381 



Winter capture of a harbor porpoise 

 in a pelagic drift net off 

 North Carolina 



Andrew J. Read 



Woods Hole Oceanographic Institution 



Woods Hole. Massachusetts 02543 



Present address Duke University Marine Laboratory 



135 Duke Marine Laboratory Road 



Beaufort. North Carolina 28516-9721 



John R. Nicolas 



Northeast Fisheries Science Center 

 National Marine Fisheries Service. NOAA 

 Woods Hole. Massachusetts 02543 



James E. Craddock 



Woods Hole Oceanographic Institution 

 Woods Hole, Massachusetts 02543 



Harbor porpoise, Phocoena phoco- 

 ena, of the Bay of Fundy and Gulf 

 of Maine are among the best-stud- 

 ied small cetaceans owing to their 

 coastal nature, frequent encounters 

 with commercial fisheries, and sub- 

 sequent accessibility to research- 

 ers. Unfortunately, our knowledge 

 of these animals is limited prima- 

 rily to observations made during 

 summer. In autumn most porpoises 

 leave these coastal waters, and 

 their winter distribution is un- 

 known. Various hypotheses have 

 been constructed to explain the 

 apparent disappearance of these 

 animals during the winter months, 

 including that of migration to off- 

 shore banks or to a southern coastal 

 area (Gaskin, 1984). Information on 

 the winter distribution of harbor 

 porpoises in the northwest Atlan- 

 tic is needed to understand better 

 the effects of human activities on 

 this population, which is subject to 

 large removals in coastal gill nets 

 during the spring, fall, and summer 

 (Readetal., 1993). 



Existing information on the win- 

 ter distribution of porpoises comes 



from strandings and a small num- 

 ber of dedicated surveys. From 

 January to May, porpoises strand 

 on the coasts of Massachusetts to 

 North Carolina ( Polacheck et al. , in 

 press), but most of these individu- 

 als are very young. Stranded adults 

 are seldom encountered. Winter 

 surveys are hampered by poor 

 sighting conditions and so far have 

 failed to find any significant con- 

 centrations of porpoises (Palka 1 ). In 

 this report, we document the inci- 

 dental capture of a harbor porpoise 

 in a pelagic drift net off the coast 

 off North Carolina, during winter. 

 The record is significant for two 

 reasons. First, it is the southern- 

 most incidental capture of a harbor 

 porpoise in the northwest Atlantic. 

 Second, observations of the stom- 

 ach contents of this specimen sug- 

 gest that the ecology of this popu- 

 lation may be quite different in win- 

 ter than in summer months. 



The porpoise was captured on 25 

 February 1993, 75 km east of Nag's 

 Head, North Carolina, at 35°55'N 

 and 74"47'W, in water 229-293 m 

 deep. Surface water temperature 



was 12-13°C. The net was set the 

 previous evening and hauled early 

 (0630-0830 h) in the morning. The 

 float line was approximately 10 m 

 below the surface of the water, and 

 the porpoise was entangled near 

 the top of the net. The porpoise was 

 examined at sea by an observer, 

 who noted that the porpoise had 

 been killed recently "because the 

 insides were steaming." Also in the 

 net were a basking shark (Cetor- 

 hinus maximus), 2 ocean sunfish 

 (Mala mola), 2 swordfish (Xiphias 

 gladius) and 3 bluefish (Porna- 

 tomus saltatrix). 



The porpoise was male, with a 

 standard length of 129 cm and 

 mass of 28.5 kg. Measurements of 

 girth and blubber thickness indi- 

 cated that the animal was healthy 

 and robust. The observer collected 

 life history tissues (teeth, stomach, 

 and reproductive tract) from the 

 carcass and transported them to 

 Woods Hole. The age of the porpoise 

 was estimated in the laboratory 

 from counts of dentinal growth lay- 

 ers in thin, decalcified, and stained 

 sections of teeth. Two independent 

 estimates of the age of the animal 

 were made, both indicating that the 

 porpoise was born between April 

 and June 1991. One testis measured 

 5.3 x 2.4 x 1.2 cm and weighed 11 g 

 without the epididymis. Histological 

 examination of the testis and epid- 

 idymis (Read and Hohn, 1995) re- 

 vealed that the porpoise was sexu- 

 ally immature. 



The forestomach contained the 

 remains of many small mesoplagic 

 prey not recorded from other har- 

 bor porpoises in the northwest At- 

 lantic (Smith and Gaskin, 1974; 

 Recchia and Read, 1989; Fontaine 



1 Palka, D. 1995. Preliminary cruise re- 

 port of the spring distribution survey of 

 harbor porpoises in the mid-Atlantic. 

 Northeast Fisheries Science Center, Natl. 

 Mar. Fish. Serv., Woods Hole MA 02543. 



Manuscript accepted 26 October 1995. 

 Fishery Bulletin 94:381-383 (1996). 



