It is hard to imagine how many oysters were present in Mobile Bay before we got here. It is hard, even, to understand how many there were just 100 years ago. According to AL.com calculations, it is likely we have removed about 1.8 billion adult oysters from the bay in the last century.

Oysters were one of the primary attractions for the earliest Alabamians. Ancient shell middens in Bon Secour, Grand Bay, on Dauphin Island, along Mobile Bay and elsewhere attest to the importance of oysters in the diet, and as an architectural building tool. The native peoples actually lived atop the mounded shells of oysters they had eaten. The mounds, some 20 feet high, helped the early coastal inhabitants get above sea level and the wet, soft ground along the coast. Testing shows that some of those mounds were heaped up more than 6,000 years ago. And a decrease in the size of the shells deposited on those mounds most recently suggests that these earliest people were actually having a measurable effect on the reefs of Mobile Bay long before Europeans arrived here.

We have a more precise knowledge of the modern harvest beginning in 1880, the first year the state kept records. That year, about 327,000 pounds of oysters were tonged from the bay. That is pounds of meat, not including the shell. The harvest quickly ramped up. Just a decade later, in 1890, the harvest was up to 1.5 million pounds, and by 1928 it was up to 1.8 million pounds annually. To put that in perspective, a pound of oyster meat usually contains about 15 oysters, according to estimates from federal officials, meaning the 1928 harvest consisted of around 27 million oysters.

This series: Can 100 trillion oyster eggs save Mobile Bay?

Between 1880 and today, records show that we have harvested at least 85 million pounds of oyster meat from our reefs (again, that weight doesn't include the heavy shells). Given that the state harvest data is missing for 50 out of 137 of those years, the true total is probably close to 120 million pounds harvested from our reefs, or about 1.8 billion live oysters. To really understand the problem facing us today, take a look at the annual harvest totals beginning in the 1950s, compared to the harvest today.

1950s annual harvest 1.3 million pounds

1970s annual harvest 756,495 pounds

1980s annual harvest 628,497 pounds

1990s annual harvest 594,137 pounds

2000s annual harvest 669,394 pounds

2010s annual harvest 142,359 pounds

2014 annual harvest 58,066 pounds

2015 annual harvest 33,586 pounds

Annual production in the bay has declined by 98 percent compared to a century ago.

In part, the harvest numbers for the most recent years are down because state officials enacted a much more robust management system for our oyster reefs in 2011. The century-old system of year-round, virtually unrestricted harvest was ended.

Instead, oyster reefs are only opened for harvest when the population on a particular reef is healthy enough to support it. The state conducts assessments of all the public reefs before, during, and after any harvest. And every oyster removed from the reef is accounted for as oystermen weigh in their catch at official Oyster Management Stations set up near popular reefs.

In the last several years, the management change has meant harvests measured in weeks, not months, and tens of thousands of pounds caught, not hundreds of thousands.

That is a great change going forward, but doesn't undo the damage inflicted from an era when Mobile Bay oysters were shipped around the country aboard specially designed rail cars. Imagine, back in the golden age of the railroads, miners in Colorado and cattle merchants in Chicago dined on fresh Alabama oysters that had been pulled from Mobile Bay just two days before being served in those far away places.

That harvest at the dawn of the 20th century fed six canneries operating around the bay, including Grahams Seafood Company, Hidenheim Company, McPhillips Packing Company, Marco Skremitti, Coffee Island, and the Alabama Oyster Company. In a sad bit of history, those factories operated largely thanks to plentiful child labor. In fact, Lewis Hine, a federal photographer tasked with documenting child labor practices for the government, captured numerous images of children as young as 7-years-old shucking oysters in Alabama canneries in February, 1911. The kids worked for as little as 30 cents a day. In one devastating picture captured by Hine's camera, nearly the entire work force of the Alabama Oyster Company appears to be made up of school age children. A few goonish looking adults are in the photo as well, apparently a management team right out of the pages of Dickens.

As early as 1882, the state legislature enacted various laws to prevent out of state fishermen from harvesting Alabama oysters, and laws requiring that any canning be done by Alabama canneries, not those in Mississippi or Florida. A survey conducted by the state Department of Game and Fisheries in 1923 found that almost none of the oysters consumed raw in Alabama at that time were from Mobile Bay. Instead, the Mobile Bay oysters were going straight to the canneries, while residents ate raw oysters from Florida and Mississippi. By 1950, there were just three canneries left, and by 1967, there was just one.

"The decline of the canneries from their peak years of the 1920s was largely due to loss of productive oyster bottoms in Portersville Bay," reads the state history of the reefs.

That's a delicate way of saying we harvested all of the oysters from Portersville Bay in a few short years. Beginning in 1909, state officials began attempting to rebuild that reef by depositing baby oysters dredged from the nearby Mississippi Sound. In a harbinger of things to come, that attempt failed because the muddy bottom, minus its ancient covering of oyster shells, was too soft to support the oysters as they grew. They sank into the mud and suffocated.

Reading through the history of the state's oyster harvest and management, it becomes clear that we are today paying the price for a series of moves made to keep the annual harvest high between 1910 and the year 2000. You can see it in a handful of laws that were changed, and practices that were adopted.

The most important law changes came in 1923 and 1933, when portions of the bay were opened to the dredging of oysters. Previously, oysters could only be harvested in Alabama via tongs, which are long wooden poles with metal rakes attached to the ends. This is the preferred method of harvest in terms of protecting the reef itself. But tonging can only work in water less than about 10 feet deep. An oyster dredge, by contrast, can work at any depth. The dredge is a heavy metal box that is dragged behind a boat. The dredge plows through the reef, scooping up live oysters as it scrapes through and destroys the reef community they were growing on. A national study in 2012 pinpointed the use of dredges as causing "the functional extinction" of oyster reefs on the east and west coasts. In the words of Sean Powers, a senior scientist at the Dauphin Island Sea Lab, "where they've allowed dredging on wild reefs, the lesson is pretty clear. You will lose your oyster reef."

Luckily, dredging wasn't allowed for most commercial harvesting in Alabama, as it has been in other states. Unfortunately, even the limited bit that was allowed may have been even more damaging to the overall health of the bay. The state allowed dredging in vast areas of the bay for the collection of seed - or baby - oysters to replenish the commercial reefs beginning in the 1920s. 117,000 barrels of seed oysters were collected in this fashion between 1925 and 1934. These oysters were collected from the north end of the bay, beginning at Mullet Point, and from Bayou La Batre, Coden, and the Mississippi Sound. The young oysters were then deposited on the reefs closest to the canneries, where they'd grow to market size within a year.

The problems with that practice are obvious, and were quickly revealed. The efficient machinery worked like a giant vacuum, sucking up all the baby oysters to be found in huge areas of the bay. Of course, an indiscriminate machine wouldn't just pick up small oysters in an area. It would pick up all the oysters it encountered, leaving behind bare bottom, where no new oysters could grow.

Oysters are opportunistic creatures. In the old days, larvae would settle anywhere they encountered something hard, from another oyster shell, to a sunken boat, a lost anchor, a log, or just a hard patch of bottom. In this fashion, the bottom of a bay like Mobile Bay would be populated with what scientists term "scattered oysters," meaning there are oysters present in numbers, but not heaped up in a classic oyster reef. These "scattered oysters" were still a vital part of the ecosystem, serving as water filterers and tens of millions of sheltering places for all sorts of organisms.

It is easy to imagine how, in just a decade, the practice robbed the bay at large of huge numbers of both its adult oysters and generations of young oysters. You can even see the root of our problem today of too few larvae in the water to replenish the natural population. Imagine if not only the reefs were spawning, but millions of oysters once scattered far and wide all over the bay bottoms were in on the action too. Interestingly, accounts from the time report that the oystermen of the bay were adamantly opposed to the practice as early as the 1920s, though the state moved ahead despite their opposition.

Then, in 1946, the most destructive of all practices began, with the bay opened for the mining of old oyster and clam shell deposits for use as filler material in concrete.

These shell deposits were sometimes dozens of feet thick, dating back tens of thousands of years. Understanding why such thick layers were present requires a trip back in time to the last ice age, 18,000 years ago. At that time, sea levels were close to 400 feet lower than they are today, with most of the water on Earth frozen in glaciers. At the time, what is now Mobile Bay was actually a valley with a river flowing through it. As the Gulf of Mexico began to rise at the end of the ice age, Mobile Bay slowly filled back in. Over the course of thousands of years, layer upon layer of oysters grew on the bottom, new generations on top of the old as new sediment deposited by the rivers of the Mobile-Tensaw Delta filled in the now-drowned river valley, constantly raising the seafloor and burying older oysters.

The importance of these layers of shell to the integrity of the seafloor in the bay cannot be overstated. Think of them as the foundation under a house. They provided a stable platform for new generations of shells to rest upon, and ensured that those new shells didn't sink below the mud under their own weight as they grew. As those layers of shell were removed from the bay, more and more of the bottom was rendered too soft to support the weight of oysters.

It is estimated that 40 million cubic yards of oyster shell were mined from Mobile Bay between 1946 and 1968. That's about 4 million dump truck loads. The dredging continued until 1982, though it had been ended in other estuaries more than a decade before, meaning a total of around 8 million dump truck loads of shell were culled. The state of Alabama reaped around $180,000 a year in royalties for this most destructive of practices. Worst of all, the practice was allowed to continue in Alabama even after Florida and Louisiana banned it in their waters in the 1960s.

While the dredge worked, a plume of thick mud 1,500 feet long oozed across the bottom away from the dredge covering and killing "everything in its path," according to a federal environmental assessment from the 1970s titled "Dredging of Dead Reef Shells, Mobile Bay." At the same time, a plume of mud 12 miles long was visible on the surface of the bay spreading away from the dredge. The report described the conflict between the bay's oystermen and the dredging company, acknowledging that many smaller live reefs were destroyed by the practice. It also concluded that "it is doubtful that oysters can be grown on or in the immediate vicinity of old dredge cuts within several generations." Nearly the entire floor of the bay was mined in this fashion.

The lingering effects of this dredging can be seen every time the wind blows. Instead of a bay bottom underlain with a matrix of old shells that trapped sediment and supported live oysters, our bay is now home to a soupy layer of soft mud that oozes between the toes of swimmers. Even a slight breeze stirs this layer into the water column. Anytime the wind blows stronger than about 15 miles an hour, the water turns the color of chocolate milk, and stays that way for days.

The result is a murky bay where you can seldom see the bottom in more than about a foot of water. That's a far cry from stories told by people who remember what the water looked like even in the 1960s, when it was not uncommon to see the bottom in water as deep as eight feet.

The one-two punch of the loss of the incredible water-filtering power of a bay full of oysters, and the added wind-driven turbidity caused by the shell mining proved to be the death knell for sea grasses in Mobile Bay. While the eastern and western shores of the bay were home to expansive sea grass beds up to the 1970s, decades of dirty water wiped them out.

The only hope to bring back our sea grass beds is to bring back our oysters. And the only hope to bring back our oysters is a concerted effort to replace what we've lost, just the sort of effort we now propose. On the East Coast, areas immediately around the oyster farms of Chesapeake Bay, scientists describe seeing "halos" of clear water, where the farmed oysters are filtering the water. What's more, many of these farms now report new seagrasses growing around their equipment. In some cases, the grasses are so lush they are causing problems for the oyster farmers. Oh that Mobile Bay could have that problem!

Instead, the recent history of oysters in Mobile Bay has been a distressing one. The commercial harvest crashed in the decade beginning in the year 2000. At the time, the state's oystermen blamed an influx of predatory oyster drills. creatures they suggested were flourishing during a prolonged drought and eating up Mobile Bay's entire oyster population.

For a variety of reasons, I have come to believe the widely accepted theory about oyster drills was apocryphal. The drills, an ever-present menace on Gulf oyster reefs, didn't suddenly spiral out of control. Instead, I think we humans had finally eaten up Mobile Bay's entire oyster population, reducing the biomass to unsustainable levels.

After nearly a century of year-round harvest of Mobile Bay's historic bounty, we had finally eaten so many oysters we reached a tipping point. There simply weren't enough adult oysters left to repopulate the bay with babies for next year's harvest.

Natural systems are designed to cope with extremely high rates of attrition among the young of any given year. In the marine environment, mortality rates for larval creatures, from shrimp to fish to oysters, can approach 95 percent. To cope with that, marine creatures, including oysters, compensate by releasing literally millions of babies. A single adult oyster can release 9 million larvae in a spawning event. That's works when you have a healthy adult population. But the whole house of cards comes crashing down when there aren't enough adults.

Working on the assumption that oyster drills, and not a century of overharvest, were the problem, Gov. Bob Riley appointed the former mayor of Bayou La Batre, Stan Wright, as "Oyster Czar." Apparently, the idea was that no one understood oysters better than Mayor Wright, who was also owner of Wright Brand Oysters, one of the state's largest purveyors of shucked oysters. While Wright has since been imprisoned for stealing funds related to the BP oil spill, he was, for a time, given free reign over management of the state's oyster population.

Wright was an aggressive advocate on behalf of the state's oystermen and the goal of increasing the harvest. He pushed for the "relocation" of one of the state's largest natural oyster reefs, which sat next to Brookley Air Field. That reef had been left to grow in peace because it was north of a line that runs across the bay, roughly from Pt. Clear to Fowl River. No harvest is allowed north of that line because bacterial counts are generally too high in the north end of the bay due to runoff from populated areas and sewage outfalls for the cities of Mobile, Daphne and Fairhope.

Wright suggested moving the oysters from the closed waters at the top of the bay to the site of the old White House reef near Fowl River, which had been destroyed by overharvest. The plan was to allow the oystermen to move most of the reef to the open water area and let the oysters purge themselves of contaminants for a month. Then the millions of oysters would be scooped up off the bottom by oystermen and sold to Wright's company and other commercial seafood operations.

However, when the oystermen descended on the reef a few weeks later to reap this sudden bounty, they found that all of the oysters were dead. The oysters died of two causes, according to state officials. Many of them sank into the soft bottom of the old reef and suffocated. While others died due to low oxygen water at the location. The old White House reef sits in an area now known to have persistent low oxygen levels part of the year.

Which brings us to where we are today. The commercial harvest of wild oysters is almost non-existent. The state's oystermen brought in about 30,000 pounds of oysters last year. This from a bay that used to support harvest of a million pounds a year. While state officials hope to see the bay's oyster population rebound, they acknowledge that there has been poor survival of the tiny, larval oysters in recent years. Many of the baby oysters "set" and attach to a hard surface, only to die before they reach adulthood.

Almost all of the harvest that comes out of the bay these days is from the various oyster farms around the bay. This has proven to be a quickly expanding industry, which is wonderful. But those farms almost exclusively raise the sterile "triploid" oysters, which are genetically engineered to grow more quickly than wild oysters. The big difference is the sterile farm-raised oysters do not spend any of their energies on reproduction.

To turn the tide and recreate a spawning population of oysters in the bay, we must provide a helping hand. If we are successful, it is possible to envision a time when the bay is home to numerous and thriving wild reefs providing the biological functions that nature intended for oysters to provide. Those reefs would be filtering billions of gallons of water, providing habitat for fish, shrimp and crabs, and helping to hold the muddy sediments on the bottom where they belong. Meanwhile, imagine dozens of farms producing a premium oyster crop for the table.

Right now, there is a hole in our coastal ecosystem. It is a hole that can only be filled by a healthy oyster population. We have literally eaten our way into this mess, one oyster at a time. If we are smart, we can work our way out of it and reverse a century of bad decisions, one baby oyster at a time.

Coming Friday - How to grow oysters under your pier and become an oyster rockstar! By Andy DePaola

Ben Raines specializes in investigations and natural wonders. You can follow him on Facebook, Twitter at BenHRaines, and on Instagram. You can reach him via email at braines@al.com.