688 



Fishery Bulletin 93(4). 1995 



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Length (cm) 



Figure 1 1 



Monthly length-frequency distribution for windowpane, 

 Scophthalmus aquosus, collected during an inshore trawl 

 survey off the coast of New Jersey, 1988-92. See Table 1 

 for additional details. 



(Fig. 10). In subarea 4 off New Jersey, where spawn- 

 ing was shown to be bimodal, the earliest peak was 

 in May and the second was in October-November 

 (Fig. 4; Table 2). However, there is no evidence of 

 large numbers of small juveniles in the spring or fall 

 in the NMFS survey (Fig. 10) or in the monthly 

 catches of the New Jersey trawl surveys (Fig. 11). 

 Conversely, in the vicinity of Little Egg Inlet, New 

 Jersey, the appearance of eggs and larvae in both 

 the estuary and in nearshore ocean waters corre- 

 sponds well with two spawning periods (Fig. 7). Evi- 

 dence of spring-spawned fish is first indicated by 

 small numbers at 4 cm TL in June (Fig. 12). By July, 

 these fish are 3-8 cm TL and in August they are 4- 

 11 cm TL. In September, catches of small fish de- 

 creased, and fish lengths ranged from 8 to 17 cm TL. 

 Catches of these spring-spawned fish further de- 

 creased by October, when very few juveniles were 

 captured. This same cohort first appeared in 



nearshore surveys off New Jersey in August and by 

 September the fish were 11-19 cm TL (Fig. 11). By 

 October they cannot be easily differentiated from 

 older fish on the basis of length, but some of these 

 fish were probably captured in the fall collections by 

 NMFS surveys on the continental shelf (Fig. 10). 

 They do not appear to be abundant in estuary or 

 ocean collections until the following April-May when 

 most are >16 cm TL (Fig. 12). 



Fall-spawned larvae were first collected in Septem- 

 ber in subarea 4 at lengths of 2-4 mm (Fig. 4; Table 

 2). The peak abundance was in October and Novem- 

 ber when they were 2-10 mm. These fish first ap- 

 peared as settled juveniles in the vicinity of Little 

 Egg Inlet in November at 3-4 cm TL, and by Decem- 

 ber they were 4-7 cm TL (Fig. 12). Fall-spawned ju- 

 veniles were not evident in the nearshore (Fig. 10) 

 or in deep-water surveys (Fig. 12). During January- 

 March, fish 4-8 cm TL were abundant in the ocean 

 catches and may not have grown much during these 

 cold-water months (Fig. 12). From March to May, 

 small juveniles moved gradually into the bay and 

 began to grow again. A clear separation between the 

 fall-spawned fish (5-12 cm TL) and the spring- 

 spawned fish (>16 cm TL) can be seen in May (Fig. 

 12 ). The fall-spawned fish continued to grow and were 

 18-26 cm TL by October when they were about 1 

 year old. They may not have grown during the late 

 fall and winter, given the similarities in length fre- 

 quencies from October to December. These fish left 

 the bay beginning in June, and by October few fall- 

 spawned fish were present in the bay. The evidence for 

 the existence of spring- and fall-spawned cohorts is most 

 evident in July and August in New Jersey where both 

 are represented by the two dominant length-frequency 

 modes in both the bay and the adjacent ocean (Fig. 12). 



Discussion 



Distribution and abundance 



Windowpane is a resident of the Middle Atlantic 

 Bight and Georges Bank, although it does show some 

 small-scale seasonal inshore-offshore movement. 

 Evidence from ocean trawl surveys throughout the 

 study area showed little difference in the preference 

 of juveniles for relatively shallow waters from spring 

 and fall depth distributions (Table 4). Evidence from 

 tagging experiments in Long Island Sound (Moore, 

 1947 ) indicates that windowpane do not undertake ex- 

 tensive migrations in response to either seasonal 

 temperature changes or for purposes of spawning. How- 

 ever, research trawl surveys show some evidence of an 

 offshore movement during winter in response to low 



