Rutherford and Houde: The influence of temperature on growth of Morone saxatilis 



327 



Potomac River 1987 



as 



■a 



2 

 o 

 H 



2 



2 



u 



as 



73 



a 



o 

 H 



April 



May 



Potomac River 1988 



a 



3 



o 



H 



3 

 e 

 (- 



18 24 30 6 12 18 24 30 

 April May 



Cohort Hatch Date 



Potomac River 1989 



Upper Bay 1989 



17 23 29 5 11 17 23 29 

 April May 



Cohort Hatch Date 



Figure 1 1 



Relative abundance of striped bass, Morone saxatilis, larval cohorts by hatch date, col- 

 lected in the 2m 2 Tucker trawl from the Potomac River, 1987-89, and Upper Bay, 1989: 

 (A) 4-5 June, 1987; (B) 2-3 June, 1988; (C) 8-9 June, 1989; (D) 14-15 June, 1989. 

 Relative abundance estimates were adjusted for age-specific survival differences among 

 cohorts. 



mortality rates of striped bass larvae allowed us to 

 examine the larval stage dynamics of a species that 

 develops over a broad temperature range. Past re- 

 search on survival and growth of striped bass larvae 

 has depended upon modal-length analyses, assumed 

 hatch dates, and assumptions about developmental 

 stages and stage-durations to make inferences about 

 early-life dynamics and recruitment potential 

 (Polgar, 1977; Dey, 1981; Uphoff, 1989; Low 3 ). Our 

 otolith microstructure analysis demonstrated that in 

 1987-89, only a few cohorts contributed significantly 

 to Potomac River and Upper Bay recruitments and that 

 successful cohorts were hatched late in the season, grew 

 relatively fast, and had short larval-stage durations. 



The critical role of temperature, particularly its 

 potential to cause episodic mortalities and its effect 

 on growth, has been identified in previous research 

 on striped bass. For example, Dey (1981) and 

 Kernehan et al. (1981) argued that year-class fail- 



ures in the Hudson River and Upper Chesapeake Bay, 

 respectively, were caused by low-temperature events. 

 Positive relationships between mean growth rates 

 of larval striped bass year classes and temperatures 

 have been reported for the Potomac River (Setzler- 

 Hamilton et al., 1980; Martin and Setzler-Hamilton 7 ), 

 the Choptank River (Uphoff, 1989), the Hudson River 

 (Dey, 1981), and the Sacramento-San Joaquin Riv- 

 ers (Low 3 ). 



In our study, it was clear that estimated produc- 

 tions of cohorts at 8 mm SL were positively corre- 

 lated with cohort-specific growth rates. Growth rates, 

 in turn, were strongly and positively correlated with 



Martin, F. D., and E. M. Setzler-Hamilton. 1983. Assessment of 

 larval striped bass stock in the Potomac estuary. Final report 

 to U.S. National Marine Fisheries Service. Ref. No. 

 [UMCEES1CBL83-55, 37 p. Available: University of Maryland 

 Center for Environmental and Estuarine Studies, Chesapeake 

 Biological Laboratory, 1 Williams St., Solomons, MD 20688. 



