Fine-tuning Fish and the Importance of Balance

By Marjorie Lieuwen, Conservation Science Coordinator, A Rocha Northern BC

March 17, 2023

At the Buck Creek Canfor Hatchery and Nature Centre in Houston, home of A Rocha Canada’s Northern BC project, we raise up to 10,000 coho fry each year for release into local streams. In October 2022 we collected and fertilized 9,906 eggs from coho spawners who had returned to the Upper Bulkley River. The eggs were incubated and by January 2023 they had all hatched into alevin. During the first week of March they were reaching the fry stage where they must begin swimming and eating. By this point we had about 9,400 fry. We moved the fish from their incubation trays to our rearing tub and were happy to see nearly all the fish take to swimming. However a couple days later we noticed a problem, something we had not experienced before. About a thousand of the fry were floating on their side or upside down, but still responsive. Their bellies were inflated with air. Over the next couple days nearly all the fry developed this condition and we transferred them all to separate aquariums. Amazingly nearly all of them recovered, their belly shrank back and they could swim normally again. We suspect our water recirculation system was introducing high levels of dissolved gas into the water and are working to resolve the issue! 

When I was asked to write a blog post about our fish I began reflecting on the balances and fine tuning we see in creation. Fish are very sensitive to changes in pH, dissolved gasses, and ammonia levels. God designed the systems in our body with so many intricate signaling pathways that modulate chemical, mechanical and electrical processes that keep everything in balance. When aspects of this break down or dysfunction it can result in disease. Similarly when balance is disrupted in ecosystems we can see far reaching effects. Removal of wetlands results in loss of their filtering and flood reduction capacity. Removal of the riparian zone along a river leads to scouring of the bank, excess deposition of sediment in the riverbed, loss of salmon spawning habitat and warmer water temperatures. 

We have all been given the task of stewarding the earth. Let us continue to learn about and wonder at the amazing creatures and ecosystems God has made, and strive to care for them as best we can. 

How many are your works, Lord!

    In wisdom you made them all;

    the earth is full of your creatures.

Psalm 104: 24