Prehistoric seal carcass exploitation at the Shag Mouth site, New ZealandIntroductionChanging carcass exploitation of sealsChanging bone fragmentation patterns of sealsOtariid transport, processing and breakage patterns at Shag MouthSummary and conclusionsAcknowledgementsReferencesPrehistoric seal carcass exploitation at the Shag Mouth site,New ZealandLisa Nagaoka*Department of Geography, Box 305279, University of North Texas, Denton, TX 76203-5279, USAReceived 12 October 2005; received in revised form 30 January 2006; accepted 1 February 2006AbstractSeal populations in New Zealand declined dramatically during the prehistoric period. The loss of this important resource significantly af-fected the foraging practices at the Shag River Mouth site. Previous research documented substantial changes to the diet with the decline ofseals and the corresponding decline in foraging efficiency. In this study, I examine how New Zealand foragers altered their use of seal carcassesas the availability of these marine mammals declined. Otariid seal data from the Shag River Mouth site in southern New Zealand are analyzed totest changes in butchery/transport and skeletal element breakage patterns expected with resource depression and declining foraging efficiency.This research shows that at Shag Mouth, seal carcasses were used more intensively over time. However, bone breakage patterns showed littlechange in the exploitation of within-bone nutrients.Ó 2006 Elsevier Ltd. All rights reserved.Keywords: New Zealand; Seals; Foraging theory; Carcass exploitation; Butchery; Transport1. IntroductionThe impact of prehistoric humans on native fauna in NewZealand is well documented. The arrival of human colonizersabout 800 years ago led to decline in population abundancesand/or a reduction in geographic distribution of many faunathrough predation by human and introduced mammals, aswell as habitat alteration [1,27,41,42]. My previous researchon the Shag Mouth fauna has documented how this change inthe availability of faunal resources impacted human subsis-tence practices in southern New Zealand. Using foragingtheory to model change, I found that dietary changes werelinked to declines in abundances of large-bodied taxa such asseals and the extinct moas [31,32]. As the populations of thesetaxa were reduced due to human predation pressure, human for-agers expanded their diet to include a wider range of vertebrateresources. In addition, animals smaller in size, and thus lowerin net caloric returns, comprised a larger proportion of the diet,resulting in an overall decline in foraging efficiency.With the decline in availability of moas and seals, human de-cision making in regards to transporting and processing the car-casses of these large animal is likely to have changed. Indeed,my analysis of moa carcass exploitation demonstrates thatforagers had to journey farther over time to hunt moas, andas a result of the increased travel costs, the range of body partstransported became restricted to mainly high utility elements[33]. In addition, moa elements that were transported back tothe site were used more intensively over time for marrow andpossibly grease extraction. Moa carcass exploitation strategyis clearly linked to a decline in foraging efficiency throughtime. Like moas, the exploitation of seal carcasses is also ex-pected to change over time as foraging efficiency declined.As one of the largest vertebrate resources in New Zealand,seals were also commonly exploited by human foragers. Be-cause of prehistoric human predation pressure, seal popula-tions, particularly New Zealand fur seals (Arctocephalusforsterii), declined dramatically and their geographic range be-came constricted [41,42]. When people arrived in New Zealand800e1000 years ago, fur seals could be found across New* Tel.: þ1 940 565 2510; fax: þ1 940 369 7550.E-mail address: [email protected]/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.jas.2006.02.001Journal of Archaeological Science 33 (2006) 1474e1481http://www.elsevier.com/locate/jasZealand, and were common in archaeological middens datingto this early period [40,41]. But by about AD 1500, fur sealsdisappeared from North Island archaeological sites. On theeast coast of the South Island, breeding colonies were replacedby non-breeding colonies during late prehistoric times aboutAD 1500e1700 [41,42]. By European contact, fur seals werefound only along the south and west coasts of the South Islandwhere prehistoric human presence was limited.Patch choice models predict that given the general declinein the availability of seals across New Zealand and the corre-sponding decrease in overall foraging efficiency at the ShagMouth site, the intensity with which seals were exploited is ex-pected to have changed over time. Specifically, carcass exploi-tation and bone fragmentation patterns should change. Theseexpectations are tested here using the otariid seal assemblagefrom the Shag River Mouth site.The Shag River Mouth site is located on the east coast of theSouth Island (Fig. 1). As the name implies the site lies at themouth of the Shag River as the river flows into the Pacific Ocean.The extent of the site is about 30,000 m2. Over the last125 years, several areas of this expanse have been excavated.The material used in this analysis comes from the 1986 Dune ex-cavation, for which an 8 m by 10 m unit was excavated [2].The Dune excavation is one of the best stratified and bestdated excavations in New Zealand. Nine cultural layers (layers2, 4e11) were excavated to a depth of 2.5e4.0 m. Over 30 ra-diocarbon dates p roduced a sequence that spanned the earlyperiod of occupation in New Zealand (AD 1250e1450) [4].The site is also important because it contained habitation fea-tures that were the best example of a prehistoric permanentvillage in the region [3].In terms of zooarchaeological material, the excavation pro-duced a large sample of vertebrate faunal remains with over26,000 identified specimens representing 75 species of fish,bird, and mammal [30], as well as a large molluscan assem-blage [18] . Two otariid seal species (New Zealand fur seal(Arctocephalus forsteri) and Hooker’s sea lion (Phocarctoshookeri)), and one phocid seal (elephant seal (Mirounga leo-nina)), are represented at the site (Table 1). This study focuseson the otariid seals, because they comprise the vast majority ofthe seal assemblage.In the Shag Mouth assemblage, New Zealand fur seals