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 Sagittse, 2 pteropods (Limacina), 3 or 4 larval rosefish (Sebastes), a few small 

 medusas (Phialidium) , 51 euphausiid shrimps, and an odd Euchseta, 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 Euchseta were represented in the proportion of about 30, 

 5, and 2, revealed only a few Pseudocalanus, 21 Thysanoessa longicaudata, odd 

 amphipods (Euthemisto), 24 Meganyctiphanes, 7 Thysanoessa inermis, 6 or 8 ptero- 

 pods (Limacina), 1 worm (Tomopteris), a few Sagittse, 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 (Thysanoessa 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 

 Sagittse. 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), Sagittse, 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 chsetognaths (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 Sagittse 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 pure Calanus finmarchkus. 



• 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); ofl the slope of German Bank on Aug, 12, 1913 (station 10095); northeast of Mount Desert Rock 

 on Aug. 13, 1913 (station 10100); and ofl Cape Elizabeth on Aug. 15, 1913 (station 10104). 



