PEARCY and MYERS: LARVAL FISHES OF YAQUINA BAY 



Cithcu'iclitliys stignuwus (30-80 mm) were con- 

 centrated in the lower estuary and were rarely 

 captured up-estuary of Buoy 21. They were 

 most common in May and June. Hypomesus 

 pretiosHs (35-50 mm) were abundant at all 

 trawling stations, but only in January and 

 February (Johnson, pers. comm.). 



The importance of estuaries as nursery 

 grounds for flounder, and especially for Par- 

 (iphrys vi'tuliis, has been emi)hasized by others. 

 Westrheim (1955) reported appreciable num- 

 bers of small Parophrys vetulus, Cithanchthys 

 s())-didiix-^ and Platichthys stellatus (starry floun- 

 der) in Yaquina Bay. Sand sole (Psettichthyyi 

 ni(Io)i(>><ticti(s) were also encountered frequently. 

 Although no adults of the commercially impor- 

 tant English sole were caught, juveniles (20- 

 180 mm) were common until autumn when 

 most emigrated from the bay. Olsen and Pratt 

 (1973) also reported that juvenile English 

 sole were abundant in lower Yaquina Bay from 

 April to Sei^tember 1971, emigrating to offshore 

 areas in October. Based on the incidence of a 

 parasitic infection, apparently acquired only 

 in estuaries, they concluded that estuaries are 

 likely to be the exclusive nursery grounds for 

 Parophrys vetulus on the Oregon coast, a 

 conclusion that is supported by the absence of 

 0-age English sole in Demory's (1971) ocean 

 trawling survey off the Oregon-Washington 

 coast. Misitano (1970) and Eldridge (1970) 

 found large numbers of English sole in Humboldt 

 Bay, California. Villadolid (1927, as cited in 

 Misitano, 1970) captured 0-age English sole by 

 trawling in San Francisco Bay but found none 

 off the coast. Shallow protected waters along the 

 indented British Columbia coastline also provide 

 nursery grounds for this species (Ketchen, 

 1956). Bays and estuaries are therefore vital as 

 nurseiy areas for P. vetulus in their first year 

 of life, perhaps because the sediments in these 

 protected waters provide an ideal feeding hab- 

 itat for the young as opposed to coarse sand 

 sediments at similar depths along the open 

 coast. 



Sexually mature (ripe) P. vetulus were not 

 caught in Humboldt or Yaquina Bay but are 

 known to spawn offshore (Westrheim, 1955; 

 Harry. 1959; Jow, 1969). Young larvae were 

 uncommon in plankton collections from these 



Table 5. — Relative abundance (7c) ot juvenile fishes 

 collected at four stations in Yaquina Bay (Bridge to 

 Buoy 29) in a 1.8-m beam trawl (1.5 mm stretch mesh), 

 January-June, 1970 (courtesy Wm. Johnson). 



Hypomesus preiiostis 

 Parophrys vetulus 

 Citharichthys siif-niaeus 

 Enophrys bison 

 CI u pea h. pal las i 

 Ammodytes hexaplerus 

 Leplocoitus annatus 

 HexaKrammos decaf^rainnuis 

 Pholis ornata 

 Raja hinuculala 

 Platichthys stellatus 

 Heniilepidotus heiuilepidotus 

 Lumpenus sa>>itta 

 Eiigraulis mordax 

 Lepidoi>ohiiis lepidus 

 Cyiuatofiaster aggregata 

 Sehastes nielaiiops 

 Artedius fenestralis 

 P\ettichthys mehmostictus 

 Ophiodon eloitf;atiis 

 Syanathus i;riseolineatus 

 Pallas Ilia barhatu 

 Syinphurus airicauda 

 Artedius harriniitoui 

 Anoplarchus purpurescens 

 Phanerodoii furcatus 

 Einbiotoca lateralis 

 Occella verrucosa 

 G obi e SOX maeandricus 



36.2 



24.6 



18.2 



4.1 



3,6 



2.5 



2.3 



1.1 



1.0 



0.7 



0.7 



0.7 



0.7 



0.6 



0.5 



0.5 



0.4 



0.4 



0.4 



0.3 



0.3 



0.1 



<0.1 



<0.1 



<0.1 



<0.1 



<0.1 



<0.1 



<0.1 



'■'■ Probably C. siifiinaeus, 

 by others in Yaquma Bay. 



the species usually Found 



bays (Eldridge, 1970; Misitano, 1970). In our 

 study P. vetulus larvae were common offshore 

 but were absent or rare in Yaquina Bay (Table 

 4). Therefore young English sole must be trans- 

 ported into the bay from offshore waters as late 

 larval stages or migrate in as juveniles. In 

 Humboldt Bay, Misitano (1970) captured meta- 

 morphosing English sole (average length, 23 

 mm) by midwater trawling, especially after 

 dark. These larvae were active swimmers in 

 aquaria but usually resided on the bottom. As 

 a result they would be relatively inaccessible to 

 daytime plankton collections. 



The question remains, however, how these 

 larvae enter estuaries. Currents off the northern 

 Pacific coast during the winter and spring are 

 largely inshore and northerly (Burt and Wyatt, 

 1964; Wyatt, Burt, and Pattullo, 1972) and 

 would transport buoyant fish eggs such as those 

 of English sole (Budd. 1940; Ketchen, 1956; 

 Alderdice and Forrester, 1968) toward and 

 then along the coast. Retention in estuaries 

 would seem to require active behaviorial re- 

 sponses by the larvae, such as a change in depth 

 distribution to enhance transport into and reduce 

 advection out of estuaries. Since a two-layered 

 transport system prevails in Yaquina Bay dur- 

 ing the winter (Kulm aiid Byrne, 1967; Burt 



211 



