Prior to 1975 the NEFSC surveys tended to show lower population sizes than commercial landings did. Despite this, the NEFSC survey landings and commercial landings showed similar declines from 1968 to 1971. After 1975 the NEFSC surveys appear to show higher population sizes than the commercial landings did. After plateauing in the late 1970's and early 1980's both the commercial landings and the NEFSC survey landings generally declined for the next 2 decades. It is interesting to note that the NEFSC surveys do not reflect the same jump in landings that the commercial fishery experienced in 1991, nor do the NEFSC surveys reflect the record low commercial landings in 1999. These discrepancies may occur because bottom trawl surveys are not conducted in the same manner that commercial trawls are conducted. The NEFSC conducts the trawl surveys independent of the weather, around the clock, for only 30-minutes per tow, and at randomly-selected sites. Commercial fishers, on the other hand, will only trawl at the most productive times (which depend on the weather and the time of day) at the most productive places (areas of bottom where they know produce cod) and until their nets are filled (most often requiring more than thirty minutes).