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SAMPLING STATIONS 



FIGURE 3. — Number of species of larval, post-larval, and 

 juvenile fishes collected at each station in the Columbia River 

 estuary during 1973. 



Spawning on Provided Substrate 



Evergreen boughs placed in the water attracted 

 two species to deposit eggs, Clupea harengus 

 pallasi and unidentified snailfish (Cyclopteridae). 

 Thirty-three ripe adult C. h. pallasi, 163 mm 

 average length, were trapped 10 April through 17 

 July confirming identification of the eggs. Light 

 spawning was first observed on the boughs 10 

 April; moderate deposition 1-3 July. Ova were 

 viable, eyed eggs were observed. 



Adult snailfish began entering the trap 13 

 February. Eggs were deposited on boughs 12 and 

 26 February. Eggs were viable and emergent 

 larvae were observed. Fifteen gravid adults were 

 captured 13 February through 3 March. This 

 snailfish has some characteristics in common with 

 Liparis rutteri, which is also present in the es- 

 tuary. The unknown snailfish has been closely 

 examined and is now considered to be an unde- 

 scribed species by Carl Bond at Oregon State 

 University, Corvallis, Oreg. 



Gravid adults of two species of Cottidae were 

 captured by trapping. Ripe Leptocottus armatus 

 were taken 18 February and 19 March but no 

 spawning was observed. Jones (1962) found egg 

 survival for this species optimum at 10-15% in- 

 dicating a probably spawning population in the 

 Columbia River estuary. Ripe Cottus asper were 

 trapped 26 March, 4 and 9 April. This cottid's 

 newly hatched larvae, as described by Stein 

 (1972), was the third most abundant species in the 

 estuarine ichthyoplankton. Krejsa (1967) noted 



that coastal populations of this cottid migrate 

 downstream to spawn in brackish water. The 

 capture of ripe adults and large numbers of newly 

 hatched larvae verifies spawning of C. asper in the 

 estuary. 



Utilization of the Estuary 



Data obtained from this investigation indicated 

 four species, Clupea harengus pallasi, Cottus 

 asper, Leptocottus armatus, and a new species of 

 snailfish, utilized the Columbia River estuary for 

 spawning in 1973. The greatest number of species 

 was captured near the mouth suggesting most 

 species are oceanic in origin. 



Spirinchus thaleichthys, the most numerous 

 species, was captured at all stations. This 

 anadromous osmerid was reported by Hart (1973) 

 to spawn in streams near the sea. The presence of 

 newly hatched larvae, as described by Dryfoos 

 (1965), confirms the presence of a spawning 

 population in the lower Columbia system. The 

 capture of early stages almost the year round 

 indicates a major importance of the estuary to this 

 species. 



Thaleichthys pacificus is also an anadromous 

 osmerid in the Columbia River. Some mainstream 

 spawning occurs, but the majority of the run 

 spawns in the Cowlitz River, a tributary 109 km 

 upstream (Smith and Saalfeld 1955). Although 

 large numbers of larvae were captured February 

 to May, they were yolk bearing stages, 6-8 mm, 

 indicating a downstream drift through the estuary 

 to the ocean soon after hatching. Similar findings 

 were reported by Larkin and Ricker (1964). 



No evidence of estuarine spawning by 

 pleuronectids was indicated. Although the upper 

 estuary is a nursery for juvenile Platichthys 

 stellatus (Haertel and Osterberg 1967), no larvae 

 or postlarvae of this species were captured. Pearcy 

 and Myers (1974) captured only three larvae in 11 

 yr in Yaquina Bay, indicating entry into the es- 

 tuary is accomplished after metamorphosis. 

 Parophrys vetulus were captured at two size 

 ranges: 4-6 mm and 20-21 mm. Information from 

 other estuaries (Pearcy and Myers 1974; Misitano 

 1976) indicates young P. vetulus enter estuarine 

 nurseries after completion of metamorphosis. 



Isopsetta isolepis utilizes the Columbia River 

 estuary as a nursery. The National Marine 

 Fisheries Service conducted a bottom trawling 

 survey in the estuary from March 1973 to June 

 1974 (J. T. Durkin pers. commun.). Parophrys 



221 



