January 3, 2012 — The following is an excerpt from the article "PolitiFact calls claims of menhaden declines “Mostly False”, is completely wrong" posted on the website Southern Fried Science:
Despite their small size and plain appearance, menhadenhave been called “the most important fish in the sea” because numerous coastal fish species rely on them for food. Although they aren’t typically eaten by humans, there is still a huge fishery for them for bait, aquaculture food, and oil. That fishery has been essentially unregulated, allowing fishermen to take as many as they want. Recently, there’s been a campaign among certain environmental groups to fix this problem and put catch limits in place for menhaden.
I was surprised to see PolitiFact, a non-partisan political fact-checking website, address this issue. I’ve checked PolitiFact pretty regularly for years, and I’ve never seen them cover a topic like this before. They focused on a claim by the Pew Environment Group that “In recent years, menhaden numbers along our coast have plummeted by 90 percent.” While I admit I am not familiar with specific details of menhaden population trends, anyone who has paid any attention at all to the ocean knows that we’re overfishing at alarming rates. According to the UN Food and Agriculture Organization, approximately 1/3 of all global fisheries are depleted or overexploited, many by more than the 90% referenced for menhaden.
Read the full story on Southern Fried Science
Analysis: The same day the Atlantic States Marine Fisheries Commission (ASMFC) was set to place historic restrictions on Atlantic menhaden harvest, The Providence Journal and Politifact Rhode Island released an analysis which accused the Pew Environment Group of bending the truth on the status of menhaden with their widely circulated claim that the stock had fallen 90 percent “in recent years.” Ultimately, because Pew’s assertion excluded much of the menhaden fishery’s historic data, the Journal and Politifact found the claim to be “mostly false”.
However, a recent article posted on the website Southern Fried Science criticizes the Providence Journal and Politifact Rhode Island piece. The article’s author, David Shiffman, alleges that Politifact’s conclusions are “completely wrong,” but he openly admits that he is “not familiar with specific details of menhaden population trends.” The author demonstrates this absence of knowledge throughout his writing, ultimately employing a comparably misguided rationale to that used by Pew. In turn, both Pew and Mr. Shiffman misrepresent the status of Atlantic menhaden.
Mr. Shiffman accuses Politifact of “shifting baselines” to arbitrarily reach their conclusion that Pew Environment Group had misrepresented menhaden-related statistics in a recent ad, but when the full time series of the menhaden fishery is examined, it reveals that Pew Environment has actually manipulating the years to create a dramatic pattern in the menhaden population. If Mr. Shiffman had taken the time to examine the complete timeline of available data, he would find that the alleged 90 percent decline is completely selective, and does not represent the patterns that have occurred over the complete history of the fishery.
Over the 50-plus years that data on menhaden biomass has been recorded by the Atlantic States Marine Fisheries Commission (ASMFC), biomass has fluctuated based on the strength of menhaden recruitment (the number of menhaden that are born). Current biomass figures are similar to the levels seen in the late 1960s, when biomass was lower, but the levels that followed in the 1970s and 1980s were the highest on record. The full time series shows that menhaden recruitment is highly variable by year, and periods of high recruitment, such as those naturally resulting after years of low recruitment, are more likely to be the result of favorable environmental conditions than a reduction in fishing activity.
Because Pew starts to chart the decline at the record-high biomass in 1983, fluctuations in menhaden biomass that occurred over the total 50 years of available data are left out of the picture entirely. The decline that Pew cites is simply part of an alternating cycle of strong and weak recruitment.
The largest flaw in Mr. Shiffman’s logic is assuming that Pew’s initial argument was true solely based upon the statistic that “approximately 1/3 of all global fisheries are depleted or overexploited.” Tying to compare aggregate global fisheries data to a single fishery is completely illogical, especially when considering that the United States comprises only a very small portion of these globally overexploited populations. “The U.S. is actually a big success story in rebuilding fish stocks,” explained Dr. Ray Hilborn, of the University of Washington, in a September Washington Post article. “In parts of the world, like in the North Atlantic, we’re starting to see reduced fishing pressure after 150 years of being fished hard.” A 2009 Science study by Dr. Hilborn indicated that a majority of the third “of all global fisheries” that are depleted or recovering are found in Africa and Asia, making Mr. Shiffman’s assertion that “anyone who has paid any attention at all to the ocean” should assume that the menhaden population is overfished, despite other contradictory evidence, incorrect.