SHEIXFISH RESOURCES OF NORTHWEST COAST. 5 



Cape Arago and Sunset Bay are a short distance south of the 

 Coos Bay bar and, while induded in this region, may be dismissed 

 with brief consideration. The chief economic Molhisca of this 

 rocky point and small bay, of which mention need be made, are two 

 species of sea mussels, Mytilus edulis Linnaeus and Mytilus calif or- 

 nianus Conrad, the latter being of much larger size, when adult, and 

 possessing a rougher shell than the former. The larger species is 

 the more characteristic of the outer rocks where the waves are strong. 

 Although these two species are plentiful in the vicinity of Cape 

 Arago they are seldom used as food. 



Experimental investigations carried on in the Coos Bay region 

 included studies concerned with the determination of the spawnino; 

 seasons of certain clams and mussels inhabiting those waters. It 

 was believed that microscopic examination of the ovaries and sper- 

 maries of large numbers of individuals of a given species through 

 as many months or seasons of the year as possible would reveal the 

 limitations of the spawning period or periods of that species. Such 

 investigations in the Coos Bay locality comprised work upon Paphya 

 staminea^ Cardium corbis, and Mytilus edulis. As a result of these 

 observations it can be said with assurance that Pajyhya staminea 

 spawns in this region during .the late summer and early fall, or 

 during the months of August and September. No definite assertion 

 regarding the spawning of f'ardium corbis or Mytilus edulis could 

 be made after many examinations at North Bend during the periods 

 spent there in 1917 and 1918. 



THE SIUSLAW REGION. 



The Siuslaw River flows into the Pacific Ocean in western Lane 

 County, Oreg. It is a broad, expansive river for more than 10 miles 

 from its mouth and the influence of salt water is felt for about twice 

 that distance during high tides. About 4 miles from the mouth of 

 the river are the towns of Florence, on the north bank, and Glendale, 

 on the opposite side. The village of Acme is a few miles up the 

 river on the same side as Florence. Between these two towns, mostly 

 on the north side of the channel of the river, are some excellent beds 

 of Mya arenaria, the eastern mud clam. The writer has examined 

 beds of this species in many localities of the northwest but no finer 

 specimens of Mya have come to his Jiotice anywhere than those found 

 near Florence. The beds here occupy mud flats which are very acces- 

 sible from the shore and are uncovered during a moderately low tide. 



No other economic mollusk is associated with Mya arenaria here. 

 In this respect the Siuslaw River flats differ from others of this State. 

 Even SchizotJuierus nuttalli., the " great blue clam," common both to 

 the south and north of this region, has not gained a foothold here. 

 Mya arenaria was carried to the Siuslaw River from Coos Bay by 

 one David Morse more than 30 years ago and has done exceedingly 

 well in this locality. 



That food is sufficient for the mollusks may be indicated by the 

 large size which they may attain in this environment. The author 

 has measured numerous shells from these beds which were well over 

 6 inches in length. That the waters are well supplied with micro- 

 organisms which serve as food for the clams is shown by opening the 



