Sea turtles exhibit remarkable resiliency
Texas’ setting a record for the number of cold-stunned green sea turtles rescued from inshore water in the wake of the unusually cold stretch that gripped the coast over the first four days of this new year is an event worth celebration and consideration.
And not just for the obvious reasons.
Yes, it is wonderfully heartening that scores of concerned Texans worked together to save more than 2,000 potentially doomed sea turtles found floating or washed ashore in bays along the length of the state’s coast.
But what those numbers say about the current status of green sea turtles in Texas’ waters and how they got to this point, is, perhaps, even more encouraging and illuminating. Considering the history of green sea turtles in Texas, it is remarkable that there were that many sea turtles to rescue. Or almost any at all.
For almost a century, green sea turtles were rarely encountered in Texas bays outside of the Lower Laguna Madre, the shallow bay system at the tip of the state. Even there, the turtles were far from common. Most Texans who fished and boated or otherwise spent time on the waters of the middle and upper coast from the early 1900s through the early 2000s never encountered a green sea turtle. The turtles were a piece of the coastal mosaic that hung by a thin thread. It was not always so. For millennia, Texas inshore waters hosted swarms of green sea turtles — one of the five species of sea turtles native to Texas waters and, by all accounts, historically the most numerous.
Seafaring nomads like Texas
The green sea turtles in Texas waters aren’t born here. They are hatched from eggs that adults lay in nests dug in the sand on beaches in Florida, Mexico and the Caribbean.
The adult turtles travel on the currents and tides, pelagic creatures ranging over hundreds, even thousands of miles in the open ocean. But juveniles gravitate to inshore waters, especially bays, which offer more protection from predators and a rich seascape of grasses, algae and other foods on which to forage. And young green sea turtles like Texas bays.
Adult green sea turtles, which can weigh as much as 400 pounds, typically arrive in Texas waters in April and remain in the bays until November when most migrate from the bays ahead of winter. Some of the juveniles follow them. But many overwinter in Texas bays, especially in the more temperate waters along the middle and lower coast.
Around 1870, that abundance of turtles in Texas bays began drawing the interest of commercial fishers. Turtle meat, the main ingredient of turtle soup, was in high demand.
By the 1880s, Texas held a booming commercial fishery for green sea turtles, aided by the development of new technology for processing and canning the meat and the growing web of railroads to transport the product to markets across the country.
At one point in the late 1800s, six turtle canneries operated along the Texas coast. They were sprinkled along the coast from Galveston to Port Isabel, with the biggest concentration on the mid-coast.
The canneries were supplied by commercial fishers, who used gill nets to entangle the turtles, setting the nets in and around passes and channels the turtles used to travel in the bays and move between bays and the ocean.
Most of the turtles taken were juveniles weighing between 2 and 20 pounds. And they took them by the tens of thousands.
In 1890, at least 250 tons of sea turtles were commercially harvested from Texas bays, according to Charles Stevenson’s “Report on the Coastal Fisheries of Texas.” Stevenson, commissioned by the U.S. Bureau of Fisheries, spent almost a decade — 1889-97 — in Texas conducting in-depth reporting on the state’s commercial fisheries.
Most of those turtles were taken from the middle coast, especially the Rockport/Fulton area, where the largest turtle cannery, opened in 1881, was located. In 1890, that cannery handled 121 tons of turtles. But turtles were commercially harvested from every Texas bay. Almost 1.75 tons of green sea turtles were taken from Galveston Bay in 1890, Stevenson reported.
Fishing frenzy takes toll
That frenzy of unregulated commercial fishing took a devastating toll on Texas’ turtles. By 1897, the annual harvest had dropped by more than half. By 1900, green sea turtles’ numbers had fallen so low that the industry collapsed. The canneries closed. The commercial fishers moved to new targets.
By the early 1900s, the only remaining vestiges of Texas’ commercial turtle industry were scattered “turtle pens,” enclosures made of wooden posts driven into the bay bottom in shallow water along shorelines, where commercial “turtlers” had held their catches until taking them to market.
The ghost of those wooden structures haunt Texas bays, even now. While the pens’ wooden posts are long deteriorated, their locations served so long as navigational landmarks to anglers and other boaters that, even today, several Texas bays have stretches of shoreline, coves or other locations that are known as “the turtle pens.”
The population of green sea turtles in Texas bays, devastated by commercial harvest, did not rebound in the wake of the reduced pressure. Their numbers fell even further across their entire range, driven down by a combination that included continued heavy harvest in other areas, loss of habitat, deteriorating water quality.
The development of otter trawls and the expansion of inshore and offshore commercial shrimping through most of the 1900s added to the drain on sea turtles. Slow-moving turtles inadvertently were swept up in the nets and drown.
The paucity of green sea turtles in Texas waters, particularly in the bays, through most of the last century can be seen in the number of cold-stunned or coldkilled green turtles documented during major cold snaps as late as the 1980s.
During a record-setting freeze in December 1983 that dropped bay-water temperatures into the 30s and kept them there for days, state fisheries staff surveyed the bays and estimated 14 million finfish were killed. Only five coldstunned green sea turtles were found, according to data collected by the Sea Turtle Stranding and Salvage Network. Since 1980, STSSN, a partnership between state and federal agencies and private conservation organizations, has maintained detailed records of sea turtle strandings.
During another record-setting stretch of freezing temperatures that began at Christmas 1989 and continued into February 1990, a total of 14 cold-stunned turtles were documented in Texas bays.
But over the last 30 years or so, the number and range of juvenile green sea turtles have dramatically increased in Texas bays. That expansion has come in the wake of increased protection for the turtles.
In the 1970s, the federal Endangered Species Act prohibited any harvest of sea turtles; currently, green sea turtles are classified as a threatened species under the ESA.
By the early 1990s, state and federal laws mandating use of turtle-excluder devices (TEDs) in shrimp trawlers took effect. A turtle excluder, a strainertype devices fit into the throat of shrimp trawlers, ejects any turtle swept into the net, preventing them becoming trapped and drowning.
Also, the average water temperatures in Texas bays during winter months has increased over the last 30 years or so, a phenomenon that has allowed several cold-intolerant marine species such as sea turtles to expand their range up the coast.
Conservation efforts help
It is hardly a coincidence that green sea turtle numbers and range greatly expanded in Texas waters as those legal protections took hold and water temperature shifted.
And that dramatic increase can be seen in the number of sea turtles that appear on bay surfaces or washed along shorelines when bay-water temperatures tumble and hold below 50 degrees for more than a few hours.
Before this latest brief siege of unusually frigid weather, the largest number of cold-stunned green sea turtles, dead and alive, from Texas bays and documented by the Sea Turtle Stranding and Salvage Network was 1,670 during the winter of 2010-11.
Preliminary numbers indicate approximately 2,200 to 2,500 sea turtles were found along the Texas coast, from Galveston Bay to the Lower Laguna Madre, during the first week of this year. About 70 percent of those turtles were alive when found, with approximately 90 percent of those rescued turtles recovering to be released back in Texas waters.
And those numbers are just a fraction of the green sea turtles in Texas bays; many avoided ill effects of the cold by moving into the Gulf or into deeper, more insulated water as the temperature dropped.
There were a lot of coldstunned green sea turtles in Texas bays earlier this month because there are a lot of green sea turtles in Texas bays — something that could not be said just a couple of decades or so ago. And that is good news for turtles and Texans.