ADStraCt. — The windowpane, 

 Scophthalmus aquosus, is a shallow 

 water (<110 m), resident species of the 

 Middle Atlantic Bight (and adjacent 

 estuaries) and Georges Bank, although 

 it may undergo short (both inshore-off- 

 shore and alongshore) migrations in 

 response to seasonal temperature 

 changes. Spawning occurred through- 

 out the Middle Atlantic Bight during 

 the period from 1977 to 1987 but was 

 most pronounced on Georges Bank. The 

 timing of spawning, determined from 

 the collection of 2-4 mm larvae, varied 

 with location; and a split spawning sea- 

 son (April-May and October-Novem- 

 ber) was evident in the Middle Atlan- 

 tic Bight. Spawning on Georges Bank 

 peaked in August. Although spawning 

 occurred over a broad temperature 

 range (5-23°C), the optimal tempera- 

 ture was 16-19°C in the Middle Atlan- 

 tic Bight and 13-16°C on Georges Bank. 

 Larval development occurred in areas 

 of spawning and was most prolonged 

 on Georges Bank, where the largest 

 larvae (13-20 mm) were consistently 

 found. Few larvae >8 mm were cap- 

 tured in the Middle Atlantic Bight. On 

 the basis of samples from southern New 

 Jersey, settlement probably occurs on 

 the continental shelf and in adjacent 

 estuaries of the Middle Atlantic Bight. 

 The growth patterns of young of the 

 year varied with the timing of spawn- 

 ing and subsequent settlement. In the 

 first six months, fish of the spring- 

 spawned cohort grew to 11-19 cm TL 

 whereas those of the fall-spawned co- 

 hort grew to just 4-8 cm TL within that 

 time. These data contribute to our un- 

 derstanding of the distribution and 

 early life history of windowpane on the 

 continental shelf, though the role of es- 

 tuaries in the Middle Atlantic Bight is 

 incompletely known. 



Distribution and life history 



of windowpane, 



Scophthalmus aquosus, 



off the northeastern United States 



Wallace W. Morse 



James J. Howard Laboratory 



National Marine Fisheries Service, NOAA 



Highlands, New Jersey 07732 



Kenneth W. Able 



Marine Field Station, Institute of Marine and Coastal Sciences 

 Rutgers University, 800 Great Bay Blvd. 

 Tuckerton, New Jersey 08087 



Manuscript accepted 24 April 1995. 

 Fishery Bulletin 93:675-693 ( 1995). 



675 



The windowpane, Scophthalmus 

 aquosus, is an endemic bothid of the 

 northwest Atlantic Ocean and is 

 distributed from the Gulf of Saint 

 Lawrence (47°N) to Florida (27°N) 

 (Scott and Scott, 1988) but is most 

 abundant from Georges Bank (42°N) 

 to Chesapeake Bay (38°N) (Bigelow 

 and Schroeder, 1953; Dery and 

 Livingstone, 1982). Windowpane 

 are distributed in shallow waters 

 (<110 m, mostly <56 m) (Wenner 

 and Sedberry, 1989; Thorpe, 1991). 

 Their distribution extends shore- 

 ward to depths of 1-2 m ( Warfel and 

 Merriman, 1944) and they are of- 

 ten abundant in large estuaries 

 such as Chesapeake Bay (Hilde- 

 brand and Schroeder, 1928), Dela- 

 ware Bay (de Sylva et al., 1962), 

 Sandy Hook Bay (Wilk and Silver- 

 man, 1976), Long Island Sound 

 (Moore, 1947), and Narragansett 

 Bay (Oviatt and Nixon, 1973; Jeffries 

 and Johnson, 1973). Distribution 

 patterns of juveniles and adults on 

 the continental shelf between Nova 

 Scotia and Cape Hatteras, North 

 Carolina, are similar and indicate 

 limited seasonal movement (Dery 

 and Livingstone, 1982; Azarovitz 

 and Grosslein, 1987; Thorpe, 1991). 

 However, tagging experiments 

 showed that some adults traveled 



about 150 km along the coast in 

 three months (Moore, 1947). Juve- 

 niles (<24 cm total length [TL]) in 

 the Georges Bank area were concen- 

 trated along the southern boundary 

 of the bank and inshore along Long 

 Island during spring (mean depth 

 26.6 m) and on the central portion 

 of the bank in fall (mean depth 38.3 

 m) (Wigley and Gabriel, 1991). Re- 

 cent estimates of length at sexual 

 maturity show that 50% were ma- 

 ture between 21 and 23 cm TL 

 (O'Brien etal., 1993). 



Windowpane are currently ex- 

 ploited for human consumption, pri- 

 marily in the Georges Bank area. 

 Annual commercial landings from 

 1975 through 1988 averaged 2.03 

 million kg and peaked in 1985 at 

 4.21 million kg (ICNAF, 1977-85; 

 NAFO, 1982-91). Relative abun- 

 dance indices estimated from Na- 

 tional Marine Fisheries Service 

 (NMFS) research trawl surveys 

 (Azarovitz, 1981) for 1964-89 show 

 considerable year-to-year fluctua- 

 tions in both numbers and biomass 

 (Thorpe, 1991). Peaks in biomass 

 appear to have occurred on Georges 

 Bank during the mid-to-late-1970's 

 and again in the mid-1980's. 



Gonadal development (Wilk et al., 

 1990) and egg and larval distribu- 



