Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands

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Comment citer

Les chercheurs doivent citer cette ressource comme suit:

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

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L’éditeur et détenteur des droits de cette ressource est Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Ce travail est sous licence Creative Commons Attribution (CC-BY) 4.0.

Enregistrement GBIF

Cette ressource a été enregistrée sur le portail GBIF, et possède lUUID GBIF suivante : 44c33d16-84bd-41d3-8e39-bed4786eca9c.  Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node publie cette ressource, et est enregistré dans le GBIF comme éditeur de données avec lapprobation du Ocean Biodiversity Information System.

Mots-clé

Samplingevent

Contacts

Couverture géographique

Tongareva Lagoon, Cook Islands

Couverture taxonomique

Giant clams

Couverture temporelle

Méthodes déchantillonnage

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.

Description des étapes de la méthode:

1. 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.
2. 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.

Citations bibliographiques

1. Chambers, C. 2007. Trochus (Trochus niloticus) size and abundance in Tongareva Lagoon, Cook Islands. SPC Trochus Information Bulletin #13 – July 2007, pg. 2-6.

Métadonnées additionnelles