10 CALIFORNIA FISH AND GAME 



are taken by tlie elnb members, but no consistent effort is made to catch 

 them throughout the year. Contests sliould be held on IMission Bay, 

 not once a year but continually. The park board or possibly some 

 sportsmen's organization could publicize the contests and award prizes 

 for the largest bat ray and the largest round ray taken each month. 

 While trying to catch large ones, the anglers would destroy hundreds 

 of others and would learn what sport the bat ray affords Avlien taken 

 on rod and reel. 



Introduction of Xcw Species 



Any native species of plant or animal that could thrive in the bay 

 under present conditions Avould already be there in numbers. Non- 

 native species form an entirely different problem. An introduced 

 species may seem highly desirable in itself and yet crowd out or devour 

 many valuable native species and become a serious pest. For this 

 reason, new species should never be introduced until a thorough investi- 

 gation has been made to determine what harm they may do. 



Striped bass have been introduced into Mission Bay. These fish 

 may perish, they may migrate out of the bay, or they may grow up 

 and stay in the bay. They will not re]:)roduce and any striped bass 

 fishing will have to be kept up by continued planting. Striped bass 

 require fresh water for spawning and there is no suitable stream enter- 

 ing the bay. Tt is to be ho]ied that these fish will not markedly interfere 

 with native game fishes. 



The soft-shell clam (Mya arenaria) is an introduced species which 

 thrives in San Francisco and Tomales bays. It might do well in 

 ^Mission Bay if introduced there. It is equal to the native jack-knife 

 clam as bait and is superior as food. However, it might prove more 

 attractive to sting rays (which feed upon and destroy great quantities 

 of soft-shells in northern California bays) and less attractive to game 

 fishes. It might supplant the now abundant jack-knife clam almost 

 entirel}- and then prove to be useless to local game fishes. (It has 

 supplanted other si)ecies in San Francisco Bay.) We do not recom- 

 mend introducing this or any other species of shellfish into IMission 

 Bay without a fairly extensive investigation, and certainly not without 

 consulting F. W. Weymouth, Paul Bonnot, or II. C. ]\lcMillin, authori- 

 ties on shellfish. 



PHYSICAL IMPROVEMENTS IN MISSION BAY 



Flood Coiifrol Channel 



The largest proposed change of which we have heard is to make 

 a wide flood control channel to lead the San Diego River straight 

 out to the mouth of the bay. Several years ago the river was diverted 

 from the same route and forced to enter the bay east of Crown Point. 

 Since then, it has been showing tendencies to silt up the marshes and 

 fill in the bay. The new channel should be a great improvement. 



Breakwaters 



In connection with the flood control channel, it is proposed to run 

 one or two jetties into the ocean at the entrance of the bay. If this 

 is done, we recommend that fishing be permitted from the jetties, and 



