Diadromous fish

About Diadromous fish: 

• These are those fish species which migrate between saltwater and freshwater environments.
• Some of the examples for diadromous fish: the allis shad (Alosa alosa), twait shad (Alosa fal- lax), Mediterranean twaite shad (Alosa agone) and the European eel (Anguilla anguilla) etc.
• In order to better understand these movements, scientists have classified these migrations into several categories.
  • Anadromous fish: These are born in freshwater, then migrate to the ocean as juveniles where they grow into adults before migrating back into freshwater to spawn.
  • Catadromous fish: These are born in saltwater, then migrate into freshwater as juveniles where they grow into adults before migrating back into the ocean to spawn.
  • Amphidromous fish: These are born in freshwater/estuaries, then drift into the ocean as larvae before migrating back into freshwater to grow into adults and spawn.
  • Potamodromous fish: These are born in upstream freshwater habitats, then migrate downstream (still in freshwater) as juveniles to grow into adults before migrating back upstream to spawn.

Threats: Diadromous fish are sensitive to anthropogenic pressures. They are subjected to terrestrial, freshwater, and marine pressures such as agricultural and pollutant runoffs, habitat destruction, barriers to migration, fishing, bycatch, and climate change.

Q1: What are Invertebrates?

Invertebrates are characterized by their lack of a backbone or vertebral column. Instead, they have other structural features that support and protect their bodies. Invertebrates comprise a vast array of animal groups, including insects, spiders, crustaceans, mollusks etc

Source: Fish moving between marine & freshwater ecosystems have designated protected areas, but no protection in them: Study