Reports of the Great Barrier Reef Committee VOL. IV. PART I. j With Seven Plates. i i ISSUED 15th May, 1933. FRED ERICK P H IL L IP S, Government Printer, Brisbane. Great Barrier Reef Committee, List oí Representatives of various Institutions, etc., and other Members who form the Committee. OFFICERS: Patrons .. Sir Matthew Nathan, P.C., G.C.M.G., and Sir Leslie Orme Wilson, G.C.S.T., G.C.I.E. C.M.G., D.S.O. Chairman . Professor H. C. Richards, D.Sc. Hon. Treasurer W. M. L’Estrange, M.I.E.E. Hon Secretary Dr. E. O. Marks, B.A., B.E., M.D. Assistant Secretary Miss H. F. Todd. Hon. Editors H. A. Longman and Dr. E. O. Marks. Office : Rooms of Council for Scientific and Industrial Research, comer Ann and Edward streets, Brisbane. MEMBERS REPRESENTING INSTITUTIONS. Representative. Institution. Thomson, Dr. J. P., C.B.E. Royal Geographical Society of Australasia (Queensland) Richards, Professor H. C., D.Sc.. University of Queensland Bryan, Dr. W. H., M.C., D.Sc. Royal Society of Queensland Longman, H. A., F.L.S., C.M.Z.S. Queensland Museum, Brisbane Roberts, Captain T. F. H. Marine Department, Brisbane Herbert, Dr. D. A., D.Sc. Queensland Naturalists’ Club L’Estrange, W. M., M.I.E.E. Institute of Engineers, Queensland Hill, Colonel J., B.Sc. Department Public Instruction, Queens­ land Ball, L. C., B.E............................................. Geological Survey, Queensland Cowlishaw, I. M., B.E. Commonwealth Lighthouse Service Andrews, E. C., B.A., F.G.S. Geological Survey, New South Wales Sussmilch, C. A., F.G.S. Royal Society of New South Wales Waterhouse, Dr. G. A., D.Sc., B.E., F.E.S. Naturalists’ Society of New South Wales Walkom, Dr. A. B., D.Sc. Linnean Society of New South Wales Hull, A. F. Basset Royal Zoological Society of New South Wales Bond, G. G. Commonwealth Bureau of Meteorology, Brisbane. Marshall, Dr. P., M.A., D.Sc., F.G.S. University of New Zealand Oliver, W. R. B ............................................ New Zealand Institute, Wellington Skeats, Professor E. W., D.Sc., A.R.C.Sc., Australian National Research Council F.G.S. Caiman, Dr. W. T., F.R.S. British Museum, London Davis, Captain J. K. Commonwealth Navigation Department, Melbourne IV. GREAT BARRIER REEF COMMITTEE. Representative. Institution. Roskruge, Captain N. G. Commonwealth Navigation Department, Brisbane Johnston, Professor T. Harvey, M.A., D.Sc. University of Adelaide Pulleine, Dr. R. H., M.B., Ch.M. Royal Geographical Society of Australasia (South Australia) Nicholls, Professor G. E., D.Sc. University of Western Australia Clarke, Professor E. de C., M.A. Royal Society of Western Australia Flynn, Professor T. Thomson, D.Sc. University of Tasmania Wood-Jones, Professor F., D.Sc., F.R.S., Royal Society of South Australia M.B., M.R.C.S. Agar, Professor W. E., M.A., D.Sc., F.R.S. University of Melbourne Rivett, Dr. A. C. D., M.A., D.Sc. Commonwealth Council for Scientific and Industrial Research, Melbourne Rhodes, Captain F. Rockhampton Harbour Board Anderson, Dr. Chas., M.A., D.Sc. Australian Museum, Sydney Dakin, Professor W. J., D.Sc., F.Z.S. University of Sydney Harvey, J. P., Esq. Survey Department of Queensland Holland, C. W .................................................... Land Administration Board, Brisbane. Wilson, R. Department of Agriculture, Brisbane. ORDINARY MEMBERS: Alexander, W. B., M.A., England Julius, Sir George, Kt., B.Sc., B.E., Bage, Miss Freda, M.Sc., Brisbane Sydney Lucas, A. H. S., M.A., B.Sc., Sydney Bennett, Commander H., D.S.O., R.N. MacGillivray, Dr. W. W. K., M.D., Cameron, Sir Donald, K.C.M.G., D.S.O. Broken Hill, N.S.W. Campbell, G. P., Brisbane Marks, Dr. E. O., B.A., B.E., M.D., Chapman, Frederick, A.L.S., F.G.S., Brisbane A.R.C.S., F.R.M.S., Melbourne Moorhouse, F. W., M.Sc., Brisbane Cilento, Dr. R. W., M.D., Brisbane Morrow, H., Brisbane Clarke, Dr. Phibp, M.D., Cairns Parnell, Professor T., M.A., Brisbane David, Sir Edgeworth, K.B.E., C.M.G., Patterson, B. G., B.E., Ipswich D.S.O., M.A., F.R.S., F.G.S., Sydney Pritchard, Lieut.-Surgeon D. A., R.A.N. Edgell, Captain J. A., R.N., London Stevens, Commander C. W., R.A.N. Elkington, Dr. J. S. C., Brisbane Taylor, Professor Griffith, D.Sc., B.E., Ford, F. B. C., Brisbane B.A., F.R.G.S., Chicago, U.S.A. Goddard, Professor E. J., B.A., D.Sc., Thomson, Captain W. C., Brisbane Brisbane Twine, G. J., Darra. Hervey, Commander T. A. L., R.N. Walsh, A. D., Brisbane Henderson, J. B., O.B.E., F.C.S., F.I.C., White, C. T., F.L.S., Brisbane. Brisbane Wilkins, Sir Hubert Hopkins, Spenser M., Townsville Yonge, Professor C. M., D.Sc., Ph.D., Jones, O. A., M.Sc., Brisbane Bristol, England. Jones, T. L., Brisbane Young, J. E., Graceville MEMBERS OF SUB-COMMITTEE: Handley, C. J., Samarai, Papua Rainford, E. H., Bowen Jardine F. B.Sc., Rockhampton Contents. PAGE. No. 1.— Notes on the Green Turtle (Chelonia mydas). By F. W. Moorhouse, M.Sc. Plates I.-III. .. .. .. .. .. 1-22 No. 2.— The Commercial Trochus (Trochus niloticus). By F. W. Moorhouse, M.Sc. .. 23-29 No. 3.— Commercial Sponges from the Barrier Reef. By F. W. Moorhouse, M.Sc. Plates IV., V. 30-34 No. 4— The Recently-formed Natural Breastwork on Low Isles. By F. W. Moorhouse, M.Sc. Plates VT., VII. 35, 36 Reports of the Great Barrier Reef Committee. VOL. IV., PART I. No. 1. NOTES ON THE GREEN TURTLE (Chelonia mydas). By F. W. Moorhouse, M.Sc., late Marine Biologist of Queensland. (Plates I.-III.) 1. Introduction. 2. Marking of Adult Turtles. 3. Breeding Season. 4. Enemies of Mature Turtles. 5. Eggs. 6. Percentage Hatch. 7. Young Turtles. 8. Enemies o f Young Turtles. 9. Marking of Young Turtles. 10. Growth in Young Turtles. 11. Preservation of Young Turtles. 12. Deductions and Suggested Bestrictions. 13. Summary. 1.— Introduction. Turtles are found the world over ; some are restricted to certain wery limited areas only, while others are cosmopolitan and are found mainly in the tropical and subtropical waters of all the oceans. Along the Barrier Reef, from south to north, there are present in considerable numbers at least three species of turtles— the green turtle (Chelonia mydas), the loggerhead turtle (Thalassochelys oaretta), and the tortoiseshell or hawkbill turtle (Chelonia imbricata). As little is known of the life-history and habits of the green turtle (Chelonia mydas), and as these animals are being taken in large numbers from the many islands along the coast of Queensland, more particularly in the Torres Strait, where the natives make them an important article of their diet, observational and experimental work on the laying period and on the rate of growth of the young turtles was carried out from October to February, 1929-30, with a view, not only to the adding to our knowledge of these animals, but also to the recommending of restrictions on the taking and killing of the adult animals if such was considered necessary. Heron Island, situated at or about the southern extremity of the Great Barrier Reef and 55 miles north-east of Gladstone, was chosen as 2 REPORTS OF GREAT BARRIER REEF COMMITTEE. the centre of these inquiries. The island is somewhat cigar-shaped and approximately 1 mile in circumference, surrounded by a moat of varying width and depth which never dries even at the lowest tide. The whole of the south sandy beach is protected by beach limestone, but the north shore is composed of white coral sand, there being no limestone deposits present. The writer remained on the island from 31st October, 1929, until 16th February, 1930. Since turtles arrive mainly after nightfall and at any state of the tide, paradings of the island were carried out each night with but one exception, due to extraordinarily inclement weather. In the early part of the work parades were made from nightfall till midnight and again from 2 to 5 a.m., but as the season progressed and the actual counting of the eggs became unnecessary, owing to the fact that the hatchings would occur after our departure, paradings were at intervals, generally three times a night, viz. :— 7.30 to 8.30; 10.30 to midnight; and again at 3.30 to 5 or thereabouts. During parades, only those turtles that came up on the island and laid their eggs were counted (excepting the marked animals which were counted each time they came up, whether they laid or not). This was. done because a study of the habits of the turtle in general was one of the objects of the investigations. Canning of turtle soup had been carried on at Heron Island for some years, work commencing early in November and finishing in February, During the 1928-29 season, so scarce did the turtles become towards the end of the season that periodic visits had to be made to the neighbouring islands in order to obtain sufficient animals to keep the factory in active operation. In view of the facts that the last season’s animals were wiped out and that there was a considerable number present this season, one deduction is that turtles seen in any one season on any given island do not necessarily return the following year to lay, but that there is a period of rest between layings—that laying seasons are separated by some years. This is offered tentatively and can be proved or disproved only after some years of investigations.