Animal populations around the world are in peril, and that includes the scaly creatures that swim around in our oceans, lakes, and rivers that we call fish.
One fish species, known colloquially as a steelhead trout and to the scientific community as Oncorhynchus mykiss, are on a major decline as of late, and a new study published in the Canadian Journal of Fisheries and Aquatic Services takes on what is believed to be one of the first global collections of population data of this species to get a better understanding.
Image Credit: John McMillan, Oregon State University
"We were able to compile data from multiple reports and databases to document survival in the ocean of Oregon, Washington, and BC steelhead trout and show that these trends paralleled declines in adult abundance and also differ among populations originating from different areas," says Dr. Neala Kendall, lead author of the study.
"We believe this is the first time these data have been brought together in a single study."
While researchers still aren’t completely sure what was causing the major global population decline, this new research closely examined 48 different populations and put a magnifying glass to what could very well be the real problem.
It turns out that steelhead trout young aren’t faring too well in the wild, and their survival rate is in a spiraling decline. The survival rate decline could be as far down as 77% in some populations when comparing data from the 1980’s to data obtained in the 21st century.
In addition, there’s a severe under abundance in adults. These figures ran parallel with those found in the decline of youngling survival. A 53% decline in adults from the 1980’s to the 2000’s has been observed in the same populations that yielded the 77% figure noted previously, so there’s a pattern here without a doubt.
Obviously, if the younglings aren’t surviving well enough, then there aren’t enough fish growing up to become adults. That said, this is probably why the populations are in such a spiraling decline today.
While we don’t know for sure what’s causing these declines, we do know that we must act fast if we’re to save steelhead trout populations. Fisheries rely on steelhead trout to support the massive demand in the global economy and the environment depends on them for the right ecological balance.
While this research helped to raise flags about the problem, more research is needed to figure out exactly why these problems are occurring and what can be done to solve them.