Duffy-Anderson et at: Stage-specific vertical distribution of Pleuronectes qucidrituberculatus eggs 
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175°0'0"W 170°0'0"W 165°0'0"W 160°0'0"W 155WW 
Figure 1 
Map of study region (inset) and stations where eggs of Alaska plaice (Pleuronectes quadritubercula- 
tus) were collected with the multiple opening and closing net and environmental sampling system 
(X) and neuston net (•) tows in the eastern Bering Sea during 2002-06. The polygon delineates the 
sampling area. 
Materials and methods 
Alaska plaice eggs were obtained from a series of 
fisheries research cruises conducted by the Alaska 
Fisheries Science Center (AFSC) along the Alaska 
Peninsula in the eastern Bering Sea in 2002, 2003, 
2005, and 2006 (Fig. 1, Table 1). Eggs were collected 
from surface waters (<0.5 m depth) with a Sameoto 
neuston net with 505-pm mesh (Sameoto and Jaro- 
szynski, 1969; Jump et al., 2008). Depth-discrete 
sampling was conducted by using a 1-m 2 multiple 
opening and closing net and environmental sampling 
system (MOCNESS; Wiebe et al., 1976) with 505-pm 
mesh nets in 2003 and 2005. Depth intervals sampled 
were 0-10 m, 10-20 m, 20-30 m, 30-40 m, 40-50 m, 
and >60 m. Oceanographic variables were collected 
simultaneously with all sampling, and these data 
have been published elsewhere (Duffy-Anderson et 
al., 2010). 
All eggs were fixed in 5 % formalin, sorted, identi- 
fied, and enumerated at the Plankton Sorting and 
Identification Center in Szczecin, Poland. Egg identi- 
Table 1 
Number of Alaska plaice ( Pleuronectes quadritubercu- 
latus) eggs collected and staged by year and gear type. 
MOCNESS =multiple opening and closing net and envi- 
ronmental sampling system. 
Year 
Cruise 
dates 
Gears used 
Number of eggs 
collected 
and staged 
2002 
12-21 May 
Neuston net 
16 
MOCNESS 
2 
2003 
17-24 May 
Neuston net 
26 
MOCNESS 
353 
2005 
10-20 May 
Neuston net 
295 
MOCNESS 
867 
2006 
8-19 May 
Neuston net 
615 
fications were verified, and Alaska plaice eggs were 
measured and staged at the Alaska Fisheries Science 
Center in Seattle, WA. 
