scholarly journals Morphometric Relationships in the Blue Swimming Crabs, (Portunus pelagicus) (Linnaeus, 1758) from the Palk Bay, Sri Lanka

Author(s):  
S. S. K. Haputhantri ◽  
S. J. W. W. M. M. P. Weerasekera ◽  
K. H. K. Bandaranayake

The blue swimming crab (Portunus pelagicus) has become the focus of an important export-oriented fishery in Sri Lanka for a decade. The Palk Bay in the Northern coastal waters of Sri Lanka is one of the best-known fishing grounds for blue swimming crabs in Sri Lanka. This study was undertaken with the aim of establishing some morphometric relationships for P. pelagicus in the Palk Bay. Biological sampling was conducted for five consecutive days per month from November 2014 - October 2015 in the Northern landing sites in the Jaffna District where the catch of Palk Bay blue swimming crab fishery was landed. P. pelagicus specimens were also randomly collected for laboratory analysis. The morphometric measurements of the specimens for the following parameters were undertaken: CW - carapace width with the spine, CWW - carapace width without spine, MW – mouth width, TL - total length, LCPL - left chelar propodus length, LMOV - left movable part Length, RMOV - right movable part length, LCPH - left chelar propodus height, RCPH - right chelar propodus height, ABW - abdominal width, ABL - abdominal length and BW - body weight. The least squared method was used to obtain the Length-Length (L-L) and Length-Weight (L-W) relationships. Of the 65 L-L relationships obtained for P. pelagicus from the study, 34 relationships were correlated (r2>0.5). The estimated relationships between BW and CW for males and females were BW=0.0001 CW 3.01 (r2 =0.84) and BW= 0.0001 CW 2.90 (r2 =0.86), respectively. Positive allometric growth was observed for male P. pelagicus, whereas a negative allometric growth was observed for female P. pelagicus. Most of the morphometric relationships of P. pelagicus obtained in this study were not isometric.

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Dyah Ika Nugraheni ◽  
Achmad Fahrudin ◽  
. Yonvitner

<p><em>Fishing effort enhancement would put pressure on blue swimming crab resources and its ecosystem. The objective of this study was to determine the spatial distribution based on the size of the carapace width (CW), abundance, temperature, salinity, depth, and fishing intensity in Pati waters which was divided into two zones (zones 1=nearshore, zone 2=offshore). The result showed that the average of carapace width in zone 1 to zone 2 was significantly different (p &lt;0.05), as well as between males and females. Average number of individual (abundance) was significantly different according to fishing areas and sex (p &lt;0.05). The average of water temperature in zone 1 was higher than in zone 2, salinity in zone 1 was smaller than in zone 2, and the water depth in zone 1 was shallower than in zone 2. The higher the crab catch intensity leaded to the smaller the abundance and size of carapace width. Alternative management strategies were proposed such as to divert fishing grounds from coastal waters to offshore during low productivity season, to uphold rules on minimum legal size for catching (Lm = 107 mm),  to release of berried females catch, and to reduce accretion rate of gear and fishing fleet mainly in the coastal zone waters.</em></p><p><em><strong><em>Keywords:  </em></strong><em>blue swimming crab, carapace widht (CW), abundance, intensity of fishing</em></em></p>


2018 ◽  
Vol 6 (1) ◽  
pp. 149
Author(s):  
Frank Rijkaard Makahinda ◽  
Rose O.S.E Mantiri ◽  
Boyke H. Toloh

Portunus pelagicus (blue swimming crab) is one of the important economical marine commodities produced from Indonesian coastal waters that has increasing market demand among fishery commodities. The purpose of this research is to reveal the relationship of carapace width and weight, the growth pattern and the carapace width-weight ratio of P. pelagicus crabs at two different research sites in Manado Bay. The benefits of this study, can be a reference for further studies on blue swimming crabs, P. pelagicus, and information obtained in this study could become important information needed for the maximum sustainable utilization of blue swimming crab, P. pelagicus.This research was conducted at two locations, namely Kelurahan Bahu, Sub-district of Malalayang with coordinates of 1 ° 27'49.86 "North and 124 ° 49'35.79" East and second location in Tumumpa Dua, Sub-district of Tuminting with coordinates 1 ° 31'14.51"North - 124 ° 50'28.67"East. Samples of blue swimming crabs were collected by deploying traps which are placed at 5-7 meters with the distance between traps 10 meter. Traps were placed at 17.00 pm and lifted on the next day at 06.00 am. Measurement of the width of the carapace conducted by using the ruler with 0.1 cm accuracy and weight measurement using the scales with 0.1 gram accuracy.The correlation value obtained for the wide and weight relationship of blue swimming crabs in the Sub-district of Malalayang is 0.953 for males and 0.898 for females. In Kelurahan Tumumpa Dua, Sub-dis ittrict of Tuminting 0.829 for males and 0.920 for females respectively. Based on these values the increase in the width of the carapace will affect the weight gain of the crab. The growth pattern of P. pelagicus crab in Kelurahan Bahu, Sub-district of Malalayang and Tumumpa Dua Sub-district Tuminting showed negative allometric growth pattern with b <3 value which means faster carapace growth compared to the weight of crab. From the result of chi square test on wide body and weight relationship analysis, is found same for both locations with value x2 table = 7.815 <x2 count = 112.3134. This is presumably due to one of the external factors is the availability of food.Keywords: Rajungan, growth pattern, Manado Bay AbstrakPortunus pelagicus merupakan salah satu komoditi hasil laut ekonomis penting yang dihasilkan dari perairan pantai Indonesia dengan permintaan pasar terhadap komoditas rajungan yang terus meningkat. Adapun tujuan penelitian ini yaitu mengetahui hubungan lebar berat rajungan P. pelagicus, pola pertumbuhan rajungan P. pelagicus dan perbandingan lebar berat rajungan P. pelagicus di dua lokasi penelitian yang berbeda di Teluk Manado. Manfaat penelitian ini, dapat menjadi bahan acuan untuk studi lebih lanjut mengenai rajungan P. pelagicus serta infomasi yang didapat dalam penelitian ini bisa menjadi bahan kajian untuk pemanfaatan rajungan P. pelagicus secara maksimal serta berkelanjutan.Penelitian ini dilaksanakan pada dua lokasi yakni di Kelurahan Bahu Kecamatan Malalayang dengan koordinat 1°27'49.86"LU - 124°49'35.79"BT dan lokasi kedua di Kelurahan Tumumpa Dua Kecamatan Tuminting dengan koordinat 1°31'14.51"LU - 124°50'28.67"BT. Pengambilan sampel dilakukan dengan alat tangkap bubu yang diletakan pada kedalam 5-7 meter dengan jarak antara bubu 10 meter. Bubu diletakan pada pukul 17.00 wita dan diangkat pada esok harinya pukul 06.00 wita. Pengukuran lebar karapas menggunakan mistar dengan ketelitian 0,1 cm dan pengukuran berat tubuh menggunakan timbangan 0,1 gr.Nilai korelasi yang didapat untuk hubungan lebar berat rajungan P. pelagicus di Kelurahan Bahu Kecamatan Malalayang 0,953 untuk jantan dan 0,898 untuk betina. Di Kelurahan Tumumpa Dua Kecamatan Tuminting 0,829 untuk jantan dan 0,920 untuk betina. Berdasarkan nilai tersebut pertambahan lebar karapas akan berpengaruh pada kenaikan berat tubuh dari rajungan. Pola pertumbuhan rajungan P. pelagicus di Kelurahan Bahu Kecamatan Malalayang dan di Kelurahan Tumumpa Dua Kecamatan Tuminting menunjukan pola pertumbuhan yang bersifat allometrik negatif dengan nilai b < 3 yang berarti pertumbuhan karapas lebih cepat dibandingkan pertambahan berat rajungan. Dari hasil analisis chi square lebar berat tubuh, sama untuk kedua lokasi penelitian dengan nilai x2 tabel =  7,815 < x2 hitung = 112,3134. Hal ini diduga karena salah satu faktor eksternal yakni  ketersediaan makanan.Kata  kunci : Rajungan,  Pola pertumbuhan, Teluk Manado.


2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Dyah Ika Nugraheni ◽  
Achmad Fahrudin ◽  
. Yonvitner

Fishing effort enhancement would put pressure on blue swimming crab resources and its ecosystem. The objective of this study was to determine the spatial distribution based on the size of the carapace width (CW), abundance, temperature, salinity, depth, and fishing intensity in Pati waters which was divided into two zones (zones 1=nearshore, zone 2=offshore). The result showed that the average of carapace width in zone 1 to zone 2 was significantly different (p <0.05), as well as between males and females. Average number of individual (abundance) was significantly different according to fishing areas and sex (p <0.05). The average of water temperature in zone 1 was higher than in zone 2, salinity in zone 1 was smaller than in zone 2, and the water depth in zone 1 was shallower than in zone 2. The higher the crab catch intensity leaded to the smaller the abundance and size of carapace width. Alternative management strategies were proposed such as to divert fishing grounds from coastal waters to offshore during low productivity season, to uphold rules on minimum legal size for catching (Lm = 107 mm),  to release of berried females catch, and to reduce accretion rate of gear and fishing fleet mainly in the coastal zone waters.Keywords:  blue swimming crab, carapace widht (CW), abundance, intensity of fishing


Author(s):  
Adi Susanto ◽  
Ririn Irnawati ◽  
Mustahal ◽  
Hery Sutrawan Nurdin ◽  
Yeni Marliana ◽  
...  

Blue swimming crab (Portunus pelagicus) is an important economical fishery commodity for fishermen in Banten Bay that are caught using gill nets and collapsible traps. The increasing of fishing pressure has highly potential to reduce the quality of the catch as exposed in previous studies. However, the comprehensive, and time series analysis of the previous research results have not been conducted. The purpose of this study is to analyze the variations of blue swimming crab caught in Banten Bay through a combination of meta-analysis techniques, fishing trials and field obser-vations to determine the effect of fishing activities on swimming crab sizes, and evaluate the status of swimming crab fisheries in Banten Bay. Standard mean difference from 10 different studies was used as a meta-analysis parameter. The results of the meta-analysis showed that fishing activities were conducted from 2004 to 2018 had a significant effect on the decreasing of the swimming crab size. The average of swimming crab carapace width caught in 2019 approximately 121.66 mm. The proportion of legal swimming crabs in 2014, 2015 and 2019 was more than 80%, so that the status of swimming crab fisheries in Banten Bay is still environmentally friendly.Keywords: carapace width, meta analysis, fisheries, Portunus pelagicus, blue swimming crab


2019 ◽  
Vol 8 (4) ◽  
pp. 402-408
Author(s):  
Nathanael Ganang Anindityo Wibowo ◽  
Chrisna Adhi Suryono ◽  
Ibnu Pratikto

Rembang merupakan salah satu kabupaten di Jawa Tengah yang dikenal sebagai daerah penghasil sumberdaya rajungan yang cukup tinggi permintaannya dan terus meningkat setiap tahunnya. Hal tersebut dapat menyebabkan terjadinya penurunan potensi hasil rajungan akibat intensifnya penangkapan di Perairan Rembang. Kajian tentang kondisi stok sumberdaya rajungan  terkait sebaran dan dinamika populasi ini sangat diperlukan dalam pengelolaan potensi rajungan. Tujuan dari penelitian ini adalah untuk menganalisis struktur ukuran dan parameter pertumbuhan rajungan di Perairan Rembang. Penelitian ini dilaksanakan pada bulan Maret – Juni 2019 di Perairan Rembang, dengan menggunakan metode survei yang bersifat deskriptif. Total sampel rajungan selama penelitian adalah 1200 ekor yang terdiri dari 574 ekor jantan dan 624 ekor betina. Hasil penelitian menunjukkan kelas ukuran lebar karapas rajungan didominasi oleh rajungan muda, dengan rata – rata 105.01 ± 11.99 mm untuk jantan dan 107.73 ± 10.68 untuk betina. Berat rata – rata rajungan jantan yaitu sebesar 95.2 ± 27.1 gram dan rajungan betina sebesar 97.9 ± 23.1 gram, sehingga menunjukkan rajungan jantan lebih kecil dibandingkan dengan rajungan betina. Pola pertumbuhan rajungan di Perairan Rembang bersifat allometrik negatif. Laju pertumbuhan rajungan di Perairan Rembang yang didapatkan adalah berupa nilai panjang asimptotik (L∞) sebesar 71.4 mm dengan koefisien pertumbuhan (K) sebesar 1.5/tahun.Rembang is a coastal region in Central Java which known as to producer of blue swimming crab resources that are in high demand and continues to increase every year. It will because decreasing the potential yield of blue swimming crab due to intensive fishing in Rembang Waters. Study on the stock condition of the blue swimming crab resource related to the distribution and dynamics of the population is required for the management of the blue swimming crab potential. The current research aims to assess the size structure and growth parameter of blue swimming crab in the Rembang Waters. The research was conducted from March to June 2019 in Rembang Waters, using a descriptive survey method. The total number of crab samples during the study was 1200 animals consisting of 574 male and 624 female. The results showed that the size of the crab carapace width class was dominated by young crabs, with an average of 105.01 ± 11.99 mm for males and 107.73 ± 10.68 for females. The average weight of male crab is 95.2 ± 27.1 gram and female crab is 97.9 ± 23.1 gram, indicates that male crab is smaller than female crab. The crab’s growth in Rembang Waters is allometric negative. The growth rate of crab in the Rembang Waters obtained is in the form of asymptotic length (L∞) was 71.4 mm with a growth coefficient (K) 1.5/year.


2020 ◽  
Vol 25 (2) ◽  
pp. 85-90
Author(s):  
Yustika Permatahati Intan Permatahati ◽  
Nila Nikmatia Bugis ◽  
La Sara ◽  
Tezza Fauzan Hasuba Hasuba

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<0.05). It was found out that SPR of BSC from both fishing ground was 22.46% and 23.71%, respectively which indicates that population stock status of BSC in Tiworo strait waters is “moderate level” (SPR > 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. 


F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1780 ◽  
Author(s):  
Efrizal Efrizal ◽  
Indra Junaidi Zakaria ◽  
Rusnam Rusnam ◽  
Suryati Suryati ◽  
Nofa Yolanda

Background: Currently, great progress in the artificial propagation of commercially important   portunid crabs of the genus Portunus has been achieved, and various methods have been adopted in mass-scale hatchery activities. This study analyzed the biological testing of formulated diets with different dose supplementations of vitamin E for the broodstock of female blue swimming crabs, P. pelagicus (Linnaeus, 1758) Methods: Female crab samples were collected from the coastal region of Padang, West Sumatra. The method used in this study was completely randomized design, with four treatment regimens (n=5 crabs each) of dietary vitamin E (0, 300, 600, and 900 IU/kg formulated diets). Results: The results show that the supplementation of vitamin E in the formulated diet had a significant effect (P <0.05) on the absolute weight growth, carapace length and carapace width. Conclusions: Supplementation of vitamin E on in formulated diet causes broodstock blue swimming crab molting, with a percentage value of 40–80% on day 20 and 20% on day 30, with a 100% survival rate.


2021 ◽  
Vol 10 (2) ◽  
pp. 175-183
Author(s):  
Iqbal Maulana ◽  
Irwani Irwani ◽  
Sri Redjeki

Rajungan (Portunus pelagicus) merupakan komoditas laut yang memiliki nilai ekonomis yang tinggi, dimana berbanding lurus dengan penangkapan yang terus meningkat. Tingkat pemanfaatan yang tidak mengindahkan ukuran dan kondisi rajungan dapat mempengaruhi struktur ukuran dan stok rajungan di suatu perairan. Penelitian ini bertujuan untuk mengetahui distribusi ukuran, hubungan lebar dan berat rajungan serta distribusi tingkat kematangan gonad (TKG) di perairan Betahwalang, Demak. Penelitian menggunakan metode survey dengan analisis yang bersifat deskriptif yang dilakukan secara “time-series”. Pengamatan sampel rajungan sebesar 10% dari hasil tangkapan yang didaratkan oleh setiap nelayan di pengepul rajungan.. Hasil dari penelitian ini menujukkan dari 3030 ekor rajungan yang diamati diketahui distribusi lebar karapas rajungan berkisar antara 35 – 185 mm dan kisaran berat sebesar 10 – 350 gram. Rajungan yang terdapat di perairan Betahwalang memiliki pertumbuhan yang bersifat allometrik positif pada rajungan jantan dan betina pada bulan Januari serta Februari.  Hasil nilai b sebesar 3,29 dan 3,08 (Januari & Februari) pada rajungan jantan. Nilai b sebesar 3,10 dan 3,15  pada rajungan betina (Januari & Februari) serta nilai b sebesar 3,14 pada keseluruhan rajungan. Sehingga diketahui pertumbuhan lebar karapas lebih cepat dibandingkan bobot rajungan. Sedangkan distribusi tingkat kematangan gonad rajungan betina adalah 21% pada TKG 1; 63% pada TKG 2; serta 16% pada TKG 3, dengan ukuran pertama kali matang gonad adalah 141,51 mm. Blue swimming crab (Portunus pelagicus) is a marine commodity has a high economic value , which is causing the crab catch to rise as well. The catch rate that does not consider the size and maturity of sea crab can affect the size structure and population stock of sea crab in waters. This study aims to determine the size distribution,the relationship of width and weight of Blue swimming crab and distribution of gonad maturity in Betahwalang, Demak. There’s a descriptive survey method used in this study with time-series observations. The sample size is about 10% of the total number landed crab from each fisherman. The results of this study showed that from 3030 crabs observed, the distribution of crab carapace width ranged from 35 – 185 mm and the weight range at 10 – 350 gram. The results showed the all crabs has a positive allometric on growth parameters. The value of  b 3,29 and 3,08 (January & February) in male blue swimming crab, 3.10 and 3.15 (January & February) on female sea crabs, and 3.14 on whole sea crabs. So it is known that the growth of carapid width is faster than the weight of crab. While the distribution of female crab gonad maturity level is 21% in level 1; 63% in level 2; and 16% in level 3, with the first size of mature gonad at 141,51 mm.


F1000Research ◽  
2019 ◽  
Vol 7 ◽  
pp. 1780 ◽  
Author(s):  
Efrizal Efrizal ◽  
Indra Junaidi Zakaria ◽  
Rusnam Rusnam ◽  
Suryati Suryati ◽  
Nofa Yolanda

Background: Currently, great progress in the artificial propagation of commercially important   portunid crabs of the genus Portunus has been achieved, and various methods have been adopted in mass-scale hatchery activities. This study analyzed the biological testing of formulated diets with different dose supplementations of vitamin E for the broodstock of female blue swimming crabs, P. pelagicus (Linnaeus, 1758) Methods: Female crab samples were collected from the coastal region of Padang, West Sumatra. The method used in this study was completely randomized design, with four treatment regimens (n=5 crabs each) of dietary vitamin E (0, 300, 600, and 900 IU/kg formulated diets). Results: The results show that the supplementation of vitamin E in the formulated diet had a significant effect (P <0.05) on the absolute weight growth, carapace length and carapace width. Conclusions: Supplementation of vitamin E on in formulated diet causes broodstock blue swimming crab molting, with a percentage value of 40–80% on day 20 and 20% on day 30, with a 100% survival rate.


2021 ◽  
Vol 10 (1) ◽  
pp. 147-157
Author(s):  
Parameswari Iccha Nirmalabuddhi Wishnuputri ◽  
Sri Redjeki ◽  
Retno Hartati

Rajungan (Portunus pelagicus) adalah salah satu sumber daya hayati laut Indonesia. Rajungan merupakan komoditas utama  perikanan di Indonesa, baik untuk lokal maupun ekspor. Nilai ekonomis rajungan yang tergolong tinggi mengakibatkan penangkapan rajungan dilakukan secara besar-besar dan dapat memicu terjadinya kepunahan. Penelitian bertujuan untuk mengetahui tingkat kerentanan rajungan di Perairan Desa Tunggulsari dan mengetahui karakteristik morfometri dari rajungan yang ditangkap pada lokasi tersebut. Metode yang digunakan dalam penelitian ini adalah metode Productivity and Susceptibility Analysis (PSA). Wawancara dilakukan kepada 60 nelayan di Desa Tunggulsari. Pengukuran parameter kualitas perairan meliputi suhu, oksigen terlarut, salinitas, dan pH. Pengukuran morfometri dilakukan pada salah satu pengepul di desa. Hasil dari wawancara diketahui bahwa nelayan di Desa Tunggulsari menggunakan 2 macam alat tangkap yaitu bubu lipat dan jaring insang dasar. Penilaian atribut produktivitas rajungan masuk dalam kategori tinggi, sedangkan penilaian atribut kerentanan tergolong pada resiko rendah untuk penggunaan kedua alat tersebut. Nilai MSC untuk alat tangkap bubu lipat adalah 96,0 dan 98,2 untuk alat tangkap jaring insang dasar. Nilai MSC > 80 menunjukkan bahwa tingkat kerentanan rajungan pada lokasi tersebut masuk pada kategori rendah. Selanjutnya, pola pertumbuhan rajungan di Desa Tunggulsari adalah allometrik negatif baik untuk rajungan jantan maupun betina. Hal ini menunjukkan pertumbuhan panjang dan lebar karapas lebih cepat dibandingkan penambahan berat rajungan. The blue swimming crab (Portunus pelagicus) is one of the Indonesian marine biological resources. The blue swimming crab is a main commodity of fisheries in Indonesia, both for local and export. Economic value of blue swimming crab classified as high involve over-exploitation of blue swimming crab and can lead to extinction. This research is aimed to determine level of vulnerability of blue swimming crab in Tunggulsari waters and to discover morphometry characteristic of blue swimming crab that caught at that location. The method used in this research is Productivity and Susceptibility (PSA) method. Interviews were conducted with 6 fishermen in the village of Tunggulsari. Measurement of water quality parameters including temperature, dissolved oxygen, salinity, and pH. Morphometry measurement was carried out in one of the collectors in the village. The results of the interview revealed that fishermen in the village of Tunggulsari used 2 fishing tools namely bubu lipat and bottom set gillnet. Assessment of blue swimming crab productivity attributes is included in the high category, while the assessment of vulnerability attributes is classified as low risk for the use of both tools. The MSC value for bubu lipat is 96,0 and 98,2 for bottom set gillnet. The MSC value is more than 80 indicates that the level of blue swimming crab vulnerability at that location is in the low category. Further, blue swimming crab growth pattern in the village of Tunggulsari are negative allometrics for both male and female blue swimming crabs. This shows the growth in length and width carapace is faster than the addition of blue swimming crab weight.


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