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Fishery Bulletin 100(2) 



relation (P<0.001) between prey and bluefin tuna lengths 

 was found for all prey-size data (Fig. 5). Despite this cor- 

 relation, there appeared to be httle association between 

 predator and prey length for most species. The positive 

 correlation was influenced by 29 larger prey items (>40 

 cm) all consumed by bluefin tuna larger than 230 cm. The 

 larger prey were spiny dogfish, skate, bluefish, or Atlantic 

 cod. Size data on the four most common prey species pro- 

 vided evidence of the consistency of prey size across a wide 

 range of bluefin lengths in the Gulf of Maine. A signifi- 

 cant positive size relationship was found for sand lance 



and Atlantic mackerel (both P<0.001), although both may 

 have contained biases. The relationship for sand lance 

 was influenced by smaller bluefin tuna that ate smaller 

 sand lance (/-test, P<0.001) in Great South Channel than 

 at Stellwagen Bank. All mackerel were YOY or age-1, 

 except for two large mackerel consumed by larger bluefin 

 tuna (>200 cm). The predator-prey size relationships for 

 Atlantic herring (P=0.36) and squid (P=0.16) were not sig- 

 nificant. A large majority (939f ) of Atlantic herring prey 

 were 18-27 cm in length, which corresponds to age-2 to 

 age-4 cohorts for the western Gulf of Maine (Penttila et 



