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

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.””

Dave Orrick: Walleye Decline with Global Warming →

Pioneer Press:

“Natural walleye lakes could be a rarity in Wisconsin by mid-century, thanks to climate change, a new study warns. And the largemouth bass shall inherit the warmer waters — and flourish, the government-funded study further predicts.

By as soon as 2040, a mere 4 percent of Wisconsin lakes might be able to support naturally sustained walleye populations — a 60 percent reduction from today — while the number of lakes conducive to high-abundance largemouth bass populations could rise to 89 percent, up from 60 percent today, according to the study, co-authored by researchers from state and federal agencies...

The bass-walleye transformation isn’t new. For 30 years, researchers have watched traditional walleye lakes become bass-dominated lakes, often to the chagrin of anglers and cabin owners. The root cause is not known for certain, but it correlates with lakes getting warmer as summers have grown hotter and winters have become shorter and less severe, said Gretchen Hansen, the study’s lead author. The warming climate is a likely culprit because biologists have long established that in similar lakes, walleyes dominate in cooler waters and largemouth bass in warmer waters.”

State of Europe's Seas→

Nature's News Blog:

“The report notes that the levels of various pollutants — such as nutrients causing algal blooms and subsequent oxygen depletion in the Baltic and Black seas — are above acceptable limits; that fish stocks are over-exploited; and that the seas are full of litter. Gaps in data are also a huge problem, and very few member states have put forward a strategy to close these gaps, the Commission complains.

Another report on the same subject — released today by the European Environment Agency — notes that between 2001 and 2006, conservation status was inadequate or bad for 50% of the marine habitats assessed in the EU, with only 3% of marine species deemed to be in a “favourable” state and 70% being of unknown status.”

Monitoring is the first step in attempting to find solutions -- assess, adapt management, repeat.

Point of No Return→

Natasha Loder, writing for Conservation Magazine [a good read selection]:

“There is no quick and easy way to integrate the complexity of fish population dynamics into management. But all scientists seem to agree on the need to preserve large, old fish and maintain the balance of age classes in the population. From a conservation perspective, there may be most traction to be gained by focusing on protecting the largest fish, which play both an evolutionary and an ecological role.”

The solution of maintaing a balance of age classes means a harvest policy that targets multiple age classes and all at a sustainable rate. Such a harvest policy is difficult. First, most harvest is size or age selective, so a fishery might need to be harvested with several different gears. Second, harvesting all ages at a sustainable rate requires great management that fights managing to the margins with diligent use of feedbacks to leverage against the power of commerce.

How Desperation, Ipads, and Real-time Data Revived a Fishery→

Megan Molteni, reporting for Conservation Magazine:

“When The Nature Conservancy, the nation’s largest environmental group, came into Morro Bay, California, in 2006 and bought out all the fishing rights—effectively closing millions of acres of marine habitat to fishing almost overnight—it was every fisherman’s worst nightmare. But then something interesting happened. TNC began leasing fishing rights back to fishermen, provided they followed more sustainable practices. Then iPads were doled out, and boats began sharing information with the environmental group and each other. Fishermen started thinking beyond pounds landed. And, realizing there were customers willing to pay more for a more environmentally sound product, they discovered an economic incentive for the changes. They started thinking less like takers and more like stewards.”

This paradigm change may work elsewhere, and I advocated such an approach some time ago. 

Commercial Overfishing and Property Rights