5. CONCLUSIONS 



The intensive studies conducted in response to the Avgo Mevchant oil 

 spill have resulted in some significant findings, not only on the fate of the 

 oil from the tanker, but also on the behavior of spilled oil in general. 



Preliminary chemical analyses for oil content have been completed for 

 all water and sediment samples taken up to February 12, 1977, by cooperating 

 scientists. Selected samples have been sent to the NOAA National Analytical 

 Facility in Seattle, Washington, for more detailed study. Biological studies 

 primarily based on the six stations occupied during the first cruise of the 

 Delaware II (DE 7 6-13) have been reported by NMFS scientists. However, the 

 chemical and biological studies are not complete. Further analyses are being 

 conducted by all concerned to complete the assessment of the fate and impact 

 of the oil spilled from the Avgo Merchant. With these cautions in mind, the 

 following preliminary findings are presented and supported by this report. 



Notable among these findings are: 



(1) The oil from the Argo Merchant stayed on the ocean surface with the 

 exception of some of the "cutter stock," which entered the water column, and 

 an as-yet undetermined amount of whole oil that was mechanically worked into 

 the bottom in the immediate vicinity of the wreckage. The cutter stock, 

 which comprised 20 percent of the oil, was found in the water column in 

 concentrations up to 250 parts per billion. The highest levels were only 

 found beneath fresh oil slicks. After a few days, these levels were reduced 

 to background levels by turbulent mixing. 



(2) Oil in significant amounts has not been found in the sediments to 

 date, except within 10 miles of the bow section where it has been found in 

 concentrations up to 100 parts per million. 



(3) Most of the oil remained on the surface and moved offshore under 

 the influence of the prevailing west winds. Surface oil was never observed 

 north of 41°21' or west of 70°10', nor was it observed within 15 miles of any 

 land. Operational modeling efforts were successful in predicting the off- 

 shore movement of the surface oil primarily because the movement was con- 

 trolled by predominantly offshore winds while the complicated circulation of 

 near-shore areas and Nantucket Shoals played only a minor role. 



(4) There is evidence of oil contamination in fish, shellfish, ichthyo- 

 plankton, and zooplankton populations in the area of the spill. Mortalities 

 of developing cod and pollock embryos in eggs contaminated with oil were 

 observed. No. 6 fuel oil caused significant mortalities of cod embryos in 

 laboratory experiments conducted by NMFS and collaborating scientists of EPA 

 and the University of Kiel. Noticeable decreases in the abundance of sand 

 launce larvae were observed in the spill zone that may have been caused by 

 oil. Large numbers of zooplankters, which are an important food of larval 

 and adult fish, were contaminated with petroleum hydrocarbons similar to No. 



6 fuel oil, indicating that an important pathway in the food web of the 

 Nantucket Shoals ecosystem was impacted. The extent of this impact is under 



126 



