Trophy fisherman in Florida are being short changed, according to a new study which has worrying implications for the marine ecosystem.
Using historical photos, Scripps Institution of Oceanography researcher Loren McClenachan estimates that the size of fish being caught near the Key West reefs has dropped precipitously since the 1950s. While fish in the 1950s appear to weigh around 20 kg, in 2007 this had dropped to a paltry 2.3 kg.
The image right shows, top to bottom, fish caught in 1957, the early 1980s and 2007 (click to embiggen).
“These results provide evidence of major changes over the last half-century and a window into an earlier, less disturbed reef fish community, but communities of coral reef fish of the Florida Keys in the 1950s were themselves not undisturbed,” writes McClenachan in a paper in Conservation Biology (published in January and newly press released by Scripps).
“Commercial fishing for reef sharks in the 1930s and 1940s reduced shark populations before the 1950s, and large groupers have been commercially fished since at least the 1880s. Thus, pristine coral reef ecosystems supported far more large fish than are implied by these historical photographs.”
This damage isn’t likely to be just down to sport fisherman. Commercial boats have also been plying their trade on the reefs.
“Managers mistakenly assume that what they saw in the 1980s was pristine, but most prized fish species had been reduced to a small fraction of their pristine abundance long before, says Scripps professor Jeremy Jackson. “Historical ecology provides the critical missing data to evaluate what we lost before modern scientific surveys began.”
Back in September last year the Smithsonian magazine featured McClenachan’s then-unpublished research:
McClenachan … is part of a new field called historical marine ecology. Its scientists analyze old photographs, newspaper accounts, ships’ logs and cannery records to estimate the quantity of fish that used to live in the sea. Some even look at old restaurant menus to learn when certain seafood became more costly, usually due to scarcity. McClenachan’s study and others are part of the Census of Marine Life, a ten-year effort sponsored by foundations and governments worldwide that aims to understand the ocean’s past and present, the better to predict the future.
McClenachan, who fishes herself, also says that people appear to be paying roughly the same amount to fish now as they did back when they were catching much larger fish. This implies that declines in marine ecosystems might not come with similar declines in tourism revenue.
Related
Human hunting speeds up evolution of prey – January 13, 2009
Image:Monroe County Library