Origin of Northern Juveniles 



The foregoing analysis of the origin composition of stocks of adult 

 weakfish is based on a scale character which is not formed until the end of 

 the juvenile summer. This provides no direct evidence of the actual origin 

 of the juvenile weakfish in each locality, for it is possible that extensive 

 migrations may occur in the period b etween spawning and the end of the juven- 

 ile summer. A number of facts bearing on this possibility are available, 

 but on the whole the evidence is so conflicting as to be inconclusive. The 

 information available is presented below. 



As shown by the following reports, eggs and/or larvae are present in 

 various localities: Beaufort, N. C, Hildebrand and Cable, 193h; entrance 

 to Chesapeake Bay, Pearson (I9UI) ; vicinity of Cape May, N. J., Welsh and 

 Breder, 1923s various localities from Bay Head, N. J., to Cape Henlopen, 

 Del,, Prof. A. E. Parr (unpublished manuscript). Eggs were also found hy 

 the writer in May, 1931, in Peconic Bay, L. I., N. I. Tracy, I908, reports 

 larvae from Wickford, R. I. 



There is, however, considerable uncertainty as to whether reproduction 

 is actually successful in all of the localities where eggs have been reported, 

 for with the exception of the few larvae fo\ind by Tracy in lobster-rearing 

 pools at Wickford, intensive search has not disclosed weakfish larvae north 

 of the entrance to Chesapeake Bay. This is in marked contrast to the obser- 

 vations of Hildebrand and Cable (193U) in t he vicinity of Beaufort and of 

 Pearson (19iil) in lower Chesapeake Bay, for the former report taking more 

 than 300 larvae less than 10 millimeters in length and the latter more than 

 li,000 less than 7 millimeters in length. 



The absence of larvae from Parr's extensive collections (Delaware Bay) 

 is particularly surprising in view of the remarkable concentrations of eggs 

 taken by him (up to 500,000 per 10 to 20 minute surface tow with a meter 

 net). The stations in lower Delaware Bay were occupied so frequently 

 (thrice weekly) and covered so great an area in each of several years that 

 there is no possibility that the tows happened to coincide with peaks of 

 discontinuous spawning and missed the periods when pelagic larvae were pre- 

 sent. It is also impossible to account for absence of larvae on the assump- 

 tion that the eggs drift away from the spawning localities so rapidly as to 

 pass beyond the limits of the area covered by the observations. For eggs 

 taken i n tow nets were observed to begin hatching within s even hours of the 

 time of capture when placed in finger bowls at temperatures mthin the range 

 of those observed in the waters where eggs were taken in abundance. Since 

 the areaobserved extends about 30 miles in each direction along the coast 

 from the center of egg concentration, it is obvious that the moderate drift 

 along the New Jersey coast (certainly not more than 10 miles per day) could 

 not possibly carry the eggs out of the area of observation before hatching. 



At times, considerable numbers of small medusae and of a Ctenophore 

 (Mnemeopsis) were observed, but not weakfish larvae were found in them. 



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