Fishing practices and biological characteristics of blue swimming crab (Portunus pelagicus): a case study based on onboard observations and landed catch data in the Ao Por small-scale gillnet fishery, Phuket, Thailand

Abstract. Yuliana E, Winata A, Setijorini LE, Yani DE, Hewindati YT, Djatmiko WA. 2024. Ecosystem approach for blue swimming crab (Portunus pelagicus) sustainability in Bekasi District, West Java, Indonesia. Biodiversitas 25: 4117-4126. There is concern that the sustainability of blue swimming crab (BSC) (Portunus pelagicus Linnaeus 1758) resources is threatened by ever-increasing consumption. This has led to increased BSC fishing pressure, which can result in over exploitation. The study aims to analyze BSC sustainability based on the indicators of the ecosystem approach for fisheries management (EAFM) and to determine the follow-up in the form of management tactical steps. The study site was the waters of Segara Jaya Village, Taruma Jaya Sub-district, Bekasi District, West Java, Indonesia. The sampling location was the mudflats around the mangrove ecosystem. Data on BSC were collected from fishermen’s catches; the crabs’ carapace width (CW) and weight were measured, and their sex was identified. The fishermen data were collected from the entire population of Segara Jaya fishermen (40 people). We analyzed BSC sustainability using the CW-based stock assessment. The life-history parameters consisted of growth parameters, mortality, and exploitation rate estimated using the “TropFishR” package in RStudio; the rest used descriptive analysis. The results indicated that the BSC caught had an average CW of 7.25 cm (not compliant with the government policy) and an average weight of 29.24 g. There was overexploitation, with the exploitation rate value being 0.94 for males and 0.85 for females. The results of the water quality measurements were in accordance with seawater quality standards for marine biota. To properly educate fishermen, several counseling and motivational approaches are needed to build the fishermen’s awareness. Regarding fishing techniques, educating fishermen to catch BSC larger than the minimum size set by the government (CW of >10 cm) is needed. Motivation-building to fishermen so that they are invested in conserving BSC resources is also needed in the socio-economy domain.

Blue swimming crab Portunus pelagicus is one capture fisheries commodity which offers promising prospects in Pangkep Regency, South Sulawesi, Indonesia. This study aimed to determine the fishery management of blue swimming crab based on spatial zoning areas. The research was conducted between April-November 2016 and May-November 2017 in the coastal waters of Pangkep Regency. Primary and secondary data were collected and analysed for water suitability and zonation using mapping and geographic information system analysis (GIS). The water quality parameters were: dissolved oxygen (1.5-11.0 mg/L), temperature (31-37 °C), salinity (9.0-31.0 ppt) and pH (6-8). The fishery management of blue swimming crab was classified into two integrated zoning area types: conservation zone (56,855 Ha) and commercial blue swimming crab fishery zone (36,153 Ha). However, the conservation zones are opened to the commercial fishery at certain times outside the critical periods for blue swimming crab reproduction. These critical periods are the zoea, megalopa and juvenile crab phases which occur from May to October, with an annual spawning peak in August. Fishing is not allowed in the conservation zone during the critical periods in order to accommodate sustainable exploitation. The findings were based on data analysis of water quality suitability, existing environmental conditions, fishing grounds, and the life cycle of blue swimming crab, overlaid on the 2013 zoning plan for the coastal area and small Islands in Pangkep Regency.

Blue swimming crab (Portunus pelagicus) is the important world fishery resource, but the crab larval rearing faces high mortality problem. The aim of the research was to compare survival and growth rate of larvae resulted from wild and domesticated broodstock blue swimming crab. Domesticated and wild broodstock were used to produce larvae. Domesticated broodstock was selected from repeated reared crab until third generation. Selection of the broodstock mainly based on the survival and growth rate. The wild broodstock was collected from Makassar Strait Sea. Larvae from the two sources of broodstock were reared in the conical tanks with density of 50 zoeas per liter. After reaching megalopa phase, then, the larvae were transfered into concrete tank completed with shelter and it were reared until crab phase. Crab phase was reared for 18 days, then these seed were released into the brackishwater pond for further domestication step. Larva from zoea to crab were fed with rotifer, artemia, fresh small shrimp and diet. The result showed that domesticated broodstock produced higher survival rate (P<0.05) larvae, faster larval stage changes (P<0.01) and uniform larval growth compared to the larvae from wild broodstock. It is clearly shown, the use of domesticated broodstock of blue swimming crab produced better larva quality and quantity than the wild broodstoock crab. Keywords : blue swimming crab, larvae, domestication, broodstock selection, faster growth

Abstract. Supmee V, Sawusdee A, Sangthong P, Suppapan J. 2020. Population genetic structure of Blue Swimming Crab (Portunus pelagicus) in the Gulf of Thailand. Biodiversitas 21: 4260-4268. The Blue Swimming Crab (Portunus pelagicus) is an important commercial fishery product in the Gulf of Thailand. To provide a strategy for management, information on genetic features is needed. In our study, the population genetic structure and demographic history of the P. pelagicus living in the Gulf of Thailand were analyzed based on the variation of the nucleotide sequence of the mitochondrial DNA in the control region (mtDNA CR). Ninety-seven samples were collected from 5 sampling sites: Rayong, Chonburi, Chumphon, Surat Thani, and Nakhon Si Thammarat provinces in the Gulf of Thailand. Forty-nine haplotypes were identified and 39 private haplotypes were found. An AMOVA showed no genetic structure among populations. The pairwise FST also indicated no statistically significant difference between all possible regional combinations. The topology of a minimum spanning network revealed a star-like topology that was not separated by geographic structure. The historical demographic analysis revealed a stable population size for a long period and followed by a very recent expansion. An absence of a population structure of the P. pelagicus was possibly caused by a high level of gene flow. The results of this study differ from previous studies that used genetic markers in nuclear DNA. Thus, to clear the genetic structure information of P. pelagicus in the Gulf of Thailand, we suggested that more sensitive markers to detect genetic structure should be used in further analysis.

Blue swimming crab (Portunus pelagicus) is one of the sought-after fisheries products in Indonesia. Additionally, the blue swimming crab (Portunus pelagicus) has a broad market, both domestically and internationally. The increasing demand for crab products has led to a rise in capture intensity. Uncontrolled exploitation, coupled with climate and aquatic environmental changes, is feared to cause a decline in crab populations, posing a threat to the sustainability of crab fisheries. The objective of this research is to describe the fishing units and areas for crab capture, identify the composition of catch results, determine the crab (Portunus spp.) capture season, and evaluate the utilization status of crab resources along the southern coast of Kebumen Regency. Fishing units, catch composition, and crab capture seasons are analyzed descriptively. The analytical method used to determine the status of crab resource stocks is the estimation of the spawning potential ratio (SPR). The fishing gear used includes trawl nets and fiber boats for crab capture. The captured crabs consist of three species: Portunus pelagicus, Charybdis feriata, and Portunus sanguinolentus. The crab capture season is from February to June, peaking in March. The SPR analysis for swimming crab (Portunus pelagicus) resulted in 25%. The crab stock status (Portunus pelagicus) in the southern coast of Kebumen Regency indicates a fully-exploited category, and one management option is to control crab capture efforts to increase crab biomass and maintain sustainability.

Whole blue swimming crab (Portunus pelagicus) is usually steamed or boiled before taking the meat for canning. The choice of the cooking process between steaming or boiling can determine the characteristics of blue swimming crab (Portunus pelagicus) meat. This study aims to determine and compare the flavor profile of blue swimming crab cooked by steaming and boiling. Whole blue swimming crab were steamed and boiled for 15 minutes at 100°C respectively. The cooked blue swimming crab meat was then tested for yield, sensory value, proximate analysis, amino acid and fatty acid profile. The results showed that the steaming process gave higher yields and sensory value than boiled blue swimming crab.

Blue swimming crab (Portunus pelagicus) is one of the high economic value commodities which causes increased efforts to catch blue swimming crab in Indonesia. The effort of catching continues to increase the blue swimming crab resources in the nature that has decreased. Cirebon Regency is one of the largest blue swimming crab fishing centers in West Java with a total value of blue swimming crab production in 2017 by 7,347 tons/year. This research was conducted to determine the selecitivity level of the crab gillnet and collapsible crab trap based on the proportion and total of catches obtained in Gebang Mekar Village, Cirebon Regency. Research was conducted in September 2019 – October 2019 in Gebang Mekar Village. For this research we used are primary data; collected directly during the observations includes catch type and weight of the catches and then interviews with several crab gillnet and collapsible crab trap fisherman and secondary data; data from official agencies and some literature. Our research suppose the moonlight phase effect of the blue swimming crab catch. Based on the research, it can be concluded that the crab gillnet with 3.5 inch mesh size and collapsible crab trap that operated in Gebang Mekar Village may be called a selective fishing gears but crab gillnet is more eficient as compared to collapsible crab.

After absorption of heavy metals in the tissues of aquatic organisms in aqueous solution accumulate and enter the human body through the food chain and proportional to the concentration of toxic metals absorbed, clinical effects observed. The objective of this study was to evaluate and compare the concentration of heavy metals, lead, nickel, iron and copper in muscle tissue of blue swimming crab Portunus plagicus in three regions (Qeshm, Khamir port and Laft port) was conducted in the Hormozgan Province. Sampling was conducted in summer and winter 1394. After the captured biometric sample 180, were isolated muscle tissue. The preparation and analysis of samples was performed according to standard methods MOOPAM. The results show that the studied concentration in muscle tissue of blue swimming crab (Portunus pelagicus) at sample locations statistically significant difference shows. Also studied in terms of concentration in the muscle tissue of blue swimming crab in the study area between summer and winter statistically significant difference was observed ( p<0/05). As both in summer and winter concentrations of lead, nickel, iron and copper in muscle tissue of blue swimming crab in Qeshm is greater than the other two regions. Meanwhile, the results of the study compared concentration in muscle tissue showed blue swimming crab with international standards. The studied concentration in muscle tissue of blue swimming crab in Qeshm, Khamir port and Laft port international standards is less than the limit. Which indicates that the health of aquatic ecosystems contamination is not a problem.

Blue swimmer crab ( Portunus pelagicus ) can increase the country’s incomes due to its high demand of export. This study aims to determine biological analysis on the population of blue swimmer crab in Lamongan, Tuban, Pasuruan, and Rembang. The sampling location was based on the fishing area and the method used survey method from collectors in each location. The blue swimmer crab’s biological characteristics which observed are the correlation on wide of carapace and blue swimmer crab weight, sex ratio, and gonad maturity level. The results showed the correlation between the wide and weight of carapace in Lamongan (male: 113.80-122.99 mm and 87.98-121.60 g then female: 108.21-117.27 mm and 71.80-99.74 g), Tuban (male: 113.26-117.74 mm and 89.63-102.76 g g then female: 114.36 mm and 106.51 g), Pasuruan (male: 87.66-94.43 mm and 39.68-49.90 g then female: 101.94-110.89 mm and 66.98-82.89 g), and Rembang (male: 120.30-126.69 mm and 93.53-118.43 g then female: 125.30-132.13 mm and 134.42-157.47 g); sex ratio (male: female) in Lamongan (1.4: 1), Tuban (1: 1.5), Pasuruan (2.8: 1), and Rembang (1: 1.46); and also gonad maturity level in Lamongan (dominant male at level III was 30.29%, female at level II and III was 30.40%), Tuban (dominant male at level II was 41.93%, female at level III was 33.33%), Pasuruan (dominant male at level III was 25.79%, female at level III was 48.10%), and Rembang (dominant male at level II was 32.35%, female at level II was 33.33%). These results indicate that the total of Portunus pelagicus which was being caught had fulfilled the standards rules by No.1/PERMEN-KP/2015. However, it requires continuous direct monitoring and counseling to maintain the stock of blue swimmer crab resources. Keywords: Blue swimmer crab ( Portunus pelagicus ), gonad maturity level, sex ratio, wide and weight.

Blue swimming crab (Portunus pelagicus) is a fishery commodity with a fairly high selling value, both as a local commodity and as an export commodity. The high level of utilization and trade of blue swimming crabs is not matched by knowledge of how to conserve these resources so that it can result in a decrease in blue swimming crab resource stocks. Sampling was carried out in November 2021 using a selected random sampling method. The density of the male blue swimming crab is 94,118 ind/km2 and the female is 58,824 ind/km2. The results of the analysis of the width-weight relationship of the blue swimming crab showed the nature of the blue swimming crab growth was negative allometric with a b value of 2.579.Keywords: blue swimming crab; density; Letman; width-weight relationship

Blue swimming crab (Portunus pelagicus) is a fishery commodity with a fairly high selling value, both as a local commodity and as an export commodity. The high level of utilization and trade of blue swimming crabs is not matched by knowledge of how to conserve these resources which can result in a decrease in blue swimming crab resource stocks. Sampling was carried out in November 2021 using a selected random sampling method. The density of the male blue swimming crab is 94,118 ind/km2 and the female is 58,824 ind/km2. The results of the analysis of the width-weight relationship of the blue swimming crab showed the nature of the blue swimming crab growth was negative allometric with a b value of 2.579.Keywords: density, width-weight relationship, blue swimming crab, Letman

Blue swimming crab (Portunus pelagicus) fishery has emerged to become an important export-oriented fishery in Sri Lanka over a decade and recently resulted in a rapid increase in the exploitation. The present study attempts to understand the reproductive biology and feeding ecology of blue swimming crab which will be vital in the management of capture fishery. Five major landing sites in the Jaffna district in Northern Sri Lanka, where blue swimming crab is frequently landed throughout the year were selected for the study. Biological parameters relating to sex, carapace width, body weight, maturity, and egg sac colour with egg sac weight were recorded at the field from November 2014 to October 2015. Randomly selected crab samples were brought to the laboratory and analysed for their maturity stages, length at first maturity, Gonadosomatic Index, fecundity, and gut contents. The study revealed that male crabs mature at a smaller size than females. The sex ratio varied greatly with time and males were always dominant in the catch. The blue swimming crabs in the Northern waters of Sri Lanka spawn throughout the year, with two spawning peaks in February and May. The total fecundity of ovigerous blue swimming crab increased with increased carapace width and body weight and it ranged from 123,482 to 3,179,928 eggs, with an average of 884,982 ± 676,420. A remarkably higher percentage of empty stomachs were observed under the present study in both mature and immature crabs and this could be due to lack of food availability in the environment and different digestibility rates of food items. The diet of blue swimming crab is highly variable reflecting the ability to adopt to different modes of feeding.

Blue swimming crab is one of Indonesia’s most valuable marine crustaceans, experiencing high fishing pressures for export, which could lead to the depletion of stocks. Knowledge of blue swimming crab spawning potential is imperative for understanding the stock’s status. This study aimed to estimate the spawning potential of blue swimming crab (Portunus pelagicus) based on their life history parameters. Fourteen thousand five hundred thirty-three crab samples were collected from fishers caught using the collapsible traps from January to December 2021 in Pamekasan. The biological data, including carapace width, weight, sex, and maturity level, were measured. Length-based spawning potential ratio method was used to estimate the spawning potential ratio. Results showed the growth parameters, CW∞= 179.55 mm, K = 0.98 year−1, and tmax=3 years. Size at first maturity was estimated at 102 mm carapace width, while the size at first capture was 112-121 mm. Egg-berried female crabs were observed throughout the year, with two distinguishable peaks occurring in Jan-Feb and Aug-Sep. The overall estimates of the SPR met the reference point limit. This study gave insights that the stock status of BSC in Pamekasan was not at risk of recruitment impairment, but management actions should be initiated for stock rebuilding.

The high demand for the crab export market has resulted in the crab commodity experiencing a decline and leading to exploitation. Prediction of crab stocks in Sumenep Regency is minimal due to a need for further information regarding crab data. This study aims to determine the biological characteristics of the blue swimming crab (Portunus pelagicus), limiting blue swimming crab (Portunus pelagicus), and water quality characteristics around Sumenep. Research methods is observation methods or directly contact fishermen. Data collection included blue swimming crab biology, including morphometric aspects, which consisted of measurements of carapace width, carapace length, weight, and level of gonadal maturity. Data collection for water quality parameters used the insitu method at each research location. The results of this study were variations in the morphometric characters of the crabs in the distribution of the carapace width of the male crabs found in class 121-138 mm, as many as 137 individuals, while the female crabs were found in class 121-138 mm as many as 136 individuals, the distribution of size class based on the length of the female crab in class 60 .42-68.42mm as many as 112 people. The size class distribution of male crabs was mainly found in the 51.42-59.42mm class of 96 individuals; the distribution of size classes based on the weight in male crabs in the 126-157 gram class was 65 individuals. The size class of female swimming crabs was found in the 158-189 gram class; as many as 67 individuals applied for crabs around Sumenep. Based on the crab data collection at the first location, Talango was 289 ind/700 cm2, the second location was Tanjung Saronggi, 65 and/700 cm2, and in the third location, Gili Genting, there was as much as 104 ind/700 cm2. The waters of Tanjung Saronggi are a location that has more male crabs than female crabs. The air quality characteristics around Sumenep waters are categorized as optimal for blue swimming crab habitat.

Species identification of the blue swimming crab Portunus pelagicus in Thai waters using mtDNA and RAPD-derived SCAR markers