An Investigation of the Waters Adjacent to Ponape 



Oceanography 



The basic oceanographic investigations consisted of observations made 

 three times each month. They revealed the following conditions in these 

 waters. For the sake of convenience in describing this area it is divided 

 into the lagoon waters and the open sea with the barrier reef as the 

 boundary. 



The outer face of the reef drops off steeply at some places and more 

 gradually at others, but for the most part it is an almost vertical wall 

 where the surf breaks at all seasons and w^.ere there are no places which 

 offer important possibilities for fishing. 



A current of ^- to 1 knot stril-es thp eastern point of the island at 

 the reef off Metalanim, and divides into two branches. One branch flows 

 westward and then follows the reef north. Near the Ponape Harbor channel 

 it develops a southerly current (counter-current), hut it continues north- 

 ward and joins the northern current off the northern tip of the island 

 after which it continues westward. 



Away from the reef face the water is several hundred meters deep and 

 the bottom cannot be seen. Consequently nothing is known of the weeds, 

 fish, or shellfish which occur there. Visibility in the water '='xtends 

 from 12 to 15 fathoms. The northeast trades blow continuously from November 

 to May and during this period the sea is rougli everywhere to the north- 

 east of the island, the only calm areas being in the lee of the island 

 within 3 or U miles of the southwestern shores. From June to October the 

 winds are from the southwest and the sea is calm all around the island. 



The barrier reef may be divided into a northern and a southern part 

 by a line draxvn from east to west through the center of the island. On 

 t'v= south coast the reef is very close to the shore, but the northern part 

 is rather extensive in places. Channels such as the Tauak, Barukiru, 

 Jokaj, Ponape, Mant, and Aru passages connect the lagoon and t'^e open sea. 

 The depth of the lagoon is irregialar, but shoal patches under 30 fathoms 

 are found only rarely near the moutlis of rivers and the greater part of 

 the lagoon has depths of over 4.0 fathoms. 



The bottom is mud with a good deal of reef rock. There are no sand 

 beaclies on the main islanc, white sand being seen only around the small 

 islands within the lagoon. The lagoon is calm even during the trade wind 

 season, but it gets rather rough in the vicinity of Jokaj and Mant. 



The currents vary with the topogr.-;.phy and the tide, however, near all 

 the entrances the current runs into the lagoon with the rising tide and 

 out to sea as the tide falls. These tidal currents are rather swift. 



There is some danger due to the tnrbid condition of the water in the 

 lagoon which makes it difficult to see shoal patches. 



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