Jilted lovers used to be consoled by friends with the reassurance that "there are plenty more fish in the sea." That analogy may not be valid much longer. Here are some excerpts from a column in the Guardian's Datablog:
This image shows the biomass of popularly-eaten fish in the North Atlantic Ocean in 1900 and in 2000...The study itself was published in Fish and Fisheries in 2003. Here's part of the abstract -
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...
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... 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...
As Prof Roberts writes: "The greater part of the decline of many exploited populations happened before the birth of anyone living today."
We estimate the biomass of high-trophic level fishes in the North Atlantic... from 1880 to 1998. We extract over 7800 data points that describe the abundance of high-trophic level fishes as a function of year, primary production, depth, temperature, latitude, ice cover and catch composition.We then use a multiple linear regression to predict the spatial abundance for all North Atlantic spatial cells for 1900 and for each year from 1950 to 1999. The results indicate that the biomass of high-trophic level fishes has declined by two-thirds during the last 50-year period, and with a factor of nine over the century. Catches of high- trophic level fishes increased from 2.4 to 4.7 million tonnes annually in the late 1960s, and subsequently declined to below 2 million tonnes annually in the late 1990s... Our results raise serious concern for the future of the North Atlantic as a diverse, healthy ecosystem; we may soon be left with only low-trophic level species in the sea.Writing this post has reminded me that I need to revisit my review of the excellent book Paradise Found: Nature in America at the Time of Discovery, by Steve Nicholls. I wrote one post about the topic last year, but there's much more amazing information to present.