Status Survey of Endangered Species Status Survey on Trochus niloticus (Linnaeus, 1767) in Andaman and Nicobar Islands RAMAKRISHNA * C.RAGHUNATHAN AND C. SIVAPERUMAN *Zoological Survey of India, M-Block, New Alipore, ,Kolkata 700 053 Zoological Survey of India, Andaman and Nicobar Regional Centre Port Blair 744 102 (A & N Islands) Zoological Survey of India Kolkata CITA110N Ramakrishna, Raghunathan, C. and Sivaperuman, C. 2010. Status Survey on Trochus niloticus (Linnaeus, 1767) in Andaman and Nicobar Islands. Status Survey of Endangered Species, : I-SO. (Published by the Director, Zool. Surv. India, Kolkata) Published: September, 2010 ISBN 978-81-8171-274-5 © Govt. of India, 2010 ALL RIGHTS RESERVED • No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the publisher. • This book is sold subject to the condition that it shall not, by way of trade, be lent, resold hired out or otherwise disposed of without the publisher's consent, in an form of binding or cover other than that in which, it is published. • The correct price of this publication is the price printed on this page. Any revised price indicated by a rubber stamp or by a sticker or by any other means is incorrect and should be unacceptable. PRICE ~400.00 Foreign : $ 30; £ 2S Published at the Publication Division by the Director Zoological Survey of India, 234/4, AlC Bose Road, 2nd MSO Building, 13th floor, Nizam Palace, Kolkata - 700020 and printed at Power Printers, New Delhi - 110002. CONTENTS INTRODUCTION ................................................................................................................. 1 Avant Propos .................................................................................................................... 1 Fishing Zone ..................................................................................................................... 1 Method of Fishing ........................................................................................................... 2 Fisheries and Statistics .................................................................................................... 2 Processing of shells ........................................................................................................ 3 Commercial value ............................................................................................................ 3 Systematic position .......................................................................................................... 4 CLASSIFICATION OF TROCHUS NILOTICUS ............................................................... 8 Morphology ...................................................................................................................... 8 Reproduction and Larval Development ......................................................................... 9 Age and Growth .............................................................................................................. 9 Food and Feeding .......................................................................................................... 10 Animal Association ........................................................................................................ 11 Distribution ..................................................................................................................... 11 Legislation on Trochus niloticus ................................................................................... 12 REVIEW OF LITERATURE .............................................................................................. 13 International Status ........................................................................................................ 13 National Status ............................................................................................................... 14 Studies on key areas ..................................................................................................... 15 OBJECTIVES OF THE STUDY ........................................................................................ 15 Rationale ......................................................................................................................... 15 Period of Study ............................................................................................................. 16 AIM ................................................................................................................................... 16 STUDY AREA ..................................................................................................................... 16 MATERIAL AND METHODS ............................................................................................ 20 Physico-chemical Parameters ..................•.................................................................... 20 Biological Parameters .................................................................................................... 22 Estimation of Trochus niloticus standing stock .......................................................... 22 Personal interaction ....................................................................................................... 23 ;v RESULTS AND DISCUSSION ........................................................................................ 23 Physico-chemical Parameters ....................................................................................... 23 Biological Parameters .................................................................................................... 24- Phytoplankton ........................................................................................................... 24- Zooplankton .............................................................................................................. 24- Status of Trochus niloticus ........................................................................................... 26 Density ..................................................................................................................... 27 Size ........................................................................................................................... 28 Habitat ..................................................................................................................... 30 SIGNIFICANT FINDINGS ............................................................................................... 55 ILLEGAL FISHIN'G AND TRADIN'G .............................................................................. 55 SUMMARY .......................................................................................................................... 55 RECOMMENDATIONS ...................................................................................................... 57 ACKNOWLEDGEMENTS .................................................................................................. 58 REFERENCES ..................................................................................................................... 59 INTRODUCTION Avant-Propos The seas around Andaman and Nicobar Islands are a rich ground for a variety of commercially important molluscs. Among the seas shells, Trochus or Top shell and Turbo or Turban shell have unique position in commercial point of view. As early as 1927, the Trochus fishery was initiated in Andaman Islands, however the regular fishery on Trochus organised during October 1929 at these Islands. In the initial season, the fishery yielded not less than 500 tons of shells within the first three months, but the yield, however, began to steadily decline and although the period of fishing has since then been doubled the quantity of shells obtained was reached the low figure of 40 tonnes in one fishing season. The scarcity of full-sized specimens has also resulted in an indiscriminate fishing of shells of all sizes by both the licensed and unlicensed Japanese fishermen, so much so that, at the present day, the Trochus beds of Andaman and Nicobar waters were rapidly depleted. Subsequently, a consolidated scientific report was published in 1938 by Zoological Survey of India (ZSI, 1939) on the shell fisheries of these Islands during 1930-35 dealing with the history of Andaman shell fisheries, fishing methods, important beds of top and turban shells and the scientific work. Considering the importance of Trochus fisheries is threatened with almost complete extinction in its natural beds, the Government of India on the recommendations of ZSI initiated to control the Trochus fishery on scientific basis. The Andaman and Nicobar Administration after realising the importance of this fishery, started giving the fishing grounds on lease to merchants for fishing and collecting royalty from them (Appukuttan, 1979). Fishing Zone The Andaman and Nicobar Administration has identified nine Trochus fishing zones and leased out all these zones for fishing every year. There are seven licensed shell collectors in the island and each is permitted to raise up to 25 tonnes of Trochus and Turbo per year during the initial days of shell fisheries. The categorized nine important fishing zones and their port and latitude are given below: 1. Cape Price to Mayabunder, between Lat. 12° 56.5' and 13° 34.5'N. Port-Mayabunder 2. Cape Price to Austen Straight, between Lat. 12° 54' and 13° 34.5'N. Port-Mayabunder