In June 1985, a focused study was initiated to assess the spatial and temporal extent, intensity, and potential causes of oxygen depletion in the northern Gulf of Mexico. Hypoxic bottom waters were studied along two transects (one off Cat Island Pass near Cocodrie and one off Belle Pass near Port Fourchon). The number of transects was reduced to one in 1986 (Transect C off Cat Island Pass) and the number of sample periods increased. Sixteen cruises were conducted aboard the R/V Acadiana or the R/V Pelican between late January and mid-November, 1986. Sampling was most intense (bi-weekly) from mid-April through late September. A reduced sampling scheme (four stations) was followed for the first two cruises. In addition a shelf-wide cruise was conducted from the Mississippi River to the Texas border during July, 1986
