Study: Over-harvesting of reef fish IS reducing the catch

[ricki]

"A. was taken in 1957. B. taken in 1958. C & D between 1965 and 1979."
http://turningoversmallstones.blogsp...shrinkage.html


Dr. Loren McClenachan, a grad student performed an in-depth study while at Scripps Institute Of Oceanography of imagery of "trophy" fish catches off Key West, FL going back to 1956 . She has concluded that the sizes of "trophy" fish being landed have shrunk, drastically.

"She found the average size of sport fish landings has declined substantially over five decades, likely as a result of overfished and damaged reef communities, and uncovered evidence that the ecosystems’ compositions increasingly are dominated by smaller fish species."
http://www.psmag.com/environment/fis...got-away-3914/


I concluded the same thing, in part based on similar but far sparser photographic evidence and reef sightings off SE Florida. I quit spearfishing and line fishing as a result. The difference is I was 16 years old. Move the clock forward almost 40 years and now we have scientific study to support this same conclusion.

What the hell? If a 16 year old, decades back could figure this out based on far more cursory information, what is WRONG with folks these days? People with money and livelihoods at risk are actively promoting spearfishing as a hook for free diving, dive shops, charter boats, resorts, etc.. Diving, particularly free diving can give a great deal more rewards than a fish dinner. That is if people bother to experience it at that level.

Harvesting of jewfish or goliath grouper has been banned in Florida since 1990 I understand. That might explain the falloff of those captures and many of us seen them quite commonly on the reefs today. What about all the other trophy species however? Is there a big come back in blacks, nassau or other larger species? Seems to be going the other way fast from what I have seen.

Major die offs of coral species, deterioration of what is left, increase in algal dominance of coral reefs, add in overfishing, etc. etc. When are we going to stop trashing our reefs with unsustainable practices?


You can see an overview of Dr. McClenachan's work at:
http://scrippsnews.ucsd.edu/Releases/?releaseID=959


a Q and A at:
http://www.psmag.com/environment/fis...got-away-3914/





and a 2009 article in "Conservation Biology" at:
http://noss.cos.ucf.edu/papers/McClenachan%202009.pdf

Here is the abstract from that paper:
"Abstract: A loss of large vertebrates has occurred in aquatic and terrestrial ecosystems, but data to measure
long-term population changes are sparse. Historical photographs provide visual and quantitative evidence of
changes in mean individual size and species composition for groups of marine fish that have been targeted by
sport fishing. I measured such trends for 13 groups of recreationally caught “trophy” reef fish with photographs
taken in Key West, Florida, from 1956 to 2007. The mean fish size declined from an estimated 19.9 kg (SE
1.5) to 2.3 kg (SE 0.3), and there was a major shift in species composition. Landings from 1956 to 1960
were dominated by large groupers (Epinephelus spp.), and other large predatory fish were commonly caught,
including sharks with an average length of just <2 m. In contrast, landings in 2007 were composed of small
snappers (Lutjanus spp. and Ocyurus chrysurus) with an average length of 34.4 cm (SE 0.62), and the average
length of sharks declined by more than 50% over 50 years. Major declines in the size of fish caught were not
reflected in the price of fishing trips, so customers paid the same amount for a less-valuable product. Historical
photographs provide a window into a more pristine coral reef ecosystem that existed a half a century ago
and lend support to current observations that unfished reef communities are able to support large numbers
of large-bodied fish."


A summary of Dr. McClenachan's publications on related subjects:
https://sites.google.com/site/lorenmcclenachan/


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