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TOTAL LANDINGS AND PERCENTAGE YIELD OF

C. RAMOSUS AND H. PUGILINUS

INTRODUCTION

The marine molluscs form the important fishery next to fishes and

crustaceans in terms of commercial value. They constitute a good source of protein,

glycogen, and minerals on a par with other animal food conventionally consumed by

human beings (Durve and Bal, 1961; Ansari et al., 1981). The gastropods are mainly

fished for their beautiful shells, which are of ornamental value and for the

manufacture of lime (Edward and Ayyakkannu, 1992). The operculum of the

gastropods is commercially more important and it is used in cosmetic industry.

The underutilized marine gastropods like Chicoreus ramosus and

Hemfusus pugilunus are abundantly available in all seasons in Gulf of Mannar

region of southeast coast of India. Nowadays only smaller sections of the fisherfolk

consume the flesh of this gastropod after converting into chips. But the meat of C.

ramosus had a good export value and is being exported to South East Asian

countries. The present study shows the annual catch of C ramosus and H. pugilinus

in Tuticorin coastal region and the percentage yield of the gastropod meat.

MATERIALS AND METHODS

Monthly surveys were done in the gastropod landing centres in Tuticorin

coastal region from April 2002 to January 2003 to estimate the annual total catch of

these gastropods. The shell meat dealers were also regularly interviewed to know

the extent of exploitation of these gastropods.

PERCENTAGE YIELD OF EDIBLE MEAT

The percentage yield of edible meat of C. ramosus and H. pugilinus meat

was calculated at monthly intervals using 10 animals in each species. The seasonal

variation in percentage yield of edible meat was observed for the seasons such as

Summer (April, May, June), Pre monsoon (July, August, September), Monsoon

(October, November, December) and Postmonsoon (January, February, March).

The whole animal (C. ramosus and H. pugilinus) was collected from the landing

centers and brought to the laboratory. After taking the whole animal weight (shell

and operculum), the shell was broken and the soft body was removed and the edible

portions such as foot and adductor muscles were separated (Fig 1 & 2) and weighed.

The percentage ratio of the edible meat weight to the whole animal weight gives the

percentage yield. It was calculated using the formula given below.

Edible meat weight (g)

Percentage yield (%) = -------------------------------- X 100

Whole animal weight (g)

Fig 1:Soft body of Chicoreus ramous and separated edible portion

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Fig 2: Soft body of Hemifusus pugilinus and separated edible portion

RESULTS

Landing Data

The total catch of C. ranwsus and H. pugilinus in Tuticorin coastal area are

given in Tables 1 and 2.

Table 1: Total catches of C. ramosus from April 2002 - January 2003

MonthsWhole animal weight Edible meat weight

(Tonnes) (Tonnes)

April 2002 7.5 2.3

May 6.0 2.0

June 1.5 2.0

July 1.5 0.7

August 2.0 0.9

September 1.5 0.1

October 2.0 0.1

November 7.0 0.2

December 9.0 0.2

January 2003 18 0.3

February 22 0.7

March 21 1.2

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Table 2: Total catches of H. pugilinus from April 2002 - January 2003

Whole animal weight Edible meat weightMonths

(Tonnes) (Tonnes)

April 2002 4.7 0.58

May 5.3 0.61

June 5.0 0.44

July 7.2 0.85

August 6.9 0.46

September 6.7 0.49

October 6.8 0.65

November 3.2 0.35

December 7.1 0.60

January 2003 8.0 0.77

February 7.5 0.77

March 9.5 0.97

The highest landing for C. ramosus was observed during the month of

February (22 tons) and the lowest in June, July and September (1.5 tons each). In

H. pugilinus, the highest landing (9.5 tons) was observed in March and the lowest in

November (3.2 tons).

Percentage yield

The average seasonal percentage yield of C. ramosus and H. pugilinus

edible meat is represented in Tables 3 and 4.

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Table 3: Seasonal variation in percentage yield of C. ramosus meat

. MonthsWhole animal Edible meat Percentage yield

weight (g) weight (g) (%)

Summer 773.3 83.6 12.2

Pre monsoon 721.1 76.3 10.9

Monsoon 660.6 84.7 13.2

Post monsoon 705.6 74.2 10.7

Table 4: Seasonal variation in percentage yield of H. pugiinus meat

MonthsWhole animal Edible meat Percentage yield

weight (g) weight (g) (%)

Summer 118.17 11.43 9.35

Pre monsoon 99.49 19.97 12.46

Monsoon 125.24 13.07 10.49

Post monsoon 123.58 12.36 9.97

The highest percentage yield of C. ramosus edible meat was (13.2%)

observed during monsoon and lowest percentage yield was (10.7%) observed during

post monsoon period. In the case of H. pugilinus, the percentage of edible meat was

high in pre monsoon period (12.46 %) and low in summer (9.35 %).

DISCUSSION

The C. ramosus and H. pugilinus fishing in Tuticorin coastal area is year

round. The main fishing method involved for C. ramosus is skin diving. They are

also caught as by-catch from lobster and trawl nets. These gastropods are collected

from rocky area of 10 - 40 feet depth when the water is clear. The peak fishing

season for C. ramosus is January to March.

The H. pugilinus are mainly landed as by-catch from crab nets (modified gill

nets) (60%), trawl net (30%) and a small portion (10%) by skin diving. They are

collected from sandy area with a depth of 7.5 to 37 feet. The peak fishing season of

this gastropod is also from January to March.

The gastropod fishing is normally low I nil in windy season between May

and September. The landing area for the present study includes fishing harbour,

Thirespuram, Pudukadakarai and New port area. The highest landing was observed

in these areas during the months of January to April. Shanthini (2003) reported that

the sea is relatively calm and the visibility is high in these months. These factors are

favorable for skin diving to collect large quantities of gastropods. The lean fishing

season for C. ramosus and H. pugilinus is June to November. Edward et al. (1994)

have reported that during the period of northeast monsoon months such as October

to February, the fishermen faces difficulties due to rough sea conditions in the

Gulf of Mannar.

In the present study, the total landings of C. ramosus in Tuticorin during the

year 2002 - 2003 was 99 tonnes and H. pugilinus, 77.9 tonnes. Edward et a. (1994)

recorded the landing of C. ramosus in Tuticorin coastal area during July 1992 - June

1993 as 173.5 tonnes, but in the present study comparatively low number of animals

was landed and it may be mainly due to the stop of skin diving (Shanthini, 2003).

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The percentage yield of C. ramosus meat was higher during the monsoon

season and lowest in post monsoon season and for H. pugilinus, it was higher in pre

monsoon and lower in summer. Suryanarayanan et al. (1973) have reported that the

gastropods and bivalves possess much heavier shells and have comparatively lesser

percentage of edible portions. The general percentage yield of meat obtained from

different species of molluscs varied between 3.5-31.5%. Sarvaiya (1977) reported

that the fluctuations in percentage edibility followed a distinct seasonal cycle

correlated to the sexual cycle in oysters. Tagore (1989) has reported that the meat

weight of Thais biserialis and Thais bufo was decreased during spawning period.

Shanthini (2003) has reported that the percentage edibility of the meat of gastropod,

Pleuroploca trapezium falls considerably during January - April and it indicates the

spawning period. Many workers have also reported that the percentage of meat

weight was influenced first by reproductive cycle, food availability and salinity of

the environment (Ansell and Lander, 1967; Giese et al., 1967; John, 1980).

The present study highlights that these underutilized gastropods are largely

caught from the Tuticorin coastal areas as by-catch through crab nets (modified gill

nets), trawl nets and skin diving, but the local people are not properly utilizing the

meat. It is therefore essential to popularize these underutilized gastropod meats

among the people to create awareness about the nutritive value of these marine

resources and its wise utilization.