18 
BULLETIN OF THE BUREAU OF FISHERIES 
water) are the dominant factor, and it occasionally happens that they practically 
monopolize the water locally. Such, for instance, was the case in the Eastern Basin 
on August 13, 1914 (station 10249), when the net from 50 meters captured only 3 
or 4 Sagittae, 2 pteropods (Limacina), 3 or 4 larval rosefish (Sebastes), a few small 
medusae (Phialidium) , 51 euphausiid shrimps, and an odd Euchaeta, among millions 
of Calanus (3 to 4 liters, by measure; no other copepods were detected in sample 
examined by Doctor Esterly). Near Mount Desert Rock, too, on the same day 
(station 10248), a cursory examination of about 3 quarts of copepods, among which 
Calanus, Metridia, and Euchaeta were represented in the proportion of about 30, 
5, and 2, revealed only a few Pseudocalanus, 21 TJiysanoessa longicaudata, odd 
amphipods (Euthemisto) , 24 Meganyctiphanes, 7 Thysancessa inermis, 6 or 8 ptero- 
pods (Limacina), 1 worm (Tomopteris), a few Sagittae, 1 Pleurobrachia, and frag- 
ments of the ctenophore Beroe. 
Similarly, the only other animals detected in a preliminary examination of the 
2 to 3 quarts of copepods 5 captured in the 60-0 meter haul on the eastern part of 
Georges Bank, on July 23 of that same year (station 10224), were 89 euphausiid 
shrimps ( Thysancessa inermis), a few amphipods (Euthemisto), half a dozen young 
fish, and one caprellid, the latter being an accidental straggler from the bottom. 
The most notable shoal of Calanus we have encountered was off Cape Cod on 
July 22, 1916 (station 10344), where a 15-minute haul with a net 1 meter in diameter 
captured 6 quarts at 40-0 meters, together with many thousands of silver-hake larvae 
(Merluccius), but nothing else except a few small Sagitta elegans, an odd pteropod 
(Limacina), and an occasional larval crab and euphausiid, though the deeper waters, as 
exemplified by a haul at 90-0 meters, supported comparatively few copepods but many 
Sagittae. We have found Calanus (with its relatives, Pseudocalanus and Metridia) 
hardly less dominant at enough other localities 6 to prove that it is a common event 
for these copepods to monopolize the plankton of any part of the Gulf in summer. As 
a rule, however, the animal plankton is more diversified at all levels by the hyperiid 
amphipods, euphausiids of several species, pteropods (Limacina), Sagittae, etc., men- 
tioned above, even though copepods may dominate the planktonic community as a 
whole (figs. 10, 11, and 12). Some of these other groups may be a major element in 
the plankton locally. For instance, the chastognaths ( Sagitta elegans) often rival the 
copepods in bulk (if not in actual numbers) at the mouth of Massachusetts Bay and 
in the Isles of Shoals regions; indeed, our second towing station, 12 miles or so off 
Cape Ann (10002), yielded a swarm of these arrow worms on July 10, 1912 (Bigelow, 
1914, p. 100), and we have encountered similar swarms of Sagittae at other localities 
since then (fig. 13). 
An abundance of the large pelagic shrimps Meganyctiphanes (fig. 14) and Thy- 
sanoessa is regularly characteristic of the deep northeastern corner of the Gulf 
throughout the year and of the Eastport-St. Andrews region in summer (p. 134), 
while various larval forms (crustaceans, especially) are extremely numerous locally 
near shore in their appropriate seasons, as noted elsewhere (p. 31). As other instances 
of the swarming of one characteristic boreal animal or another we may add that the 
• Sample examined by Doctor Esterly was nearly pore Calanus finmarchicus. 
8 Notably off Gloucester on Aug. 9, 1913 (station 10087); in the Western Basin on July 15, 1912 (station 10007); near Platts 
Bank on Aug. 10, 1913 (station 10089) ; off the slope of German Bank on Aug, 12, 1913 (station 10095) ; northeast of Mount Desert Rock 
on Aug. 13, 1913 (station 10100); and off Cape Elizabeth on Aug. 15, 1913 (station 10104). 
