Essington et al.: Shifts in the estuarine demersal fish community after a fishery closure in Puget Sound, Washington 
207 
Figure t 
Map of the locations of the study area (rectangle at the center) where bottom trawl surveys were 
conducted in Port Madison from 1991 to 2012 and of 2 nearby monitored sites (labeled West point 
and Jefferson Head) where time series data on environmental conditions, such as temperature and 
surface salinity, were recorded. Map inset in upper-right corner shows location of Puget Sound, 
Washington, along the U.S. Pacific coast, and map inset in lower-left corner shows detailed view of 
the Port Madison study area and locations of 4 sampling sites with corresponding depths listed. 
of 5 m and net width of 3.5 m during fishing. 5 The bot- 
tom trawl was fitted with a 3.8-cm body mesh and 3.2- 
cm codend mesh with a 0.4-cm codend liner. The net 
primarily targets flatfishes but also catches small de- 
mersal fishes, such as gadids and some elasmobranchs. 
Fish were identified to species on deck with the aid 
of dichotomous keys (Hart, 1973), but a few individu- 
als were retained for examination in the laboratory. We 
measured fork length for all species except length of 
Spotted Ratfish ( HycLrolagus colliei), for which precau- 
dal length (tip of snout to second dorsal fin; Anderson 
and Quinn, 2012) was measured; all length measure- 
ments were made to the nearest millimeter. Consisten- 
cy in field identification was facilitated by the presence 
of one of us (T. Quinn) for virtually every tow in the 
entire time series. 
J Eaton, C. M., and P. A. Dinnel. 1993. Development of a 
trawl-based criteria for assessment of demersal fauna (mac- 
roinvertebrates and fishes): pilot study in Puget Sound, 
Washington, 87 p. Final report to the U.S. Environmental 
Protection Agency. Bio-Marine Enterprises, Seattle ,WA. 
Environmental data 
We obtained data from 2 monitoring sites on water- 
column characteristics (temperature and salinity pro- 
files) for March, April, and May. The King County 
Water and Land Resources Division samples a loca- 
tion 4.4 km northeast of Port Madison called Jeffer- 
son Head, and the Washington State Department of 
Ecology samples a location 8.5 km southeast of Port 
Madison called West Point — both on a monthly basis 
(Fig. 1). We used data from both of these sampling pro- 
grams (1990-2008 for West Point, 1992-2008 for Jef- 
ferson Head) to identify years and time periods with 
unusual environmental conditions on the basis of sub- 
mixed-layer temperature and surface salinity. Surface 
salinity gives a measure of seasonal runoff and, there- 
fore, indicates seasonal weather events (years with 
high precipitation have low surface salinity). Sub- 
mixed-layer temperature is indicative of the thermal 
habitat experienced by groundfishes. Sub-mixed-layer 
temperature was used instead of bottom temperature 
because the latter was not always sampled. When bot- 
