Global warming has serious consequences for the international fishing community, but I’m also concerned that our soaring sense of wonder about something greater than ourselves might also be at risk.
A study published in the prestigious Proceedings of the National Academy of Sciences indicates that individual fish have lost half their average body mass, that fish populations have thinned drastically, and that smaller species are starting to dominate European fish stocks. Although overfishing probably played a significant role, the long, steady increase in fresh water and ocean temperatures caused by global warming takes the lion’s share of the blame.
“It’s huge,” said study author Martin Daufresne of the Cemagref Public Agricultural and Environmental Research Institute in Lyon, France. “Size is a fundamental characteristic that is linked to a number of biological functions, such as fecundity – - the capacity to reproduce.”
Marine biologists know that smaller fish have fewer innate resources, and tend to produce fewer eggs. Lower individual weights also mean that the same number of fish feed fewer people and, by extension, fewer predators. This study builds on previous work and further establishes that marine life has shifted migratory and breeding patterns in response to rising sea temperatures. And warmer seas favor smaller breeds of fish.
Dr. Daufresne and his colleagues examined long-term surveys of fish populations in rivers, streams and the Baltic and North Seas and also performed experiments on bacteria and plankton. They have determined that many individual species have lost 50% of their mass in just 25 years, and that stocks have declined by 60%.
While commercial and recreational fishing does impact some of the fisheries studied, it “cannot be considered as the unique trigger” for the changes in size, Daufresne’s group found. “Although not negating the role of other factors, our study provides strong evidence that temperature actually plays a major role in driving changes in the size structure of populations and communities.
So, what should we do? Water is the source of all life on this planet, but we haven’t been paying attention. The problems of renewable energy seem small potatoes when we look at our oceans, and what we might do to save them.
This problem really hits home for me. I live in Nova Scotia, and the ocean is never more than a hop, skip and jump away. When Giovanni Caboto first visited this area in 1497, sailing under the British flag, his crew were able to lower baskets into the water, catching dozens of massive cod easily and without effort.
I doubt he’d recognize the waters off Newfoundland and Nova Scotia today, because we’re already living this study; ocean populations of fish in Eastern Canada plummeted in the 1990s, and fishing villages running the length of the province have fallen on hard times. We’ve been practicing conservation, and fishing fleets and fisher folk are much smaller in number, and now far less wealthy. But after 15 years, we probably need to face facts. The fish aren’t coming back.
That’s also true in our lakes and rivers. Acid rain in the 1970s and 80s destroyed the ability of Atlantic Salmon to breed in our waters, and the sports fishing industry has also died.
Might I suggest a visit to the Ocean Conservancy to get a better handle of the issues involved.