Key Ideas about Shellfish
15Kb Jpeg image double handful of cockles

You can join a national programme to help restore the health of New Zealand's shellfish beds. You'll swap information with other schools and send your research findings to the Ministry of Fisheries.

Your research data will not be lost, but will become part of a growing body of knowledge about the health of New Zealand's Beaches. Your accomplishments will become recorded as important scientific base-line data that others will use for many years to come.

Your studies will enable your local and regional councils and fisheries officers to make important decisions about how to regulate the use of shellfish and the beaches.

Cockles, Pipis, Tuatua , Toheroa and other common shellfish on beaches are important Indicator species that tell us about many different aspects of the health of the beach. If the shellfish beds are healthy, environmental conditions must be acceptable for them. If they are not, your studies can lead to finding out what is wrong and what needs to be done to return the beaches to good health.

Cockles (Chione stutchburyi) are the most common New Zealand beach shellfish. They are most abundant on broad sandy mudflats extending off beaches protected from strong wave action. In some places there are up to 2000 cockles per square metre, or 20 million per hectare with a weight of 160 tonnes. They are so abundant the surface is really a pavement of cockles sprinkled with sand.

Shellfish have vanished from many New Zealand beaches. Some of the possible causes for this decline are:
----- Sediment eroded from farming or construction sites smothering the shellfish.
----- Greedy overharvesting.
----- Pollution from stormwater run-off.
----- Toxic algal blooms.

Scientists are baffled by the disappearance of shellfish from beaches where there seems to be no reason for their loss. Because there has never been adequate monitoring of the shellfish, the reasons for and the extent of shellfish declines have not been documented.

Regular shellfish sampling can provide interesting and valuable information that can help prevent the loss of existing resources and possibly aid in the restoration of depleted resources.

Beach Keeping is a learning experience. Every beach has it's own special characteristics so the activities must be considered a general guide. Each student researcher must use imagination and resourcefulness to suit the chosen beach.

The Maori protect beach resources with Rahui, or temporary closures to harvesting. Recently, the tangata whenua and others in communities near some of Auckland's beaches have set up Rahui to help the shellfish recover.

The legal daily bag limit of cockles, pipi and tuatua is 150 shellfish per person.

Cockles are the favorite food of the Oystercatchers (Torea). They use their strong orange-red bills to spear open a cockle. They might gobble up 350 on a winter day when they are cold and hungry. During the summer they feed less, but can still put away 250 cockles a day.

Resources to use

Animals of the Rocky Shore of New Zealand by Margret A. Leslie. Reed.

The Children's Guide to Collecting New Zealand Sea Shells by Derick Lamb. The Bush Press.

Coasts and Us Teachers Education Kit. Northland Regional Council

Common Seashells by J.R. Penniket. Reed Publishers

Native Animals of New Zealand by AWB Powell. Auckland Institute and Museum.

Nature Watching at the Beach by John Walsby. Wilson and Horton.

New Zealand Shells and Shellfish by Glen Pownall. Dai Nipon Publishing.

New Zealand Shells by John Child. William Collins (NZ).

Seashore Life of New Zealand by Erick Heath and R.K. Dell. Reed Publishers

New Zealand Seashells in colour. Geoff Moon and J.R. Penniket. 1970 Reed Publishers.

Shellfish of Soft Shores! Neighbourhood Biology Projects for Teens. Mary Gardner YWCA at 203 Stuart St. Dunedin. Fax 03 477 6783.

Protecting Sand Dunes Royal Forest and Bird Journal February 1996.