An energy budget for northern 

 sand lance, Ammodytes dubius, 

 on Georges Bank, 1977-1986 



Sharon L. Gilman 



University of Rhode Island, Narragansett Bay Campus 

 Narragansett, Rhode Island 02882 



The northern sand lance, Ammo- 

 dytes dubius, is a small planktiv- 

 orous fish, classified as a "ubiqui- 

 tous shelf species" (Sherman et al., 

 1983 ) and is found off the northwest 

 Atlantic coast from North Carolina 

 to Greenland (Nizinski et al., 1990). 

 Sand lance are consumed by many 

 piscivorous marine vertebrates. 

 They have been found in the stom- 

 achs of dogfish, Squalus spp., 

 skates. Raja spp., Atlantic cod, 

 Gadus morhua, haddock, Melano- 

 grammus aeglefinus, pollock, Polla- 

 chius virens, sculpin, Myoxocephalus 

 spp., Atlantic salmon, Salmo salar, 

 various flatfishes, Paralichthys, 

 Limanda, and Pseudopleuronectes, 

 and other fishes (Scott, 1968; Reay, 

 1970; Meyer et al., 1979; Bowman 

 and Michaels, 1981; Winters, 1981), 

 as well as seabirds (Backus and 

 Bourne, 1987). Humpback whales, 

 Megaptera novaeangliae, have also 

 been observed feeding on sand 

 lance (Payne et al., 1986). Negative 

 correlations have been shown be- 

 tween the abundance of sand lance 

 and right whales, Eubalaena gla- 

 cialis, and it has been suggested 

 that in the northwest Atlantic these 

 two animals may actually compete 

 for their primary food source, the 

 copepod Calanus finmarchicus 

 (Kenney et al., 1986; Payne et al., 

 1990). Therefore, although the sand 

 lance is not commercially impor- 

 tant, as a plankton feeder and an 

 important prey species, it may ex- 

 ert significant influence over the 



efficiency of energy transfer from 

 primary to higher trophic levels. 



Georges Bank was chosen as a 

 study area in which dramatic 

 changes in the northern sand lance 

 population might be examined in 

 terms of the consumption and pro- 

 duction of fish relative to the pro- 

 duction of the region as a whole. 

 This 41,809 km 2 , 50-m deep plateau 

 (Sherman et al., 1984) is located off 

 the northeast coast of the United 

 States and is a highly productive 

 fishing ground with high annual 

 primary production (350 g 

 carbonm^-y^ 1 ) owing to the reten- 

 tion of nutrients (Sherman et al., 

 1984; Backus and Bourne, 1987). 

 Because of its commercial signifi- 

 cance, Georges Bank has been well 

 studied. Energy budgets have been 

 developed for the entire Bank 

 (Cohen et al., 1982; Jones, 1984; 

 Sissenwine et al., 1984) and offer a 

 convenient way to examine the sig- 

 nificance of the consumption and 

 production of an individual species 

 within an important area of the 

 Northeast Shelf ecosystem. 



Individual energy budgets offish 

 have been developed for many spe- 

 cies (Edwards et al., 1972; Adams, 

 1976; Kitchell et al., 1977; Kitchell 

 and Breck, 1980; Cho et al., 1982; 

 Kerr, 1982; Diana, 1983; Durbin 

 and Durbin, 1983; Rice and 

 Cochran, 1984; Kerr and Dickie, 

 1985; Cui and Wooton, 1989). In 

 this study, the energy budget of the 

 northern sand lance was developed 



from experiments that measured 

 the following parameters: growth, 

 metabolism, feeding and assimila- 

 tion efficiency ( Larimer, 1992), and 

 reproductive production. These pa- 

 rameters were assembled into an 

 annual energy budget based on the 

 daily activity of the fish in the field 

 associated with temperature and 

 food availability. Monthly growth 

 was used to estimate annual ration 

 and the budget was extrapolated to 

 northern sand lance population 

 abundance levels measured on 

 Georges Bank from 1977 to 1986. ' 

 The potential predatory impact of 

 the northern sand lance population 

 on seasonal and annual zooplank- 

 ton productivity on the bank 2 (Sher- 

 man et al., 1987) was examined. 

 Finally, the annual production and 

 consumption by these populations 

 were compared with energy budget 

 model values for Georges Bank. 



Methods 



Individual energy budget 



An "average" adult northern sand 

 lance was considered to be age 1+, 

 the dominant age in a population of 

 adults (Nelson, 1990). The average 

 size was 142 mm fork length, 6.02 g 

 wet weight, and 1.40 g dry weight 

 based on the following wet-weight 

 fork length relationship of Larimer 

 (1992): 



weight = 4.0665 e" 1 length 361 . 



The annual energy budget for an 

 individual northern sand lance was 

 described by the following equation 

 adapted from Winberg ( 1956): 



1 Kane, J. 1992. Macrozooplankton seasonal 

 abundances on Georges Bank. 1977-1986. 

 NOAA, Nat. Mar. Fish. Ser., Northeast 

 Fish. Sci. Center, Narragansett Lab., 

 Narragansett, RI 02882. Unpubl. data. 



2 Fogarty, M. 1992. Survey biomass esti- 

 mates for sand lance on Georges Bank. 

 NOAA, Nat. Mar. Fish. Ser., Northeast 

 Fish Sci. Center, Water Street, Wood's 

 Hole, MA 02543. Unpubl. data. 



Manuscript accepted 16 February 1994 

 Fishery Bulletin 92:647-654 ( 1994). 



647 



