Researchers from the University of British Columbia have uncovered alarming findings regarding the impact of road salt on salmon populations. Their study reveals that exposure to elevated salt levels during the winter months leads to a staggering 70% mortality rate in coho salmon eggs. This research highlights the environmental risks associated with winter road salting practices, particularly as salmon spawn in streams at this time.
The study, conducted in a laboratory setting designed to mimic stream conditions, focused on the effects of salt pulses lasting 24 hours. Lead researcher, Winter, noted that such exposure was surprisingly detrimental to the salmon eggs. “A 24-hour exposure, it's not that long at all,” Winter remarked, emphasizing the unexpected severity of the results. The researchers replicated their experiments multiple times to ensure accuracy and reliability in their findings.
The research indicated that salt levels in various streams often peak during winter and can exceed water quality guidelines by eight to ten times. This high concentration of salt proved to have a "shocking" magnitude of mortality in fish eggs. Winter expressed concern over these short exposure concentrations, stating, “Short exposure concentrations we are frequently seeing in streams causing such significant mortality definitely was alarming.”
Interestingly, the study found that while the eggs suffered considerably from salt exposure, the hatched fish were not as negatively affected. This suggests that while early developmental stages are vulnerable, the mature fish may have a greater resilience to salt exposure. However, the implications for salmon populations during their critical spawning period remain serious.
The timing of road salting activities coincides with the development of salmon embryos, raising questions about the sustainability of current winter maintenance practices. The researchers advocate for greater awareness regarding road salt usage and its environmental impact. They emphasize that effective de-icing can be achieved with significantly less salt than is typically used. For instance, only about two tablespoons of salt are needed for every square meter of ground.
In light of these findings, the researchers recommend that cities and large salt users consider transitioning to brine solutions instead. Brine is known for its efficiency in ice management and has been successfully implemented by several cities in British Columbia. Lyndsey Barton, a representative from one of these cities, noted that they have been using a brine solution for over a decade, as it utilizes far less salt and distributes more effectively.
The City of Port Moody exemplifies this approach by employing both salt and brine depending on specific road conditions. The researchers hope that their study will encourage municipalities to adopt "smarter salting practices" that protect salmon-bearing streams while still effectively managing winter roads.
Furthermore, Winter clarified some misconceptions surrounding road salt usage. “I think there is sometimes a conception that we're trying to ban the use of road salt, which is not the case at all,” he stated. Instead, the research aims to promote sustainable practices that balance environmental protection with public safety.
