694 



Fishery Bulletin 88(4), 1990 



right whales were most abundant in the study area 

 (April 1970, reported by Watkins and Schevill 1982; 

 and during 1986) were during periods of documented 

 low adult sandlance densities and observed copepod 

 maxima. The March 1975 observations by Watkins 

 and Schevill (1979) of a sei and right whales feeding 

 together in Cape Cod Bay were also made in the inter- 

 val between the reduction of planktiverous herring and 

 mackerel stocks and the subsequent population explo- 

 sion of adult sandlance. These observations further sup- 

 port the theory that planktiverous fish abundance has 

 negatively impacted the occurrence of planktiverous 

 whale species in the region. 



In this paper, we have examined species interactions 

 between sandlance (as prey and competitor), C.finmar- 

 chicus (as prey), and the abundance of four species of 

 baleen whales in the southern Gulf of Maine. The inter- 

 pretation of these interactions, although largely induc- 

 tive, provide useful management insights into the 

 relationships between planktiverous finfish and the 

 cetacean community. This interpretation also presents 

 an interesting multispecies-management dilemma re- 

 garding finfish and cetacean populations in this region, 

 as well as potential conflicts between single-species re- 

 covery plans and two ecologically different groups of 

 endangered whales, pisciverous and planktiverous. 



The present abundance of sandlance in the Gulf of 

 Maine followed a long-term depletion of other plank- 

 tiverous fish species through overfishing (Grosslein et 

 al. 1980). Although it is impossible to reconstruct the 

 extent of competition between finfish (herring and 

 mackerel stocks) and planktiverous whales prior to the 

 mid-1960s, the similarities in prey preference and 

 trophic relationships between mackerel, herring and 

 sandlance (Bowman et al. 1984) certainly suggest that 

 competition between herring-mackerel stocks and 

 planktiverous whales could have existed. We hypothe- 

 size that the abundance and distribution of planktiv- 

 erous fishes have played a significant, perhaps critical, 

 role in structuring (as prey and competitor) baleen 

 whale populations in the Gulf of Maine. 



The present, concentrated distribution of humpbacks 

 in the Gulf of Maine is directly related to the distribu- 

 tion and increased abundance of sandlance in that 

 region. Alternatively, the recovery of the stenophagic 

 right whale (historically and at present) may indeed be 

 inhibited in large regions of the northwest Atlantic by 

 competition for its prey by herring, mackerel, and 

 sandlance. Despite decades of protection Schevill et al. 

 (1986) suggested that the [abundance of the] right 

 whale population [now] which passes Cape Cod is "at 

 worst slightly smaller than it was in the 17th century". 

 The abundance and distribution (and continued recov- 

 ery) of right whales, in contrast to humpback and fin 

 whales, may be contingent upon anomalous disrup- 



tions in the occurrence of abundant, ecologically equi- 

 valent finfish stocks, which at present are largely 

 human-induced. 



Acknowledgments 



The authors would like to thank Stan Tavares, Al 

 Avellar, and Aaron Avellar for supporting whale 

 research and the collection of data aboard their vessels, 

 and for helping establish rational whale-watching 

 guidelines throughout the New England region. We 

 would also like to thank anonymous reviewers for their 

 constructive criticisms, and the following members of 

 the North Atlantic Marine Mammal Association for 

 reviewing previous drafts of this manuscript: Vicki 

 Rowntree, Mason Weinrich, Steve Katona, Peter 

 Tyack, Gordon Waring, Dave Mountain, Fred Wenzel, 

 Bob Kenney, Scott Kraus, and Amy Knowlton. We 

 would also like to thank Howard Winn for his suppor- 

 tive comments regarding this study following its 

 presentation at the Eighth Bienniel Conference on the 

 Biology of Marine Mammals. The authors have been 

 funded by the Manomet Bird Observatory, the National 

 Marine Fisheries Service/Northeast Fisheries Center, 

 Massachusetts Whale Watching Center, Center for 

 Coastal Studies, and l>y private funding. 



Citations 



Allen. (i.M. 



1916 The whalebone whales of New England. Mem. Boston 

 Soc. Nat. Hist. 8:107-322. 

 Allen, .I.A. 



1908 The North Atlantic right whale and it.'; near allies. Bull. 

 Am. Mus. Nat. Hist. 24:277-329. 

 Anthony, V.A., and G. Waring 



1980 The assessment and management of the (Jeorges Bank 

 herring fishery. Rapp. P.-V. Reun. Cons. Int. Exi>lor. Mer 

 177:72-111. 

 Bowman. R., .1. Warzocha, and T. Morris 



1984 Trophic relationshijis between Atlantic mackerel and 

 American sandlance. Int. Counc. Explor. Sea (K'ESl. CM 

 I!t84/H:27, 10 p. 

 Brodie, P.F. 



197.5 Cetacean energetics, an overview of intraspecific size 

 variation. Ecology ,'36:1.'J2-1()1. 

 Brown. C.W., and H.E. Winn 



1989 Relaticinshi|.) between tlie distril)ulion pattern of right 

 whales, Eiihalaena yliiciiilis, and satellite-derived sea surface 

 thermal structure in the (ireat South Channel. Cont. Shelf 

 Res. 9:247-2(iO. 

 CeTAP 



1982 A characterization of marine mammals and turtles in the 

 mid- and North Atlantic areas of the U.S. outer continental 

 shelf. P'inal Rep. Cetacean and Turtle Assessment Program, 

 L'niv. Rhode Island. Bur. Land Manage.. Contract AA551- 

 CT8-48. U.S. Dep. Int.. Wash.. DC, 450 p. 



