If you’re a recreational fisher, and like to spend your morning out on a calm lake with a reel in front of you, it’s likely you should thank the government for your catches.
Fish stocking is a common practice, and is employed by many provincial governments (including Ontario and British Columbia). Reasons for adding nonnative fish species into a lake vary, and are often for recreational, commercial, or subsistence fisheries. It may also generate food supplies, or supply a brood stock for future culture purposes.
Although not all fish stocking practices are purposefully done, most are done with good intentions. The unfortunate part is that we often don’t know all the impacts we could be having on the local ecosystem.
For example, rainbow trout are often stocked in British Columbia lakes. However, it wasn’t until 2007 when researchers from Simon Fraser University investigated the potential impacts that these trout may have on amphibian populations. Through field collections from both “troutless” lakes and lakes containing the fish (through stocking and natural means), we see some impacts that may affect how salamanders and frogs live and reproduce within their habitats.
When you think about it, it makes sense from an ecological perspective. When you introduce a species into an area, you’re bound to have some impact of the species that currently live there. Niches will be adjusted, and all will have to figure out how they can co-inhabit the area, if at all.
Overall, fish stocking has both positive and negative impacts. The precautionary approach isn’t widely used with fish stocking practices, and it may not need to be. Our current practices (that we have used purposefully) haven’t led to great disasters, and if we can continue to use them with precision, this practice could be appropriate for use for years to come.