21 



the only hard bottom; although some small areas of sufficieut 

 firmness to support seed oysters are found outside the limits 

 of the reefs. The salinity of the water in these bays is about 

 the same as in Bayou Grand Caillou, and the food supply was 

 abundant in all instances where an examination was made. 



From the mouth of Bayou Grand Caillou the shore line 

 runs in a southeasterly direction toward Last Island, which at 

 this point is separated from the inshore marsh only by a narrow 



bayou . 



Grand Pass des Isles, the first inlet of any size south of 

 Bayou Grand Caillou, opens to the Gulf some six miles frofti 

 the latter. It is about four miles long, and at its upper end 

 opens into Dog Lake. In the lower part of the bayou the depth 

 of the water varied from fifteen to thirty-three feet. In the 

 upper portion there is from twelve to twenty feet. Throughout 

 the entire length of the bayou there are extensive mud flats on 

 cither side of the channel, which are exposed at low water. In 

 the lower part of the bayou the bottom in the channel is com- 

 posed of rather firm sticky mud. There are numerous reefs of 

 small oysters along the flats in this section of the bayou. In 

 the upper part of the bayou there are some reefs where good 

 oysters occur, and several bedding grounds that occupy bottoms 

 where there were formerly productive reefs. 



The water in Grand Pass des Isles is more saline than in 

 the bodies of water farther to the north, the average of all the 

 determinations made during the past spring being 1.0158. The 

 supply of food materials is abundant and well distributed. 



Dog Lake, at the head of Grand Pass des Isles, is a body of 

 Vv-ater about three miles long and two miles wide. Its principle 

 outlet is by Grand Pass 4es Isles, but it has conne'ctions on its 

 south side with Bayou Go to Hell and Charlie's Bay. There is 

 a narrow channel along the western side of the lake where the 

 depth of water is from eight to twelve feet, while over the greater 

 part of the lake the depth is from two and one-half to four 

 feet. The bottom in most places is quite soft, the only places 

 where there was any hard bottom having been taken up for 

 bedding grounds. There are no productive natural reefs any- 

 where in the lake at the present time. The salinity of the water 

 was 1.0138. The number of diatoms in the water was consider- 



