July 07, 2021
On our way home from Kansas Melissa and I decided to stop at the big outdoor retailer in Tulsa. This chain of stores is known for the staged displays of stuffed trophy animals as well as the fish displayed in large aquariums. The store in Tulsa has a small stream/pool that holds several ten-pound Rainbow Trout. While I went up the elevator to look for a new pair of hiking shoes (the last ones only lasted 10 years of near daily wear), Melissa watched the trout in the pool. It was not long before she texted me saying I needed to come down and see what she was watching. When I arrived, she pointed out a pair of fish that were spawning. The female would swim around in the same spot and occasionally lay a flurry of eggs, which the male would quickly fertilize. We continued to watch for several minutes.
When I looked online, I found the rainbow trout (Oncorhynchus mykiss) is a species of salmonid native to cold-water tributaries of the Pacific Ocean in Asia and North America. The popularity of the fish as a fighter and for food have spread the species around the world. The exact timing for the spawn varies slightly based on the river system. In most cases however, rainbow trout spawn in the spring or late spring (March through late May). The snow runoff often hits a few weeks after the spawn is complete. In tailwater fisheries where the water temperatures see little variance below the dam, the spawn can even cycle out of season at random. The constant temperatures of the human made stream had obviously resulted in a random July spawn, several months later than normal in the wild.
The real show we watched was the male defending his territory. There were two other large Rainbows of the same size who were constantly challenging the male for access to the female. While the female stayed relatively still over her improvised nest, the male was constantly on the move. The other big fish would take turns entering the basin where the female was only to be driven back by the protective male. This was happening as he kept an eye on the female to see when she showered the bottom with eggs. While I never saw him, Melissa said there was another much smaller male who would sneak in and try to eat the eggs. While I had not thought much about trout eating their own eggs, I did know salmon eggs are one of the preferred natural baits when fishing for trout. I guess one spawn is as good as another.
Thoughts: In the wild, the female trout will build a nest, called a redd, to lay the spawn. The redd is easy to identify either by the fish gathered or by the cleaned section of pea gravel. When building a redd, the females fan their tails over the gravel to create the nesting zone, and the area stands out visually when compared to the rest of the river bottom. It is not uncommon for the female to stay on the redd as other males wait downstream, jostling for position to spawn or eat any free-floating eggs. The store fish live in an anomalous environment. There were no pea gravel beds to form the redd, nor were there additional females for spawn. The fish adapted as their innate nature allowed. While humans are driven by natural instincts, we are not bound by them. We make individual choices that ensure personal survival (or wants), and at times at the expense of others. We can choose to protect others as well. Do the work. Follow the science. Change is coming and it starts with you.