The Marine Environment of the Pitcairn Islands by Robert Irving Principal Consultant, Sea-Scope Marine Environmental Consultants, Devon, UK and Terry Dawson SAGES Chair in Global Environmental Change, School of the Environment, University of Dundee, UK Report commissioned by The Pew Environment Group Global Ocean Legacy August 2012 The Marine Environment of the Pitcairn Islands The Marine Environment of the Pitcairn Islands Dedication This book is dedicated to the memory of Jo Jamieson, underwater photographer extraordinaire and Robert Irving’s diving colleague in 1991 on the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands, who sadly died just five years after what she described as “the adventure of her lifetime”. Acknowledgements The authors are grateful for the support of the Pew Environment Group and a Darwin Initiative Overseas Territories Challenge Fund (Ref. no. EIDCF003) awarded to Terence Dawson. In addition, we should like to thank the following for commenting on the final draft of this report: Dr Michael Brooke and Dr Richard Preece (University of Cambridge); Jonathan Hall (RSPB); The Pew Environment Group’s Global Ocean Legacy staff; The Government of the Pitcairn Islands and the Head of its Natural Resources Department (Michele Christian); and especially the entire community of Pitcairn. While the majority of photographs featured in the report have been taken by the authors, we should like to thank the following for the use of their photographs, namely Dr Enric Sala (National Geographic Society), Dr Michael Brooke, Kale Garcia, Jo Jamieson (posthumously), Andrew MacDonald, Dr Richard Preece, Dr Jack Randall, Tubenoses Project ©Hadoram Shirihai and Dr Stephen Waldren. [The photo credit SPSCEPI stands for the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands in 1991/92]. Citation Irving, R.A. and Dawson, T.P. 2012. The marine environment of the Pitcairn Islands. A report to Global Ocean Legacy, a project of the Pew Environment Group. The warm-hearted and welcoming people of Pitcairn, whose good fortune it is to live on a wonderful island and be surrounded by a beautiful and plentiful sea. Photo: Courtesy of Pew Environment Group/Global Ocean Legacy Cover Galapagos reef sharks Carcharhinus galapagensis swimming above the reef at Ducie atoll. © Enric Sala / National Geographic. The Marine Environment of the Pitcairn Islands The Marine Environment of the Pitcairn Islands CONTENTS Executive summary i 1. Introduction 1 1.1 Historical background 1 1.2 The Islands today 2 1.3 Geology / geomorphology 4 1.4 Marine biogeography 4 First published in Great Britain in 2012 by Dundee University Press 2. Information relevant to all four islands 6 University of Dundee 2.1 Differences and similarities 6 Dundee 2.2 Endemism 9 DD1 4HN 2.3 Measures of protection 10 3. Nearshore waters 11 Dundee 3.1 Pitcairn Island 11 University 3.1.1 Introduction 12 Press 3.1.2 Intertidal zone – habitats and species 12 3.1.3 Bathymetry and marine habitats 13 3.1.4 Marine species 14 3.1.5 Nearshore fisheries 19 Copyright – The Pew Charitable Trusts 3.2 Henderson 21 ISBN – 9781845861612 3.2.1 Introduction 22 3.2.2 Intertidal zone – habitats and species 22 All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form, 3.2.3 Bathymetry and marine habitats 22 or by any means electronic or mechanical or photocopying, or recording or otherwise without the express 3.2.4 Marine species 23 written permission of the publisher. 3.2.5 Nearshore fisheries 28 The rights of Robert Irving and Terry Dawson to be identified as the authors of this work has been asserted 3.3 Oeno 29 in accordance with the Copyright, Designs and Patents Act, 1988. 3.3.1 Introduction 30 3.3.2 Lagoon – habitats and species 30 British Library Cataloguing-in-Publication Data 3.3.3 Bathymetry and marine habitats 30 A catalogue record for this book is available on request from the British Library 3.3.4 Marine species 30 3.3.5 Nearshore fisheries 31 Typeset by Communications Inc 3.4 Ducie 33 Printed by Dundee University Press 3.4.1 Introduction 34 3.4.2 Lagoon – habitats and species 34 3.4.3 Bathymetry and marine habitats 34 3.4.4 Marine species 34 3.4.5 Nearshore fisheries 37 4. Offshore waters 38 4.1 Introduction 38 4.2 Geology/geomorphology 38 4.3 Marine species 38 4.4 Fisheries 41 4.4.1 Non-commercial 41 4.4.2 Commercial 42 Appendix 1: Bibliography 45 Appendix 2: Additional data sources 49 Appendix 3: IUCN Red List Species 50 Appendix 4: Scientific research expeditions to the Pitcairn Islands 54 Appendix 5: Marine species recorded from the Pitcairn Islands 57 The Marine Environment of the Pitcairn Islands The Marine Environment of the Pitcairn Islands 20° Pacific Ocean 200-nautical-mile limit / EEZ boundary Tropic of Capricorn Oeno Island Henderson Island Ducie Island Crough * Pitcairn Island Seamounts * * Bounty Seamount * 40 Mile Reef (Adams Seamount) Pitcairn Exclusive Economic Zone / 0 km 100 0 nautical miles 100 * Submarine volcano (seamount) 130° 120° ©2012 Pew Environment Group; used by permission Executive summary The extent of the Pitcairn Islands’ Exclusive Economic Zone The extent of the Indo-West Pacific biogeographic (EEZ), which defines the geographic extent of this report. province (shown in dark blue). (Source: http://en.wikipedia.org/wiki/File:Indo-Pacific_ biogeographic_region_map-en.png) Introduction occupation lasted until about 14502. In 1606, Fernández The Pitcairn Islands are a group of four near-pristine small de Quirós was the first European to discover Henderson islands which can claim to be some of the most remote Island (by now uninhabited) and Ducie Island. British islands in the world. They are situated between latitudes interest in the islands (and in Pitcairn in particular) began 23° and 26° south and longitudes 124° and 131° west more than a century-and-a-half later in 1767 when HMS and located in the crystal-clear waters of the central South Swallow, under the command of Captain Philip Carteret, Pacific, about 2,200 km south-east of Tahiti and 2,100 km encountered Pitcairn and mistakenly plotted its position west of Easter Island. The group comprises: 188 nautical miles west of its actual location. This mistake, l Pitcairn Island, a high volcanic island of 450 ha with however, was to be of great benefit to the island’s next lava cliffs and rugged hills rising to a peak at 347 m; inhabitants, the mutineers from HMS Bounty, who were it is the only inhabited island, with a population of looking for a safe island hideaway in 1790, and remained around 60 as of 2012; undiscovered there for 18 years. Pitcairn Island officially l Henderson (200 km east-north-east of Pitcairn) is the became a British dependency on 29 November 1838. The largest island in the group with an area of 4,310 ha. other three islands (Henderson, Oeno and Ducie) were It is a raised fossilised coral atoll which rises to 33 m. annexed by Great Britain in 1902 and were included in the It is designated a UNESCO World Heritage Site on dependency in 1938. The Pitcairn Islands remain the only account of its unique natural history and ecological UK Overseas Territory in the Pacific. intactness, and it has been described as “a South Pacific conservation jewel”1; Biogeography l Ducie (472 km east of Pitcairn), the most southerly The Pitcairn Islands are located at the south-eastern coral atoll in the world, consists of a central lagoon extremity of the Indo-West Pacific biogeographic province, surrounded by four islets covering an area of 70 ha; resulting in a number of barriers to the establishment of l Oeno (120 km north-west of Pitcairn) is a low coral species. atoll of 65 ha comprising a central low-lying island l Prevailing winds and currents are dominantly from the surrounded by a shallow lagoon and a fringing reef east in the central South Pacific, with the Islands lying (diameter approximately 4 km). upwind and upstream of all Indo-Pacific source areas. l The Islands lie south of the Tropic of Capricorn Together, all four islands and their surrounding waters out (23°26’S), with relatively cool waters and climates to the 200 nautical mile limit – also known as the Exclusive imposing further barriers to the establishment of Economic Zone (EEZ) – span a vast area of ocean of about tropical species. 836,000 km2, more than three times the size of the UK. Studies of groups as diverse as corals, reef fishes, vascular A brief history plants and land birds support the arguments that It is believed that Pitcairn and Henderson were first colonisation has been from the biologically rich source colonised by Polynesians in about AD 900 and their areas to the west on the margins of South-East Asia, The Marine Environment of the Pitcairn Islands The Marine Environment of the Pitcairn Islands i taking advantage of the inter-island connectivity of the with each of the islands being declared Important Bird Endangered marine species* known to be present within the Pitcairn Islands EEZ south-west Pacific Ocean3. As a consequence of these Areas. Henderson is, without question, one of the petrel factors, the diversity of marine species present within the capitals of the world9. It is the only location in the world Species Status* Notes** nearshore waters of the EEZ4, when compared to island where the Henderson petrel Pterodroma atrata is known Humpback whale EN Has a circumglobal distribution but subpopulations now recognised in groups further to the west, is limited5. It also reflects to breed, with over 16,000 pairs being resident (>95% of Megaptera the South Pacific and Australia.