What This Study Was About

 

The basic idea behind our study was that if fish labeled as “MSC-certified Chilean sea bass” were in fact harvested from the lone certified fishery for this species, a retail sample of multiple fish should genetically resemble a similar sampling of fish taken directly from the SGSR stock (i.e., directly from fishing boats).  In science, this is called a “null” hypothesis, a hypothesis where “no” difference is expected between two treatments or samples.  A null hypothesis can be rejected or falsified with data, but most scientists understand that a null hypothesis cannot be proven to be true.


Obtaining retail samples of fish is simple, but samples of Chilean sea bass taken directly from individual fisheries are hard to come by.  However, our study was made possible by an earlier genetic analysis of the SGSR population published in the journal Molecular Ecology (Shaw et al., 2004) in which the authors used a technique called mitochondrial DNA (mtDNA) restriction digestion to compare the genetics of Chilean sea bass in the SGSR fishery to nearby populations along the coast of South America (Patagonian shelf).  By using the same genetic analysis as Shaw et al. (2004), we were able to accomplish our goal of compare the genetic composition of fish sampled at the retail end of the supply chain to a sample of fish acquired at the start of the supply chain (i.e., the fishery stock). 


The results showed that the frequencies of mtDNA variants or “haplotypes” differed significantly between the MSC-retail sample (our sample) and the MSC-fishery sample (Shaw et al.’s sample).  There are several potential explanations for this difference, but our paper concluded that the simplest and most likely explanation is that some fish from uncertified fisheries were introduced into the MSC supply chain.