Presentation on theme: "By Manraj Singh Introduction Scientific Name: Anguilla Dieffenbachii Maori Name: Tuna The New Zealand Longfin eel are freshwater fishes. They are slender-bodied."— Presentation transcript:
Introduction Scientific Name: Anguilla Dieffenbachii Maori Name: Tuna The New Zealand Longfin eel are freshwater fishes. They are slender-bodied fishes and are elongate. When they are small the Longfin eel has a small head but as they grow their head becomes bulbous with prominent muscular dome behind the eyes.
Location & Habitat Location: Longfin eels are found throughout the whole of New Zealand and some parts of Tonga where they spawn. Habitat: Longfin eels mainly live in rivers and inland lakes but can be found in almost all types of waters, usually well inland from the coast.
Life Cycle Longfin eels make their journey from New Zealand to their spawning grounds in Tonga. They are around 15- 30 years old before they breed. The female eels eggs are fertilized in deep tropical water. After the female eel subsequently dies, their eggs float to the surface hatching into very flat larvae that then drifts along the oceanic currents back to New Zealand. After when the larvae reaches New Zealand the larvae undergoes a transformation into glass eels. Then the eel transforms into a elver by occupying estuaries. The elvers migrate upstream where they develop into adults.
Size & Food Size: When longfin eels begin their life they are only one millimetre. But during their life they can grow up to two metres long. Compared to fishes, eels grow slowly, longfin eels growing only between 15-25mm a year. Food: Longfin eels eat live food. Small longfin eels feed on insect larvae, worms, and water snails. When they get bigger they will start to feed on fish, freshwater crayfish, and small birds.
Predators & Threats One of the most common threats is fishing. In 1975, eels were the most valuable fish export after rock lobsters. Five years later, eels were the fifth most valuable finfish export. Another thing is a habitat loss. Habitat loss happens by changes caused by hydro development, drainage and irrigation schemes and river diversions. Culverts and dams also effect eels as it prevents them from migrating. The main threat is pollution. Sewage and effluent from meat works and pulp and paper plants discharged into rivers can remove large amounts of oxygen from the water. The result of this is bad as the eels might die or have to move to a new place.
Significance For Maori Longfin eels were important to the Maori because it provided an important food source. The Maori also knew the longfin eels migratory route.
Interesting Facts Lack of light is not a problem ; it uses its sense of smell to locate its prey, It slips through rivers, streams and lakes unseen, hunting for native galaxiid fish. Some dams have special eel passes to help them conquer the massive concrete walls. Once at their final destination, the elvers begin the serious business of growing to breeding size.
How Can We Help We can reduce the limit on how many longfin eels you can get per person per day.
Glossary Dorsal fin: An unpaired fin on the back of a fish or whale, e.g., the tall triangular fin of a shark or killer whale. Ecosystem: A biological community of interacting organisms and their physical environment. Endemic: (of a disease or condition) Regularly found among particular people or in a certain area.
Migration: The movement of persons from one country or locality to another. Diadromous: (used to fish) Migratory between fresh and salt waters. Catadromous: (of a fish such as the eel) Migrating down rivers to the sea to spawn. Spawn: (of a fish, frog, mollusk, crustacean, etc.) Release or deposit eggs.
Otolith: Each of three small oval calcareous bodies in the inner ear of vertebrates, involved in sensing gravity and movement. Larvae: An immature form of other animals that undergo some metamorphosis, e.g., a tadpole. Transparent: (of a material or article) Allowing light to pass through so that objects behind can be distinctly seen.
Elver: A young eel, esp. when undergoing mass migration upriver from the sea. Carnivorous: (of an animal) Feeding on other animals. Omnivorous: (of an animal or person) Feeding on food of both plant and animal origin. Galaxiids: The Galaxiids are a family of mostly small freshwater fishes in the southern hemisphere.
Nocturnal: Done, occurring, or active at night. Hinaki: New Zealand Flax. Pollution: The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects.