Small Crabs Research Articles

Impact of steaming and peeling on the weight loss in blue swimming crabs in Pangkajene Islands, South Sulawesi

Abstract The blue swimming crab (Portunus pelagicus) is an important fishery resource in Indonesia because it has a high value and involves a lot of human resources. The pasteurized crab goes through several main stages, namely steaming, stripping, and canning. Steamed crabs will experience weight loss and produce a yield of meat in a certain amount and composition after peeling. This study aims to determine the weight loss during crab steaming and stripping processes on different sizes of crabs. The crabs were classified into three categories, namely small crab (carapace width <10 cm), big crab (carapace width >10 cm), and egg-berried female crabs. Technically, crabs were steamed for 20 minutes after the water boils with temperature of steaming of 80–90 °C. Steaming process wereallowed to stand for 60 minutes, followed by. peeling process where crab meat were separated from the skin. Weight measurements were taken on fresh, warm (shortly after steaming), and cooked crab (adjusted to room temperature) to calculate weight loss due to steaming while considering temperature adjustments and total loss. Results revealed the weight decrease about 16.75% during steaming, 19.61% during relaxation, and 27.47% during overall process. The highest meat yield was obtained from small crab by 30.64%, followed by large crab by 27.25%, and egg berried female by 24.39%.

The effectiveness of crab apartment to shelter egg berried female of blue swimming crab (Portunus pelagicus) in Rembang, Central Java, Indonesia

Abstract Blue swimming crab is an Indonesian fishery commodity with high economic value for export to America, Asia, and Europe. The increase in crab fishing activities every year results in diminishing stocks in nature, in addition to predator attacks around spawning areas. The purpose of this study was to determine the growth of blue swimming crabs and identify types of fish in the crab apartment shelters in Rembang Regency, Central Java Province, from March to May 2023. The egg berried female crabs were put in a floating apartment for three months and monitored every 2 weeks to determine the growth of the hatched crab eggs. Our observations showed as many as 50 egg berried female crab with with an average size of 8–10 cm and a weight of 40–65 g. There were other marine organisms found in the shelter, including rabbit fish, shrimp, small crabs, and therapon-perch. Rabbit fish and therapon-perch often result in reduced juveniles. Therefore, add and installing shelter is highly recommended to the entry of these fish. This study found crab apartment brings positive impacts on the survival of hacthing crabs and protected them from the threat of predatory fish.

Connectivity of the social-ecological system of the blue swimming crab fisheries in Rembang

Abstract The management of blue swimming crabs requires several aspects to be considered, such as social and ecological aspects for the sustainability of small crab fisheries. Fishery management is currently still focused on economic interests, so if this is allowed to continue, it will result in ecosystem degradation. This study aims to determine the components of the social-ecological system of the blue swimming crab fishery and the interrelationships of the crab management factors in Lasem District, especially in Gedongmulyo Village, Rembang from March to June 2023 using a purposive sampling method, including socio-economic data and fishermen’s interviews. Analysis of social-ecological connectivity including resource systems (RG), resource units (RU), resource actors (RA), and resource governance (RG) subsystems, and analyzes management variables using the participatory prospective analysis (PPA) method. The results show the connectivity of the social ecological system of the blue swimming crab fishery in Lasem between Resource Actors and Resource Systems, Resource Units, and Resource Governance. While Resource Governance is negatively related to the Resource System. Re-education about the regulations for the use of non-environmentally friendly fishing gear, the impact on the environment, and fishermen’s awareness of the need to comply with these regulations needs to be carried out.

Unveiling the diets of Eurasian Curlew and Bar-tailed Godwit through droppings analysis on the west coast of India

This study examines the population dynamics and dietary patterns of the near-threatened Eurasian Curlew and Bar-tailed Godwit along west coast of India, underscoring critical conservation issues. From 2010 to 2023, both species experienced significant declines, with peak abundances observed on sandy beaches, deviating from their usual mudflat and mangrove habitats. Analysing 231 droppings identified seven key prey types, with polychaetes and small crabs being most common in mangroves and mudflats, while Cosmonotus crabs were predominantly found on sand beaches. Species-specific prey preferences were evident, with Bar-tailed Godwits showing a significant association with polychaetes and medium crabs. The findings highlight the urgent need for habitat restoration, pollution reduction, and focused conservation efforts to ensure the resilience and survival of these critical shorebird species.

Differences in organic carbon accumulation in mangrove soils due to foraging by herbivorous crabs

Crabs in mangroves could enhance the transfer of organic carbon (OC) from leaf litter to soils, whose variation with the difference in crab size is, however, not well known. A 32-day laboratory feeding experiment was conducted to explore the effects of different sizes of the crabs Parasesarma plicatum foraging on leaf litter of Kandelia obovata on OC accumulation in mangrove soils. Mean rates of soil OC accumulation due to leaf foraging by large, medium, and small crabs were 21.11, 16.11, and 0.77 mg C ind−1 d−1, corresponding to the rates of OC removal from leaf litter of 62.60%, 51.37%, and 2.19%, respectively. Large and medium crabs ingested larger amounts of leaf litter, and soil OC accumulation rates resulting from leaf foraging by large and medium crabs were approximately 8 times higher than those by leaf litter decomposition and triple those by non-leaf foraging. Small crabs ingested the smallest amount of leaf litter, which was almost used for their growth and metabolism. These results underline the key ecological roles of leaf foraging by crabs, especially those with large and medium sizes, in OC accumulation in mangrove soils, which is conducive to estimating carbon sequestration in mangrove soils.

Winter Epibiotic Community of the Red King Crab Paralithodes camtschaticus in Sayda Bay (Barents Sea).

The species composition of epibiotic communities on red king crab was investigated in Sayda Bay, Russia, during November of 2015 and 2016. The community consisted of 12 species in total. Among epibionts, the barnacle Balanus crenatus was most prevalent (67.0%), while the amphipod Ischyrocerus commensalis was the most frequent symbiont (77.3%). Infestation levels in May-June 2005 and September 2004 were higher, as a larger proportion of small crabs without fouling species were present during those seasons. The lower infestation intensities recorded for other common associated organisms during winter can be attributed to their increased mortality due to unfavorable temperature conditions. The localization of epibionts and symbionts were related to larval settlement patterns of attached species and feeding behavior of mobile species. Monthly growth increments for I. commensalis and B. crenatus were estimated at 2 mm in body length and 1.35 mm in basal diameter, respectively. Size-at-age data for epibionts can aid in the age determination of large male crabs that may skip an annual molt.

Karakterisasi Precipitated Calcium Carbonate (PCC) dari Cangkang Rajungan dengan Metode Karbonasi sebagai Biomaterial

Precipitated Calcium Carbonat (PCC) merupakan produk pengolahan material alam yang mengandung kalsium karbonat melalui serangkaian reaksi kimia. Karbonasi menjadi salah satu proses yang paling banyak digunakan untuk membuat PCC. Penelitian ini bertujuan untuk dapat mengetahui karakterisasi dari PCC yang dapat diaplikasikan menjadi biomaterial dari cangkang rajungan berdasarkan jenis kristal yang dihasilkan. Bahan baku utama cangkang rajungan yang digunakan diambil dari Pulau Madura, kandungan kalsium karbonat dalam cangkang dapat menjadi PCC dengan adanya reaksi kimia. Cangkang rajungan yang sudah dihaluskan dan diayak ukuran 100 mesh dibakar di dalam furnace pada suhu 900˚C selama 1 jam, kemudian dilarutkan dalam HCL 2N. Pelaksanaan penelitian dengan melakukan proses karbonasi melalui mengontakkan gas CO2 dengan larutan HCl dengan temperatur pengontakan sesuai dengan variabel. Pengujian yang dilakukan adalah analisa kadar cangkang rajungan menggunakan XRF (X-ray Fluorescence), XRD (X-rayDifraksi) untuk mengetahui jenis kristal dan SEM (Scanning Elec-tron Microscopy) untuk melihat bentuk kristal.

Analysis of calcium levels in the carapace of rajungan crab (<i>Portunus pelagicus</i>)

This research aims to determine differences in calcium levels in small crabs (Portunus pelagicus) in three parts, namely carapace/shell, claw feet and abdomen. This research was conducted from May to June 2023 at UD. Bumi Nusantara Pattiro Sompe, Sibulue, Bone Regency, South Sulawesi. The research method used is an experimental method. with three types of samples (abdomen, claw feet and carapace/shell), calcium level parameters with two repetitions. Data were analyzed using T-test. Based on the research results, it shows that the highest calcium levels are in the carapace/shell (46.77%), followed by the claws (41.91%), while the lowest are in the abdomen (40.76%). The conclusion of this study is that there is a significant difference in levels calcium between the carapace/shell and the abdomen and claw legs but did not differ significantly between the abdomen and claw legs.

Population biology of the endangered land crab Johngarthia lagostoma (H. Milne Edwards, 1837) in the Trindade Island, Brazil: Identifying crucial areas for future conservation strategies

AbstractThe life history of insular gecarcinid crabs is divided into a marine larval and an adult phase, adapted to the terrestrial environment. As adults, individuals migrate seasonally to locations near the sea, engaging in reproductive behaviors. Therefore, identifying breeding and recruitment areas is crucial for the conservation of insular gecarcinids, especially for those endangered, such as Johngarthia lagostoma (H. Milne Edwards, 1837). We used sex ratio and sexual dimorphism analyses (body and cheliped size) as well as records of juveniles and adults to describe the population structure of J. lagostoma in the Trindade Island, Brazil. During the reproductive period, several population parameters were compared among sites with different altitudes, comprising two beaches (Andradas and Tartarugas) and two hills (Príncipe, 136 m; and Desejado, 612 m). Overall, males predominated in the population and invested more in body and cheliped growth than females. However, at Andradas Beach, it was observed a similar frequency of adult males and females as well as a small difference in the body size between the sexes. In comparison, the smallest crabs were found at Príncipe Hill. The analyzed population presented a predominance of adults, especially at Andradas Beach (93.1%). Compared to the other sites sampled, Príncipe Hill showed the highest abundance of juveniles (males: 22.2%; females: 40.8%). Thus, Andradas Beach was considered a reproductive site, while Príncipe Hill had the highest density of juveniles, which makes them priority areas for the conservation of J. lagostoma in Trindade Island.

The impact of mangrove environmental conditions on the growth rate of juvenile blue swimming crab (Portunus pelagicus) in Polagan Beach, Pamekasan, Madura Island

Mangrove forests have essential ecological functions, especially for coastal areas, one of which is as a shelter for small crab species at the juvenile stage. The research was conducted in Polagan Beach, Pamekasan Regency in November 2020-January 2021. The methods were divided into three sequential parts: pre-survey (processing of mangrove density data through Sentinel 2 satellite imagery), survey (calculating water quality and mangrove density parameters) and post-survey (determining each point/station that was used to support the continuity of the research). Data used in analysis are primary data (field) and secondary data (satellite image). The satellite image used in this research was acquired from Sentinel 2 satellite. The result concluded that temperature and salinity affect the growth rate of juvenile blue swimming crabs, but it does not occur significantly. The pH and heavy metal levels affect the survival rate of juvenile blue swimming crabs. Optimal temperature and salinity levels that can produce maximum juvenile growth are temperatures around 28-32°C and salinity around 32-34ppt. The level of mangrove density affected the water quality parameters (temperature and salinity).

Predatory behavior under monocular and binocular conditions in the semiterrestrial crab Neohelice granulata.

Neohelice granulata crabs live in mudflats where they prey upon smaller crabs. Predatory behavior can be elicited in the laboratory by a dummy moving at ground level in an artificial arena. Previous research found that crabs do not use apparent dummy size nor its retinal speed as a criterion to initiate attacks, relying instead on actual size and distance to the target. To estimate the distance to an object on the ground, Neohelice could rely on angular declination below the horizon or, since they are broad-fronted with eye stalks far apart, on stereopsis. Unlike other animals, binocular vision does not widen the visual field of crabs since they already cover 360° monocularly. There exist nonetheless areas of the eye with increased resolution. We tested how predatory responses towards the dummy changed when animals' vision was monocular (one eye occluded by opaque black paint) compared to binocular. Even though monocular crabs could still perform predatory behaviors, we found a steep reduction in the number of attacks. Predatory performance defined by the probability of completing the attacks and the success rate (the probability of making contact with the dummy once the attack was initiated) was impaired too. Monocular crabs tended to use frontal, ballistic jumps (lunge behavior) less, and the accuracy of those attacks was reduced. Monocular crabs used prey interception (moving toward the dummy while it approached the crab) more frequently, favoring attacks when the dummy was ipsilateral to the viewing eye. Instead, binocular crabs' responses were balanced in the right and left hemifields. Both groups mainly approached the dummy using the lateral field of view, securing speed of response. Although two eyes are not strictly necessary for eliciting predatory responses, binocularity is associated with more frequent and precise attacks.

Segregation by size in the mouthless crab Cardisoma crassum (Brachyura: Gecarcinidae) from Ponuga, Veraguas, Panama

The mouthless crab Cardisoma crassum is an important socioeconomic fishery resource; thus, understanding its distribution pattern is key for its fishery management. The present study aimed to determine if mouthless crabs show segregation by size in contrasting habitat types. Three plots were sampled from February to June 2022 to collect data on biometric variables in Ponuga, Veraguas, Panama Pacific. A total of 151 crabs with average cephalothorax width of 56.24 ± 8.56 mm were captured; 97 were male and 54 were female. This proportion difference was significantly skewed towards males at 1.8:1. Subjects from plot 1 were larger and heavier than those from plots 2 and 3. Ovigerous females were found only in plots 1 and 2 during June (rainy season). The minimum cephalothorax width of functionally mature females was 47.11 mm. By this measure, mature females were present in higher proportions in all plots and were significantly more abundant in plot 1. Small crabs were segregated in plot 3; the plot of origin and size were significantly associated. This is the first report of segregation by size in Cardisoma crassum. The findings highlight the importance of habitat features and lead the way for further studies on the factors influencing this distribution pattern.

Modification of Eco-Friendly Collapsible Crab Pot of Blue Swimming Crab in Pangkep Regency, Indonesia

The aim of this study is to determine the effect of mesh size on the catches of small crab (Portunus sp.) both in number, carapace length (CL), and catchability between modified and control collapsible crab pot. This study used mesh size of the wrapping net (PE) from 2.5 cm (± 1 inch) to 7.0 cm (± 2.5 inches) with 20 units and 20 repetitions (trips). The results showed that different mesh size has a significant effect on the catch of the pot. However, the catch of a 2.5-inch mesh size- showed a larger carapace length = 42 individuals (85.7 %), while the escaped number was 44 individuals (63.7%) in the unfeasible category catch while the remaining 25 samples (36.2%) are eligible to catch. The Anova test on the catch of crab pot with a mesh size of 2.5 inches and 1 inch based on CL showed F-count > F_table (54.213 > 3.016) or sig. value <0.05 (0.00<0.05) which means that the size of the crab pot had a significant effect on CL. This identified that the size of the collapsible crab pot with a mesh size of 2.5 inches could pass small crabs and can only catch large crabs.

The exploitation of crabs by Last Interglacial Iberian Neanderthals: The evidence from Gruta da Figueira Brava (Portugal)

Hominin consumption of small prey has been much discussed over the past decades. Such resources are often considered to be unproductive in the Middle Paleolithic due to their limited meat yield and, hence, low energy return. However, ethnographic studies suggest that small prey—including shellfish—are a reliable, predictable and by no means marginal resource, and there is increasing evidence for their inclusion in hominin diets during the Middle Paleolithic and even earlier. Gruta da Figueira Brava features a MIS 5c-5b Neanderthal occupation that left behind substantial, human-accumulated terrestrial and marine faunal remains, capped by reworked levels that contain some naturally accumulated, recent Holocene material, namely the remains of small crab species and echinoderms. The brown crabCancer pagurus(Linnaeus, 1758) predominates in the intact Middle Paleolithic deposit, and reconstruction of its carapace width, based on regression from claw size, shows a preference for relatively large individuals. The detailed analysis of theCancer pagurusremains reveals that complete animals were brought to the site, where they were roasted on coals and then cracked open to access the flesh.

Macroecotoxicological approaches to emerging patterns of microplastic bioaccumulation in crabs from estuarine and marine environments

Despite the increasing plastic discharge into the environment, few articles have dealt with the macroecological implications of microplastics (MPs) bioaccumulation on organisms. We performed a meta-analysis of MPs accumulation in true crabs and pseudocrabs worldwide and made use of macroecotoxicological approaches to know if: I) functional traits influence the bioaccumulation of MPs in the tissues of crabs; II) there is a latitudinal pattern of MPs bioaccumulation; III) there are tissues that can accumulate more MPs; IV) crabs can sort particles according to size, color, shape and type. Our results showed that functional traits influence the accumulation of MPs. Smaller crabs in size and weight and with shorter lifespans tended to exhibit more plastic particles. According to the environment, estuarine crabs from the intertidal and muddy substrates held more MPs. Also, burrowers exhibited significantly more particles in the tissues than omnivorous crabs. Besides, we recorded that crabs from low latitudes tended to exhibit more plastic particles, probably because of the mangroves' location that acts as traps for MPs. Non-human-consumed crabs accumulated significantly more MPs than human-consumed ones. Considering the tissues, gills were prone to accumulate more debris than the digestive tract, but without significant differences. Finally, colorless fibers of 1–5 mm of PA, PP and PET were the predominant characteristics of MPs, suggesting that crabs accumulated denser types but did not sort plastic according to color. These results indicate that functional traits might influence the accumulation of MPs and that there are coastal regions and geographical areas where crabs tend to accumulate more MPs. Analyzing MPs accumulation patterns with macroecological tools can generate information to identify the most affected species and define priorities for monitoring and implementing actions toward reducing plastic use globally.

Lethal and sublethal effects of simulated dredged sediment deposition on overwintering blue crabs Callinectes sapidus

Regular maintenance of waterways and ports requires dredging and disposal of accumulated sediment, which can injure or kill infaunal and epifaunal species. Our understanding of the lethal and sublethal effects of dredged sediment deposition in marine communities is based predominantly on benthic infaunal species, whereas knowledge of the effects of these additions on mobile macrofauna is limited. We explored lethal and sublethal effects of simulated dredged sediment (hereafter, sediment) on blue crabs Callinectes sapidus. Twenty mature female crabs were allocated into 4 treatments: no sand, no sediment; sand, no sediment; sand + 2.5 cm sediment; and sand + 10.0 cm sediment. Accounting for size, mortality in the 10 cm sediment treatment was immediate and 10- to 20-fold higher than that in other treatments. Crabs that eventually died also experienced sublethal effects as evidenced by a reduced behavioral repertoire. These results suggest that in winter, all mature female crabs will suffer high mortality under 10 cm of dredged sediment deposition, while smaller crabs may suffer substantial mortality and sublethal effects at even lower levels. As blue crab activity is temperature dependent, the detrimental effects can be minimized by disposing of dredged sediment either where crabs are not abundant or when water temperatures are higher and blue crabs can avoid burial.

Assessing Low Value Crustacean Bycatch Species Using Length Based Bayesian Biomass (LBB) Method, a Tool for Data Poor Fish Stock Assessment

The majority of tropical fish stocks lack sufficient data for conventional fish stock assessment, making them data-poor fisheries. The status of stock assessment is even more dismal for the low value fishes or crustaceans landed by the trawlers in a significant quantity. Crustaceans like non-edible small crabs (Charybdis spp) and stomatopods form a significant component of the low-value bycatch landed along the northwest coast. Despite the high ecological importance of these groups and the recent declining trend in catches (2007-19), no attempts so far have been made to evaluate the stock status of these groups from the study region. As reliable time series catch and effort data for the individual species are not available, a recently developed length-based approach, LBB (Length Based Bayesian Biomass) estimation method is adopted for the present study. Two of the evaluated stocks, Charybdis hoplites and Miyakella nepa were found abundant (B/BMSY>1.1), whereas Oratosquillina interrupta (B/BMSY=0.94) was found slightly overfished. The sufficient number of larger individuals were found lacking in all three species (L95th/L∞<<1.0). A higher incidence of juveniles in catches was estimated for C. hoplites and O. interrupta (Lmean/Lopt<<1.0).

Study of household welfare level of crab fishermen using Fisherman Exchange Rate (FER) indicators in East Lombok

The aims of this study were: 1) to analyze the household income of crab fishermen, 2) to analyze the household expenditures of crab fishermen, 3) to analyze the welfare level of crab fishermen based on the fisherman’s exchange rate indicator (FER), and 4) to analyze the socio-economic factors that affect the welfare of fishermen’s households. Crabs based on FER indicators in East Lombok Regency. This research uses a descriptive method. In addition to interviews with respondents, the Focus Group Discussion (FGD) method was also conducted. Respondents in this study were small fishermen. The number of respondents was determined to be as many as 30 people by Simple Random Sampling. Analysis of the data used is a descriptive analysis based on tabulation, and after processing, it is then presented in tabular form, analysis of cost and income analysis, and analysis of income and expenses as well as multiple Linear Regression analysis. The results showed: 1) The household income of crab fishermen is IDR 27,046,415 per year, which comes from income from crab catching IDR 19,492,091, fishing for IDR 4,138,324, income as laborers IDR 1,116,000, other sources IDR 2,300,000, 2) The household expenditure of crab fishermen is IDR 15,098,533 per year, which includes food expenditure of IDR 6,922,800 and non-food expenditure of IDR 8,175,733, 3) The Fisherman’s Exchange Rate (FER) for crab fishermen is 1.86. in the indicators of prosperity, and 4) The factors that significantly affect the welfare level of small crab fishermen are household income and expenditure, while the level of education, experience and number of family dependent are not significantly different.

OPTIMALISASI KEPITING RAJUNGAN MENJADI PRODUK KERUPUK KEMASAN DALAM MENINGKATKAN PEREKONOMIAN MASYARAKAT PESISIR PANTAI KARANGANTU KOTA SERANG

This community service departs from a desire to provide skills that can improve the economy in the Karangantu coastal community, Serang City, Banten Province by utilizing marine products in the form of crab crabs so that they are more economically valuable. The benefits of crab crab natural resources can not only be sold individually, especially now that the price of crab crab is very cheap/falling in the market based on the statements of the fishermen of the Karangantu coast. Based on this phenomenon, small crabs are processed into small crab crackers and are suitable for consumption. The method and approach used is problem solving with educational methods which are carried out through lectures, discussions and practice. While the results obtained from this activity are 1) the knowledge and skills of processing small crabs into small crab crackers, 2) The resulting product is in the form of small crab crackers. 3) product packaging is very attractive so that it increases consumer interest in knowing the product and then being able to buy it. The two results above are expected to be able to improve the economy of the Karangantu coastal community, the majority of whom work as fishermen

Investigating the potential of escape openings and reduced mesh size to optimize snow crab (Chionoecetes opilio) pot catches in the Barents Sea

In the Barents Sea Norwegian pot fishery for snow crab (Chionoecetes opilio), fishing effort regulations and bait expenses create incentives to improve the catch rates. The fishery also currently captures a large proportion of sub-legal sized crab which must be sorted out and released. In this study, we used comparative fishing trials to determine the size dependent capture efficiency of three modified pot types designed to address these issues. A pot constructed with 40 mm mesh caught ∼35% more (CPUE, number of individuals per soak time) large crab (≥ 100 mm carapace width [CW]) than the pot typically used in the commercial fishery (140 mm mesh). However, it also retained massive amounts of small individuals (< 100 mm CW). The addition of four stadium shaped escape openings into the 40 mm and 140 mm mesh designs resulted in large reductions in catches of small crab, but also a ∼30% reduction in large crab. Analysis of size dependent catch comparison rates and selectivity parameters supported the CPUE findings. Of the tested designs, catches were best optimized by the currently used commercial pot. However, we conclude that a small mesh pot with escape openings has the potential to increase catches of large crab and reduce catches of non-commercial small crab. Further development of this design, particularly in terms of the dimensions of the escape openings, is therefore required.