340 



Abstract.— Age structure, longevity, 

 and mortality were determined for a 

 population of blackcheek tonguefish, 

 Symphurus plagiusa. in Chesapeake 

 Bay. Blackcheek tonguefish (36-202 

 mm TL) were randomly collected by 

 means of otter trawl in lower Chesa- 

 peake Bay and major Virginia tributar- 

 ies (James. York, and Rappahannock 

 rivers) from April 1994 through August 

 1995. Ages were determined by inter- 

 preting growth increments on thin 

 transverse sections of sagittal otoliths. 

 Marginal increment analysis showed 

 that a single annulus was formed in 

 June of each year. Blackcheek tongue- 

 fish caught during this study reached 

 a maximum age of 5-i- years. Growth 

 was rapid during the first year, then 

 slowed rapidly at a time coincident with 

 maturation. We used the following von 

 Bertalanffv growth equations: for 

 males— L, = 196.5(1 -e-«^«5(, + 0.92.). anj 



for females— L, = 190.6(1 -e-^^^"" *'"*"). 

 Von Bertalanffy parameters were not 

 significantly different between sexes. 

 Extrapolated instantaneous mortality 

 rates for a possible seventh year class 

 were 0.73 ( Hoenig's equation i and 0.77 

 (Royce's equation I. High estimates of 

 instantaneous total mortality may re- 

 flect either loss due to emigration of 

 adults from Chesapeake Bay onto the 

 continental shelf or high natural mor- 

 tality occurring in this northernmost 

 population. Compared with sympatric 

 pleuronectiforms, blackcheek tongue- 

 fish have a relatively high mortality 

 rate, small asymptotic length, and high 

 growth parameter A'. Species, such as 

 blackcheek tonguefish. that feature this 

 combination of growth parameters are 

 hypothesized to be better adapted at 

 exploiting seasonally dynamic and 

 highly unpredictable environments, 

 such as those estuarine habitats within 

 Chesapeake Bay. 



Age, growth, longevity, and mortality of 

 blackcheek tonguefish, Symphurus plagiusa 

 (Cynoglossidae: Pleuronectiformes), 

 in Chesapeake Bay, Virginia* 



Mark R. Terwilliger 



School of Marine Science, Virginia Institute of Marine Science 

 College of William and Mary 

 Gloucester Point, Virginia 23062 

 Present address: 104 Nash Hall 



Department of Fisheries and Wildlife 



Oregon State University 



Corvallis, Oregon 97331 

 E-mail address terwillm d ucs orst edu 



Thomas A. Munroe 



National Marine Fisheries Service National Systematics Laboratory, MRC 153 

 National Museum of Natural History 

 Washington, DC. 20560 



Manuscript accepted 15 June 1998, 

 Fish. Bull. 97:340-.361 (1999). 



The blackcheek tonguefish, Sym- 

 phurus plagiusa (Linnaeus, 1766), 

 ranges from Connecticut southward 

 through the Florida Keys, northern 

 Gulf of Mexico, Cuba, and the Ba- 

 hamas (Ginsburg, 1951; Topp and 

 Hoff, 1972; Munroe, 1998). Chesa- 

 peake Bay is the northernmost lo- 

 cation of a major population of this 

 species (Munroe, 1998). South of 

 Chesapeake Bay, blackcheek tongue- 

 fishes are an abundant component of 

 the fish fauna occurring in estuaries 

 and inshore coastal waters. Within 

 this region, they occur in sufficient 

 numbers to form a minor component 

 of the bycatch of demersal fisheries 

 and also constitute a minor inclu- 

 sion in landings reported for several 

 industrial fisheries. In the shrimp 

 trawl fishery, they are a potential 

 nuisance because individuals fre- 

 quently become embedded in the 

 webbing of trawls to such an extent 

 that they interfere with the gear's 

 effectiveness (Topp and Hoff 1972). 

 The blackcheek tonguefish is the 

 only member of the pleuronectiform 

 family Cynoglossidae occurring in 

 Chesapeake Bay (Ginsburg, 1951; 

 Murdy et al., 1997; Munroe, 1998), 



This species is among the top three 

 most abundant pleuronectiforms 

 occurring throughout lower Chesa- 

 peake Bay and its tributaries 

 (Bonzek et al., 1993; Geer et al,, 

 1997 ). Only the hogchoker, Trinectes 

 maculatus, is commonly taken in 

 greater abundance in bottom trawls 

 made within the Bay. Occurrence of 

 all life history stages in Chesapeake 

 Bay (Olney and Grant, 1976; Ter- 

 williger, 1996) suggests that black- 

 cheek tonguefish is a resident spe- 

 cies in this system. 



Despite its abundance in differ- 

 ent estuarine and nearshore marine 

 habitats in the northwest Atlantic, 

 life history parameters of S. pla- 

 giusa are largely unknown. Some 

 previous works have described dis- 

 tribution, relative abundances and 

 length frequencies for blackcheek 

 tonguefish in South Carolina estu- 

 aries (Shealy et al., 1974); some 

 have summarized size-related ma- 

 turity patterns for individuals from 

 throughout the entire range of the 

 species (Munroe, 1998); some have 



' Contribution 2203 of the Virginia Institute 

 of Marine Science, College of William and 

 Marv Gloucester Point. VA 23062. 



