Описание
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.
Записи данных
Данные этого sampling event ресурса были опубликованы в виде Darwin Core Archive (DwC-A), который является стандартным форматом для обмена данными о биоразнообразии в виде набора из одной или нескольких таблиц. Основная таблица данных содержит 10 записей.
Также в наличии 2 таблиц с данными расширений. Записи расширений содержат дополнительную информацию об основной записи. Число записей в каждой таблице данных расширения показано ниже.
Данный экземпляр IPT архивирует данные и таким образом служит хранилищем данных. Данные и метаданные ресурсов доступны для скачивания в разделе Загрузки. В таблице версий перечислены другие версии ресурса, которые были доступны публично, что позволяет отслеживать изменения, внесенные в ресурс с течением времени.
Версии
В таблице ниже указаны только опубликованные версии ресурса, которые доступны для свободного скачивания.
Как оформить ссылку
Исследователи должны дать ссылку на эту работу следующим образом:
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
Права
Исследователи должны соблюдать следующие права:
Публикующей организацией и владельцем прав на данную работу является Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Эта работа находится под лицензией Creative Commons Attribution (CC-BY 4.0).
Регистрация в GBIF
Этот ресурс был зарегистрирован в GBIF, ему был присвоен следующий UUID: 44c33d16-84bd-41d3-8e39-bed4786eca9c. Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node отвечает за публикацию этого ресурса, и зарегистрирован в GBIF как издатель данных при оподдержке Ocean Biodiversity Information System.
Ключевые слова
Samplingevent
Контакты
- Metadata Provider ●
- Originator ●
- Point Of Contact
Географический охват
Tongareva Lagoon, Cook Islands
| Ограничивающие координаты | Юг Запад [-9,04, -158,01], Север Восток [-8,98, -157,92] |
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Таксономический охват
Giant clams
| Species | Trochus niloticus |
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Временной охват
| Дата начала / Дата окончания | 2006-05-03 / 2006-05-31 |
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Методы сбора
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.
| Охват исследования | Tongareva Lagoon, Cook Islands |
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Описание этапа методики:
- 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.
Библиографические ссылки
- Chambers, C. 2007. Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands. SPC Trochus Information Bulletin #13 – July 2007, pg. 2-6.
Дополнительные метаданные
marine, harvested by iOBIS
| Альтернативные идентификаторы | https://nzobisipt.niwa.co.nz/resource?r=tongareva_clams_trochus |
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