Doug Johnson: Fish Get Smaller with Harvest→

Ars Technica:

Anton Petrus

“Generation over generation, catch after catch, fishing changes fish evolution. This phenomenon, called fisheries-induced evolution, is well documented, though it impacts the myriad species of fish differently. For the North Sea cod, it has meant that early bloomers thrive, while fish that are slower to mature get taken out of the gene pool. This has meant that the fish population is evolving toward smaller sizes. A recent paper models what it would take to reverse this effect through conservation, and what it would mean economically to do so.

“In general, fishing is one of the main drivers of change in marine ecosystems,” Hanna Schenk, a postdoctoral researcher at the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig and one of the paper’s authors, told Ars.

Fishing increases mortality rates among fish—particularly large fish, which are caught in higher numbers because they are more likely to stay within fishers’ nets. In turn, this puts selective pressure on a species: fish that mature quicker (but remain smaller) gain an advantage. These smaller, early bloomers then pass on their genes more often, which impacts the whole population over time. “There is a trade-off between those two [factors], and once a cod matures, it grows less. So, when that happens earlier, it usually doesn’t reach such a large size as if it wasn’t spawning,” she said.”

The science paper is here

The Guardian: High Carp Prices Affect Poles→

Reuters in Warsaw:

Wojtek Jargiło/EPA

“For most Poles, no Christmas would be complete without carp for dinner. But with prices rising and shopping budgets already stretched by surging inflation, consumers are having to fork out more for their favourite festive fish.

Polish people hold their main celebration on Christmas Eve, with carp the centrepiece of a 12-dish feast that is traditionally meat-free.

While the bottom-feeding lake dweller is considered inedible in parts of the world, in Poland and some other central European countries carp is served cold in jelly as well as fried or baked and has long been seen as a relatively cheap way of feeding a large group of people.”

Ian Rose: Restaurant Menus and Climate Change→

The Atlantic:

City of Vancouver Archives

“In a new study, a team from the University of British Columbia (UBC) shows one unexpected way that climate effects are already manifesting in our daily lives. To find it, they looked not at thermometers or ice cores, but at restaurant menus.

“With a menu, you have a physical and digital record that you can compare over time,” explains William Cheung, a fisheries biologist at UBC and one of the study’s authors. Cheung has spent his career studying climate change and its effects on the world’s oceans. He has contributed to several of the landmark reports of the United Nations Intergovernmental Panel on Climate Change, but along with John-Paul Ng, an undergraduate student at UBC, he wanted to find a different way to both study and communicate those changes...

Using their records, the scientists created an index called the Mean Temperature of Restaurant Seafood (MTRS), which reflects the water temperature at which the species on the menu like to live. Predictably, they found that the MTRS of Los Angeles was higher than that of Anchorage, with Vancouver falling in the middle. But by analyzing how the MTRS for Vancouver has changed over time, they found a significant trend of warmer-water species becoming more common on restaurant menus. In the 1880s, the MTRS for Vancouver was roughly 10.7 degrees Celsius. Now it is 13.8 degrees Celsius.”

Kieran Lindsey: The Great Pumpkinseed

Center for Humans and Nature:

August Rode

This colorful Centrarchidae with scarlet-lipped ear flaps is sheathed in seedy speckles of colors that range from Caramel orange to Lemon Drop yellow, Red Hots red to Starburst blue-raspberry blue and Lifesavers lime green. The “official” origin story is that the common name for this mid-sized fish (4-11″ or 10-28 cm, tipping the scales at a maximum of 1.5 lbs or 680 g) derives from the oval contour of the body rather than the coloration pattern.

Jeff Renaud: Predicting Fish Recovery from Mercury Pollution

University of Western Ontario:

“Reducing mercury pollution entering lakes lowers how much harmful mercury is found in freshwater fish destined for consumers’ plates. This is according to a new paper, published today in Nature. During the study, conducted over 15 years, scientists intentionally added a traceable form of mercury to an experimental lake and its watershed.

The interdisciplinary research team, including Western University’s Brian Branfireun, discovered that the new mercury they added quickly built up in fish populations, and then declined almost as quickly once they stopped additions.

Notably, the fish populations were able to recover from mercury much quicker than previously understood, which suggests that curbing mercury pollution through policy initiatives now will have a rapid and tangible benefit on the quality of fish we consume.”

More information: Paul Blanchfield, Experimental evidence for recovery of mercury-contaminated fish populations, Nature (2021). DOI: 10.1038/s41586-021-04222-7. www.nature.com/articles/s41586-021-04222-7

Emma Bryce: Fish for Food with Low Impact→

Anthropocene Magazine

“First, the major source of emissions in aquaculture is the production of feed for the farmed fish. In fact this accounted for a striking 70% of emissions for most farmed fish, most notably flatfish and crustaceans, the researchers found. The footprint is attributable to the land conversion and fertilizers that are needed to produce the feed, which are typically soybeans. This land-based food production also gives farmed fish a relatively high footprint where water use is concerned.

In wild-caught fisheries meanwhile, the primary emissions culprit is fuel-use for boats, especially true for high-seas industrial fleets that may travel long distances to capture fish.

This assessment also revealed which are the ‘greenest’ blue foods to consume. The researchers found that across all fish – farmed and wild-caught—the lowest-impact were farmed bivalves and seaweeds, mainly because they don’t need to be fed. In fact, their self-sufficiency gives them an ecosystem benefit, because shellfish and seaweed can remove nitrogen and phosphorus pollution—usually originating from terrestrial agriculture—from the water. What’s more, bivalves especially have some of the highest nutritional value of all available blue foods, presenting a clear win on all fronts.”

Mike McFeely: Bigmouth Buffalo Centenarians→

Duluth News Tribune:

“Don’t call the bigmouth buffalo a “rough fish,” a common and derisive moniker slapped on species viewed as less desirable than the sainted walleye and other hotly pursued fish. “They are amazing,” said Alec Lackmann, a North Dakota State University researcher in the Department of Biological Sciences. “They are one of the most exceptional freshwater fish species in the world.”

Lackmann would know. He led an NDSU team that unearthed this amazing fact: Bigmouth buffalo can live to be more than 100 years old, making them the oldest age-validated freshwater fish in the world. Lackmann’s study included one specimen that was 112 years old, and most of the fish he researched were more than 80 years old. The oldest fish came from lakes near Pelican Rapids, Minnesota...

According to NDSU, the bigmouth buffalo is now known as the longest-lived freshwater teleost (ray-finned fish) and the oldest age-validated freshwater fish in the world. “This is a paradigm shift in how we’re looking at these fish and should open a discussion about their real value,” Lackmann said. “They should not be called ‘rough fish,’ which carries a negative connotation. They should be viewed as an ecological asset.””

Kirsti Marohn: Surveying Fish in Streams for Water Health→

MPR:

“Chad Anderson and John Sandberg slosh through a muddy stream in hip waders, pausing occasionally to duck under overgrown branches or swat a mosquito.

Sandberg carries a long pole with a metal ring on the end. He moves it through the water, sending out an electrical current that temporarily stuns the fish. Anderson comes behind him with a net, scooping them up. “We want to capture every single species, every fish,” Anderson said. “The little species are sometimes just as important as the big ones...”

This slow and sometimes painstaking work is part of the MPCA’s effort to document and monitor all 80 of Minnesota’s major watersheds. The work has produced a wealth of data about the health of Minnesota’s rivers, lakes and streams.”

Boom times for fish populations→

NSF:

“We’re all familiar with the idea of extreme events. Meteorologists keep us up to date on hurricanes, floods and high temperatures. Economists watch the stock market for signs of crashes or rallies. Researchers spend a lot of time trying to better predict these events, yet are often surprised by the outcomes. According to a new study in the journal Limnology & Oceanography Letters, when it comes to nature’s extremes, nothing seems to beat what happens underwater.

Scientists at the National Science Foundation (NSF) North Temperate Lakes Long-Term Ecological Research (LTER) site — one of 28 NSF LTER sites — are routinely measuring everything from water temperature to nutrient concentrations to fish populations in Wisconsin lakes.

Taking advantage of several decades’ worth of data, Ryan Batt, the paper’s lead author, and a team of researchers compared data on various physical, chemical and biological variables — 595 variables in total. They found that as the lakes’ temperatures rose and their nutrient concentrations increased, so did the number of organisms living there.”

Solomon David: Bowfin, North America’s Underdog Fish→

Cool Green Science:

“Mudfish, dogfish, grinnel, swamp-muskie: the names alone suggest why bowfin (Amia calva) are generally not the most highly-revered among fishes.

With their prehistoric appearance and tenacious attitude, one may say they deserve their poor reputation. But the bowfin is in reality a fascinating, resilient, and even beneficial species.

What we see today in the backwaters and wetlands of eastern North America is a modern representative of a very ancient line of “primitive” fishes or “living fossils,” organisms that appear to have changed little over time. The sole remainder of a once diverse group; bowfins (order Amiiformes), have been around for over 150 million years.”

One of my favorite fish to observe!

Krishnadev Calamur: A Fish With Cancer Raises Questions→

NPR

“Late last year, an angler caught a smallmouth bass in the Susquehanna River near Duncannon, Pa. That fish, officials from the Pennsylvania Fish & Boat Commission said this week, had a malignant tumor. It’s the first time this type of tumor has been found on a smallmouth bass in the river, the agency says.

Cancerous growths and tumors on fish are “very, very infrequent,” John Arway, the agency’s executive director, said in an interview.

”These cancers can be initiated by contaminants,” he said.”

In addition to this story, more Information on the fish populations in the Susquehanna River is available here.

Forests are Good for Fish→

Jason G. Goldman, writing for Conservation:

“Fish rely on forests for their very survival. That’s because, in a way, they eat them. Debris from forests finds their way into rivers, lakes, and streams. The bacteria in the water break down the leaves and bits of tree bark and dead animals. Then the zooplankton eat those bacteria, and the fish eat the zooplankton.”

Matt Tillett

One can eat only what is brought in.

Fish forced into the ‘foraging arena’ when lakes lose their trees→

Adam Hinterthuer, writing for University of Wisconsin-Madison:

As water levels drop and submerged trees rise above the waterline, some fish are forced into the "foraging arena" to face predators

“In attempts to predict what climate change will mean for life in lakes, scientists have mainly focused on two things: the temperature of the water and the amount of oxygen dissolved in it.

But a new study from University of Wisconsin-Madison researchers is speaking for the trees — specifically, the dead ones that have toppled into a lake’s near shore waters.

For fish in northern Wisconsin lakes, at least, these trees can be the difference between pastures of plenty and the Hunger Games.”

Interesting study from the Center of Limnology.