The Status of Invertebrate Resources in Mauke and Mitiaro, Cook Islands © Teariki Rongo By Ngere George and Trinilobe Kea Miscellaneous Report 03/14 Ref No. NG-3/0914 September 2014 Contents Acknowledgments ................................................................................................................................... 2 Summary ................................................................................................................................................. 3 1.0 Introduction ................................................................................................................................ 4 2.0 Objective of the assessment survey ........................................................................................... 5 3.0. Methods ...................................................................................................................................... 5 4.0 Results and Discussion ............................................................................................................... 6 4.1 Survey coverage ...................................................................................................................... 6 4.2 Species recorded and density ................................................................................................. 6 4.3 Sea cucumber (rori) size distribution ...................................................................................... 7 4.4 Comparison of resources ........................................................................................................ 9 5.0 Recommendations .................................................................................................................... 13 6.0 References................................................................................................................................ 14 7.0 Appendices ............................................................................................................................... 15 Appendix 1. Locations of survey stations. ........................................................................................ 15 Appendix 2: Survey stations locations for Mauke and Mitiaro......................................................... 17 Appendix 3: Statistics for reef benthos transect (Rbt) assessment .................................................. 19 Appendix 4. Invertebrate species recorded at Mauke and Mitiaro .................................................. 21 1 | P a g e Acknowledgments Many have contributed to the completion of this report from, data collection, analysis, interpretation and writing. Many thanks to MMR Secretary, Ben Ponia, Director of Inshore Fisheries and Aquaculture, Kori Raumea for general guidance, MMR staff, Tai George, Ngarouru Tou and Georgia Langdon for your efforts in the field and GIS work. Franck Magron and Ian Bertram of the Secretariat of the Pacific Community (SPC) for support in GIS, analytical and guidance in drafting the report. Acknowledgement also goes and with gratitude to the partnering and financial support provided by the EU Funded Global Climate Change Alliance: Pacific Small Island States (GCCA: PSIS) Project; Environmental Monitoring to Enhance Community Livelihoods and Build Resilience to Climate Change in Low Lying Atolls of the Cook Islands, for providing funding to print this report. Lastly meitaki ranuinui to the Mayors and members of the Island Councils, Executive Officers and the community of Mauke and Mitiaro, our visits wouldn‟t have been successful without your support. 2 | P a g e PO Box 85, Avarua, Rarotonga, Cook Islands. Tel: +682 28722 Fax: +682 29721 E-mail: [email protected] Summary This report presents the results of invertebrate resource assessments completed in March 2014. Transect were used to assess invertebrate resources over four and a half days on reefs of Mauke and Mitiaro. Invertebrate assemblages are low in terms of species recorded and size structure. Lollyfish (rori toto) is the most dominant invertebrate assessed however, they were less abundant compared to other islands in the Cook Islands assessed between 2012- 2014.Trochus was not recorded in these surveys. Trochus introduced to Mauke and Mitiaro in the 1980‟s and late 1990‟s have not established viable populations. This is due to the very narrow reef habitats on both islands. There is no potential for commercial fishing of sea cucumber and trochus at this time. Pa‟ua (rugose giant clam), ungakoa (large worm shell) and ariri (rough turban shell) are important food resources for Mauke and Mitiaro communities, however densities are low. The low densities and limited invertebrates species recorded in this assessment is consistent with results by Ponia et al 1998 and Ponia and Raumea 1998. Pa‟ua, ungakoa and rori toto (lollyfish) which were recorded as relatively abundant in 2009 has dramatically decreased. These resources are not able to sustain added fishing pressure such as commercial exploitation and should be left for local food security. Resource management controls, such as Ra‟ui has proved to be effective in improving the condition of stocks therefore should be considered for the benefit of local communities. 3 | P a g e 1.0 Introduction Mauke and Mitiaro are two islands of a group of three that form “Ngaputoru” in the southern islands of the Cook Islands. Ngaputoru are upraised coral islands surrounded by rugged cliffs (uruatete) and narrow reefs with limited access through the reef. The islands lack lagoons and have limited coral reef areas, with steep outer reef slopes. Due to this limited reef habitat diversity and abundance of marine resources are relatively low. In addition during extreme low tides the reef is exposed stressing corals, small fishes and invertebrates and at times during prolonged exposure some of these resources die. Those, that survive to adult stage are harvested particularly invertebrates such as ariri (turban snail) and other marine resources. Turban snail flesh is a delicacy for the island communities and is sometimes consumed while on reef gleaning excursions. Turban snail flesh can fetch prices of $40 for a two kilogram plastic container when sent to Rarotonga. Other resources such as the sea cucumbers are rarely harvested on both islands. Men generally fish the reef and outer reef slope while women dominate -reef gleaning activities. In the past the communities have used Ra‟ui (traditional form of conservation or protection) to conserve marine resources for communal use. However this system is eroding and today there are no Ra‟ui to control the use of marine resources. In 2009, as part of the local school project, a small area of the reef at Anai‟o (Mauke) was placed under Ra‟ui to show the effects of Ra‟ui for the management of marine resources. The results were positive according to Basilio Kaokao Mauke Environment Officer (Makikiriti 2009) where an increase in the number of resources was observed. The Ra‟ui was lifted a year later and remained open due to the lack of wider community support for its continuation. The use of under-water-breathing apparatus (UBA), poisons or stupefying subsistence, whether of plant or chemical origin to harvest marine resources, is forbidden in Mauke and Mitiaro. Few assessments have been conducted on reef resources on Mauke and Mitiaro. Ponia (et al 1998) conducted an assessment at three in each island as part of baseline monitoring of marine resource project by the Ministry of Marine Resources to assess the reef resources of the Cook Islands. Ponia (et al 1998) concluded that many of the important invertebrate‟s food resources at Mauke and Mitiaro recorded were of small populations. An assessment of the Anai‟o Ra‟ui on Mauke was conducted by Makikiriti (2009) before the Ra‟ui was lifted. Ungakoa (large worm shell), pa‟ua (Rugose giant clam) and rori toto (lollyfish) were the most common invertebrate found in the Anai‟o Ra‟ui. 4 | P a g e 2.0 Objective of the assessment survey The objective in this study was to collect data quantitative information on the current status of invertebrate resources with a focus on sea cucumber. Specifically, the objectives of the surveys were to: • Assess the status of sea cucumber resources on Mauke and Mitiaro to provide information on sea cucumber species present. • Provide population estimates of stocks and fishable stock estimates for those species present in commercially viable quantities for decision-making purposes. • Provide stock status information on the species of importance to subsistence fishing, and determine whether or not there is a need for management. 3.0. Methods Each island was divided into four sectors (North, East, South and West) and within each sector five locations were selected. At each location two stations were sampled within the reef crest and reef flat. No surveys were carried out along the outer reef slope. Fine scale reef benthos transects (RBT) were used to assess invertebrate resources (species presence, abundance and size) and to determine population structure. The method involves two surveyors equipped with measuring and record instruments for recording presence and size of invertebrates within transects. An RBT station comprises of six 40 x 1 metre transects and each transect was spaced approximately 5 metres apart (Figure 1). At Mauke and Mitiaro the depth of the reef crest and reef flat habitats were mostly very shallow, surveyors walked the reef crest and used GPS to measure the 40 m x 1 m transects. Species and habitat data were