A salmon run is an annual fish migration event where many salmonid species, which are typically hatched in fresh water and live most of the adult life downstream in the ocean, swim back against the stream to the upper reaches of rivers to spawn on the gravel beds of small creeks. After spawning, all species of Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again with the new generation of hatchlings.
A grizzly bear ambushing a jumping salmon during an annual salmon run
Sac fry remain in the gravel habitat of their redd (nest) until their yolk sac, or "lunch box", is depleted.
After depleting their yolk sac nutrients, the young salmon emerge from the gravel habitat as parr to feed.
Salmon jumping a fall
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water ; the physical act is known as spawning. The vast majority of aquatic and amphibious animals reproduce through spawning. These include the following groups:Bony and cartilaginous fishes
Crustaceans
Mollusks
Echinoderms
Amphibians
Aquatic insects
Coral, which are living colonies of tiny, aquatic organisms—not plants, as they are sometimes perceived to be. Corals, while appearing sedentary or botanical by nature, actually spawn by releasing clouds of sperm and egg cells into the water column, where the two mix.
The spawn (eggs) of a clownfish. The black spots are the developing eyes.
Pacific salmon are semelparous or "big bang" spawners, which means they die shortly after spawning
The pickled and dehydrated roe of mullet
Cutthroat trout are monogamous pair spawners