SPOTLIGHT: ATLANTIC STRIPED BASS

INTRODUCTION

	The striped bass, Morone saxatilis, has played an important role in the life of U.S. Atlantic coast communities since the days of the colonists. In 1637 Thomas Morton wrote  The basse is an excellent Fish,  which  for daintiness of diet, excell the Marybones of Beefe... I ... have seene such multitudes passe out of a pound, that it seemed to mee, that one might goe over their backs drishod. 1  In 1670, the first public school in the New World was funded in part through taxes on sales of striped bass.2  In succeeding centuries, striped bass stocks would undergo dramatic fluctuations in abundance; however, the importance of striped bass to coastal communities has never diminished.
Also called rockfish or rock, the striped bass is anadromous, spawning in brackish to freshwater reaches of estuaries. Once distributed from Canada to northern Florida, Atlantic coast spawning stocks are now reduced to three major areas: Hudson River, Chesapeake Bay, and the Roanoke River. Most juvenile striped bass live in estuarine waters for the first several years of life, and then they migrate to coastal waters of southern New England and the Gulf of Maine to feed. In spring, the mature bass return to brackish or freshwater reaches to spawn. The Chesapeake and Hudson stocks produce most of the fish which sustain east coast fisheries; Roanoke fish appear to be less migratory than the more northern stocks. Striped bass can reach a size of 75 pounds or more and probably live at least 30 years.
As early as the mid-1700's, concern over depletion of striped bass stocks began to surface. Several reports of that era document scarcities caused by  very great numbers having been imprudently, or rather wantonly taken in one season. 3 More recently, similar concerns have been raised, particularly over the status of the Chesapeake Bay stock. During the late 1960's and early 1970's, Chesapeake Bay produced the majority of striped bass found in coastal waters. Strong year classes had been produced about every 2-4 years, with an exceptionally large one appearing in 1970. Commercial landings were rising steadily and reached a peak of 6,700 metric tons (t) in 1973. Then the picture began to change. Year after year, strong year classes failed to appear. Landings began a sharp decline and by 1983 had slipped below 1,000 t (Fig. 1). This situation alarmed fishermen, biologists, and managers alike, and prompted unprecedented research and conservation efforts. 

STRIPED BASS MANAGEMENT

	Prior to 1981, no comprehensive management plan existed for Atlantic striped bass; however, many of the states from North Carolina to Maine had started issuing their own regulations by the 1940's. These typically included minimum size limits of 10-12 inches in states south of New Jersey and around 16 inches in the northerly states. While the regulations may have provided some measure of protection, they were clearly inadequate to preserve spawning stocks in the face of escalating fishing pressure. To complicate matters, the migratory habits of striped bass meant that if only some states raised their size limits, fish protected by one state would likely be harvested by others. A cooperative approach to management was needed. This prompted the Atlantic States Marine Fisheries Commission (ASMFC) to begin development in 1979 of an interstate striped bass management plan.
The ASMFC, a compact of 15 Atlantic coast states and jurisdictions, was formed in 1942 to promote conservation of shared fishery resources. Although it had no regulatory authority, the ASMFC provided a forum for developing management recommendations which coordinate conservation efforts among its member jurisdictions. In 1981, the ASMFC adopted its  Interstate Fisheries Management Plan for the Striped Bass  which called for minimum size limits of 14 inches total length (TL) in bays and estuaries and 24 inches TL along the coast. In addition, the plan recommended that major spawning areas be closed to fishing during the spawning season. The plan's recommendations were gradually adopted by most states; however, striped bass recruitment remained near record low levels.
Recognizing that more stringent measures were necessary, ASMFC amended the plan three times during 1984 and 1985 to further restrict fishing. The first two amendments set general targets for reducing fishing mortality rates and allowed flexibility in the methods for achieving reductions. The third and most stringent amendment focused on protecting the 1982 year class, which, though only average, was the best since the plan had been implemented. Specifically, the amendment recommended that the states protect 95% of the females of the 1982 and subsequent year classes until 95% had an opportunity to spawn. This meant each state must either institute a complete moratorium on fishing or increase minimum size limits to stay ahead of the females' growth. Most states chose to increase size limits. Since 95% maturity of Chesapeake Bay striped bass probably does not occur until age 8, size limits would have to reach 38 inches TL as 1990 approached. The sliding size limits were tantamount to a closure, since there were virtually no fish remaining from earlier year classes which might exceed the size limits.
ASMFC's adoption of the third amendment to the plan, with its drastic measures, was a major milestone in the attempt to restore Chesapeake Bay striped bass. Equally important, however, was passage by the U.S. Congress of the Atlantic Striped Bass Conservation Act (Conservation Act) in 1984. This law significantly streng-thened the ASMFC's position by providing an indirect mechanism, beyond consultation and prescription, that stipulated that if any state did not comply with the plan, that state would be subject to a Federal moratorium on striped bass fishing in its waters. Because ASMFC does not have explicit regulatory powers over striped bass, its plans are only recommendations to the states; prior to the Conservation Act the states could simply ignore the recommendations if they chose. It seems likely that few states would have fully complied with the third amendment, given the political and economic unpalatability of its measures. Indeed, Federal moratoria had to be threatened in several instances and implemented once before regulations were brought into compliance with the plan. Further, the Conservation Act ensured equality   that all states would share equally in the hardship imposed by the plan. 
An additional act of Congress prompted by the striped bass decline was to play an important role in supporting striped bass management. In 1979, the Anadromous Fish Conservation Act was amended to provide for an  Emergency Striped Bass Study.  This study, now the  Striped Bass Study  (SBS), was to monitor the status of the striped bass stocks and determine the reason(s) for the decline of the coastal population. Because striped bass occur pri- marily in coastal waters, fishery-independent monitoring is conducted by the states. During the 1970's, monitoring efforts were so sporadic that it was not even possible to demonstrate definitively that the decline in landings was due to a decline in the stock. Fishing mortality rates were not available and the status of the spawning stock was not clear. In addition, the reasons for the decline were poorly understood. The SBS provided funding and a Federal administrative framework for developing a coordinated research program involving states, universities, and private corporations.
The two Acts of Congress forged a unique partnership between the states and the Federal government. While the states have primary responsibility for management through the ASMFC, the Federal government plays a strong role through the Conservation Act and the SBS. Federal responsibility in both areas is shared equally between NOAA's National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS). The NMFS has primary responsibility for overseeing monitoring programs through the SBS, and the USFWS has the lead on investigating causes for the decline. Both agencies are jointly involved in all decisions emanating from the Conservation Act, including the imposition of any Federal moratorium. In addition, the Federal agencies participate in the ASMFC management process by providing voting members to the striped bass scientific committees and the management board. 

CAUSE OF THE DECLINE

	When the SBS was organized, a number of hypotheses were formulated which could explain the decline of the Chesapeake stock. These included the effects of ecological interactions such as competition, predation, and starvation; environmental problems including eutrophication, toxic contaminants, degradation of water quality, and changes in water use practices; the occurrence of unfavorable natural climatic events; disease; and overfishing. Not all hypotheses could be evaluated equally well. For instance, with striped bass populations at extremely low levels, it was difficult to address hypotheses dealing with ecological interactions. Further obstacles to reaching a definitive conclusion included the retro-spective nature of the problem and the likelihood that several interacting factors were involved.
Despite the difficulties, significant progress has been made in clarifying probable causes of the decline of the Chesapeake stock. It is highly likely that excessive fishing pressure decimated the spawning stock and set the stage for the decline. Reproductive success of the remaining spawners may have been compromised by water quality problems which reduced survival in the early life stages. Additional factors may have also contributed, but their role is less clear. 
The evidence implicating overexploitation is piecemeal but compelling. Fishing mortality estimates from the 1970's are insufficiently frequent to reveal trends; however, the intermittent estimates that exist are extremely high. Along the coast, annual fishing mortality estimates range from 24% to 59% per year. Estimates from Chesapeake Bay indicate total annual mortality rates of 45% on 1970 year-class females at age 6 and 93% on males at age 5. Models predicting mortality rates needed to explain observed catches during the 1970's similarly suggest excessive fishing mortality. Recreational fishing effort increased steadily throughout the 1960's and 1970's. In the absence of significant conservation measures, striped bass fishing mortality undoubtedly followed a parallel trend. 
The evidence suggesting that water quality problems may have contributed to the decline is based primarily on in situ bioassays conducted during the 1980's. Historical data on pH in major spawning rivers have been examined, but no evidence of a general decrease in pH or of increased frequency of low pH events has been found. However, the data would have been adequate only for detecting major changes, not changes on small spatial or temporal scales. The importance of small-scale effects was clearly demonstrated during larval bioassay tests conducted in 1988. A low-pH rainfall occurred which decreased the pH in a nursery area of the Nanticoke River from 7.2 to the low 6's in an 8-hour period. Within 24 hours, the pH had returned to normal. Mortality of larvae held in the river water was 100% during the 24-hour period of the pH excursion, whereas mortality of controls held in well water was only 10%. This and several years of in situ bioassays, water quality monitoring, and laboratory experimentation suggest that conditions that could periodically cause catastrophic mortality do occur in some (but not all) spawning and nursery areas of Chesapeake Bay. Whether the frequency of such events increased during the 1970's or was severe enough to cause a decline remains unknown.
Excessive fishing and episodic poor water quality could have had synergistic effects far more disastrous than either alone. Fishing reduced the number of striped bass and truncated the age composition of the spawning stock. This may have reduced the duration of the spawning season as well as the number of eggs produced, since older fish appear to spawn earlier than younger fish. With spawning concentrated in a shorter time period, a catastrophic mortality event potentially could kill a larger proportion of a given year's spawn. An additional effect of the truncated age structure may have been to reduce viability of the spawn. Younger females not only produce fewer eggs than older ones, but their eggs are less viable as well.

POPULATION MONITORING

	Establishment of the SBS provided a unique opportunity to develop or 
expand monitoring programs at a time when a major management experiment was 
about to begin. Prior to the 1980's, fishery- independent monitoring for striped
 bass was limited to juvenile surveys conducted in New York, Maryland, and North
 Carolina waters. Virginia had begun a juvenile survey in 1967 but abandoned it
 after 1973. Occasional sampling to characterize the spawning stock had been 
conducted in all three stock areas; however, consistent, continuing programs 
for spawning stocks and the coastal migratory population had never been 
developed. In addition, sampling of commercial landings was inadequate for 
biological characterization of the catch.
	NMFS funding through the SBS was used to begin a juvenile survey in the
 Delaware River, to reestablish the juvenile survey in Virginia's waters, and 
to augment the existing survey in the Hudson River. Spawning stock sampling 
programs were initiated in the Chesapeake Bay and in the Hudson River. 
A program for monitoring the coastal stock during its fall migration was 
started. In addition to the sampling programs, a coastwide tagging study was 
established which involved most of the states from North Carolina through 
Maine. During the early 1980's, while commercial fisheries were still active, 
fishery-dependent monitoring was expanded in many of the states. 
	In addition to monitoring, the SBS funded research to reevaluate
 population characteristics such as maturation and migration rates. These 
were used directly in management and were critical to the development of
 models to predict the response of the population. For example, Amendment 3 
to the ASMFC's plan depended on estimates of maturation rates to develop the 
schedule of increasing size limits. At the time the amendment was written, 
the least biased maturation schedule available for Chesapeake Bay striped bass 
was developed during the 1930's and was based on only 109 females spread across 
six age classes.

POPULATION RESPONSE

	When spawning stock monitoring began in Maryland during the early 
1980's, females were virtually absent on the spawning grounds. Most were 10 
years old or older, rare survivors from the strong 1966 and 1970 year classes 
(Fig. 1). As the 1980's progressed and the 1982 year class began to mature, the
 protection afforded by the ASMFC plan began to be reflected in the spawning 
stock. Females of the 1982 year class began to make a significant contribution 
to the spawning stock as early as 1986, when they first began to mature. By 
1988, the 1982 and subsequent year classes were responsible for the bulk of 
the egg production. Older, more fecund females were very rare and contributed 
relatively little to the population fecundity after 1988.
	The results of the conservation efforts soon became apparent in other 
areas as well. Sampling of the migratory population showed that the bulk of the 
mixed stock was composed of members of the protected year classes. The Hudson 
stock, although never depressed, also benefitted from the regulations designed 
to protect Chesapeake fish in coastal waters. Recruitment in the Hudson reached 
record high levels, and the abundance of the spawning stock increased. Juvenile 
indices in Virginia rose to their highest recorded levels during the late 
1980's. The recreational catch increased, and over 90% were released alive as
minimum size limits continued to increase (Fig. 2). More recently, there is
evidence for a partially restored spawning stock returning to the Delaware 
River. 
	Despite the effectiveness of the ASMFC plan in rebuilding the stock, 
recruitment in Maryland's waters of the Bay remained at or near the lowest 
recorded levels throughout most of the 1980's. Then in 1989, the catch of 
juveniles was extremely high in portions of Maryland's Choptank River, 
producing a recruitment index which was second only to the index for the 
dominant 1970 year class. Recruitment in other Maryland nursery areas was not 
exceptional that year, but it was high in Virginia's waters of the Bay.
	The significance of Maryland's 1989 juvenile index went beyond its 
potential implications for recovery of the Chesapeake stock. Amendment 3 of 
ASMFC's plan stipulated that the stringent regulations protecting the 1982 
and subsequent year classes would remain in place until the 3-year average of 
the Maryland juvenile index exceeded 8.0, the approximate long-term average. 
Although the 1987 and 1988 juvenile indices were low, the 1989 index was 
sufficiently large to bring the 3-year average over 8.0 and to initiate a new 
management regime.

CURRENT MANAGEMENT

	Amendment 4 to the ASMFC's plan, adopted in October 1989, represents a 
new, adaptive approach to conservation of Atlantic striped bass. Its basic 
premise is that the populations must be managed first to restore and maintain 
the spawning stocks and secondarily for fishery yield. The management 
objectives are to be achieved by monitoring fishing mortality rates and 
adjusting regulations should the rates differ from target levels. Two levels 
of fishing mortality are identified. The first level is projected to allow the 
stock to continue to increase, although at a slower pace than under no 
exploitation at all. The second level is a maintenance level appropriate to 
a fully recovered stock. The decision to move from the restoration level to 
the maintenance level is to be based on several indicators of stock status, 
including recruitment indices and condition of the spawning stock. 
	Under Amendment 4, the states have been allowed to relax regulations 
and prosecute tightly controlled fisheries since 1990. Along the coast, minimum 
size limits for the recreational fishery now range from 28 to 36 inches. 
Minimum size limits are lower (e.g. 18 inches) in estuarine waters because 
larger striped bass are not available except during the spawning season. In 
addition to size limits, daily bag limits of 1-2 fish are imposed, and some 
states enforce seasonal closures as well. One state (Maryland) employs a quota 
system to control its harvest. 
	The commercial fishery is much reduced compared to historical levels. 
Several jurisdictions have made striped bass a sport-catch-only species, and 
those which retain commercial fisheries impose strict seasonal restrictions in 
addition to minimum size limits. Commercial fisheries are further limited by
 harvest caps equal to 20% of each state's landings during 1972-79. Although 
not required by the plan, many states close their commercial fisheries if 
landings exceed the cap before the end of the open season.
	Adaptive management and the use of caps on commercial landings require 
intensive monitoring of stocks and fisheries. As part of Amendment 4, each 
state has certain monitoring requirements which it must carry out to be in 
compliance with the plan. For example, states with significant recreational 
fisheries must estimate their recreational catch with a coefficient of 
variation (a statistical measure of uncertainty) not to exceed 20%. States 
with spawning habitat must conduct spawning stock assessments and juvenile 
surveys. Most states are required to participate in fishery-independent 
monitoring and/or tagging studies used to estimate mortality rates. 
	Three years of fishing under Amendment 4 were completed as of the end 
of 1992. Fishing mortality estimates during these three years have approximated 
the target rates. Some liberalization of regulations has occurred since 
fisheries reopened in 1990; however, most states have voluntarily kept their 
regulations more stringent than allowed by the amendment. Indices of adult 
stock status show continued broadening of the age structure and increased 
abundance in many areas. Recruitment in Maryland's waters was poor in 1990 
and 1991; however, in 1992 recruitment rose to average levels and in 1993 
exceeded all previous record highs. The 1993 index was particularly encouraging
because juveniles were abundant in many areas of the Chesapeake Bay. 
Recruitment was similarly high in other spawning stock areas during 1993.

CONCLUSIONS

	The Atlantic coast striped bass fisheries of the 1970's and 1980's can 
be viewed as a large-scale experiment in fisheries management, the results of 
which are still being evaluated. Several lessons have been learned and more 
undoubtedly remain to be uncovered.
	Perhaps the key to setting the stage for recovery of the Chesapeake 
striped bass stock was the Atlantic Striped Bass Conservation Act, which lent
 authority to the ASMFC's plan. Without the clout provided by the Conservation 
Act and its assurance of equality among the states, political and economic 
impediments undoubtedly would have prevented the states from undertaking the 
dramatic measures recommended in the plan. 
	Historical precedence is often invoked as a reason to continue unwise 
fishery management practices. The striped bass experience demonstrates that it 
is possible to break with long-established patterns. Unfortunately, the striped
bass stock had to be driven virtually to economic extinction before significant 
changes were made. As Jeremy Belknap wrote in 1792 regarding depletion of 
striped bass in the Piscataqua River,  After the mischief was done, a law was
 made against it... 4  ASMFC and the states have wisely embarked on a new 
management regime as the stocks recover, rather than returning to former ways. 
Hopefully, they will resist the temptation to allow overharvesting as the stock 
becomes fully restored and will prevent the mischief of the 1970's from 
recurring.
	At present, much is being learned about applying the concept of 
adaptive management to Atlantic striped bass. In practice, a major commitment 
of time and money as well as extensive cooperation among the states is needed. 
A potential roadblock in the striped bass process is the mismatch between 
monitoring required by the plan and the ability of the states to supply the 
funds and manpower to conduct it. Without <%-2>extensive monitoring, 
information will be in<%0>-adequate to guide management changes, yet no 
dedicated funds exist for conducting this research. Along similar lines, 
the issue of deciding whether management targets are met is not a trivial one. 
Uncertainty in parameter estimates can be used in the political arena to 
justify avoiding action when a management change would be the conservative 
response.
	The positive response of Atlantic striped bass populations to the 
management initiatives of the 1980's provides a dramatic demonstration of 
the impact that effective fishery management can have, and furnishes an 
encouraging example for other seriously overexploited fisheries. Building on 
this experience, Congress passed new legislation in late 1993 extending the 
striped bass management paradigm to other Atlantic coastal species. 
	The increase in the spawning stock and improved recruitment in 1992 
and 1993 are cause for optimism that the Chesa-peake population is truly on 
the road to recovery. However, it would be premature at this point to consider 
the cure complete. To the extent that water quality problems compromise early 
life-stage survival, strong year classes may occur infrequently despite the 
improved status of the spawning stock. To ensure the best chances for a 
complete, sustained recovery, diligent conservation efforts must continue 
into the future.

FOOTNOTES

1Thomas Morton. 1637. New English Canaan, or New Canaan, Containing an Abstract 
of New England. Amsterdam. Cited in Fearing, D.B. 1903. Some early notes on 
striped bass. Trans. Am. Fish. Soc. 33:90-98.
2Pearson, J.C. 1938. The life history of the striped bass, or rockfish, Roccus 
saxatilis (Walbaum). Fish. Bull. 49:825-860.
3Samuel Tenney, in  Topographical Description of Exeter in New Hampshire, in 
Massachusetts.  Historical Society Collections, 1st Series (Boston, 1795) IV.
4Jeremy Belknap in  History of New Hampshire,  Boston, 1792.