Ecology ;^ ' , 



In many areas ^. ucayalemis is seasonally abundant and frequently utilized as 

 a food source, largely as a bycatch of fishing efforts for other species. 



Smith (1981) reported the presence of ^. ucayalemis in schools of mixed 

 species that migrate upstream annually in main channels of the Amazon river. 

 These migrations, known locally as piracemas, are dominated by jaraqui 

 (Semaprochilodus insignis and S. taeniurus), but include many other species (up to 41 

 according to Smith 1981). The piracemas begin in June when water levels begin to 

 drop, and continue through early October. Ageneiosus ucayalemis is most abundant 

 in piracemas at Itacoatiara during June and July. 



At Tucurui on the Rio Tocantins, Brazil, the peak abundance oiA. 

 ucayalemis during migration occurs from November to January, and the species was 

 reported to comprise about 20% of the catch during that period (Santos et al. 1984). 

 These authors speculated that, prior to the impoundment of a large reservoir in that 

 area,^. ucayalemis migrated further upstream to spawn. 



In the Orinoco basin, Novoa (1982) provided cursory notes on the ecology; 

 however, it is unclear if his observations applied exclusively to ucayalemis, inasmuch 

 as a figure accompanying his account was mislabelled 2&A. brevifilis, and the 

 maximum length reported for ucayalemis (54 cm TL) is considerably greater than 

 any of the material examined in this study. Novoa and Ramos (1978) had earlier 

 identified brevifilis as Ageneiosus sp., so I assume that the account by Novoa (1982) 

 was indeed based on^. ucayalemis. Fish remains were identified as the principal 

 dietary items. Individuals in reproductive condition were found in the middle 

 Orinoco in July. The species was not considered by Novoa (1982) to be of 

 significant commercial importance. ,,„. 



