The history of our planet is defined by climate change. One hundred million years ago, dinosaurs roamed a temperate land that we now know as Antarctica. Then, a warm Earth turned frigid and glaciers covered much of North America.
Thousands of years later, a warming planet allowed black bass to flourish on this continent and Viking culture to expand in Europe. But then came the Little Ice Age. By the time that Columbus set sail in 1492, frozen seas had forced the Vikings to abandon settlements in Greenland, while those in Iceland struggled to survive.
Of course, we can see these dramatic shifts only through the lens of history. Pinpointing definitive start and end dates is impossible. And those who lived during those frigid times knew nothing of climate change. They knew only that it was cold.
Today, we recognize that climate’s only constant is perpetual change. What we don’t know is where today’s changes are in context with what occurred before and what will come tomorrow. Are we on the precipice of a major shift? Are we in the midst of a long, gradual change? Are we experiencing an anomaly?
Today, we also know that our climate --- the prevailing weather conditions, which include temperature and precipitation, averaged over a series of years --- is moderating. (The “causes” of that change have become a political issue, only slightly less controversial than abortion, and I won’t get into that here.)
“The underseas world is on the move,” says National Geographic. “Climate change is propelling fish and other ocean life into what used to be cooler waters, and researchers are scrambling to understand what effect that is having on their new neighborhoods.”
On the sportfishing front, that’s demonstrated by the fact that the snook, a cold intolerant species, is expanding its range up the east coast of Florida. In freshwater, northern fisheries are experiencing warmer year-around temperatures. For example, Lake Champlain annually freezes over two weeks later than it did in the early 1800s.
At a glance, that might seem like good news for bass and bass anglers, with cold-water species as the only casualties.
That’s not the case, and that’s why fisheries managers will find their jobs increasingly difficult, as well as complicated, in the years to come. One of the reasons for that is not because bass will expand their range, but because they are likely to become more dominant in fisheries where they now are marginal. That’s a formula for friction among users regarding management strategies.
As to the negatives for bass, remember Largemouth Bass Virus? Scientists found that outbreaks were most lethal in warm water.
And a longer growing season for bass also is conducive to larger and longer blooms of algae, some of them toxic. Additionally, warmer temperatures could invite invasion by parasites, diseases, new exotic species, and problematic, invasive plants.
“Giant salvinia and hyacinth that are now limited by freezing winters will spread north,” said Gene Gilliland, B.A.S.S. National Conservation Director and a former fisheries biologist. “The result will be the need for expensive control to prevent them from causing ecosystem chaos. Ask Texas or Louisiana what they spend on weed control each year! That could be Oklahoma or Kansas or Nebraska in the future.”
Southern waters, meanwhile, might become too warm for healthy bass fisheries. “You don’t see great bass populations at the equator and it would likely get even warmer there and other parts of the tropics and subtropics. Maybe even Mexico and peninsular Florida,” he explained.
The conservation director also is concerned about climate fluctuations that seem to accompany warming waters. Short-term droughts can degrade or destroy until precipitation returns and those fisheries recover, probably with assistance from resource managers.
Up in Wisconsin, study of a lake during drought revealed that shoreline species lose refuge areas, forcing them into open water where they become more vulnerable to predation, and, as a consequence, the entire ecosystem is altered.
Also, excessive rains can flush systems and deplete nutrients, causing changes in the food chain that bass and other species may not adapt well to.
What can managers do to help fisheries cope with climate change?
“As waters warm and cool-water species decline, it will be imperative that agencies adapt quickly to avoid getting behind the curve,” Gilliland said. “Although it will be difficult for them to persuade older/traditional constituents that the past cannot be revived, they will need to move on and adopt new technologies, new protocols, learn new science, and manage evolving warmer-water ecosystems.”
(This column appeared originally in B.A.S.S. Times.)