NOTE Rooper et a\ Partitioning and competition among [uvenile flatfish in nursery estuaries 



617 



1 2S''0'0"W ! 2T(fO-V,' 1 26'0'0"W 

 I I 1 



i:5"0'iv'\v i:4"0'0"\v 



'■"^r^^ ' 



GiLfvs Harbor 



Pacific Ocean 



fl iJiiipa Bay 



Washinjiton 



'\-.jB^_ 



Yaqtnna Bay^ ^^ 



Oregon 



Coos Bay 



50 



100 



I 



200 km 



Figure 1 



Map of coastal Oregon and Washington with insets showing the four estu- 

 aries studied: Grays Harbor (total subtidal area=8545 ha). Willapa Bay 

 (total subtidal area = ll,200 hal, Yaquina Bay (total subtidal area=471 ha), 

 and Coos Bay (total subtidal area=1195 ha). 



periods by approximately 50 m. Benthic organisms, 

 including the four target flatfish species, were collected 

 during daylight with a beam trawl (Gunderson and Ellis, 

 1986). The beam trawl had an effective opening width 

 of 2.3 m and a height of 0.6 m. The net was towed at a 

 speed of 0.8-0.9 m/s behind a 6.4-m research vessel with 

 a minimum 5:1 scope of line out to depth. The distance 

 towed averaged 139 m in 1998-2000. Trawls were made 

 against the prevailing current over a variety of tide 

 stages, although efforts were made to conduct trawling 

 near the time of daylight slack low water. Sampling 

 was not conducted at high current velocities during 

 maximum ebb and flood tides to ensure the greatest 

 adherence of the beam trawl to the substratum. All fish 



and invertebrates captured were identified to species and 

 English sole were measured for total length (TL) to the 

 closest 1.0 mm. Other species of flatfish were measured 

 (TL) only in 1999 and 2000. 



Data analysis 



There was considerable variability in the data associ- 

 ated with each sampling period that was not related to 

 habitat use. This variability was due to other factors, 

 such as patterns in interannual variability in recruit- 

 ment to individual estuaries or to differences in overall 

 abundance among the four flatfish species. To minimize 

 the effect of this variability on the analyses, it was 



