Biomass, CPUE and size frequency distribution of blue swimming crabPortunus segnis(Forskal, 1775) in coastal waters of the northern Persian Gulf, Iran

Abstract

Size frequency distribution, catch per unit effort (CPUE) and biomass of blue swimming crab Portunus segnis were studied in the northern Persian Gulf. A total of 1689 male and 1824 female crabs were collected by swept area method on a monthly basis from May 2010 to September 2012. The populations of male and female crabs were dominated by adult crabs (carapace width >100 mm) from December to May. The juvenile crabs were dominant from June to October and the averages of CPUE did uptrend from June to October. The CPUE increased in full moon and the highest value was observed in shallow coastal areas below 10 m and significantly decreased as depth increased. The maximum CPUE was recorded at 415 and 450 engine powers and the vessel speeds of about 2.5 and 2.8 knots. The monthly biomass estimations showed an upward trend from June to October within the study period, so that the maximum biomass was 110 tonnes in October 2011. Given the CPUE trend and biomass estimation, the results of the present study suggest that October is the optimum time as open fishery season for blue swimming crab in the northern Persian Gulf and the highest CPUE is achievable in shallow coastal areas at less than 10 m depth.

Feeding habits of blue swimming crab Portunus segnis (Forskal, 1775) in the northern coastal waters of Iran

“…Previous studies on crab stocks in the northern Persian Gulf have mainly focused on population parameters, estimation biomass and size distribution and reproductive biology of blue swimming crab (Kamrani et al 2010;Safaie et al 2013a, b;Safaie et al 2015) and on some biological aspects of P.pelagicus in north western Persian Gulf (Jazayeri et al 2011;Hosseini et al 2012). The sole study on Dietary Compositions of the blue swimming crab P. segnis have been studied by Pazooki et al (2012) in Boushehr coastal waters, south Iran.…”

Condition factor and carapace width versus wet weight relationship in the blue swimming crab Portunus segnis

“…The total body weight-carapace width relationship and the condition factor have been previously evaluated for some Portunids such as Callinectes bocourti (Costa et al, 1980), Callinectes danae (Branco & Thives, 1991;Branco et al, 1992), Callinectes sapidus (Atar & Seçer, 2003), Charybdis helerii (Mantelatto & Garcia, 2001), Arenaeus cribrarius (Pinheiro & Fransozo, 1993), Portunus spinimanus (Santos et al, 1995), Portunus pelagicus (Josileen, 2011;Efrizal, 2014), Portunus sanguinolentus (Sumpton et al, 1989;Sukumaran & Neelakantan, 1997) and Portunus segnis (Safaie et al, 2013b). Almost in all the studies, the relationship between body weight and carapace width was not compared seasonally in detail, but were rather restricted to comparisons between the sexes.…”

PERIKANAN DAN DINAMIKA POPULASI RAJUNGAN (Portunus pelagicus Linnaeus, 1758) DI TELUK JAKARTA

“…Puncak CPUE dan musim penangkapan rajungan antar wilayah dan antar negara, dapat terjadi pada bulan yang berbeda. Puncak CPUE di Teluk Jakarta terjadi pada Mei sebesar 9,4 kg/trip/tarik/hari, berbeda dengan di perairan bagian utara Teluk Persia CPUE tinggi terjadi antara Juni-September dan rendah Januari-Maret (Safaie et al, 2015). CPUE rajungan di Teluk Jakarta tergolong tinggi jika dibandingkan di perairan Dar es Salaam-Tanzania 1,08-2,24 kg/tarik (Chande & Mgaya, 2003).…”

“…Kontribusi rajungan di Teluk Jakarta, lebih besar dari pada perairan lainnya seperti di Tanzania dengan kisaran 39,1-81,5 % (Chande & Mgaya, 2003). Safaie et al (2015) di Teluk Persia mendapatkan total portunid meliput 9,27 % dan diantaranya 68,59 % merupakan rajungan. Rajungan dominan pada hasil tangkapan ini, disebabkan alat dan teknik operasional penangkapan ditujukan untuk menangkap rajungan.…”

“…Penyebaran ini dimungkinkan perairan sekitar P. Bulat, P. Damar dan Ancol Tengah mempunyai dasar yang lebih dalam dan salinitas lebih tinggi dibandingkan lokasi lainnya, sedangkan di perairan di sekitar Tembakan, Sikutan dan Kelip Ijo mempunyai dasar dangkal dan salinitas rendah. Menurut Batoy 1980 dalam Safaie et al (2015) dan Kamrani et al (2010), rajungan betina ovigerous bermigrasi ke perairan yang lebih dalam karena adanya salinitas yang lebih tinggi.…”