Mateship/Marriage in Nature and Science
List and explain the following:
1. Where do Salmon lay eggs?
2. Where do Salmon grow and develop?
3. List and explain the obstacles that Salmon must overcome to successfully reproduce? 4. How do Salmon feed their young?
1. Salmon lay their eggs in gravel nests called redds, usually in clear, cold, and oxygen-rich freshwater streams or rivers. The female salmon excavates the redd by using her tail to move gravel out of the way before depositing her eggs in the nest.
2. After the eggs are laid, they are fertilized by male salmon and then incubate in the redd for several weeks to several months, depending on the species. The eggs eventually hatch into sac fry, which remain in the redd until they have consumed their yolk sac and are ready to swim and feed on their own.
3. Salmon must overcome several obstacles to successfully reproduce. Some common obstacles include the following:
- Predators: Salmon eggs, sac fry, and juvenile salmon are vulnerable to predation by birds, mammals, and other fish while they are developing in the stream.
- Water quality: Pollution, sedimentation, and temperature fluctuations can all negatively impact the survival of salmon eggs and fry.
- Physical barriers: Dams, culverts, and other human-made structures can block or hinder salmon from reaching their spawning grounds.
- Competition: Other species of fish may compete with salmon for resources or pose a threat to their survival.
4. After hatching, salmon fry depend on their yolk sac for nourishment for a short period. Once the yolk sac is depleted, the fry begin to feed on small invertebrates and plankton in the stream. As they grow, they transition to larger prey such as insects, small fish, and crustaceans. Eventually, adult salmon return to the ocean where they feed on a diet consisting of fish, squid, and plankton before returning to freshwater to spawn.