Objective: The aim of this study was to determine the reproductive cycle and spawning frequency of the sea cucumber Holothuria tubulosa in the northeastern Aegean Sea. Methods: The study covered a period of 12 months, beginning in October 2018 and concluding in September 2019. During this period, sea cucumber samples were collected monthly. Macroscopic and histological examinations of gonadal tubules were conducted to provide credible information for fishery management and aquaculture. Result: The sex ratio of the sampled population was 1:1.3, with 95 males and 130 females. The drained body weights at 50% maturity were 70.90 g for females and 70.80 g for males. The total length at 50% maturity was estimated at 18.58 cm for females and 18.05 cm for males. Gonad maturation was initiated in March and progressed to spawning stages between July and August. From September to February, the gonads were in postspawning and recovery stages. A strong linear correlation was determined between the gonad index and the seawater temperature in the area. Conclusion: The information provided is expected to improve stock management, enforce fishery regulations, and support controlled breeding programs. These measures aim to preserve the natural populations of Holothuria tubulosa and guarantee the long-term viability of the species in the wild. Abstract Impact statement The Holothuria tubulosa is the most abundant commercial sea cucumber species found in the Mediterranean Sea, particularly in the Aegean Sea. This species plays an important ecological role in nutrient regeneration and surface sediment mineralization in the benthic zone; however, there is significant catch pressure on natural stocks. This study revealed the reproductive cycle of this Mediterranean Sea cucumber species, offering crucial data for sustainable fisheries and aquaculture. By understanding their breeding patterns, we can better manage wild populations and develop controlled breeding programs, ensuring the long-term survival of the species and supporting healthy marine ecosystems.

In the study, the approaches of employees in marine fish hatcheries on occupational health and safety were determined. The Cronbach's α coefficient was calculated as 0.858 in the reliability of the scale and scale factors based on internal consistency. In addition, factor analysis according to the varimax method was found to be approximately 64%. It was determined that 68% of the employees were not aware of the relevant laws. In addition, 85% of the employees are aware of the dangers and risks in their workplaces. In the event of a negative situation in the workplace, the rate of those who know their legal rights is 73% (p≤0.05). In addition, 91% of the employees stated that they would use their right to object in a risky situation and quit the job. 60% of the employees stated that their jobs can satisfy them sociologically and economically throughout their life.

The Mediterranean sea cucumbers including Holothuria polii has become commercially important in international trade due to the high demand of consumers from Far East countries. Sea cucumbers fisheries is a valuable income for the regional fishermen but natural stocks endangered by overfishing in recent years. Fisheries regulations and aquaculture studies are important precautions for preserving natural stocks. All these efforts are based on reproduction biology of this species which slightly differed among regions. In this study, the reproduction biology including morphological characteristics, gonadosomatic index and gonadal development stages of H.polii at the eastern coast of Aegean Sea (Izmir, Turkey) were investigated during the reproduction (spawning) period from July to October 2018. Gonads and gonad sections of 60 sea cucumbers (120.60 ± 19.56 g) have been observed by macroscopic and microscopic inspections. Three gonadal development stages have been identified by histologic observations as mature (III), spawning (IV) and post-spawning stage (V) in gonadal tubules. Results indicate that both female and male gonads are at mature and spawning stage in July and all gonads are at post-spawning stage in October. The mean gonad weight was 12.53 ± 1.33 g at the beginning of the spawning period (July) and 1.87 ± 0.58 g at the end of the spawning period (October). Gonadosomatic index decreased from 17.53 ± 0.02% (July) to 3.37 ± 0.01% (October) after spawning. The gonadosomatic index, gonad weight, and spawning were related to the seawater temperature. According to this study, the spawning period of H.polii at the eastern coasts of the Aegean Sea starts in July and completely ends in October. As a result, the data related to the reproduction biology in spawning period of H.polii would guide stock management and artificial breeding of this species under controlled conditions.

Common carp is one of the most important and fourth most farmed freshwater species in the world because of its good adaptability to changing environmental conditions, high reproductive rate, and a differential feeding habit, a decent level of protein source for humans. This study conducted a global comparative evaluation of common carp (Cyprinus carpio) aquaculture production from the past to the present. This research utilized the 2002-2022 dataset. The data shows that in 2022, Asia farmed 3.159.801 TLW (tonnes- live weight) of common carp. China leads with 2.843.157 TLW, while Europe has 132.902 TLW, Africa 49.945 TLW, America 1.931 TLW, and Oceania has only one country, Papua New Guinea, with 350 TLW of production of common carp. COVID-19 has become a global health crisis. Because of protocols being implemented to minimize contact, there was limited availability and access to the supplies. Therefore, after the pandemic, 2020, there is a decrease in production quantity all around the world. This study will be useful to see the total statistical production quantities of the countries and continents.

The study aimed to determine the annual reproductive cycle of Siganus rivulatusfi females based on monthly variation of the gonadosomatic index (GSI) and histological changes in gonads. A total of 240 fish samples were collected monthly from small-scale (trammel nets) and recreational (angling and pot fishery) fishing from Gökova Bay, the southern Aegean Sea, between July 2017 and June 2018. The length and weight of female fish varied from 10.8 to 26.1 cm with a mean length of 18.7 ± 0.2 cm and from 14.98 to 293.42 g with a mean weight of 91.1 ± 2.93 g. GSI values began to increase in May, peaked in June and gradually decreased in July, indicating that the spawning season was early summer. A total of 240 gonads were histologically examined. Granular, pinkish structure of eggs was observed primarily between April and June, which was consistent with the increase in the gonadosomatic index. Post-spawning follicles were determined in July. Values of the gonadosomatic index gradually decreased after August and they were minimal between September and November. During this period, ovaries were surrounded by immature oocytes at the chromatin and peri-nucleolus stages. These results revealed thatSiganus rivulatusstarted vitellogenesis in April and the gonadosomatic index peaked in June.

The length–weight relationship (LWR), condition factor (K), and biometric characteristics (body wall, viscera, and gonads) of the commercially important sea cucumber, Holothuria tubulosa Gmelin, 1791, from the northeastern Aegean Sea in Türkiye were analyzed based on 327 individuals collected monthly from October 2018 to September 2019. The total length (TL), wet weight (WW), gutted weight (BW), viscera weight (VW), and gonad weight (GW) were determined for each sea cucumber to the nearest 0.1 cm for length and 0.01 g for weight. The sex of each individual was identified through macroscopic observation of gonad coloration, facilitating the categorization of biometric relationships according to sex. Results revealed negative allometric growth (b = 1.458) for H. tubulosa, with length increasing more than weight. The allometric growth values, calculated as 1.208 in males and 1.584 in females, did not differ significantly between the sexes. The mean condition factor was 2.42 ± 1.04, displaying significant seasonal patterns, with peaks in February and October and the lowest values during summer. Notably, smaller individuals (<100 g) exhibited significantly higher K values, suggesting better health. A strong positive linear relationship was observed between wet and gutted weights (R² = 0.549). Body composition analyses revealed a declining proportion of gutted weight with increasing total wet weight, whereas the relative proportions of viscera, gonads, and water content were positively correlated with body size. These findings offer region- and species-specific insights that can enhance the accuracy of stock assessments and support adaptive management strategies for the H. tubulosa fishery.