A recent study in the journal Fish And Fisheries did not get the attention it deserved. Let's fix that. Science Daily reported on the study in Why We Need To Put Fish Back Into Fisheries (May 19, 2013).
Overfishing has reduced fish populations and biodiversity across much of the world's oceans. In response, fisheries are increasingly reliant on a handful of highly valuable shellfish.
However, new research by the University of York shows this approach to be extremely risky.
The research, published today in the journal Fish and Fisheries, shows that traditional fisheries targeting large predators such as cod and haddock, have declined over the past hundred years. In their place, catches of shellfish such as prawns [shrimp], scallops and lobsters have skyrocketed as they begin to thrive in unnaturally predator-low environments often degraded by the passage of trawls and dredges.
The ecological effects of intensive fishing. From left to right, fishing effort increases over time. As a result, large predatory fish become depleted and fishers are forced to target new species. Consequently, the marine ecosystem becomes progressively more damaged and biodiversity is reduced. In this unnaturally predator-free environment, the ecosystem can become dominated by highly valuable shellfish, or by harmful algal blooms, highly invasive gelatinous plankton and jellyfish. (Credit: University of York)
In many places, including the UK, shellfish are now the most valuable marine resource. The research by the Environment Department at York suggests that although a shellfish-dominated ecosystem appears beneficial from an economic perspective, it is highly risky.
Like simplified agricultural systems, these shellfisheries are unstable in the long-term and at great risk of collapse from disease, species invasions and climate change. Warming and acidification of our oceans due to greenhouse gas emissions is expected to affect shellfish worst. Ocean acidification, in particular, will limit the ability of scallops and other shellfish to form proper shells, and lead to widespread mortality.
Here's the abstract of the study
Many over-exploited marine ecosystems worldwide have lost their natural populations of large predatory finfish and have become dominated by crustaceans and other invertebrates. Controversially, some of these simplified ecosystems have gone on to support highly successful invertebrate fisheries capable of generating more economic value than the fisheries they replaced. Such systems have been compared with those created by modern agriculture on land, in that existing ecosystems have been converted into those that maximize the production of target species. Here, we draw on a number of concepts and case-studies to argue that this is highly risky. In many cases, the loss of large finfish has triggered dramatic ecosystem shifts to states that are both ecologically and economically undesirable, and difficult and expensive to reverse. In addition, we find that those stocks left remaining are unusually prone to collapse from disease, invasion, eutrophication and climate change.
We therefore conclude that the transition from multispecies fisheries to simplified invertebrate fisheries is causing a global decline in biodiversity and is threatening global food security, rather than promoting it.
In 2012 I saw stories like Maine's lobster explosion an economic boon, biodiversity bust.
Low prices and a market glut may be the biggest problems many Maine lobstermen had to deal with this year, but there are other looming challenges facing the industry, and they have more to do with the marine environment than money.
According to University of Maine marine biologist, Robert Steneck, the depletion of cod and the effects of global warming — along with existing economic challenges — are combining to test the ingenuity of lobstermen, even as the Gulf of Maine undergoes dramatic changes.
But the problem isn't too few lobsters; there are more than enough.
That abundance is a relatively new development, said Steneck, a professor in the School of Marine Sciences at the University of Maine's Darling Marine Center in Walpole...
The surge in the Gulf of Maine lobster population has been a boon to Maine, which now enjoys a "lucrative monoculture" in fisheries, with lobsters accounting for 85 percent of the value of harvested marine resources, Steneck said. The fishery, he said, "is better today than ever before."
Lobstermen expected this year's catch to compare favorably with last year's record catch of 100 million pounds, which was worth $330 million at last year's wholesale prices.
But with the population increase comes potential trouble. In environments of low biodiversity — the current state in the Gulf of Maine — disease and the effects of global warming can be disastrous because they can strike virtually the whole ecosystem, often swiftly and ferociously.
Even now, a synchronicity of conditions — abundant populations, an increase of 2 to 4 degrees in ocean temperatures and a resultant migration of different fish species northward into the Gulf of Maine — could create an ecosystem that makes lobsters more vulnerable to disease and stressed by new predators, Steneck said.
"Dynamic food webs and dynamic climate are colliding," he warned. Any one — or more — of these influences suggests "how on the edge this fishery is," said Steneck.
Lobstering historically has been Maine's most valuable commercial fishery, according to the state Department of Marine Resources. The once-diverse marine environment in the Gulf of Maine in the mid-19th century led to a decline in lobster numbers for a time, but by the late 1990s the same waters had been transformed into a haven for the present-day "lobster monoculture," Steneck said.
The gulf had evolved from a marine system "dominated by large predatory fish," primarily cod, into one in which such species were almost completely absent.
"Big fish are ecologically extinct," Steneck said.
The world below the surface of the Gulf of Maine "is now (one of) abundant small fish. It is an ecosystem that has fundamentally changed," with "an unbelievably high density of lobster."
Last summer, a shell disease, caused by bacteria that invade through pores in the outermost layer of the shell, ravaged the lobster fishery in Rhode Island, said Steneck, and that experience "should be a wake-up call" for all Atlantic coastal fisheries.
It is always the same story. Humans focus on short-term economic gains as long-term ecological catastrophe looms. The Gulf of Maine was once a thriving, diverse ecosystem with large predators like cod and haddock keeping shellfish and small fish populations in check. Not anymore. Now the Gulf of Maine is a "lobster monoculture" with few big predators.
In 2012, lobster populations skyrocketed, leading to a big spike in the lobster haul, which caused prices to tumble, which was a disaster for lobstermen, but a boon to "consumers".
Lobstermen are generally unable to make a profit if lobster is under $4 a pound. But a glut in soft-shelled lobsters within the last couple months has caused prices to fall as low as $1.25 a pound, close to a 30-year low for this time of year, according to The Wall Street Journal.
The mild winter, along with a relatively warm spring, seems to have contributed to lobsters losing their shells much earlier than expected — about six weeks sooner. Canadian seafood processors, which buy up a large share of Northeastern lobster, weren’t prepared for the surplus. And all this happened before the New England tourist season got fully underway as well.
All of this is artificial, which in this context means man-made. The "relatively warm spring" was part of a record-setting heat wave in the continental United States in the 2012. Such heat waves become more frequent as the Earth warms. The explosion in lobster populations in the Gulf of Maine is a consequence of fishing down the food chain, which led to the disappearance of large predators—they are now ecologically extinct. Any subsequent collapse of the Gulf of Maine lobster populations will be artificial too.
Back to the Fish And Fisheries study.
Co-author Professor Callum Roberts concludes: "The rise of shellfish has been welcomed by many as a lifeline for the fishing industry.
However, such changes are not a result of successful management, but rather a result of management failure, a failure to protect stocks and their habitats in the face of industry innovation and overfishing. This study highlights why the UK needs to urgently act to protect our seas.
We need more marine protected areas to stop our seas from becoming a wasteland and to restore the diversity and productivity of fisheries well into the future."
And now, lobsters are eating each other, which nobody had ever seen before. In a lobster monoculture, what is there for lobsters to eat?
You guessed it.
So... lobsters have been forced into their own version of Soylent Green. I wonder which species is next.
Posted by: Oliver | 05/22/2013 at 12:15 PM