124 
Fishery Bulletin 107(2) 
0.0x10° 5.0x10 9 I.OxlO 10 1.5x10 10 2.0x10 10 2.5x10 10 
Oyster (>20 mm) abundance 
3.0x10 10 3.5x10 10 4.0x10'° 
Figure t3 
The relationship between oyster abundance and unrecorded mortality for the 
eastern oyster ( Crassostrea virginica ) in 1953-2006 for the natural oyster beds 
of Delaware Bay. Irrational (positive) values on the ordinate indicate survey 
imprecision. 
-0.60 -0.40 -0.20 0.00 0.20 0.40 
Fraction of population dying (unrecorded mortality) 
Figure 14 
The relationship between box-count mortality and unrecorded mortality of the 
eastern oyster (Crassostrea virginica ), 1953-2006, for the natural oyster beds 
of Delaware Bay. Irrational (positive) values on the abscissa indicate survey 
imprecision. 
originally established circa 1970. 
In this scenario, these years were 
not unique. Nevertheless, for 
both cases, the performance of 
the stock was not representative 
of the dynamics defined by the 
remaining 50 years of observa- 
tion. As a consequence, a math- 
ematical relationship weighting 
these four observations overly 
much (e.g., the polynomial fit in 
Fig. 7) would not appropriately 
parameterize a model of the stock 
either in its high-abundance or 
low-abundance state. 
The influence of spatial 
relationships on 
population dynamics 
The relationships between brood- 
stock, recruitment, and mortality 
expressed by Equations 4 and 6 
and by Figures 7 and 9 attempt to 
portray the time series of obser- 
vations in terms of the ambit of 
the stock’s population dynamics. 
In fact, in one sense, this mis- 
represents the true range of the 
species’ population dynamics at 
any particular time because the 
ambit of the stock in one regime 
differs from that of the other. 
First-passage times support this 
conclusion, as does a closer look 
at the distribution of abundance, 
recruitment, and mortality for the 
four bay regions over the full time 
series (Powell et al., 2008). 
Consider first the broodstock 
abundance-recruitment relation- 
ship (Fig. 7). We identify two sets 
of points characteristic of times 
when the stock was relatively 
consolidated within its distribu- 
tional range (Fig. 16). In these 
periods, a large proportion of the 
stock was found on the medium- 
mortality beds (Fig. 5). Such an 
occurrence was characteristic of 
the stock in both low- and high- 
abundance regimes and for ex- 
tended periods of time, including 
most years between 1960 and 
1963 (low-abundance regime), the 
1970-77 period (high-abundance 
regime), and the 1997-2006 pe- 
riod (low-abundance regime). 
The 1970s occurrences all fall in 
quadrant 4 (high abundance+high 
