SHENKER OCEANOGRAPHIC ASSOCIATION OF NEUSTONIC MEROPLANKTON 



tinct temporal shifts in occurrence: Five taxa 

 were abundant only prior to the onset of continu- 

 ous upwelling in mid-June, three taxa were spo- 

 radically abundant following the beginning of up- 

 welling, and one species (Ronquilus jordani) was 

 present tliroughout the survey. 



Pre-upwelling Species 



The numerically dominant species in the 

 nearshore region in spring was larval English 

 sole, Parophyrys vetulus. These larvae were 

 patchily distributed (CD. = 32.5) within 30 km 

 offshore, reaching densities of 75/1,000 m'^ in 

 Manta net collections. Larval abundance declined 

 rapidly after April (Table 1). Size-frequency dis- 

 tributions indicated that the Manta net was more 

 effective than the neuston trawl for collecting fish 

 <15 mm (Kolmogorov-Smirnov test, P<0.01). 

 Eye migration in the larger fish (20-24 mm) was 

 nearly complete, indicative of their impending 

 shift to a benthic existence. Similar-sized juve- 

 niles were taken nearshore in April in benthic 

 tows (B. Mundy^). 



Cabezon, Scorpaenichthys marmoratus , larvae 

 were most abundant in Manta catches in the 

 spring (Table 1), although newly hatched larvae 

 were collected near shore through June. The 

 smallest larvae (4-6 mm.) were taken only at the 

 1-15 km stations, while larvae up to 10 mm were 

 found along the entire transect. These larvae 

 were patchily distributed, with April densities 

 reaching 207/1,000 m^ (CD. = 92.7). Frequency 

 of occurrence and larval density declined through 

 early July. Large juvenile cabezon (26-38 mm) 

 were collected by the neuston trawl (Fig. 6a). 

 These juveniles were encountered all along the 

 transect from April to mid-June. 



Two dominant taxa found at all stations prior 

 to upwelling were greenling (Hexagrammos sp.) 

 and brown Irish lord, Hemilepidotus spinosus . Ju- 

 venile greenlings were the most frequently col- 

 lected species, occurring in AA.9>% of the night- 

 time neuston trawl samples (Table 1), although 

 they were rarely taken by the Manta net (Fig. 6b). 

 They were the most evenly dispersed of the abun- 

 dant fish collected (CD. = 2.2), and never ex- 

 ceeded densities of 10/1,000 m^. The two largest 

 catches of greenling were made in association 

 with distinct hydrographic features. Nineteen ju- 



a) Scorpaenichthys marmoratus 



100 -, 



50 - 



I J Manta net 



Neuston trawl 



TT' 





4 6 8 10 20 26 32 38 



b) Hexagrammos sp. 



40 —I 



30 - 



20 - 



10 - 



c) Anoplopoma fimbria 



5B. C. Mundy, Southwest Fisheries Center Honolulu Labora- 

 tory, National Marine Fisheries Service, NOAA, 2570 Dole 

 Street, Honolulu, HI 96822, pers. commun. May 1984. 



T r 



10 20 30 40 50 60 70 80 90 100 IK) 120130 



Standard Length (mm) 



Figure 6a-c. — Length-frequency data of larval and juvenile 

 fishes collected by each net. a = Scorpaenichthys marmoratus ; 

 b = Hexagrammos sp.; c = Anoplopoma fimbria. 



veniles were collected from a convergence zone 

 near shore in mid-May (along with 150,000 Dun- 

 geness crab megalopae) and 20 juveniles were 

 taken from Columbia River plume water 50 km 

 offshore in early June. Mean lengths of greenling 

 from the neuston trawl samples increased from 



305 



