Bolles and Begg: Distinction between silver hake stocl<5 in US waters 



457 



using otolith morphometries, coupled with discriminant 

 function analysis, when analyzed with respect to fish age. 

 enabled us to distinguish between a northern stock (from 

 the Gulf of Maine to northern Georges Bank) and a south- 

 ern stock (from southern Georges Bank to the Middle 

 Atlantic), thus providing a more efficient and accurate 

 method for discriminating between silver hake stocks than 

 had been used previously. 



Typically, silver hake of the northern stock grew at a 

 slower rate, and had larger otoliths than fish of the south- 

 ern stock. Otoliths of silver hake from the northern stock 

 tended to be longer, wider, and greater in area and perime- 

 ter than similar-size fish from the southern stock because. 



for any given fish length, northern stock fish were older 

 and therefore had more time to accumulate otolith mate- 

 rial than had southern stock fish. These results were con- 

 sistent with previous growth studies where slower growing 

 fish generally had larger otoliths than those of similar- 

 size, faster growing fish (Templeman and Squires. 1956; 

 Reznick et al., 1989; Fowler and Short. 1996). 



Likewise, Helser ( 1996) found that silver hake from the 

 northern stock grew at slower rates than those fish of 

 the southern stock, and like Nichy ( 1969). Almeida ( 1978) 

 and Pentilla et al. (1989) found that the northern stock 

 reached larger asymptotic lengths. However, Helser ( 1996) 

 also found results that did not support the current stock 



