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Historic photograph of an oystermen holding a basket of live oysters beside a shell dredge

Historical Impact

The impact of oyster
shell mining

Also known as the mud shell industry — six decades of extraction that the reefs could not recover from on their own.

Shell mining had obvious direct negative impacts on oyster reefs, but there were also indirect effects that had long-term consequences and prevented ecological recovery.

Multiple accounts from Texas document shell mining that resulted in large pits — sometimes up to 80 feet deep in a normally shallow-water estuary.1 Unnaturally deep holes in estuaries cause water quality issues ranging from low dissolved oxygen to potentially toxic levels of H₂S.

Additionally, shell mining has been shown to alter freshwater flows, create hydrodynamic changes, increase wave energy, and increase erosion. The damage was not only to the reef that was removed, but to the conditions any future reef would need in order to grow back.

Illustration of a shell dredge at work, from a 1967 magazine article
Sports Illustrated, August 14, 1967. Illustration from the article “Dredging Up a Texas Squabble” by Edwin Shrike.

1880 — 1971

Ninety years of extraction

In his report published in 1965, Edwin Doran, Jr. traced how a shovel-and-wheelbarrow operation on an exposed reef became one of the largest sources of industrial aggregate on the Gulf Coast.

  1. 1880

    Shovel and wheelbarrow

    A recorded account from a shell mining company states that the earliest mining efforts in Texas occurred on July 16, 1880, when a sloop sailed from Galveston Bay to West Bay and began extracting oyster shell from an exposed reef by hand.

  2. 1905

    Mechanization arrives

    The first account of a mechanical dredge used in the shell mining industry. A hydraulic dredge followed in 1912 — and the scale of extraction changed permanently.

  3. 1916

    Shell becomes cement

    The first intensive commercial use of oyster shell in Texas: a source of lime for a cement plant constructed in Houston. By 1951, four cement companies were consuming two million cubic yards of shell a year.

  4. 1941

    Industrial demand intensifies

    After the construction of the Dow magnesium plant, lime produced from roughly a million cubic yards of shell annually was mixed with sea water to form magnesium hydroxide, and ultimately metallic magnesium.

  5. 1955

    Shell roads

    Of more than ten million cubic yards of shell produced that year, an estimated 65% went to industry and about 28% into road construction — a belt of shell roads extending fifty to seventy miles inland from the coast.

  6. 1971

    The tally

    Combining figures from several historic reports, shell mining removed approximately 300 million cubic yards of oyster shell from Texas bays between 1912 and 1971. The true volume was likely larger — the reports cover a limited number of companies.

By combining the figures from several historic reports, shell mining activities removed approximately 300 million cubic yards of oyster shell from Texas bays between 1912 and 1971. It is likely that the actual volume was larger, because the reports cited indicate the figures are based on data from a limited number of companies.
Compiled from Hensen 1993, Gaines 1965, Kerr 1967 & Doran 1965

From the Archive

What the industry left behind

Historic photograph of two oystermen tonging oysters from a sail-powered boat
Oystermen working from a traditional sail-powered oyster sloop.
Sepia photograph of a commercial oyster vessel at the dock
The commercial fleet that worked the bays before mechanized dredging.
Map showing the distribution of shell roads across the Texas coast
Figure 10 from Gaines (1965): distribution of shell roads as determined from all available evidence. Base maps: Texas Highway Department Districts 12, 13, 16 & 20.

Photo credit, page top:Oystermen in East Galveston Bay of Texas have just picked up this basket of live oysters just 20 feet from the cutter blade of the giant shell dredge shown in the background. The dredge is destroying this 25–30 acre Hargfield Reef, which produces a livelihood for commercial fishermen and provides a prime fishing spot for sports fishermen.

Literature Cited

  1. 1Hensen, M.S. 1993. The History of Galveston Bay Resource Utilization. The Galveston Bay National Estuary Program. Publication GBNEP-39.
  2. 2Oyster sloops were a traditional sail-powered oyster-dredging boat.
  3. 3Gaines, F.L. 1965. What the shell industry means to Texas. Report prepared by: Joint Organizations for Business Survival. Texas Avenue Building, Houston, Texas.
  4. 4Kerr, A. 1967. The Texas reef shell industry. Bureau of Business Research. University of Texas at Austin. Industry Series No. 11.
  5. 5A. Doran Jr., E. 1965. Shell Roads in Texas. Geographical Review. Apr. 1965, Vol. 55, No. 2, pp. 223–240. B. Kibbe, I.P. 1898. Report on the coast fisheries of Texas. Austin, TX: Von Boeckmann, Moore & Schutze. C. Environmental Impact Assessment of shell dredging in San Antonio Bay, Texas. Vol. 1. Prepared by Texas A&M Research Foundation for the U.S. Army Engineer District, Galveston. September 1973.

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Restoring Oyster Habitat

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