Why the Atlantic blue crab should be called a “beautiful swimmer” (Callinectes) strains the imagination. That their flesh is tasty (or “savory,” sapidus) is beyond dispute. With their sleek profile, spiked shells, eyes positioned at the tips of short optical stalks, menacing mouths, and jagged claws ever quick to strike, the blue crab looks more devilish than beautiful.

Of the 998 species of crab identified and named by the late Dr. Mary J. Rathburn, the pre-eminent carcinologist (a term most correctly used to distinguish crab studying scientists, not cancer researchers) who coined its Greek/Latin label, the blue crab is the most caught, sought and consumed of all the world’s crabs. Perhaps that popularity among consumers and the economic value they represent to those who rise before dawn to pursue them accounts for their attractiveness or simply underscores the adage that beauty indeed is in the eye of the beholder.

In one sense, large male blue crabs, “jimmies” in Bay parlance, with their pure white abdomens, green top shell and azure blue trim along their claws and legs are a sight to behold. Male blue crabs are distinguished from females by the shape of their segmented abdomens (and the red tint to the underside of female claws). Most describe the male abdomen as an inverted T and the females to more of a triangle or inverted V. Natives to the National Capital area, however, liken the identifying characteristics to national monuments: the Washington monument’s obelisk shape for the male and the Capitol’s dome for the female.

Crab growth takes place by molting or shedding the shell. During the molt, the crab develops a soft, new shell beneath the hard old shell prior to its being discarded. The initial indication that the molt is underway comes when a black line forms along the rim of the paddle and turns pink or red. At that point the shedding crab is called a “peeler” or “shedder.” With the old shell cast off, the crab is officially a “soft” or “soft shell” crab. Twelve hours later the “soft shell” crab transforms into a “paper shell.” Full hardening occurs within two or three days. Male crabs continue to molt and grow throughout their lives, approximately three years in duration. Females grow only until they reach sexual maturity after 21 or 22 molts.

Mating occurs from May to October after immature females, “she crabs,” achieve their final molt. A mature male will cradle the immature female as she prepares for her entrance into maturity. In this state they are known as “doublers.” The male releases the female to allow her the opportunity to shed her shell. After the molt, the “she crab” is now officially a “sook” or mature female. She lies on her back, opens her abdomen, and receives the male’s sperm during the one and only time mating occurs in her lifetime. Stored sperm from the encounter allows her numerous spawnings thereafter. After mating the soft-shelled sook is gathered back beneath the male until her shell hardens.

Male and immature female crabs head to shallow grass beds, muddy bottoms, and even the center of the Bay itself at the on set of low water temperatures. The sook sets off for the saltier waters near the Ocean. At anywhere from two to nine months after mating (depending on the time of mating), the female begins to develop an external egg mass on the underside of her abdomen. Her 750,000 to eight million eggs develop in the “sponge” that changes from orange to brown, then black. Sponge crab eggs hatch over a two-week period from June through September.

The microscopic larvae are called zoea and look like the inspiration for Hollywood’s evil bug-like space aliens and even more menacing than the blue crab they will eventually become. Carried by winds and currents, the zoea settle on the sea grass beds of their spawning and, after six or seven molts, become clawed critters named megalops. From the post larval megalops comes the first stage where they actually can be identified as a crab, albeit tiny, about a fifth of an inch from shell point to point.

By the turn of the 20th century, more than 13 million Maryland soft crabs were being sent from Crisfield and nearby Deale Island to a lucrative and an ever-northward developing market. After World War I, the New Jersey crab fishery went bust and crabs from the Chesapeake controlled the insatiable New York demand.

At strategic locations throughout the Bay, crab-picking houses provided work for women and minorities. Paid by the pound, minority pickers lived in row shanties. Men spent their winter days tonging for oysters. With the coming of warmer weather, crabs became their prey. The women, more nimble of finger, picked 4 pounds of meat an hour from 20 to 30 crabs with many tallying 40 or 50 pounds per eight-hour day.

Sent fresh and packed in ice, Chesapeake Bay crabmeat became a highly desirable luxury. In 1951, Cifford Byrd of Byrd Seafoods, created the first crabmeat pasteurization project. His plan was simple. A quick heat at 185 degrees Fahrenheit followed by a long immersion in icy water was found to extend shelf life of seafood.

Crabs flowed from the Chesapeake during the 20th century, the way Oysters did the century before. Total hard and soft shell harvests for the year of the Great Depression, 1929, was 68 million pounds. While annual yields fluctuated from a low of 39 million pounds (1934) to a record high of 97 million pounds (1966), average years saw 60-plus million pounds of crabs heading for market from the Chesapeake. (Warner 1976)

Watermen put in the bulk of their day’s work long before the sun appears on the Chesapeake’s horizon. Crab season traditionally runs from Spring through the Summer into early Autumn. In winter, Virginia crab dredgers rake the Bay’s bottom.

Crab pots, galvanized metal mesh traps that lure crabs with the promise of menhaden or herring, are the primary means of harvest. A full 60 percent of Maryland-caught hard crabs are taken in pots. Pot men retrieve each of hundreds of pots, empty captive crustaceans, and re-bait where necessary before dropping the pot back into position and moving on to the next pot.

Trotlines, used by watermen reputed to catch the largest “whales” of the crab industry, use eel or bull lips tied off at regular spacings. Either bait is tough enough to resist being pulled from the line by voracious crabs. The waterman patrols the length of the line dipping a net beneath his catch one bait at a time. For non-marsh men, it’s backbreaking work that distinguishes the city slicker from the waterman in less than a gnat’s breath. It takes its toll of watermen too. When the sun becomes unbearable, trotlines are retrieved and the shallow draft crafts with the day’s harvest head for shore and market.

Soft crabs and peelers use scrapes, peeler pots and bank traps. Working the soft and peeler crab market is a skill in itself and quite lucrative. One New York restaurant alone, the 21 Club, sold more than 40,000 soft crabs in 1976. That same year Philips Seafood Restaurant, an Ocean City, Maryland landmark, averaged 5000 a day during the peak summer months. (Warner 1976)

Until recently watermen could vary their work on the Bay beyond the oyster – crab cycle. Some worked pound nets, complex stationary net enclosures held in position by hundreds of long, sturdy wooden 65-foot poles driven deep into the Bay’s bottom. Herring are the first schools herded into the nets. Then comes the menhaden. Most are processed into fish meal, cat food or crab bait. Pound net fishing peaked in Virginia’s waters in the 1930s when more than 2200 were staked in hopes of capturing schools of fish. Relatively few are fished today. (Blankenship, 1998) Even they are in peril of fading into extinction as pound nets are under the microscope of the Federal Endangered Species “Police” who suspect they are a threat to highly protected sea turtles cruising the Bay.

Some went after striped bass, bluefish, and other edible species. Some dredged for soft clams. Soft clams, Mya arenaria, the “mani-nose” or “mano” to old watermen, are dredged for New England palates. During the 1950s, Chesapeake Bay “manos” supplied 95 percent of the New England soft clam market. A decade later 600,000 bushels of Bay clams constituted 70 percent of the U.S. harvest.

Today, the Chesapeake Bay is in a state of peril according to biologists, politicians and watermen. Each, however, has a slightly different point of view as to causes and cures. On key issues such as the scarcity of oysters and the declining numbers of blue crabs few disagree.

A 1998 analysis of the state of the Bay’s health, painted a depressed portrait. Using Captain John Smith’s 17th century description of the Bay as the epitome with a 100 rating, the Chesapeake Bay Foundation said the Bay barely rated a 27 suggesting even that number was misleading. (Bay Journal, 1998)

Over-fishing is inevitably the first complaint. Certainly a persuasive case can be made by fishery critics. The Bay’s waters support 6145 commercially licensed crabbers, according to the number of commercial licenses issued. (MD DNR, 2000) Virginia issued 5316 commercial licenses that same year. (VMRC, 2000) The total 1999 Chesapeake Bay hard and soft crab harvest was 66,808,107 pounds. Of that amount 35,371,030 pounds came from Maryland. Virginia watermen took the remaining 31,437,077 pounds. Estimates by the Chesapeake Bay Stock Assessment Committee’s Technical Subcommittee (June 2000) state that Bay-wide commercial harvests exceeded 100 million pounds four times in the period from 1945-1998 with an average long-term catch around 70 million annually. Figures for the recreational catch don’t exist. But with approximately a half million Marylanders alone taking a few dozen crabs by nets or pots throughout the summer guesstimates run from 25 to 50 percent of the commercial catch.

A century and a half of constant crabbing with annual takes conservatively figured in the neighborhood of 50 to 60 million pounds (150 to 200 million crabs) places quite a “stress” on any eco-system and cannot be dismissed or discounted. One 1998 University of Maryland study found the Bay’s blue crab population had a full 20 years of biological overfishing. (AP, May 14, 2001) The U.S. Environmental Protection Agency saw a 70 to 80 percent decline in breeding age females. (Virginia-Pilot, May 14, 2001) Similarly, the Bay oyster harvest had been phenomenal for nearly two centuries.

Average oyster harvests through the first three quarters of the 19th century ran in excess of ten million bushels. In 1880 nearly 120 million pounds of oysters were dredged from the Bay bottom. The ensuing two decades saw fluctuations between 70 million and 110 million pounds. From the 1920s to the late 1950s harvests hovered between 30 and 35 million pounds, quite a decrease but still a heavy annual toll on Bay oyster stocks.

After 1981, the Chesapeake oyster catch nose-dived. A mere 162,000 bushels comprised the total 1995 yield. Less than 3 million pounds were harvested in 1999. Historically Virginia watermen out produced their Maryland cousins by nearly 30 million pounds in 1880 and at least equaled Maryland numbers throughout the 20th century by 1999 the Virginia harvest dipped to a scant 346234 pounds versus Maryland’s 2,439,995.

The harvest of so many oysters for so long a period definitely sets the scene for an over-fishing scenario. However, there are any factors, in addition to fishing pressure, that affect oyster stocks.

For one, the loss of billions of shell necessary to build new reef habitat is directly attributed to the Bay’s oyster industry. Physical changes to the lands surrounding the Bay play an equally important role. The deforestation of the primeval forests and loss of wetland grasses removed the barriers to environmental run-off including animal and human waste, agricultural fertilizer, chemicals and metals associated with modern development. Such run-off and silt caused by land erosion cloud the oyster’s native habitat. Predators, large and small, round off the threats to the Chesapeake’s oysters.

Oyster larvae are favorite prey for natural predators such as sea anemones, sea stars and sea nettles. The abundance of the latter in Bay waters can be attested to by countless summer swimmers. Flatworms and small crabs prefer spat. Sea ducks, fish, particularly the cownose ray are prodigious oyster eaters. The Bay experienced a boom in rays in recent years due, in part to the decrease in the pound net fishery and in part to increased water temperatures that may well have lured a greater number of migrating rays northward into the Chesapeake. Believed to winter off South America’s coast, thousands of rays travel the North Carolina coast each April with smaller groups reaching the Chesapeake by mid to late May. One school of rays was documented as eating 60,000 oysters in a single night from a Bay aquaculture project. (Bay Journal, Nov. 1998)

But the most deadly predator proved to be the microscopic parasites, Perkinsus marinus and Haplosporidium nelsoni also known as Dermo and MSX. Harmless to humans yet deadly to oysters, the deadly organisms appeared in mass in 1982 and are credited with the rapid destruction of 90 percent of local stocks in the Chesapeake. (Bay Journal, 1994)

Both the MSX and Dermo parasites invade oyster tissue and, to use scientific parlance, cause “extensive necrosis and tissue disruption.” In short, they kill oyster flesh causing its bodily functions to fail. MSX targets younger oysters and is prevalent in highly saline waters. Dermo prefers to attack as the oyster approaches market size. Unlike MSX, Dermo appears impervious to salinity changes. Where MSX tends to lie dormant during periods of low salinity, Dermo is not so benevolent. It keeps on killing. (Leffler & Greer, 1997)

One common characteristic of the parasitic invaders is their prevalence during hot weather. When the Bay’s waters experience low-oxygen conditions during summer months, chemical reactions with sediments tend to release more iron into the water column. (Maryland Sea Grant R/F-82, 1996-97) Iron is critical to both Dermo parasites and to the oyster. When the parasite wins the struggle for the soluble metal, its growth increases to the detriment of the oyster. (Leffler, 1995)

Under studies funded by the National Sea Grant College Program’s “Oyster Disease Research Program,” a team of scientists from Old Dominion and Rutgers Universities – Eileen E. Hofmann, John M. Klinck, Susan E. Ford and Eric N. Powell – discovered a direct link to climate changes and the outbreak of MSX and Dermo infestations. They examined all the various conditions identified with triggering outbreaks of the two diseases and found the key to be a “sequence of warm and dry years” important to widespread epizootic episodes. They looked at the history of the diseases and years when winter water temperatures warmed. From the data, two models were developed simulating the “host-parasite-environmental conditions of the Eastern oyster and the pathogens, Haplosporidium nelsoni and Perkinsujs marinus,” MSX and Dermo. Disease cycles, oyster mortality, and environmental factors programmed into the models demonstrated the effect of salinity and water temperature on controlling the intensity and prevalence of infections. (Hofmann et al, 1999).

In short, the researchers found that years with winters when water temperatures rise, Dermo and MSX infections appear, in specific, their reference was to El Niño years.

The health of the Bay and the future of the blue crab stock are integrally tied to the health of its oysters.

While Chesapeake Bay politicians and others are calling for a 15 percent reduction in crabbing pressure over the three years from 2001-2003, the Bay itself is in far greater need of attention and care in other areas.

Granted watermen are working their crab gear harder to make up for the loss of oyster revenues. But, the greater culprit in the slow strangulation of the Chesapeake Bay appears to be a combination of other equally or more important factors. The loss of Bay-wide oyster density, the ever-burgeoning development of the Bay’s banks, deforestation, and the loss of marshlands are proving a potent and lethal mix. Ironically and somewhat logic challenging way, the loss of the oysters themselves may be one of the most important of all factors working against the ability of the Bay to renew its lush biodiversity including conditions allowing for the resurgence of the oyster itself.

Oysters (and other bivalves) are nature’s great water purifiers straining pollutants and oxygen-devouring organisms during its filter-feeding process. Without the oysters, an important part in keeping Chesapeake waters clear and clean is missing. Without sufficient quantities of dissolved oxygen in the water, immature crabs and the prey they need cannot survive.

Further, the growing murkiness of the water lacking its purifying bivalves begins to filter out the sunlight necessary to sustain the life of submerged aquatic vegetation (SAV) such as eel grass so critical to the life cycle of the crab and other Bay creatures. No sunlight, no eel grass. No eel grass, no place for immature crabs to hide from natural predators such as the striped bass (rockfish), red drum or croaker. Nor, for that matter, can the young crabs hide from their own cannibalistic colleagues. Estimates put the Bay’s eel and other aquatic vegetation losses at 85-89 percent of original mass.

Run-off from farmlands, housing developments, soil erosion, even from automobile traffic all contribute to the aquatic cataracts blurring the Bay’s once crystal clear vision. The dense marsh weeds and lush forests first viewed by Captain John Smith not only hold the land in place, they act as sediment traps capturing run-off before it overwhelms the Bay’s waters. One key function of the tall marsh grasses is their straining effect of nitrogen from ground water. Once in the Bay, nitrogen and other plant nutrients such as phosphorus stimulate light-blocking algae growth that in turn inhibits eel grass health and welfare. Even dead algae threaten the Bay’s health. Once algae die and settle to the bottom, bacteria begin the decaying process. The bacteria, in turn, compete with crabs and other small organisms upon which crabs feed for the precious oxygen dissolved in the water. An excess of nutrients, then, causes a cycle whereby large sections of the Bay’s bottom become uninhabitable by blue crabs.

An increasingly important factor in the loss of marsh grass is the growing presence of an alien rodent species, Myocastor coypus, more commonly known as the nutria. The large South American rodents feast on the root mass of marsh bulrushes. By destroying the marsh grass, the nutria effectively turns marshland first into nude mudflats and then stretches of open water. Nutria were brought from South America to Louisiana in 1938. In 1943 (some say again in the 1950s), they were introduced to Dorchester County on Maryland’s Eastern shore. They currently reside, predator free, in eight Chesapeake Bay counties on the Eastern shore with sightings also on the western shore. Part of the reason for the unchecked damage caused by the nutria is the depressed fur market that removed the nutria’s only known North American predator, human trappers, from inhibiting its population explosion and spreading environmental havoc.

On the biotechnology horizon, hope for the Chesapeake’s oyster is growing. Today, scientists are looking at ways to use the oyster’s own immune system to fight against Dermo and MSX parasites. A second approach being investigated by marine biologists is to recommend introducing alien species not only because they are resistant to the two parasites but also to consume vast quantities of oxygen depleting and light shading algae. However, the cure using alien specie introduction could achieve the fate feared if the problem goes unsolved, namely the biological extinction of the Crassotrea virginica, from the Chesapeake Bay. It would also raise the litigious hackles of environmental groups quick to court to protest disruption of natural indigenous “ecosystems.” Raising the specter of “exotic” creatures, like the nutria, resulting in unintended consequences would have them invoking the Precautionary Principle that is being recognized more and more as a quasi-environmental anthem to halt such an experiment.

Under the Precautionary Principle, groups with at least a veneer of biological credibility urge environmental and access to a virtual legion of eager lawyers seek to invoke either by regulatory fiat or court decree a strategy of inertia. Their precautionary reasoning argues that in circumstances involving species of fauna or flora threatened with biological or commercial extinction where scientific data is lacking, the preferred approach is to do nothing. Fear of the unknown (or a refusal to replace ignorance with knowledge), to follow that line of logic, sees the path that theoretically leads to the least potential to “cause harm” to a species, is to let nature take its course. Mankind, meddling in nature, is seen as “unnatural” and therefore undesirable. Unfortunately, if the Precautionary Principle was the prevailing ethic of the medical profession, many a patient would die. But, isn’t Crassostrea virginica in every sense a patient fast approaching death? And, isn’t it the role of humans to intervene in nature where possible to eliminate suffering and restore life if at all possible? Arguments to the contrary ignore the fact that all of nature is in a constant state of change, some quicker, some slower. They not only ignore, but attempt to deny the equally cogent fact that humans are part of nature and agents of natural change. Humans, to their equally human critics, are portrayed as somehow apart from nature.

Instead of or perhaps parallel to introducing oyster species native to the Pacific such as Crassostrea ariakensis, a more eco-system friendly approach might be to apply the techniques of biotechnology to boost the native oyster’s defenses against the deadly parasitic invaders by identifying the Pacific oyster’s immunity gene or genes and using them to build Crassostrea virginica’s own resistance. It’s possible, but not without its critics (most of whom would be the same individuals and organizations protesting the introduction of oysters from elsewhere and condemning mankind’s rape of the Bay while lamenting our inability to save it).

The future of the Bay, its watermen and its blue crab and oyster industries depend, not so much on politicians piling yet more restrictions on watermen, as on their ability to take a holistic view of the Chesapeake and its problems. The problems plaguing the blue crab as well as the oyster are partly human caused and partly caused by nature. The health and welfare (and wealth) of the blue crab and the oyster depend on the well-being of the Chesapeake Bay including it’s waters, its sea grasses, its shorelines, its entire eco-system and on the men and women who best know its every feature, who care the most about it, and who are very much a part of the Bay: its watermen and marsh women.

(Exerpted from "The Fish Men Love.")