RICHARDSON and JOSEPH: LARVAE AND YOUNG OF BOTHIDS 



the year. Insufficient information is available to 

 determine whether north-south or inshore- 

 offshore movements occur, seasonal or other- 

 wise. 



Areal distribution of larvae, based on VIMS 

 collections, is not as clearly defined. While most 

 E. microstomus larvae were collected at stations 

 inside the 37-m (20-fm) isobath, some were 

 found out as far as the 183-m (100-fm) line. 

 Most C. arctifrons larvae were taken outside 

 the 37-m curve, but some were found near the 

 18-m (10-fm) line. Many samples contained 

 larvae of both species. A greater number of 

 C. arctifrons larvae were taken during 1962 

 when the sampling program was expanded to 

 cover a greater offshore range. 



Depths at which larvae occur in the water 

 column may be a specific character (Simpson, 

 1956 Ahlstrom, 1960 Rae, 1965). Data from 

 VIMS collections indicated that E. microstomus 

 larvae were more common in the upper layers 

 (0-12 m) while C. arctifrons larvae were more 

 abundant in tows made at 12-18 m. Data from 

 the Norfolk Canyon Collections (refer to section 

 on Materials and Methods) showed E. micro- 

 stomus larvae most abundant in the net towed 

 at 2 m and C. arctifrons larvae most numerous 

 in the net towed at 50 m. Additional sampling 

 is needed to give accurate profiles of depth 

 distribution for the two species. 



The spawning peak for both species ranges 

 from July through October, but spawning may 

 occur sporadically through much of the year. 

 Larvae have been taken as early as May and as 

 late as December. Examination of ovaries of 

 adults supports these conclusions. 



ABUNDANCE AND ECONOMIC 

 IMPORTANCE 



Adults of E. microstomus and C. arctifrons 

 are relatively numerous in the Chesapeake 

 Bight. Seasonal records (Table 2) indicate that 

 these two species together constituted about 

 half of all flatfishes collected by VIMS in the 

 spring and summer of 1966. Comparison of 

 numerical catches of E. microstomus and C. 

 arctifrons (Table 2) and the major commer- 

 cially important flatfish species in the bight 



(Paralichthys dentatus and Pseudopleuronectes 

 america)ius) is noteworthy. 



Larvae of E. microstomus and C. arctifrons 

 were the most numerous of all flatfish species 

 taken in VIMS plankton collections. Ahlstrom 

 (1965) reported larvae of Citharichthys spp. 

 (as a group) were similarly the most abundant 

 of all flatfishes taken in the California Current 

 System from 1955 to 1958. He stated, "Larvae 

 of . . . sanddabs (Citharichthys spp.) are . . . 

 [species] that represent present or potential 

 commercial resources." 



Despite the relative abundance of E. micro- 

 stomus and C. arctifrons in the Chesapeake 

 Bight, the two species alone do not represent 

 sufficient biomass to make exploitation econo- 

 mically feasible. Lengths probably rarely ex- 

 ceed those given by Parr (1931) of 120 mm 

 for E. microstomus and 150 mm for C. arcti- 

 frons. However, they could become part of the 

 catch of miscellaneous trash fishes used for 

 reduction into fish meal as has E. rimosus 

 (Beaumariage, 1968), a species very similar 

 to E. microstomus. 



TAXONOMIC PROBLEMS 



Original descriptions of the genera Etropus 

 (Jordan and Gilbert, 1882) and Citharichthys 

 (Bleeker, 1862) offer few characters to sep- 

 arate the two. The major difference between 

 Etropus and Citharichthys, according to the 

 original descriptions, is dentition. In Etropus 

 "the teeth . . . [are] mostly on the blind side" 

 while in Citharichthys the teeth on the eyed 

 and blind sides of both jaws are well developed. 

 Jordan and Evermann (1898) pointed out that 

 "... this genus [Etropus] is very close to 

 Citharichthys, from which it differs only in the 

 very small size of the mouth, and in the corre- 

 spondingly weak dentition." 



The separation of 10 western Atlantic 

 species of Etropus and Citharichtltys into two 

 genera has been disputed by Parr (1931). He 

 claimed that length of the maxillary did not 

 adequately segregate the species that he con- 

 sidered into two groups. He placed them all in 

 the genus Citharichthys, apparently disregard- 

 ing the dentition. Norman (1934) retained the 

 separation of Etropus and Citharichthys in his 



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