As part of the Hauraki Gulf Forum community shellfish monitoring project, the Waikato Regional Council supports annual shellfish monitoring in two Coromandel Estuaries.
The Hauraki Gulf Forum (HGF)(external link) promotes conservation and sustainable management of the Hauraki Gulf Marine Park, which includes the Firth of Thames and both coasts of the Coromandel Peninsula. As part of this role, the HGF supports community groups, schools and iwi to carry out shellfish monitoring at a number of sites in the Auckland and Waikato Regions, to provide more data on the changes in abundances of shellfish over time. This community shellfish monitoring programme is undertaken in collaboration with the Auckland Council and the Department of Conservation and is coordinated through a steering group that reports to the Hauraki Gulf Forum. The steering group also includes representatives of the Ministry of Fisheries and tangata whenua.
The two Coromandel sites are in Whitianga and Wharekawa estuaries. The first site was established in Whitianga Estuary in collaboration with Mercury Bay Area School in 2008, and has been surveyed every year since in Autumn. In 2010 a site was also established in Wharekawa estuary (Opoutere), and this site has been monitored every year in February.
Surveys are carried out each year to look at the abundance and size of the most common kinds of shellfish, such as cockles and pipis, living in sheltered estuarine beaches. The surveys sample shellfish over a large area at each site, using consistent and carefully developed methods and equipment so that results can be compared with other sites and to create a dataset that is as useful as possible. All shellfish are counted and measured where they are collected, and are returned immediately to the mudflats.
The programme provides practical assistance and equipment to supported groups undertaking the monitoring. This includes help with choosing the site and setting up sampling locations, as well as practical assistance on the day, and collation of the data afterwards.
This programme is linked with the learning outcomes and unit standards of the NZ school curriculum. Teacher resource kits have been developed for both upper primary/intermediate (Levels 3-4), and Year 12 Biology (Level 7). These can all be found on the project website.
Supported groups also obtain training for the staff involved in the project, and a range of resources to aid with student training.
Survey findings are entered into a database, reported to the school or community group involved, and collated with data from other sites to inform the Hauraki Gulf Forum. All survey results are analysed by scientists from the Ministry for Primary Industries (MPI) and presented in annual reports, which are publicly available from Auckland Council and Waikato Regional Council or from the project website(external link). Every three years the results contribute to the Hauraki Gulf State of the Environment Report(external link).
The shellfish monitoring programme gathers useful ecological information, and also aims to increase environmental awareness and help the MPI assess the effectiveness of the shellfish harvesting limits. In the Auckland Region, monitoring results from the HGF Community monitoring have been used to support a temporary closure to cockle harvesting at Umupuia Beach and a seasonal closure to shellfish harvesting at Cockle Bay.
Results show that the monitoring sites in the Waikato have high abundances of shellfish when compared with most sites from the Auckland region. At the Whitianga and Wharekawa sites, cockle density averages between 500 per m2 and 1000 per m2, with densities as high as 3000 per m2 in the mid-low tide zones. The survey results show that cockle densities change a lot from year to year, but there is no clear trend that suggests shellfish are increasing in numbers, or declining.