The arrival of spring is a time of renewal in natural systems. Flowers start to bloom, birds pair up and frogs call to one another to create future generations. Beneath the waves – escaping the notice of many park patrons – fishes throughout the parks are preparing to spawn as water temperatures rise. The fishes employ a wide variety of strategies to successfully carry on their species.
Many fishes in this area are nest builders. Redear sunfish, largemouth bass and channel catfish use their tail to fan out depressions in lake and stream beds. Redear and other sunfish even use their mouths to move larger rocks that they can’t move with their tails. After spawning, these nest builders guard the eggs deposited in the nest to keep them from getting eaten by other fish.
Bluntnose minnows have a different approach for spawning than nest-building fishes. The female prefers to spawn beneath a structure, releasing her eggs so that they adhere to the underside of vegetation, rock and other solid structures. After the eggs are placed and fertilized, the male then cares for the eggs until they hatch. These fish exhibit care for the eggs similar to the nest builders to increase the likelihood of survival of their brood.
However, some fishes offer no protection or care for their young. Walleye, white bass and paddlefish broadcast spawn across rocks and sand, spreading their eggs across the substrate and then leaving them on their own to survive. Some riverine species, such as freshwater drum, spawn in open water and just let their eggs drift with the flow of the water until they hatch. These spawning strategies often leave the eggs and young fishes open to both predators and a higher mortality rate. To offset this, many fish that do not guard or care for their brood produce much larger clutch sizes, releasing thousands of eggs with the idea that at least a few of them will survive.
Aquatic ecosystems are difficult places to survive with so many predators. These are just a few of the strategies fishes use to try to ensure their survival. Keep an eye out next time you’re on the water and you just may see a largemouth bass or bluegill building a nursery for the next generation!
Ben Braeutigam, Aquatic Resource Specialist