FISHERY BULLETIN; VOL. 85, NO. 3 



(93%) of 27 were taken in night sets: 16 at the 

 surface and 9 in obhque tows. Two were caught in 

 the oblique tows, and none, at the surface during 

 daylight. 



Size and Length-Frequency 

 Distributions 



Mean length data (Table 1) illustrate the an- 

 nual variation in mean size during the late June- 

 July period. In 1979, 1980, and 1982, the mean 

 lengths of sand lance were 22.9 mm, 18.3 mm, and 

 22.1 mm, repectively. The 34 larvae caught in 

 June 1981 were larger with a mean length of 38.4 

 mm, and the 5 caught in early July 1983 were 

 smaller with a mean length of 14.8 mm. 



Length-frequency distribution of the largest 

 samples from Fortune Bay are shown in Figure 3. 

 The distributions from June of each year indicate 

 a wide range of lengths, and although samples 

 from June of 1980 and 1981 are not large, the 

 extended range in both suggests that the distribu- 

 tion is not unimodal and that there is more than 

 one spawning cohort present. This extended 

 length range may also result from delayed hatch- 

 ing or a combination of both these processes. In 



June 1979 there is a distinct mode at 23 mm with 

 others probable at 14-15 mm and another at 29 

 mm. The length frequency of the June 1979 sam- 

 ple was subjected to modal analysis as described 

 by MacDonald and Pitcher (1979). Three modes 

 were interpreted from the length-frequency his- 

 togram. The results of the analysis indicated nor- 

 mal distributions with means at 13.4, 22.2, and 

 28.8 mm with standard deviations of 1.76, 3.02, 

 and 4.36 mm, respectively (Table 3). The June 

 1981 sample of 33 larvae has a distinct mode at 

 45 mm, which is widely separated from a group of 

 fish ranging in length from 12 to 17 mm. The wide 

 range and polymodality in the length distribu- 

 tions of the June samples is good evidence of mul- 

 tiple spawning cohorts although differential 

 hatching rates of the same cohort cannot be ruled 

 out (S. Richards^). Given that sand lance larvae 

 take 3-5 months (Reay 1970) to attain metamor- 

 phic sizes (30-40 mm, Macer 1966), the above ob- 

 servations suggest a spawning season extending 

 from December through to April. In addition, the 

 occurrence of larvae as small as 11 mm in July 

 and 8 mm in June 1980 (Table 1) suggests that 

 spawning may occur as late as May or June in 

 certain years. 



5 10 15 20 25 30 35 40 45 50 55 60 65 

 LENGTH (MILLIMETERS) 



Figure 3. — Length-frequency distributions from Fortune Bay 

 sand lance samples. 



Table 3. — Results of the MacDonald and Pitcher (1979) method of 

 analyzing length distribution mixtures of sand lance, June 1979, 

 assuming a mixture of three (spawning) components. Results as- 

 suming only one component are also shown. 



Percent of total Standard 



Compo- population in Mean length deviation 

 nent component (SE) (SE) (SE) 



13.4(0.77) 1.76(0.52) 

 22.2 (0.65) 3.02 (0.53) 



28.8 (9.2) 4.36 (3.46) 

 22.4 (0.27) 4.65 (0.19) 



This tendency for protracted length ranges is 

 also evident in the historical samples collected 

 around Newfoundland (Fig. 4). Samples are 

 small, but the two from Labrador range in length 

 from 22 to 55 mm with a break between the larger 

 and smaller groups. The 14 fish from Colliers 

 Bay, Conception Bay exhibit a protracted length 

 range from 28 to 65 mm. The two samples col- 

 lected off southern Newfoundland (Penguin Is- 



2Sarah W. Richards, Little Harbor Laboratory, Inc., 69 An- 

 drews Road, Guilford, CT 06437, pers. commun. October 1986. 



636 



