Harbours, bays and estuaries. at the edges of land and sea

Transcription

1 Harbours, bays and estuaries at the edges of land and sea

2 Whitebait in our waters Department of Conservation Scientist Dave West talks about the life and sometimes hard times of a group of freshwater fish in New Zealand that are known as galaxiids. Scientist Dave West is serious about galaxiids, but he also has another side. grow up each species becomes quite distinct from the others. Some of the larger species such as the short-jawed kōkopu and giant kōkopu can grow up to 40 centimetres long and weigh over a kilogram. What are whitebait? What do they grow up to be? Whitebait are the young of five species of fish (īnanga, banded kōkopu, short-jawed kōkopu, giant kōkopu and kōaro) that spend most of their lives in freshwater. As a group they are called galaxiids. When they re young the five species look similar to one another, but as they Can you describe the life cycle of galaxiids? Adults live and spawn (reproduce) in freshwater. Galaxiids spawn in a range of places; everywhere from the mouths of large rivers to small, fast-flowing mountain streams. The eggs are left on river banks and stream bottoms until they hatch. Eggs hatch into small, transparent, larvae that are swept downstream to the sea or, in some cases, lakes where they spend up to six months growing into juveniles that whitebaiters sometimes catch as they swim up rivers. Interesting fact 1 All galaxiids are nocturnal predators meaning they do most of their hunting at night. Juveniles that find good places to live and that are not caught by whitebaiters, or eaten by other fish and birds, can live up to 19 years of age. The smallest and most common whitebait īnanga may only live for one year, just long enough to get big enough to spawn. Adult īnanga. Illustrations by Lisa Paton.

3 Whitebait eggs. Photo courtesy DOC. Kōaro eggs. Kōaro is one of five native fish in New Zealand thats young are called whitebait. Photo courtesy Dave West, DOC. Whitebait catch in a bucket. Photo courtesy DOC. Whitebaiting with scoop nets on the Waita River in South Westland. Photo courtesy DOC, photographer Tony Lilleby. Galaxiids like this īnanga frequently feed on insects that fall into the water. Photo courtesy Stephen Moore.

4 Life cycle of the galaxiid Inanga Freshwater Whitebait Interesting fact 2 The three kökopu species are found only in New Zealand. Estuary Sea larvae eggs Illustration by Lisa Paton. What whitebait (in this case kōaro) larvae look like close up. Photo courtesy of Dave West, DOC. Whitebaiting. Photo by IanTrafford.com Kōaro adult.

5 What do adult galaxiids eat? As adults, galaxiids are important predators within the freshwater environments where they live. They eat mostly insects, crustaceans like kōura, and other fish. Kōkopu, in particular, like to eat insects like weta and cockroaches that fall in the water. They have a special set of sensors on the top of their heads that allow them to tell when and where something hits the water s surface. This makes them incredibly efficient at capturing their prey. Galaxiids are quite territorial. The biggest and strongest fish get the best feeding positions in a stream or pool and they ll fight to dominate an area to be top fish! They are particularly aggressive toward one another during spawning season. In fact, it s not unusual to see individuals with bite marks where other fish have attacked them. They have very similar habits to trout which has been a problem in some streams since trout grow bigger and often prey on galaxiids, as well as eat the food that galaxiids would normally eat. Why are clean streams important to galaxiids? Galaxiids need clean streams so they can see their food. Clean streams also do not have chemicals in them that can affect how galaxiids grow and spawn. Their eggs need to be able to breathe, but can be buried and smothered if too much mud washes into the streams. Whitebaiting. Photo by IanTrafford.com Catching whitebait Have you ever tasted a whitebait fritter? Many people around New Zealand go to the mouths of rivers and estuaries in spring, during the whitebaiting season, to catch young galaxiids as they make their way from the sea to our streams and rivers. Fishers use fishing gear like nets, screens and lines to catch whitebait. This traditional Kiwi pastime is dependent on having healthy galaxiid populations. People can help our whitebait by following the whitebait fishing regulations and looking after the water quality of our waterways by not polluting and by planting native plants near stream banks and along our coasts.

6 How do we affect their habitat by what we do on the land? A lot of things we do on land like driving cars, constructing new buildings, grazing animals can impact our freshwater environments and our estuaries. Some of the effects are because of pollution. For instance, think about the oil you see on roads after it rains much of that goes into our storm drains and into our coastal environment. Another effect is the increased amount of water that goes into our rivers and streams during a storm. Rain runs much faster off things like concrete, roofs and asphalt than it does off land that hasn t been developed. All this extra runoff increases the amount of sediment that goes into our waterways. The fast waters also sweep away plants, insects and fish. There are lots of ways to get involved in helping our coastal environment. North Shore s Bayswater School recently participated in a coastal clean up as part of the Sir Peter Blake Trust s Care for our Coast programme. Photo courtesy Ben Watson, North Shore Times. Pipes can stop fish from swimming through them. The large dams that we build to generate electricity can prevent galaxiids from getting to where they like to live and alter downstream flows where they live and breed. To stop rivers from flooding land we build stopbanks that wall off important habitat. As adults, galaxiids like to hide in amongst and eat insects that fall off plants, shrubs and trees that grow along stream banks. Mowers, sheep and cows can destroy galaxiid habitat. Interesting fact 3 Köaro are well known for their climbing abilities. They have been found in mountain streams above high waterfalls. While they are good climbers on rocks and even concrete, metal is much harder for them to scale and the amount of barriers on some streams and rivers may affect the number of galaxiids that are able to make their way upstream.

7 Life for galaxiids sounds pretty tough. In some areas it definitely is, but there are quite a few people trying to give galaxiids a hand. Farmers are fencing streams so their livestock don t get in and muddy up the water. Developers are working to maintain habitat around streams and to put in measures that slow down water run off. Local councils are looking at ways to replace barriers like dams, culverts and floodgates in streams and rivers with more galaxiid-friendly barriers. School students are getting involved in water monitoring programmes that feed into our knowledge base. Community groups are taking on stream restoration projects. All of these actions add up. Around the country, people of all ages plant native plants to help reduce the amount of sediment that goes into water. Photos courtesy DOC, photographer Sara Treadgold. Illustration by Lisa Paton.

8 Where I live in the South Island, there are a lot of great projects going on. For example, in some streams the environment has changed so much that galaxiids are unable to spawn. In some of these streams, researchers have put hay bales in the parts of the streams where galaxiids would normally lay their eggs. The galaxiids really seem to like the hay bales they burrow into them and lay their eggs which has meant an increase in galaxiid spawning in those streams. A number of iwi have also gotten involved with this issue. The Department of Conservation has recently been involved in a project with Ngāi Tahu where they ve been fencing sections of streams to stop livestock from destroying important fish habitat. In places like Waituna Lagoon in the South Island, which we know is a stronghold for giant kōkopu, the Department of Conservation has recently purchased additional land to protect the kōkopu s habitat and is working with neighbouring landowners to fence off parts of the stream from livestock. Students of Te Kura Kaupapa Mäori o Te Rawhitiroa (TKKMo Te Rawhitiroa) produced the short bilingual film entitled Tiakina o Tatou Awa based on their restoration experience. The film received best Te Reo and Tikanga Mäori in 2007 s Outlook for Someday film challenge. View at net/films/2007/035/ says Dave. Students have done everything from growing native plants to planting them on the banks of the river. Photo courtesy Nicki Wakefield, Whitebait Connection. Photo courtesy Nicki Wakefield, Whitebait Connection.

9 Students lead the way in restoration In celebration of World Environment Day 2009 over 500 students from 10 schools and Kohanga Reo planted 3000 native plants along the Waitaua River. The restoration project was student powered with students organising the event, doing the planting, and even growing the native plants at He Kakano community nursery. The He Kakano nursery project began with Te Kura Kaupapa Mäori o Te Rawhitiroa (TKKMo Te Rawhitiroa) students wanting to get involved in riparian restoration in their local area. With major support of Whangarei District Council that provided the existing facility and the Whitebait Connection programme, He Kakano community nursery was established in Since then He Kakano has produced thousands of native plants for riparian (river bank) restoration projects within the Whangarei catchment. Student environment teams from TKKMo Te Rawhitiroa and Tikipunga Primary School have learnt how to identify and raise a variety of native plants. Aspects of rongoa Mäori and other uses of native plants have also been included in the learning at He Kakano under of the guidance of Buc Cullen. The student s hard work is starting to pay off. Six large community planting day events have been held at Waitaua in the last three years with over 8000 plants being planted along one kilometre of the Waitaua River. While the students haven t recorded a change in water quality yet, the local community is really happy to see a section of their stream restored and the students know that they are making a home for native invertebrates and fish. Nicki Wakefield from Whitebait Connection says that after this last big planting the students have now completed their work on the one kilometre section of the river bank, but they have big plans to restore more sections one kilometre at a time. Students have become the leaders in protecting Waitaua River. Photo courtesy Kim Boyle, Whitebait Connection.

10 Acknowledgements The Ministry of Fisheries and the Department of Conservation have developed this web-based educational resource to help students learn more about the effects of land-based activities on our coastal environment. The student activities in this resource have been developed for Years 7&8, but many of the activities may easily be adapted for older students. Special thanks to the three scientists who agreed to be interviewed for this resource: Dave West, Department of Conservation (Whitebait in our waters); Richard Ford, Ministry of Fisheries (Getting muddy with cockles); and Mark Morrison, National Institute of Water & Atmospheric Research (Our prized snapper). Thanks also to Bruno David, Michael Hickford and Jane Goodman for reviewing and commenting on the Whitebait in our waters story. Thanks to Blake Abernethy and Richard Fanselow for their additions to Getting muddy with cockles and for reviewing this resource. Eduardo Villouta, Department of Conservation, and Simon Thomas, Ministry of Fisheries, offered valuable advice on the development of this resource. Written by Shelly Farr Biswell. Illustrations (unless otherwise noted) by Lisa Paton, Morphological Environmental Communication. Teacher resource developed and written by Sue Clement. Teacher resource reviewed by Tandi McRae. The information in this resource was drawn, in part, from A review of land-based effects on coastal fisheries and supporting biodiversity in New Zealand, New Zealand Aquatic Environment and Biodiversity Report No. 37, This scientific review from the National Institute of Water & Atmospheric Research was produced for the Ministry of Fisheries and is available at Ministry of Fisheries Te Tautiaki i nga tini a Tangaroa ASB Bank House The Terrace PO Box 1020 Wellington 6140 New Zealand Department of Conservation Te Papa Atawhai Conservation House Whare Kaupapa Atawhai Manners Street PO Box Wellington 6143 New Zealand ISBN (Online) August 2009 Front cover photo credits: Ian Trafford (top left); Chinese Conservation Education Trust (top right); Kim Boyle, Whitebait Connection (middle); Kim Westerskov (bottom).