NEVES and DESPRES OCEANIC MIGRATION OF AMERICAN SHAD 



f- il 



NOVEMBER 



DECEMBER 



Figure 9. — Mean monthly bottom temperatures dunng winter and spring along the eastern U.S. coast. Cape Cod. Mass.. to Florida. 



(From Walford and Wicklund 1968.) 



would be shad returning to natal rivers farther 

 south. Inshore temperatures are unstratified 

 along the Atlantic coast during the winter (Parr 

 1933). Since freshwater discharge generally oc- 

 curs along the surface from estuaries, water tem- 

 peratures would not preclude near-surface move- 

 ments of shad to detect essential olfactory and 



rheotaxic cues for successful homing (Dodson and 

 Leggett 1974). 



Estuarine temperatures from initial to peak ar- 

 rival of shad at home rivers along the Atlantic 

 coast are between 3° and 15°C (Talbot 1954; 

 Massmann and Pacheco 1957; Walburg and 

 Nichols 1967; Leggett 1972; Leggett and Whitney 



209 



