90 



Fishery Bulletin 98(1) 



were caught in oyster tongs during oyster harvest- 

 ing, which was conducted from October 1996 to March 



E 

 m 



i 



100 

 90 

 80 

 70 

 60 

 50 

 40- 

 30 

 20- 

 10- 

 



Pages Creek 



o 



Q. 



100 

 90 

 80 

 70- 

 60 

 50- 

 40 

 30 

 20- 

 10 

 



Whiskey Creek 



Harvest type: h 



o 



o 



o 

 Before 



Clams 



+ 

 Oysters 



£ 



TO y; 



" c 

 After 



5 Clams 

 •S, * 



>- Oysters 



Figure 2 



Mean percentage of oysters found dead before ( 5-10 July 

 1996 ) and after ( 10-23 July 1997 ) application of experimen- 

 tal harvest treatments in Pages and Whiskey Creeks. NC. 

 Data are means and one standard error (n =4 ) of counts taken 

 within 0.25-m'^ quadrats. Results of SNK pos< hoc compari- 

 sons are illustrated with letters above bars (a>b at P<0.05). 

 Separate ANOVAs and SNK tests were used to compare 

 numbers of dead oysters before and after harvesting. 



Table 2 



Mean number of clams and oysters removed from intertidal oyster reefs during 

 experimental harvesting. Reefs were harvested for clams (clamming), oysters 

 (oystering), both (clamming and oystering), or neither (controls). Transplanted, 

 hatchery-raised clams were not removed during harvesting. 



Pages Creek 



Whiskey Creek 



Harvest treatments Clams 



Oysters 



Clams 



Controls 



Clammmg 3.47 ±1.1 11.77 ±7.37 



Oystering 1.15 ±0.22 69.20 ±9.20 5.05+2.89 43.27 ±14.10 



Clamming and 

 oystering 



3.46 ±0.75 89.40 ±58.32 12.59 ±5.84 34.97 ±8.26 



1997. In both creeks, two to three times the number of 

 clams were harvested during clam harvesting treat- 

 ments than during oyster harvesting. Similar num- 

 bers of clams were removed from reefs in the clam 

 harvesting and the combined clam and oyster har- 

 vesting treatments. Similar numbers of oysters were 

 removed from plots harvested for oysters only and 

 from those harvested for both oysters and clams (Table 

 2). According to visual observations, both types of har- 

 vesting inflicted obvious wounds (holes and cracks) to 

 the shells of oysters (range: 5-13 individuals within 

 each plot) that were not removed by harvesting. 



In July 1997, after experimental clam and oyster 

 harvesting, the density of live and dead oysters, and 

 the proportion of dead oysters did not vary with the 

 interaction of creeks and harvest treatment (AN OVA; 

 creek x harvest treatment interaction, P=0.23-0.44; 

 Table 3). There was also no significant difference in 

 the density of live and dead oysters and the proportion 

 of dead oysters between the two creeks (P=0. 16—0.65; 

 Table 3). In contrast, there was a highly significant 

 effect of harvest treatment on the density of live oysters 

 and the proportion of oysters found dead (P=0.0001; 

 Table 3). At both sites, plots harvested for clams, oys- 

 ters, or both had 2-4.5 times lower densities of live 

 oysters and 2-2.5 times higher proportions of dead oys- 

 ters than did unharvested control plots (SNK, P<0.05 

 for both contrasts; Figs. 1 and 2). There were no dif- 

 ferences in the number of dead oysters among harvest 

 treatments. 



In July 1997, after experimental harvesting, the 

 density of live, naturally occurring hard clams varied 

 with the interaction of creeks and harvest treat- 

 ments (ANOVA, creek x harvest treatment interac- 

 tion, P=0.015; Table 4). At Pages Creek, there were 

 greater numbers of live, naturally occurring clams in 

 control reefs than in plots harvested for clams, oys- 

 ters, or both (SNK; P<0.05; Fig. 3). At Whiskey Creek, 

 there were more live, naturally occur- 

 ring clams in both control and oyster- 

 hai-vested plots than in plots harvested 

 for clams and for both species (SNK, 

 P<0.05 for both contrasts; Fig. 3). The 

 number and proportion of dead, nat- 

 urally occurring clams found in July 

 1997 did not vary with the interaction of 

 creeks and harvest treatment (ANOVA, 

 creek x harvest treatment interaction, 

 P=0.09-0.87; Table 4), or between 

 creeks (P=0.16-0.10; Table 4). There 

 was also no significant effect of harvest 

 treatment on the density of dead, nat- 

 urally occurring clams (P=0.17; Table 

 4). However, there was a significant 

 effect of harvest treatment on the pro- 



Oysters 



