Kuykendall et al.: A management strategy evaluation for Spisula solidissima 
301 
Weinberg, 2005; Munroe et al., 2013; Hofmann et a!., 
in press). Early evidence of this trend is the disappear- 
ance of Atlantic surfclams in Virginia and Maryland 
state waters between the 1970s and the 1990s (Loesch 
and Ropes, 1977; Powell 4 ; Hofmann et al., in press) and 
the shift of the southern fishery from the Delmarva 
Peninsula to ports north (Powell et al., 2015). From the 
1997 to 1999 period, the Atlantic surfclam population 
was considered to be near carrying capacity (NEFSC 2 ). 
Abundances were once high on the continental shelf off 
the Delmarva Peninsula, but declines in growth, maxi- 
mum size, and tissue weight (Weinberg, 1998, 1999) 
were accompanied by increased mortality in this region 
(Weinberg, 2005; Weinberg et al. 5 ). Separate fisheries- 
independent surveys conducted in 2002 by the North- 
east Fisheries Science Center of the National Marine 
Fisheries Service (NMFS) and the New Jersey Depart- 
ment of Environmental Protection revealed that a large 
mortality event had occurred sometime after 1999 that 
extirpated Atlantic surfclams from the southern in- 
shore region off Delmarva Peninsula, followed by stock 
declines in both state and inshore federal waters off 
New Jersey (Powell 4 ; Kim and Powell, 2004). An addi- 
tional survey conducted in 2004 (Weinberg et al. 5 ) con- 
firmed the northward and offshore shift in the Atlantic 
surfclam stock. 
One result of these mortality events was the re- 
distribution of the stock north: namely an increasing 
abundance off the coast of Long Island, New York; the 
expansion of the population on Georges Bank; and the 
movement of the seaward boundary of the southern 
portion of the stock offshore in response to increased 
bottom water temperatures (Weinberg, 2005; Munroe 
et al., 2013; NEFSC 2 ). Simulations by Narvaez et al. 
(2015) based on stock assessment data from the North- 
east Fisheries Science Center and bottom temperature 
time series obtained through implementation of the 
Regional Ocean Modeling System for the northwestern 
Atlantic indicated that episodic warm years caused el- 
evated mortality events in older and larger clams and 
that these events have occurred with increasing fre- 
quency over the last several decades of the 20 th centu- 
ry. In the simulation study, Narvaez et al. (2015) found 
that thermal stress decreased the Atlantic surfclam 
stock by 2-9% on the shelf regions that coincide with a 
majority of the regions used by the commercial fishery. 
The Atlantic surfclam reaches marketable sizes of 
120 to 150 mm SL within 6-7 years depending upon 
food availability and water temperature (Weinberg, 
1998; Cargnelli et al., 1999; Weinberg et al., 2002; 
NEFSC 2 ). Growth rates within the first 3 to 5 years 
4 Powell, E. N. 2003. Maryland inshore surf clam, Spisula 
solidissima, survey August 2003 cruise report. Final report 
to J. H. Miles & Co. Inc., 19 p. Haskin Shellfish Research 
Laboratory, Port Norris, NJ. 
5 Weinberg, J. R., E. N. Powell, C. Pickett, V. A. Nordahl Jr, and 
L. D. Jacobson. 2005. Results from the 2004 cooperative 
survey of Atlantic surfclams. U.S. Dep. Commer., Northeast 
Fish. Sci. Cent. Ref. Doc. 05-01, 41 p. [Available from web- 
site.] 
have been reported to be similar across much of the 
range of the Atlantic surfclam before the 1999 mortal- 
ity event (Cargnelli et al., 1999). Increased bottom wa- 
ter temperatures above approximately 20°C negatively 
affect Atlantic surfclam nutrition by reducing ingestion 
rate and leading to a reduction in growth rate, condi- 
tion, and maximum size (Marzec et al., 2010; Munroe 
et al., 2013; Munroe et al., 2016). Munroe et al. (2016) 
found that the maximum size had, in fact, declined 
for much of the stock since 1980. Simulation modeling 
of Atlantic surfclam population dynamics shows that 
this outcome can be derived solely from rising bot- 
tom water temperatures (Munroe et al., 2013, 2016), 
although a change in food supply would result in the 
same outcome. 
Along the Mid-Atlantic coast, the Atlantic surfclam 
has supported a fishery since the 1960s that reached 
total revenues of $29 million in 2011 (Weinberg, 1999; 
Weinberg et al. 5 ; NEFSC 2 ). The average rate of fishing- 
induced mortality (commonly termed “fishing mortal- 
ity”) in the stock south of Hudson Canyon has been 
higher than the fishing mortality rate over the whole 
stock and of the northern region since 2002; however, the 
fishing mortality rate, which historically has been less 
than 25% of the natural mortality rate (M=0. 15/year), 
remains below the natural mortality rate (NEFSC 2 ). 
For the last 30 years, most of the commercial land- 
ings within the U.S. Exclusive Economic Zone have 
been harvested along the coast of New Jersey and 
the Delmarva Peninsula (Weinberg, 1999; NEFSC 2 ). 
Landings in this region within the last decade have 
declined coincident with the latest phase of contrac- 
tion in the distribution range of this species. According 
to the latest stock assessment, the Atlantic surfclam 
is not overfished, and overfishing is unlikely to occur 
in the next 5-7 years (NEFSC 2 ). However, declining 
stock abundance has led to the termination of a once 
thriving clam fishery in the most southerly portions 
of its range since 2000. A decline in landings per unit 
of effort (LPUEs), coupled with rising fishing moral- 
ity rates, has generated concern for the sustainability 
of the stock off New Jersey (Powell 4 ; Weinberg et al. 5 ; 
NEFSC 2 ). The reopening of Georges Bank for harvest- 
ing of clams in 2010 (NOAA, 2012) — an area that was 
closed in 1990 owing to the risk of harvesting clams 
contaminated with paralytic shellfish poison (Jacobson 
and Weinberg 1 ) — allowed some relief from fishing pres- 
sure in other regions, but landings over much of the 
remainder of the stock continue to produce the steady 
decline observed since 2008 (Fig. 1) (NEFSC 2 ). 
Declining abundance and LPUE south of Hudson 
Canyon have driven stakeholders’ desire to enhance 
production in the New Jersey portion of the stock (Fig. 
1), possibly through the implementation of area man- 
agement, which has proven to be a useful tool for im- 
proving production in fisheries of sessile species (Pow- 
ell et al., 2008; Cooley et al., 2015). Examples of fish- 
eries where implementation of this strategy has been 
successful are the fisheries for sea scallop ( Placopecten 
magellanicus ) in the Mid-Atlantic Bight (MAB) and 
