RICHARDSON: SPAWNING BIOMASS AND EARLY LIFE OF NORTHERN ANCHOVY 



Parsons et al. 1970; Eldridge and Bryan 1972; 

 Blackburn 1973; Richardson 1973, footnote 5, un- 

 publ. data; Pearcy and Myers 1974; Laroche 1976; 

 Misitano 1977; Richardson and Pearcy 1977; 

 Waldvogel 1977; Robinson ; Cummings and 

 Schwartz'; Forsberg et al. ) spawning locations 

 have not been well defined and data are somewhat 

 contradictory. Before the present study, running 

 ripe adults had never been collected. Two nearly 

 ripe females were taken in coastal waters around 

 British Columbia; one ripening female was taken 

 in Tillamook Bay in northern Oregon; and large 

 numbers of ripening adults had been found in 

 Humboldt Bay in northern California (Figure 1). 

 Interestingly, the ripening fish in Humboldt Bay 

 leave in June or July and return again in fall in a 

 spent condition. Planktonic northern anchovy 

 eggs had been reported only from certain inlets of 

 Vancouver, British Columbia, in Puget Sound, 

 Wash., off the Columbia River mouth, and in 

 Yaquina Bay, Oreg. Small ( <10 mm) planktonic 

 larvae had been rarely taken in areas where ripen- 

 ing adults or planktonic eggs had been found. 

 Small numbers of these larvae had been reported 

 only from Yaquina Bay and Humboldt Bay. Large 

 concentrations of small larvae had been reported 

 only from ocean waters off Oregon. Larvae ^10 

 mm had been taken in small numbers in the Strait 

 of Georgia, British Columbia, inside the mouth of 

 the Columbia River, in Yaquina Bay, and in Hum- 

 boldt Bay. As with small larvae, large concentra- 

 tions had been found only off the Oregon coast. 

 Juveniles ^35 mm had been taken in ocean waters 

 off Oregon as well as in the Strait of Georgia, 

 British Columbia; Puget Sound, Wash., inside the 

 Columbia River mouth; in Tillamook Bay, Yaquina 

 Bay, and Coos Bay, Oreg.; and in Humboldt Bay, 

 Calif. Juveniles taken offshore were usually <50 

 mm while most of those in bays and sounds were 

 >50 mm. 



These data, and particularly the earlier study 

 by Richardson (1973), indicated the possible exis- 

 tence of a spawning concentration of northern an- 

 chovy within the northern subpopulation located 



«F{obinson, D. G. 1969. Data record. Number, size composi- 

 tion, weight and food of larval and juvenile fish caught with a 

 I two-boat surface trawl in the Strait of Georgia July 4-6, 

 ' 1967. Fish.Res. BoardCan.,ManuscrRep. SerNo. 1012,71p. 

 "Cummings, E., and E. Schwartz. 1971. Fish in Coos Bay, 

 Oregon, with comments on distribution, temperature, and salin- 

 ity of the estuary. Oreg. Fish. Comm., Res. Div., Coastal Rivers 

 Invest. Inf Rep. 70-11, 22 p. 



sForsberg, B. O., J. A. Johnson, and S. M. Klug. 1976. The 

 identification, distribution, and notes on food habits offish and 

 shellfish in Tillamook Bay Oregon. Oreg. Dep. Fish Wildl., Res. 

 Sect., Fed. Aid Prog. Rep.: Fish., Feb. 1974-June 1976, 117 p. 



off the Oregon-Washington coast. Richardson 

 suggested spawning might be associated with the 

 Columbia River plume. The present study was de- 

 signed to test that hypothesis and to estimate the 

 biomass of spawning adults located therein. 



METHODS 



Field Procedures 



Standard ichthyoplankton surveys (Smith and 

 Richardson 1977) were conducted off the 

 Oregon-Washington coast in the region outlined in 

 Figure 1. This survey area was designed to border 

 at least the inner bounds of the Columbia River 

 plume. Cruises were conducted at the presumed 

 time of peak spawning in mid-July: 10-18 July 

 1975 and 7-15 July 1976. 



A grid of 70 stations along seven east-west 

 transects (Figure 2) was sampled. Stations ex- 



128° 



i27» 



\2e,' 



46' 



42' 



232 157 83 28 2], ^""""^ 



269 



194 



120 



128° 



127° 



126° 



Figure 2.— Ichthyoplankton survey grid with 70 cm bongo net 

 sampling stations occupied in July 1975 and July 1976 off Oregon 

 and Washington. Numbers on upper transect represent kilome- 

 ters from the coast and apply to all seven transects. 



857 



