Lecture 30- Overview Flashcards
What is the life cycle of the Australian Short-fin eel?
- catadromous, spawn in sea and the migrate to rivers where they live most of their lives
- migrate near New Caledonia, deep water
- have leptocephalus larvae, then glass eels= they return to freshwater -sillver and yellow eel= mostly colour transformations
What are the factor having an impact on the short finned eel?
-global declines in freshwater eels due to: 1. Ocean basins- spawning and larval migrations 2. Coastal oceans- dispersion and detection of river plumes 3. Intertidal- sand transport and river mouth closure 4. Estuaries- facultative diadromy and growth 5. Small scales- swimming and upstream migration!
What could some other factors responsible for the eel decline?
-parasitism, damming and water extraction= reduction environmental quality, overexploitation= fishing -current changes due to climate change
What is the migration of the american eel like?
adult eels don’t feed when they migrate so have to have all the energy they need
- ocean scale migration
- the juveniles rely on physical transport to get back to europe -not a one off, some adults spawn repeatedly
- 3-4 years for larvae to get back to europe
How is river mouth closure bad for eels?
-rivers= chemical odour of the river change maybe cannot detect anymore and can’t get to it
Why is sand transport potentially bad for eels?
-what are the transportation process of sand - get river mouth closure -can’t get to the river the small eels, or cannot detect the presence of the river -the openings dangerous, carefully done
What did the eel ooliths show?
- higher striaum if hatch in sea water= red
- facultative catadromy= so some individuals not moving all the way to the freshwater
How is eel migration affected by humans?
-there may be issues with barriers, they cannot scale some barriers -put fish travel ways in!
