for both sexes. The hepatosomatic index and the condition index indicated that M. rosacea is not a species that requires storing of energy for reproductive events, as it seems to have food available year-round. [ABSTRACT FROM AUTHOR]

This study aimed to augment existing knowledge of the reproductive characteristics of Donax trunculus through analysis of timing variations and the influence of shell size on partial fecundity (PF) during the reproductive period. To achieve this objective, two reproductive timing characteristics were also studied: size at first maturity (SL50) and the reproductive cycle using histology and image analysis techniques. SL50 was 10.83 mm for females and 10.86 for males. Donax trunculus showed a continuous and simultaneous release of gametes and high oocyte regeneration ability during the reproductive period (from February to July). These reproductive characteristics impeded the estimation of total fecundity. However, throughout the reproductive period an increasing pattern of PF was observed followed by a significant drop at the end of the same period, which could be quantified (293,390 of vitellogenic and ripe oocytes). At the same time PF quantifications allowed for predicting and estimating the influence of shell length (SL) on the reproductive output as a function of oocyte typology (PF = 4.12 + 3.96 SL; r2 = 0.86; all types). Levels of prevalence of a digenetic trematode-like parasite with castrate ability fluctuated between 0–20% depending on the time of the year and sex. In addition, the possible consequences of two different scenarios of population size structure on the reproductive output were simulated, and highlighted how beach areas supporting high levels of anthropogenic pressure (Isla Canela) could compromise future recruitments, producing 84% less oocytes than a beach with a lower level of disturbance (Doñana). [ABSTRACT FROM PUBLISHER]

The three grouper species most heavily fished for the live reef fish trade (LRFT) in Indonesia are Plectopomus leopardus (greatest catch volume), and two species classified as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List: Plectropomus areolatus and Epinephelus polyphekadion. Understanding the reproductive biology of these fishes is essential for sustainable management, but relevant data are limited. This study aimed to determine reproductive dynamics, so as to inform management measures to maintain the reproductive capacity of these groupers. Grouper gonad samples collected from fish caught for the LRFT were analyzed histologically. Data were also collected from participatory mapping and interviews with fishermen, and underwater monitoring of three known spawning aggregation sites in the Wakatobi National Park, Eastern Indonesia. Based on observed gonad development, the respective lengths and weights at first maturity were: 37.7 cm and 759 g (P. leopardus); 36.65 cm and 771.2 g (P. areolatus); 36.95 cm and 889.9 g (E. polyphekadion). The mean weight of the groupers market-based sampled was higher than the size at first sexual maturity. Sex transition was observed in P. leopardus; sex reversal was not observed in E. polyphekadion, and the sex pattern of P. areolatus was unresolved. Based on the fisher surveys and spawning aggregation monitoring, spawning occurs around the new moon from September to April, with reproductive peaks in November and December. Fisheries management measures that are suggested to sustain grouper stocks include enforcing appropriate size limits, temporal spatial closures (spawning aggregation sites), and a trading ban during the peak spawning season (November−December).

The gonadal maturation of Atrina maura was examined by means of histological analysis and quantitative criteria. Particular features not previously described for this species are reported in this study: in both males and females the undifferentiated stage is absent and there is massive gamete resorption when the seawater temperature reaches 25°C; in males, there is continuous spawning concurrent with other gonadal development stages and the adipogranular cells surrounding the acini walls decrease with testis ripeness, which suggests they play an energetic role. Atresia displayed two stages: cytoplasmic structures with oocyte degeneration and digestion by hemocytes. The oocyte diameter was larger than that reported for cultured specimens. Size at first maturity was reached at 23.3 cm in shell height (SH) (12.2 cm in shell length, SL) in females and 22.8 cm SH (12.0 cm SL) in males.

The reproductive biology of Patagonian flounder (Paralichthys patagonicus) was studied in the Bonaerense Coastal Zone (34°-42°S) using samples collected in December 2003 and 2005. According to the literature, the data were analyzed considering two population groups: one in the northern zone (34°-38°S) and another in El Rincón (38°-42°S). The estimated size at first maturity for both sexes in 2003 was 31.57 cm TL for the northern zone and 29.58 cm TL for El Rincón. In 2005, the L50 was only estimated for the northern zone, and the value obtained was less than that of 2003 (27.82 cm TL). In December 2003, the greatest reproductive activity took place in El Rincón. However, in December 2005, the highest proportions of hydrated fe-males were observed in the northern area. This could be due to the cooler temperatures recorded for this zone, as compared with 2003. Batch fecundity showed a potential fit to size and a lineal fit to weight and ranged from 14,685 (30 cm TL) to 153,717 ( 59 cm TL) hydrated oocytes. Relative fecundity oscillated between 24 and 170 hydrated oocytes/g. The values of these parameters differed between years and among population groups. These differences could be attributed in part to the difference in seawater temperature between the two years, especially the high temperatures observed in 2005.Se estudió la biología reproductiva del lenguado (Paralichthys patagonicus) en la Zona Costera Bonaerense (34°-42°S). El material provino de muestreos realizados durante diciembre de 2003 y 2005. En base a la bibliografía los datos fueron analizados teniendo en cuenta dos grupos poblacionales, uno en el norte (34-38°S) y otro en El Rincón (38-42°S). La estimación de la talla de primera madurez en 2003 para ambos sexos fue de 31.57 cm. LT para la zona norte y de 29.58 cm LT para El Rincón. En 2005 solo se pudo estimar el L50 para la zona norte y el valor obtenido fue menor al 2003 (27.82 cm. LT). En diciembre del 2003 la mayor actividad reproductiva tuvo lugar en El Rincón. Sin embargo, en diciembre de 2005 las proporciones más altas de hembras hidratadas se localizaron en el sector norte. Esto podría deberse a que se registraron temperaturas más frías para esta zona respecto a 2003. La fecundidad parcial presentó un ajuste potencial con la talla y lineal con el peso y varió entre 14.685 (30 cm. TL) y 15.3717 ( 50 cm. TL) ovocitos hidratados. La fecundidad relativa varió entre 24 y 170 ovocitos hidratados/g. Los valores de ambos parámetros presentaron diferencias tanto interanuales como entre los grupos poblacionales. Estas diferencias podrían atribuirse en parte a la diferencia en la temperatura del agua entre los dos años, especialmente a las altas temperaturas observadas en 2005.

We present the results for the reproductive biology of Patagonian toothfish (Dissostichus eleginoides) caught off southern Chile from January to March and June to November 2006. A total of 10,896 specimens were measured (55-220 cm total length, TL) and sexed (7,049 males, 64.7%; and 3,847 females, 35.3%). Macroscopic observations showed that gonad maturation begins at 60 cm TL in both sexes, with an average maturation size of 81 cm TL in males and 89 cm TL in females. This species appears to have an ampie spawning period that occurs only off the far southern region of Chile. To date, no evidence indicates that this resource reproduces in any other areas of the Pacific Ocean off the coasts of South América, where no specimens were observed with mature gonads, percentages of atresia were high, and juvenile fish were not caught in trawl fishing operations targeting other commercial species.Se dan a conocer resultados sobre la biología reproductiva del bacalao de profundidad (Dissostichus eleginoides) capturado en el extremo sur-austral de Chile, entre enero y marzo y de junio a noviembre de 2006. En dicho período se midió y determinó el sexo a 10.896 ejemplares, comprendidos entre 55 y 220 cm de longitud total (LT), de los cuales 7.049 correspondieron a machos (64,7%) y 3.847 a hembras (35,3%). Mediante la observación macroscópica de las gónadas se determinó que en machos y hembras se observa el comienzo de la maduración gonádica a partir de 60 cm de LT, con una talla media de maduración (TMS50%) en machos a 81 cm y en hembras a 89 cm. Se sugiere que esta especie presenta un período amplio de desove y que este proceso se efectuaría únicamente en la región austral de Chile, destacándose que hasta ahora no se cuenta con evidencias que este recurso se reproduzca en otra zona del océano Pacífico frente a la costa de Sudamérica en atención a la ausencia de ejemplares maduros en las capturas, altos porcentajes de atresia y ausencia de peces juveniles en faenas de pesca de arrastre dirigidas a otras especies comerciales.

Background. In Turkey, the Mediterranean scaldfish, Arnoglossus laterna (Walbaum, 1792), is a discard fish species and it has a 'least concern' status on the IUCN Red List which indicates a low extinction risk. Although there are some studies investigating biology of this species, the knowledge of the mortality rates, spawning period, first maturity size, and age are not available for the study area. This paper, for the first time, provides some data on unknown population parameters for the east-central Aegean Sea. The aim of the presently reported study was to expand our knowledge on the biology of A. laterna. Materials and methods. Specimens of A. laterna were collected at monthly intervals by bottom trawl hauls between July 2004 and June 2007 from İzmir Bay (Turkey). The total length (L, cm), total weight (W, g), gonad weight (WG, g), and the sex were determined and the sagittal otolith pairs were removed for age reading. The length-weight relations were estimated by linear regression analysis on log-transformed data by equation: W = aLb. The growth was analysed by fitting the VBGF to size-at-age data using standard nonlinear optimization methods. Spawning period was established with monthly variations of the GSI values. Length at first maturity was estimating by the logit function. Results. A total of 2469 A. laterna individuals were sampled and the sex ratio was calculated as 1 ÷ 1.57 (F ÷ M). The length range of the sample was from 4.4 to 19.8 cm and the mean length was calculated as 9.4 ± 0.05 cm. For all samples, the length-weight relation was W = 0.0074L3.04 and the growt type was deterined as positive allometic. The age distribution of individuals varied from 1 to 8 years and the growth equation was determined as Lt = 20.62[1 - e-0.245(t + 1.071)]. The first maturity lengths were estimated as 11.88 cm for females and 11.41 cm for males. Conclusion. The presently reported study provides the age, growth, and reproduction parameters for A. laterna and the first information on the mortality rates, spawning period, first maturity size, and age parameters for the east-central Aegean Sea. These parameters can be useful for managers in the management and conservation of the stock. [ABSTRACT FROM AUTHOR]

Blue swimming crab (Portunus pelagicus) is an economical valuable fisheries important commodity due to high demand and availability jobs created for the fishermen. Therefore blue swimming crab has been heavily exploited from Salemo Island. This study aimed at comparing the sex ratio and the size at first maturity of blue swimming crab caught in mangrove ecosystems, coral reefs, and seagrass. Sex ratio was analyzed using chi square test and the size at first maturity was analyzed using the Spearman-Karber formula. The results showed the sex ratio of males and females blue swimming crab caught in every ecosystem is balanced. The size at first maturity of blue swimming crab caught in mangrove, seagrass and coral reefs, each to the male 81.08 mm, 102.36 mm and 102.87 mm in width and size of female 94.54 mm, 83.35 mm, 98.31 mm width. In a reference to government regulations, the blue male swimming crab caught in the coral reef and seagrass ecosystems have yet to size at first maturity is allowed to be captured. [ABSTRACT FROM AUTHOR]

The grooved carpet shell Venerupis decussata (=Ruditapes decussatus) (Linnaeus, 1758) is a Mediterranean autochthonous species that in Tunisia is heavily harvested from natural populations. It represents one of the important economic issues, especially in terms of employment and the trade balances of the country via its exportation. Despite its economic value, no studies have been carried out about the spread of this mollusc. Thus the status of this species is still poorly known and there is a knowledge gap about its stocks assessment. This study aimed to investigate the distribution, abundance and population structure of the carpet shell clam in Sfax coastal areas. In terms of geographic occupation, maps of the population distribution were drawn. The results showed a scattered distribution pattern of the species according to location ranging between 0 and 152 ind m-2. The consequence was a remarkable biomass which represented 891 tonnes of total fresh weight and high abundance levels reaching over 261.7+84.2 million individuals estimated in the area of 4182 hectares. The distribution of the species has also been investigated in consideration with the size which varied markedly according to location, the shell length ranged between 2 and 41 mm. The overall sex ratio (F:M) was 1:1.17, which was significantly different from parity (1:1). The size at which 50% of the population reached maturity was 24.08 and 24.76 mm shell length for males and females, respectively. Findings of the current study suggest that V. decussata proliferates along southern Tunisian coasts. [ABSTRACT FROM AUTHOR]