FISHERY BULLETIN: VOL. 77, NO. 1 



A. dubiiis in the Canadian northwest Atlantic. 

 Again, copepods, especially Calanus finmar- 

 chicus, were the most important prey. Other prey 

 included crustacean larvae, invertebrate eggs, 

 polychaete larvae, larvaceans, fish eggs, 

 pteropods, and barnacle cyprids. Comparison with 

 plankton tows made at the time the fish were 

 caught showed that A. dubttis had a definite pre- 

 ference for the larger zooplankton such as 

 copepods. From the data in Table 2, it is clear that 

 the diet of A. americaniis from Stellwagen Bank is 

 typical for this family of fishes. There are, how- 

 ever, several small differences from other pub- 

 lished results which are worth noting. For exam- 

 ple, chaetognaths occurred rarely in the stomachs 

 (2.2*^ ) but on a weight basis were only slightly less 

 important than copepods. It would appear that 

 chaetognaths are readily consumed if available. 

 One notable exception to the list of prey is phyto- 

 plankton. Both Richards (1963) and Scott (1973), 

 as well asSenta ( 1965) and Macer ( 1965), reported 

 finding diatoms or dinoflagellates in the guts of 

 the fish they examined. In our study, no phyto- 

 plankton was observed as part of the stomach con- 

 tents. It is possible that at certain times of the year 

 the occurrence of phytoplankton would be much 

 more apparent in the guts, as might also be ex- 

 pected for other prey such as crustacean larvae, 

 barnacle cyprids. and larval polychaetes. 



SUMMARY 



1. The meristic counts of sand lance reported 

 are in agreement with published data and fall into 

 the category of Ammodytes americaniis, the 

 American sand lance. 



2. Data on the relative abundance of sand lance 

 from Northeast Fisheries Center spring and fall 

 bottom trawl survey cruises indicate that there 

 has been a substantial increase in sand lance 

 abundance on Stellwagen Bank over the last 10 yr. 

 This trend was also reflected by an increase in the 

 numbers of sand lance larvae occurring in the 

 spring ichthyoplankton results measured in the 

 Gulf of Maine over the last 4 yr. This increasing 

 trend in larval and adult sand lance abundance in 

 the Gulf of Maine was typical of the northwest 

 Atlantic from Cape Hatteras northward. 



3. Sand lance encountered within the Province- 

 town slope area ranged from 12 to 17 cm long 

 (mean = 15 cm), and school strength numbered 

 from about 100 to several thousand individuals. In 

 contrast, individuals on Stellwagen Bank ranged 



from 7.4 to 24.0 cm FL (mean = 18.2 cm), while 

 school strengths ranged from about 500 to tens of 

 thousands of individuals. 



4. School shapes were constant in appearance, 

 vertically compressed, tightly compacted, and 

 bluntly linear from a dorsal and ventral view. 

 Provincetown slope schools were 1-5 m wide, 0.5- 

 1.5 m high, and 3-20 m long depending on school 

 strengths. The nearest- neighbor distance between 

 fish swimming in an undisturbed school was ap- 

 proximately V2-% BL; between fish swimming in a 

 school exhibiting a fright or avoidance reaction, 'a 

 BL; and between fish swimming in a school en- 

 gaged in feeding, approximately 1-1 '/2 BL. 



5. The swimming motion of sand lance is 

 sinusoidal in form and eellike in appearance. 

 Schools swimming undisturbed and not engaged 

 in feeding maintain an estimated swimming speed 

 of 30-50 cm/s; during feeding they maintain an 

 estimated speed of 15-25 cm/s; and during avoid- 

 ance maneuvers, 70-120 cm/s. Feeding schools 

 were observed in midwater and near the surface, 

 but not on the bottom. 



6. Sand lance were found to prefer clean sandy 

 substrates conducive to burrowing. Sand lance 

 usually disappear into the substrate in small 

 groups, initially penetrating at an angle of 60°-75° 

 from the horizontal, and continuing their sinuous 

 movement until one-quarter of the body is buried. 

 at which point the remaining three-quarters of the 

 body is brought to a 20°-40° angle to allow the 

 animal to settle into its resting position. Sand 

 lance encountered on Stellwagen Bank were occa- 

 sionally observed to partially emerge from the 

 substrate headfirst and retract back into the bot- 

 tom if approached. In contrast, sand lance along 

 Provincetown slope would exit from the bottom 

 when approached. Sand lance leaving the bottom 

 exited at an angle of between 20° and 60° with an 

 initial speed of 50-80 cm/s and built their speed up 

 to 120 cm/s within the first 1.5 m from the bottom. 

 Individual fish exiting would show schooling be- 

 havior if another fish was exiting at the same time. 



7. Copepods were the most important prey of A. 

 americanus, occurring in 38'7f of the stomachs 

 examined and making up 4Vi of the total weight 

 of prey consumed. 



ACKNOWLEDGMENTS 



The authors gratefully acknowledge the assis- 

 tance of the National Marine Fisheries Service, 

 Woods Hole, Survey Unit for bottom trawl survey 



252 



