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Wednesday, 22 February 2017

Biomass map of popularly eaten fish populations in 1900 versus 2000


It's hard to imagine the damage over-fishing is wrecking on the oceans. The effects are literally invisible, hidden deep in the ocean. But there is data out there. And when you visualise it, the results are shocking.

This image shows the biomass of popularly-eaten fish in the North Atlantic Ocean in 1900 and in 2000. Popularly eaten fish include: bluefin tuna, cod, haddock, hake, halibut, herring, mackerel, pollock, salmon, sea trout, striped bass, sturgeon, turbot. Many of which are now vulnerable or endangered.

Dr Villy Christensen and his colleagues at the University Of British Columbia used ecosystem models, underwater terrain maps, fish catch records and statistical analysis to render the biomass of Atlantic fish at various points this century

Memory vs forgetting

Professor Callum Roberts' harrowing book, The Unnatural History Of The Sea . He uses historical accounts of the ocean to depict the sheer fecundity of the sea in the times before industrialised fishing.

These early accounts and data on the past abundance of fish help reveal the magnitude of today's fish stock declines which are otherwise abstract or invisible.

They also help counter the phenomenon of "shifting environment baselines". This is when each generation views the environment they remember from their youth as "natural" and normal. Today that means our fishing policies and environmental activism is geared to restoring the oceans to the state we remember they were. That's considered the environmental baseline.

The problem is, the sea was already heavily exploited when we were young.

So this is a kind of collective social amnesia that allows over-exploitation to creep up and increase decade-by-decade without anyone truly questioning it. Today's fishing quotas and policies for example are attempting to reset fish stocks to the levels of ten or twenty years ago. But as you can see from the visualization, we were already plenty screwed back then.

As Prof Roberts writes: "The greater part of the decline of many exploited populations happened before the birth of anyone living today."

See the visualisation at the top of the page.

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