説明
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.
データ レコード
この sampling event リソース内のデータは、1 つまたは複数のデータ テーブルとして生物多様性データを共有するための標準化された形式であるダーウィン コア アーカイブ (DwC-A) として公開されています。 コア データ テーブルには、10 レコードが含まれています。
拡張データ テーブルは2 件存在しています。拡張レコードは、コアのレコードについての追加情報を提供するものです。 各拡張データ テーブル内のレコード数を以下に示します。
この IPT はデータをアーカイブし、データ リポジトリとして機能します。データとリソースのメタデータは、 ダウンロード セクションからダウンロードできます。 バージョン テーブルから公開可能な他のバージョンを閲覧でき、リソースに加えられた変更を知ることができます。
バージョン
次の表は、公にアクセス可能な公開バージョンのリソースのみ表示しています。
引用方法
研究者はこの研究内容を以下のように引用する必要があります。:
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
権利
研究者は権利に関する下記ステートメントを尊重する必要があります。:
パブリッシャーとライセンス保持者権利者は Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node。 This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.
GBIF登録
このリソースをはGBIF と登録されており GBIF UUID: 44c33d16-84bd-41d3-8e39-bed4786eca9cが割り当てられています。 Ocean Biodiversity Information System によって承認されたデータ パブリッシャーとして GBIF に登録されているSouthwestern Pacific Ocean Biogeographic Information System (OBIS) Node が、このリソースをパブリッシュしました。
キーワード
Samplingevent
連絡先
- メタデータ提供者 ●
- 最初のデータ採集者 ●
- 連絡先
地理的範囲
Tongareva Lagoon, Cook Islands
| 座標（緯度経度） | 南 西 [-9.04, -158.01], 北 東 [-8.98, -157.92] |
|---|
生物分類学的範囲
Giant clams
| Species | Trochus niloticus |
|---|
時間的範囲
| 開始日 / 終了日 | 2006-05-03 / 2006-05-31 |
|---|
収集方法
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.
| Study Extent | Tongareva Lagoon, Cook Islands |
|---|
Method step description:
- 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.
書誌情報の引用
- Chambers, C. 2007. Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands. SPC Trochus Information Bulletin #13 – July 2007, pg. 2-6.
追加のメタデータ
marine, harvested by iOBIS