348 



Fishery Bulletin 97(2), 1999 



Instantaneous total mortality (Z) estimates ob- 

 tained for a maximum age of 5 years were 0.87 

 (^=587^) with Hoenig's (1983) method, and 0.92 

 (A^eO'/f ) with Royce's (1972) method. A plot of age 

 composition of the catch (Fig. 10) indicates rapidly 

 declining numbers of fishes aged 4 and 5. 



Discussion 



Most of what we know regarding growth in cyno- 

 glossid flatfishes stems from information gathered 

 from studies conducted on species of Cynoglossus. 

 These are tonguefishes usually much larger in size 

 than species of Symphurus (Menon, 1977), and spe- 

 cies which also occur predominantly in the shallow 

 tropical seas of the Indo-West Pacific. Therefore, the 

 present study detailing information on age, growth, 

 and longevity for blackcheek tonguefish is significant 

 in being the first of its kind reporting such life his- 

 tory parameters for a member of Symphu/'us. Fur- 

 thermore, of the approximately 150 species of 

 Cynoglossidae, S. plagiusa is unique in that it is the 

 only member of the family inhabiting temperate es- 



tuarine environments in the seasonally dynamic 

 Chesapeake Bay region of the western North Atlan- 

 tic. In fact, the tonguefishes inhabiting Chesapeake 

 Bay are the northernmost major population of this 

 species (Munroe, 1998). Here, the species has ranked 

 as high as sixth in overall abundance, and in some 

 years is the second most abundant pieuronectiform 

 among fishes taken during trawling in lower Chesa- 

 peake Bay and its tributaries (Geer et al., 1993). 

 North of the Chesapeake Bay region, adult black- 

 cheek tonguefish are relatively rare (Munroe, 1998), 

 even in such proximate estuaries as Delaware Bay. 

 Just how long the Chesapeake Bay has supported a 

 significant population of this species is unknown 

 because earlier compilations on fishes of the region 

 (Hildebrand and Schroeder. 1928) regarded this spe- 

 cies as occurring only rarely within the Bay. It is con- 

 ceivable that because of its relatively small size and 

 benthic habits, the abundance of this species may 

 have been grossly underestimated during previous 

 fish surveys conducted in this region. However, given 

 the general rarity of this species in areas immedi- 

 ately to the north, and the observed incidences of 

 winter mortalities within Chesapeake Bay (see be- 



