SEA-FISHERIES LABORATORY. 447 



the opposite state of affairs was observed : the pollution 

 of the mussels at Gareg Goch was greater than that of 

 the mussels from the harbour. This was at a time when 

 there was much fresh water in the river, so that what 

 probably happened was the scouring of the sewage- 

 polluted mud and foreshore of the harbour, and the 

 transport of this contaminated mud to the channel below 

 Borth, thus leading to the pollution of the mussels 

 there. It is to be expected that this would happen 

 frequently. 



An analysis of the small mussels growing on the 

 rocks at Gareg Goch and Careg Cnwc was made, and 

 this disclosed a greater degree of pollution than I had 

 expected. However, these rocks are at some considerable 

 distance from the nearest sewer outfall, and the pollution 

 is therefore less serious than the analysis seems to reveal. 

 We may, I think, conclude that if a tank or enclosure 

 could be constructed on the rocks at Gareg Goch and 

 Careg Cnwc, so that it might be filled from the flood tide 

 near its highest level, the water would be reasonably 

 free from contamination. Whether such a tank or 

 enclosure can be built at this place, at a cost commen- 

 surate with the object to be achieved, is, of course, a 

 matter for an engineer to consider. 



I think there is no doubt that the pollution of the 

 mussels in the harbour at Port Madoc is too serious to 

 be neglected. 



(2) The Mussel Beds at Aberdovey. (Plate II.) 



I visited Aberdovey on 19th June and collected 

 samples of mussels and water for analysis. One sample 

 of mussels was obtained by raking from the bottom of the 

 channel close up to the Pier, at a distance of about 

 400 feet from the sewer outfall. The depth at the time 



