The marine crab fishery by mechanised

trawlers along the Mangalore coast is mainly

supported by those belonging to the genera

Portunus and Charybdis of the family Portunidae

Muniyappa, Y

Sreedhara, B

Sukumaran, K K

CMFRI Digital Repository

'4TqF i^TR ICAR lUElM^R&Bai MARINE FISHERIES INFORMATION SERVICE No. 14 f JANUARY, FEBRUARY, MARCH 1997 . , ^ T ] r ^ TECHNICAL AND 3Hct^ |o |< - f i E X T E N S I O N S E R I E S r ^ CENTRAL MARINE FISHERIES 3T^5^STr^ ^FTF^nFT RESEARCH INSTITUTE ^ f r f % r ^ , ^TTTrT COCHIN, INDIA INDIAN COUNCIL OF AGRICULTURAL RESEARCH THE PORTUNID CRAB. CHARYBDIS (CHARYBDIS) FERIATUS -AN EMERGING FISHERY RESOURCE OF MANGALORE COAST K.K. Sukumaran, B. Sreedhara and Y. Muniyappa Mangalore Research Centre of C.M.F.R.I., Mangalore--575 001 Introduction The marine crab fishery by mechanised trawlers along the Mangalore coast is mainly supported by those belonging to the genera Portunus and Charybdis of the family Portunidae. Among the species, Portunus (Portunus) sariguinolentus, Portunus [Portunus) pelagicus and Charybdis {Charybdis) feriatus (previously known as Charybdis cruciata) grow to large size and commercially very important. Of these, until recently P. (P.) sanguinolentus, P. (P.) pelagicus together contributed to the bulk of the catch, wMe C. (C.) feriatus along with other crabs formed less than 10%. Over the years, there has been a sea change in the pattern of trawl fishing. From single-day, the fishing has been changed to multi-day fishing to facilitate long voyages to exploit the under-exploited/unexploited resources of the deeper waters upto a depth of 100 m. Coupled with this changed scenario in the fisheries sector, there has been sharp increase in the landing of C. (C.) feriatus along the Mangalore coast. A brief account of this emerging fishery resource is reported here. C. (C.) feriatus fishery The landings of C. [C.) feriatus by mechanised trawlers at Mangalore and Malpe combined for the fishing seasons 1992-'93 to 1995-'96 are presented in Tables 1-4. The annual catch increased from a minimum of 64,659 kg (9.3% of total crabs) in 1992-'93 to a maximum of 3,29,479 kg which formed 60.5% of the total crab landings in 1995-'96 at these centres. Seasonal abundance Although trawling started by late August and extended upto May end, the catch of this crab occurred only for a short duration i.e., from February to May during 1992-'93 season (Table 1). However, during the following season (1993-'94), the fishery for this species was extended from December to May (Table 2). More recently, (during 1994-'95 and 1995-'96), this crab was caught from October to May, fairly in large quantities resulting in steep increase in its landings (Tables 3-4). The catch was so high that this species dominated the crab landings relegating the traditional species such as, P. (P.) sanguinolentus TABLE 1. Landings (in kg) oj C. (C.) feriatus by mechanised trawlers at Mangalore & Malpe centres during the period 1992-'93 Parameters Units Total crab catch C. (C.) feriatus Catch /un i t (kg) % in total c rabs Aug. 805 626 0 0 0 Sep. 5 ,447 3 ,167 0 0 0 Oct. 8.181 19,554 0 0 0 Nov. 5,145 9 ,948 0 0 0 Dec. 7 ,424 61 ,027 0 0 0 Jain. 9 ,714 3 ,09,435 0 0 0 Feb. 9 ,394 97 ,610 13,294 1.4 13.6 Mar. 8 ,312 59 ,898 7,821 0.9 13.1 Apr. 9 ,362 72 ,084 2 7 , 2 3 2 2.9 3 7 . 8 May 8,862 6 3 , 2 2 8 16,312 1.8 25 .8 Total 72 ,646 6,96,577 64 ,659 0.9 9.3 TABLE 2. Landings (in kg) of C. (C.) feriatus by mechanised trawlers at Mangalore & Malpe centres during the period 1993-'94 Parameters Units Total c rab ca tch C. (C.) feriatus Catch /un i t (kg) % in total c rabs Aug. 695 594 0 0 0 Sep. 2 ,776 3 ,320 0 0 0 Oct. 4 ,616 3 ,614 147 0.0 4.1 Nov. 6,482 10,292 0 0 0 Dec. 10,471 35 ,229 6,719 0.6 19.1 J a n . 8 ,974 86 ,040 30 ,486 3.4 35 .4 Feb. 7,062 43 ,076 15 ,785 2.2 36 .6 Mar. 8 ,171 57 ,600 21 ,777 2.7 37 .8 Apr. 8 ,597 9 9 , 6 2 4 2 9 , 8 2 0 3.5 29 .9 May 7,341 74 ,029 34 ,551 4.7 46 .7 Total 65 ,185 4 ,13 ,418 1,39,285 2.1 33 .7 TABLE 3. Landings (in kg) C. (C.) feriatus by mechanised trawlers at Mangalore & Malpe centres during the period 1994-'95 Parameters Units Total crab catch C. (C.) feriatus Catch/unit (kg) % in total crabs Aug. 340 60 0 0 0 Sep. 1,522 7 4 8 0 0 0 Oct. 4,438 3,421 3,376 0.8 98.7 Nov. 7,977 6 0 7 196 0.0 32.3 Dec. 9,150 22,440 14,416 1.6 64.2 Jan. 7,878 73,650 50,006 6.3 67.9 Feb. 7,876 49,779 33,965 4.3 68.2 Mar. 9,217 49,426 30,563 3.3 61.8 Apr. 8,882 57,114 37,042 4.2 64.9 May Total 8,671 65,951 73,435 3,30,680 38,292 2,07,856 4.4 3.2 52.1 62.9 TABLE 4. Landings (in kg) of C. (C.) feriatus by mechanised trawlers at Mangalore & Malpe centres during the period 1995-'96 Parameters Aug. Sep. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May Total Units Total crab catch C. (C.) feriatus Catch/unit (kg) % in total crabs 161 0 0 0.0 3,076 196 0 0.0 0.0 4,252 0 3,376 0.8 9,016 2,373 1.450 0.2 61.1 7,548 29,597 24,398 3.2 82.4 9,514 1,16,848 78,595 8.3 67.3 10,005 92,674 47,541 4.8 51.3 9,780 92,049 54,397 5.6 59.1 9,810 9,397 72,559 89,880 1,21,019 5,44,636 46,249 76,849 3,29,479 4.7 8.2 4.5 51.5 63.5 60.5 and P. (P.) pelagicus to second and third positions respectively. The monthly catch ranged from a minimum of 147 kg (4.1%) in October 1993 to a maximum of 78.595 kg (67.3%) in January 1996 (Table 4). The highest catch rate of 8.3 kg/unit was also realised in this month. It is Interesting to note that the percentage contribution of C. (C.) feriatus was so high that it formed 98.7% of the crab landings in October 1994 (Table 3). catch in tonnes 300 200 100 1992-93 1903-04 1004-06 Fishing seasons 1008-06 Fig. 1. Annual landings of C. (C.) feriatus by MDF and SDF at Mangalore and Malpe for the period from 1992-'93 to 1995-'96. C. (C.) feriatus is mostly caught by multi-day trawlers operating beyond 25 m depth. Present study has revealed that the annual catch of this species obtained by multi-day fleets increased from 50.3% in 1992-'93 to 87.2% in 1995-'96 (Fig. 1). It is also noteworthy that the landings of this crab showed an upward trend over the recent years, although there was a fall in annual crab landings (Fig. 2). 600 400 crab landings In tonnes 200 1002-03 1003-04 1004-06 Fishing seasons 1006-06 Fig. 2. Annual landings of C. (C.) feriatus and total crabs at Mangalore and Malpe for the period from 1992-'93 to 1995-'96. Biology of C. (C.) feriatus Unlike P. (P.) sangutnolentus arid P. (P.) pelagicus, C. (C.) feriatus is exclusively a meirine species. The size ranged from 41 to 145 mm carapace width (C.W.) for males and from 36 1992-93 l O r •3 U 71 U U tOS 11> •s r> SI u 101 1993-94 IS U 78 S3 «1 103 133 ' 43 63 63 71 M M 101 Carapace width In mm (mId-poInt) Fig. 3. Annual size frequency distribution of C. (C.) feriatus from 1992-'93 to 1994-'95. to 140 mm (C.W.) for females (Fig. 3). Sex ratio studies indicated that males outnumbered females. It was observed that most of the females were with immature or maturing ovary. Crabs with fully matured ovary were seldom found. However, berried crabs were available from January to May (in fewer numbers) indicating spawning during this period. Smallest ovigerous female measured was 65 mm C.W. Remarks With the unprecedented heavy landings of this species, the recent years have witnessed the emergence of C. (C.) feriatus as a predominant constituent of the crab resources exploited by mechanised trawlers off Mangalore coast. With the expansion of mechanised trawl fishery coupled with the introduction of more sophis-ticated fish finding equipments as fishing aids in a large number of units, it is possible that the landings of this species may further increase in the years to come. 

The portunid crab Charybdis (charybdis) feriatus -

An emerging fishery resource of Mangalore coast

http://eprints.cmfri.org.in/5029/1/Article_04.pdf

The portunid crab Charybdis (charybdis) feriatus - An emerging fishery resource of Mangalore coast

Abstract

Similar works

Full text

Available Versions

CMFRI Digital Repository