說明
Trochus (Trochus niloticus) were first introduced to the Cook Islands in 1957 from Fiji. Once the original population of 280 shells were well established in Aitutaki, trochus was introduced to the rest of the Cook Islands in the 1980s. The main purpose of the introduction was to develop commercially harvestable stocks to assist local economies. Four hundred and forty trochus were introduced to Tongareva (also known as Penrhyn) over 20 years ago in 1985 from the Aitutaki population (Sims 1988). Introduced populations usually reach commercially exploitable levels within 20 to 25 years, therefore, the trochus population on Tongareva should nearly be ready for harvest (Bertram 1998).
A 1996 survey conducted in Tongareva by the Cook Islands Ministry of Marine Resources (MMR) found that trochus were present in the western section of Tongareva Lagoon with the highest densities found at two sites: Patukiri and Seniseni (Ponia et al. 1997). The survey detailed in this report was designed to re-assess the density of trochus in Tongareva Lagoon, 10 years after the last survey and 20 years after the original introduction.
The specific aims of the survey were to: • assess the size distribution of trochus, • assess trochus abundance and density in the western section of the lagoon, and • estimate the number of trochus that could be sustainably harvested from the surveyed area of the lagoon.
資料紀錄
此資源sampling event的資料已發佈為達爾文核心集檔案（DwC-A），其以一或多組資料表構成分享生物多樣性資料的標準格式。 核心資料表包含 10 筆紀錄。
亦存在 2 筆延伸集的資料表。延伸集中的紀錄補充核心集中紀錄的額外資訊。 每個延伸集資料表中資料筆數顯示如下。
此 IPT 存放資料以提供資料儲存庫服務。資料與資源的詮釋資料可由「下載」單元下載。「版本」表格列出此資源的其它公開版本，以便利追蹤其隨時間的變更。
版本
以下的表格只顯示可公開存取資源的已發布版本。
如何引用
研究者應依照以下指示引用此資源。:
Chambers C N (2024). Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands. Version 1.1. Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Samplingevent dataset. https://nzobisipt.niwa.co.nz/resource?r=tongareva_clams_trochus&v=1.1
權利
研究者應尊重以下權利聲明。:
此資料的發布者及權利單位為 Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node。 This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.
GBIF 註冊
此資源已向GBIF註冊，並指定以下之GBIF UUID: 44c33d16-84bd-41d3-8e39-bed4786eca9c。 Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node 發佈此資源，並經由Ocean Biodiversity Information System同意向GBIF註冊成為資料發佈者。
關鍵字
Samplingevent
聯絡資訊
- 元數據提供者 ●
- 出處 ●
- 連絡人
地理涵蓋範圍
Tongareva Lagoon, Cook Islands
| 界定座標範圍 | 緯度南界 經度西界 [-9.04, -158.01], 緯度北界 經度東界 [-8.98, -157.92] |
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分類群涵蓋範圍
Giant clams
| Species | Trochus niloticus |
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時間涵蓋範圍
| 起始日期 / 結束日期 | 2006-05-03 / 2006-05-31 |
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取樣方法
The survey took place from 3–11 May 2006 with a follow-up survey in Patukiri on 31 May 2006, in conjunction with a survey of pasua (Tridacna maxima) populations. Fieldwork was conducted by the author, Mataora Marsters and Taimana Manata from the Tongareva Marine Research Centre (TMRC), with additional assistance from Tomas Samuela Jr and Tuku Marsters. Surveying was concentrated in the western section of the lagoon as this was where the highest numbers of trochus were discovered in the previous survey. However, any trochus encountered in other sections of the lagoon during the course of the pasua survey were also to be recorded although none were found.
| 研究範圍 | Tongareva Lagoon, Cook Islands |
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方法步驟描述:
- From preliminary observations and also based on previous surveys of trochus numbers, it was observed that trochus were distributed with increasing density towards the edge of the inner lagoon reef (kauniho). Transect lines were accordingly placed at the edge of the kauniho extending towards the shoreline. The survey was conducted using a 50-m transect line laid parallel to the edge of the kauniho with five transect lines running perpendicular at 10-m intervals. All trochus found within 5 m on both side of the transect line were counted and all were measured except those surveyed at TMRC, where approximately every second trochus was measured (i.e. 39% of the population) and Patukiri North where 85% of the population were measured.
- The size distribution of trochus was evaluated by recording the basal diameter of trochus using callipers. The census of trochus abundance in the lagoon was calculated by counting the number of trochus at each site; density was calculated as the total number of individuals divided by the area sampled, which at each site was 2500 m2. The calculation for the amount of trochus available for sustainable harvest was based around 30% of the population in the 8–12 cm size range as per harvest regulations established in Aitutaki. Ten sites were surveyed.
引用文獻
- Chambers, C. 2007. Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands. SPC Trochus Information Bulletin #13 – July 2007, pg. 2-6.
額外的詮釋資料
marine, harvested by iOBIS