(d) Observed kill vs. species of fish 



Heaviest total mortality, and heaviest mortality from any individual 

 explosion, expressed in numbers of dead fish observed or collected at the sur- 

 face occurred in the menhaden ( Brevoortia t3rrannus) , a fish of no food value, 

 used only for crab bait and m the manufacture of fish meal, oil and fertilizer. 



Other species killed, listed m descending order of abundance in the 

 observations, were river herring ( Pomolobus pseudoharengus and P. aestivalis) , 

 white perch ( Morone americana ), anchovies ( Anchoviella mitchilli ), striped 

 bass ( Roccus saxatalis ), gray sea trout (Cynoscion regalis) , spot ( Leiostomus 

 xanthurus) , and croaker ( Micropogon undulatus ) . All of these, with the 

 exception of the anchovy, are marketable species of value to the commercial 

 fisherman and to the jSportsman. 



Heaviest mortalities occurred rather consistently in those species wMch 

 topically live and feed at or near the surface, or which mfeve frequently into 

 the middle or upper layers of water . Menhaden, river herring, and anchovies 

 are planktonic feeders, and find their food only at or near the surface. STiped 

 bass and trout are predatory, feeding sometimes on the bottom, but foraging 

 frequently at the surface among schools of small menhaden or anchovies. Wliite 

 perch are of generally similar feeding habits, feeding much of the time on tJie 

 bottom but moving frequently into the middle or upper layers of water. 



Cioakers and spot are strictly bottom species, dependent for their food 

 on worms, shellfish, small crabs, and other marine fauna, and although 

 they may move into shallow water during the summer months , rarely come to 

 the surface. 



(e) Seasonal aspects of fish mortality 



In order that the data be grouped i;o deirionstrate most closely 

 any possible relation to the seasons, the year was divided into four 3 -month 

 periods: winter (Dec, Jan., Feb.); spring (March, April, May); summer 

 (June, July, August); fall (Sept., Oct., Nov.). 



Heaviest mortality was observed during the spring period, .followed in 

 descending order by winter, fall, and summer (table 6). 



15 



