AGE AND GROWTH OF LARVAL ATLANTIC HERRING, 



CLUPEA HARENGUS L., IN THE GULF OF MAINE-GEORGES BANK 



REGION BASED ON OTOLITH GROWTH INCREMENTS 



R. Gregory Lough, Michael Pennington, George R. Bolz, and Andrew A. Rosenberg 1 



ABSTRACT 



An estimate of the age and growth of herring larvae over their first 6 months of life is made by 

 examining presumed daily growth increments in their otoliths. A Gompertz growth curve fitted to 

 311 autumn-spawned specimens collected in the Gulf of Maine-Georges Bank region describes the 

 mean length at age (based on a range of 7-160 otolith increments (from an initial hatching size of 5. 7 

 mm SL to a mean length of 30.9 mm at 175 days. A larva with 7 growth increments isestimated to be 

 on average 25 days old with a mean length of 12.7 mm. Larvae reared in the laboratory at 10°C began 

 initial increment deposition on average 4.5 days from hatching at the time of yolk-sac absorption, 

 and the second increment was deposited an average of 12 days from hatching. The rearing experi- 

 ments were terminated before an increment-day relation could be established, but the third incre- 

 ment was estimated to be formed on average 22 days from hatching. Support for the assumption that 

 increment deposition becomes daily at least after the third increment is made by two independent 

 methods. Based on the fitted Gompertz curve, average growth rates for herring larvae increased 

 from 0.25 mm/day at hatch to 0.30 mm/day at 20 days and declined to <0.15 mm/day after 75 days of 

 age during the winter period. This agrees closely with estimated field rates. 



Atlantic herring, Clupea harengus L., spawn de- 

 mersal eggs during late summer-autumn on the 

 shoaler «40 m bottom depth) regions of Georges 

 Bank and around the perimeter of the Gulf of 

 Maine ( Bigelow and Schroeder 1953; Boyer et al. 

 1973; Lough and Bolz 1979 2 ). Hatching occurs 

 after 8-9 d at 10°C (Cooper et al. 3 ), and shortly 

 thereafter the larvae are dispersed throughout 

 the water column by the vigorous tidal stirring 

 characteristic of this region (Bumpus 1976). By 

 following length-frequency means or modes be- 

 tween successive surveys, average larval growth 

 rates have been estimated on field populations of 

 larvae in the Gulf of Maine-Georges Bank region 

 by Tibbo et al. (1958), Tibbo and Legare (1960), 

 Das (1968, 1972), Graham et al. (1972), Sameoto 

 (1972), Boyar et al. (1973), Lough et al. (1979), 4 



'Northeast Fisheries Center Woods Hole Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, Woods Hole, MA 

 02543. 



-'Lough, R. G., and G. R. Bolz. 1979. A description of the 

 sampling methods, and larval herring (Clupea harengus L.) 

 data for surveys conducted from 1968-1978 in the Georges 

 Bank and Gulf of Maine areas. Northeast Fisheries Center, 

 Natl. Mar. Fish. Serv., NOAA, Woods Hole Lab. Ref. 79-06, 

 230 p. 



Cooper, R. A., J. R. Uzmann, R. A. Clifford, and K. J. Pecci. 

 1975. Direct observations of herring ( Clupea harengus haren- 

 gus L.) egg beds on Jeffreys Ledge, Gulf of Maine in 1974. 

 ICNAF Res. Doc. 75/93, 6 p. 



4 Lough, R. G., G. R. Bolz, M. D. Grosslein, and D. C. Potter. 

 1979. Abundance and survival of sea herring (Clu pea haren- 



and others. Larval herring grow at an overall 

 average rate of about 5 mm/mo (0.2 mm/d) from 

 hatch (6 mm SL) to metamorphosis in the spring. 

 Metamorphosis is a gradual transition to adult 

 characteristics generally achieved by the time 

 the fish are 50-55 mm, but some studies report 

 metamorphosis occurring at much smaller 

 lengths of 30-35 mm (Blaxter and Staines 1971; 

 Boyar et al. 1973; Ehrlich et al. 1976; Doyle 

 1977). 



Knowledge of larval herring growth is an im- 

 portant component in the estimation of age- 

 specific mortality rates, which can be used to 

 study variations in larval survival in relation to 

 size of succeeding year classes. However, field 

 estimates of larval growth only provide average 

 rates of growth so that their use in comparative 

 studies is limited by the sometimes polymodal 

 length frequencies and subjective nature of con- 

 necting corresponding length modes. With the 

 development of accurate growth models, popula- 

 tions can be compared by region and season with 

 various environmental factors which may be 

 affecting growth and hence survival of larvae. 

 Techniques are now available for the accurate 

 aging of larval and juvenile fishes based on 



Manuscript accepted November 1981. 

 FISHERY BULLETIN: VOL. 80, NO. 2. 1982. 



gus L.) larvae in relation to environmental factors, spawning 

 stock size, and recruitment for the Georges Bank area, 1968- 

 1977 seasons. ICNAF Res. Doc. 79/VI/112, 47 p. 



187 



