270 
Abstract — Cape Cod Bay (Massa- 
chusetts) is the only known winter 
and early spring feeding area for con- 
centrations of the endangered North 
Atlantic right whale ( Eubalaena gla- 
cialis ) population. During January- 
May, 1998-2002, 167 aerial surveys 
were conducted (66,466 km of total 
survey effort), providing a complete 
representation of the spatiotemporal 
distribution of right whales in the 
bay during winter and spring. A total 
of 1553 right whales were sighted; 
some of these sightings were multiple 
sightings of the same individuals. 
Right whale distribution and relative 
abundance patterns were quantified 
as sightings per unit of effort (SPUE) 
and partitioned into 103 23-km 2 cells 
and 12 2-week periods. Significant 
interannual variations in mean SPUE 
and timing of SPUE maxima were 
likely due to physically forced changes 
in available food resources. The area 
of greatest SPUE expanded and con- 
tracted during the season but its 
center remained in the eastern bay. 
Most cells with SPUE>0 were inside 
the federal critical habitat (CH) and 
this finding gave evidence of the need 
for management measures within CH 
boundaries to reduce anthropogenic 
mortality from vessel strikes and 
entanglement . There was significant 
within-season SPUE variability: low 
in December- January, increasing to 
a maximum in late February-early 
April, and declining to zero in May; 
and these results provide support for 
management measures from 1 Janu- 
ary-15 May. 
Manuscript submitted 29 July 2007. 
Manuscript accepted 21 March 2008. 
Fish. Bull. 108:270-280 (2008). 
The views and opinions expressed or 
implied in this article are those of the 
author and do not necessarily reflect 
the position of the National Marine 
Fisheries Service, NOAA. 
Spatial and temporal distribution of 
North Atlantic right whales ( Eubalaena glacialis) 
in Cape Cod Bay, and implications for management 
Owen C. Nichols (contact author ) 1 
Robert D. Kenney 2 
Moira W. Brown 1 - 3 
Email address for O.C. Nichols: onichols@umassd.edu 
1 Provincetown Center for Coastal Studies 
5 Holway Avenue 
Provincetown, Massachusetts 02657 
Present address: School for Marine Science and Technology 
University of Massachusetts-Dartmouth 
200 Mill Road 
Fairhaven, Massachusetts 02179 
2 University of Rhode Island Graduate School of Oceanography 
Bay Campus Box 41 
South Ferry Road 
Narragansett, Rhode Island 02882 
3 New England Aquarium 
Centra! Wharf 
Boston, Massachusetts 02110 
North Atlantic right whales ( Euba- 
laena glacialis) have been com- 
mercially exploited by whalers for 
centuries and are listed as endan- 
gered under the U.S. Endangered 
Species Act (ESA). The remnant popu- 
lation of approximately 300 individu- 
als, ranging along continental shelf 
waters from the southeastern United 
States to the Scotian Shelf (Winn et 
al., 1986; Waring et al., 2007), is con- 
sidered to be a small fraction of its 
original size (IWC, 2001). Despite a 
slight increase in the minimum popu- 
lation estimate from 295 individuals 
in 1992 to 306 in 2001 (Waring et al., 
2007), there has been little sign of 
recovery since studies began in the 
1970s (IWC, 2001; Kraus et al., 2001, 
2005). Although estimates of survival 
probability decreased in the 1990s, a 
relatively modest reduction in mortal- 
ity rate could reverse the observed 
decline and reduce the potential for 
species extinction (Caswell et al., 
1999; Fujiwara and Caswell, 2001; 
Kraus et al., 2005). The most frequent 
known anthropogenic causes of right 
whale mortality are collisions with 
ships and entanglements in fishing 
gear. Of 50 documented right whale 
mortalities from 1986 through 2005, 
at least 19 (38%) were due to ship col- 
lisions, and a minimum of six (12%) 
were attributed directly to entangle- 
ments (Kraus et al., 2005). 
Cape Cod Bay (Massachusetts), a 
semi-enclosed basin approximately 
40 km in diameter (Fig. 1), is the 
only known winter and early spring 
feeding area for the remaining con- 
centrations of the right whale pop- 
ulation (Winn et al., 1986; Waring 
et al., 2007). Scientific observations 
of right whales in Cape Cod Bay 
began in 1955 (Watkins and Schev- 
ill, 1982; Schevill et al., 1986), and 
Reeves et al. (1999) reviewed whaling 
records indicating right whale pres- 
ence from the early 1600s. During 
shipboard surveys and commercial 
whale watching trips, right whales 
were sighted in Cape Cod Bay and 
Massachusetts Bay to the north in 
every month except December from 
1978 to 1986. Most of these sight- 
ings were sparse for most months, 
and peak abundance occurred from 
February through April (Hamilton 
and Mayo, 1990). With the exception 
of an unusual summer occupancy in 
1986, most right whales had departed 
