Abstract.- Pacific herring Clupm 

 palla^i eggs were collected from 

 spawning grounds in Bristol Bay, 

 Alaska, transferred to Norway for 

 hatching, and for 63 days raised in 

 a 2n00-m'^ marine basin located at 

 the Fl^devigen Biological Station. 

 The eggs were from the same spawn- 

 ing, and hatching took place over 3 

 days. Upon completion of hatching, 

 24,840 larvae (12.42 larvae/m''') were 

 released into the basin. Lai^val gi'owth 

 was rapid and metamorphosis was 

 observed 28 days after hatching at 

 a length of 25 mm. The experiment 

 was terminated by draining the 

 basin; 4891 juveniles were recov- 

 ered. The average rate of growth 

 was 0.6(5 mm/day in length and 2.89 

 mg/day in weight. The larval length 

 frequency, unimodal at hatching, 

 segregated into three modes within 

 2 weeks, which persisted until ter- 

 mination. The slowest growth rate 

 was 0.31 mm/day and the larger her- 

 ring averaged 1.48 mm/day. At first 

 feeding, copepod nauplii were abun- 

 dant but food declined later. Canni- 

 balism was observed on day 4.5 and 

 a 30-mm herring was captured that 

 contained a 20-mm herring. Survival 

 was higher in the basin than esti- 

 mated for larvae at sea. Mortality ap- 

 peared to be greatest during the first 

 2 weeks, and much of it may have 

 been due to hydromedusa predation. 



Observations on Growth 

 and Survival During the Early 

 Life History of Pacific Herring 

 Clupea pallasii from Bristol Bay, 

 Alaska, in a Marine Mesocosm 



Vidar G. Wespestad 



Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA 

 7600 Sand Point Way N E , Seattle, Washington 981 15-0070 



Eriend Moksness 



Institute of Marine Research 



FlQjdevigen Biological Station, 4817 His, Norway 



Manuscript accepted 11 July 1989. 

 Fishery Bulletin, U.S. 88:191-200. 



Pacific herring Clupea pallasii that 

 spawn in northern Bristol Bay are 

 the largest herring off western North 

 America and are genetically distinct 

 from herring in the Gulf of Alaska 

 and off British Columbia (Fried and 

 Wespestad 1985, Grant and Utter 

 1984) (Fig. 1). Very little is known of 

 the early life history of Bristol Bay 

 herring. Checkley (1982) examined 

 otoliths from age-0 juveniles for 

 growth increments and sampled post- 

 hatching larvae at several spawning 

 areas in western Alaska (Checkley 

 1983). These studies provided limited 

 information on early growth, since 

 the time of spawning and hatching 

 were unknown and otolith incre- 

 ments were not verified to be daily 

 rings. 



To investigate the growth in length 

 and weight of larval and post-larval 

 Bristol Bay herring and other aspects 

 of early life history, known-age her- 

 ring were sampled from hatching 

 to postmetamorphosis in a marine 

 mesocosm. A mesocosm study was 

 chosen because larval density could 

 be regulated as well as sources of 

 mortality, such as predators and food 

 supply which cannot be done in a field 

 study. Control of these variables is 

 possible in a laboratory experiment, 

 but 0iestad (1983) has shown that 



container size may bias laboratory 

 results. He investigated the early life 

 history of Atlanto-Scandia herring 

 Clupea harengus and the effect of 

 ration and predation on survival in a 

 large marine enclosure located at the 

 P'l0devigen Biological Station near 

 Arendal, Norway. The results of his 

 studies showed life history param- 

 eters of herring in the basin were 

 similar to those observed in nature. 



Methods 



Herring eggs on rockweed (Fucus 

 sp.) were collected at low tide on 24 

 May 1986 from a single spawning 

 that occurred on 22 and 23 May. 

 Watei- temperature at the time of 

 spawning was 4.5°C and salinity was 

 30 ppt. Fucus fronds with light egg 

 coverage (1-2 egg layers) were col- 

 lected at random within the spawn- 

 ing area and packed into half-liter 

 plastic bags filled with seawater. A 

 total of 25 bags were filled with about 

 2000 eggs per bag. The bags were 

 shipped via air in insulated containers 

 with gel ice to the Fl0devigen Biolog- 

 ical Station. After 48 hours in tran- 

 sit, the eggs were unpacked and placed 

 in hatching boxes supplied with cir- 

 culating seawater at 7.7°C and salin- 

 ity of 32 ppt. 



191 



