DALLEY and WINTERS: EARLY LIFE HISTORY OF SAND LANCE 



4). Winters (1970) gave mean vertebral counts of 

 approximately 73.8-73.9, mean dorsal fin ray 

 counts of 64.3-64.6, and mean anal fin ray counts 

 of 33.2-33.6 for A. dubius from the Newfoundland 

 Grand Banks. Comparable values for A. ameri- 

 conus from inshore areas of Newfoundland are 

 66.2-68.2, 55.7-57.8, and 27.8-30.6. We conclude, 

 therefore, that the larger larvae collected in For- 

 tune Bay in June 1979 belong to the offshore 

 form, A. dubius . 



The small larvae from February 1981 (lengths 

 6-12 mm) were examined for the presence of lat- 

 eral or pre-anal melanophores. Counts of other 

 melanophores (e.g., pectoral and subdorsal) were 

 not possible, due either to the early stage of devel- 

 opment of the larvae or to bleaching by the 

 preservative. According to Richards (1982), 

 counts of pre-anal melanophores can be used to 

 distinguish between the larvae of A. dubius and 

 A. americanus. From 6.0 to 8.9 mm in length, A. 

 americanus has 0-16 pre-anal melanophores, and 

 A. dubius has 10-21. Full or partial counts were 

 possible for 11 of the larvae. Ten were 6-7 mm in 

 length. Of these, two had 15 pre-anal melanophores, 

 four had 16, one had 17, one had 18, and two had 20. 

 One 9 mm laiva had 15 pre-anal melanophores. 

 According to Richards' ( 1982 ) criteria, four larvae 

 are definately A. dubius because the counts are 

 out of range for A. americanus. The other seven 

 are in the upper extreme of the overlap range for 

 the two species suggesting that these too are A. 

 dubius. Thus, not only do larger larvae of the 

 offshore species occupy Fortune Bay, but yolk-sac 

 larvae are also present. This suggests that spawn- 

 ing of the offshore species occurs within the bay. 



Because A. dubius is present on St. Pierre Bank 

 (Winters 1970), we have considered the possibil- 

 ity that the yolk-sac larvae collected from For- 

 tune Bay in February 1981 were transported from 

 St. Pierre Bank. Smigielski et al. (1984) gave 

 times for yolk-sac absorption from 5 to 14 days, 

 depending on temperature. Using minimum and 

 maximum speeds (0.05-0.20 ms M of the Labra- 

 dor Current along the south coast of Newfound- 

 land (Petrie and Anderson 1983), it would take 

 yolk-sac larvae 9-36 days to be carried from St. 

 Pierre Bank to inner stations in Fortune Bay 

 where they were collected. De Young ( 1983), how- 

 ever, described a seasonal cycle of water exchange 

 for Fortune Bay in which the flow of Labrador 

 Current water over St. Pierre sill (between 

 Miquelon and the tip of the Burin Peninsula 

 (Fig. 2)1 is minimal in winter months and pre- 

 dominates in the summer. Under normal current 



conditions, it appears unlikely that these yolk-sac 

 larvae were transported over St. Pierre Bank into 

 Fortune Bay with the Labrador Current during 

 the winter period. A persistent wind event from 

 the south could transport larvae in the surface 

 layers at a much faster rate than would the in- 

 shore branch of the Labrador Current. However, 

 the prevailing wind direction at St. Lawrence on 

 the southern part of the Burin Peninsula for Jan- 

 uary and February 1981 was from the west with 

 wind from the south only 17f of the time in Janu- 

 ary and 67f in February 1981 (Anonymous 1981). 

 A peak wind event from the SSE on February 9 

 did not persist into the next day when winds were 

 again from the west. We conclude, therefore, that 

 it is unlikely that the yolk-sac larvae found 

 within Fortune Bay in February 1981 were trans- 

 ported from St. Pierre Bank. More likely, these 

 larvae were spawned in Fortune Bay. Such 

 spawning is consistent with evidence from hydro- 

 graphic charts that indicate many areas of gravel 

 and sand mixtures in Fortune Bay. According to 

 Reay (1970), this is the preferred spawning sub- 

 strate for sand launce. 



Yolk-Sac Absorption 



Sixty-two percent of the larvae collected in 

 February 1981 contained yolk sacs. The mean 

 length of those in which the absorption of yolk-sac 

 (+ oil globule) was complete was 8.1 mm while 

 those with absorption incomplete had a mean 

 length of 7.4 mm. This is consistent with pub- 

 lished records. Smigielski et al. (1984) gave yolk- 

 sac absorption lengths of 7.2-7.41 for laboratory 

 reared A. americanus , and Richards (1965) found 

 that oil globule absorption was complete between 

 5 and 7.5 mm. 



DISCUSSION AND CONCLUSIONS 



The conclusion from the data collected during 

 the day-night investigations is that smaller yolk- 

 sac larvae in February and larger larvae in June 

 are more abundant or more available to the gear 

 at night. It is difficult to discern a particular pat- 

 tern of diurnal and vertical migratory behavior 

 for sand lance larvae from the literature because 

 documentation on the subject has not been consis- 

 tent. The observation that larger larvae in June 

 are more abundant at night is not unusual and 

 may be attributable to net avoidance (Norcross et 

 al. 1961; Richards and Kendall 1973; Potter and 

 Lough 1986). The observation that yolk-sac lar- 



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