Price-Cost Margins and Structural Change : Sub-Contracting within the Salmon Marketing Chain

Some recent studies have benefited from advances in time series econometrics in order to evaluate price transmission mechanisms along the marketing chain. Due to the length of time series, structural changes may affect the evaluation of price-cost margins. In the case of the fresh salmon trade between Norway and France, the gross margin between producers and retailers has changed in level between January 1988 and December 1999. This article accurately identifies the date of a structural change using a range of recent ADF testing procedures (Gregory-Hansen tests, forward and backward recursive tests), before looking for the causes of the change through a survey. Two major factors can be identified: the product form and the marketing channel. Interestingly, both the increasing level of processing and the development of supermarket chains have resulted in a new role for the intermediaries, shifting from mere commercial intermediation to sub-contracting for the big retailers