What will happen if the Texas coast gets a freeze like 1989?

NOTHING SENDS SHIVERS DOWN the spine of fishing guides and savvy Texas saltwater fishing enthusiasts like the words “coastal freeze”.

It’s not because of the prospect of boating across a chilly bay but the potential devastating impacts of sudden, deep freezes on fish populations. Coastal fisheries populations suffered devastating losses during three freeze events in the 1980s, with combined estimates of more than 30 million dead fish according to Texas Parks & Wildlife Department (TPWD) officials. There was also a less substantial but still impactful freeze kill in 1997.

According to former TPWD coastal fisheries director Larry McKinney, Ph.D. Texas has about two million acres of bays and estuaries that are susceptible to freezes. He said of the three freeze events in the 1980s, the 1989 freeze in Brownsville saw the temperature at Brownsville drop to 16 degrees and an estimated 11 million fish were killed. Historically, freezes along the Texas coast have occurred about every 15 years.

Small, isolated freeze events occur nearly annually but the most substantial in recent years were in 2010 and 2011.

TPWD biologists said the total impacts from the 2011 kill in particular were similar to the freeze of 1997, but the species makeup was drastically different.

“During 1997, spotted seatrout, black drum and red drum comprised roughly 75 percent of the impact,” biologists said. “During this year’s freeze, it appears more than 85 percent of the impacted fish are non-recreational species, like silver perch, hardhead catfish, and mullet. Of the recreational species impacted this year, black drum appear to make up a larger component with spotted seatrout, red drum, sand seatrout, sheepshead, whiting, snook, gray snapper, Atlantic croaker and gag grouper making up a much smaller percentage.”

“It could be that most fish had time to escape to deeper water before the freeze hit,” theorized Rebecca Hensley, TPWD coastal fisheries regional director. “We didn’t see the beaches covered in ice and very large numbers of dead fish like during the ‘80s freezes.”

Hensley also credits reduced mortality on game fish to conservation measures taken during the freeze, including a temporary fishing closure in deep water thermal refuges and voluntary stoppage of barge traffic in the lower Laguna Madre and through the land cut in the upper Laguna Madre.

“We appreciate the conservation ethic displayed by anglers during and immediately after the freeze when these fish were vulnerable,” said Robin Riechers, TPWD director of coastal fisheries. “It definitely helped reduce fish mortality.”

The TPWD executive director has the authority to close areas affected by freeze events until the freeze event is over. The executive director would provide adequate notice to the public regarding the closing of affected areas and similarly publicize the reopening of those areas to fishing when the freeze condition has passed. These closures would be limited to the deeper areas where fish are known to congregate in freezes and would end as soon as possible.

According to TPWD, in addition to killing game fish in shallow bay waters, a hard freeze can also cause surviving fish to congregate in a few deeper areas where they become sluggish and prone to capture.

“The high mortality that a freeze can cause may deplete fish stocks for years. Protection of the surviving fish during the few days when they are especially vulnerable to capture would likely shorten the time period for overall recovery of coastal species, especially spotted sea trout.”

Texas is not the only state that has dealt with major freeze events impacting speckled trout. The South Carolina Department of Natural Resources (SCDNR) has an interesting perspective on the issue.

“Spotted seatrout are a sub-tropical species subject to “winter kills” when water temperatures fall below about 46°F,” officials said. “Since trout spend most of their lives in relatively shallow water, they usually adjust to steadily declining water temperatures by moving to deeper water. However, the combination of rapidly decreasing temperatures and the amount of time it remains below that critical level is what has the most profound effect on seatrout.”

They noted of the most severe winter kills of spotted seatrout occurred in 2000. On November 30 of that year the water temperature in Charleston Harbor was around 60°F.

“Cold weather over the following ten days caused the water temperature to plummet to 47°F. For the next three weeks water temperatures remained below the critical level and even got as low as 42°F. Sampling conducted by the DNR that spring detected a 93 percent decrease in spotted seatrout abundance. It took almost five years for the stock to recover.”

Although not as severe as the 2000 event, back-to-back cold winters in 2010 and 2011 saw another decrease in spotted seatrout abundance in that state.

The following spring, using the slogan “Let ‘Em Spawn, Let ‘Em Live”, SCDNR initiated a campaign asking anglers to voluntarily release all spotted seatrout caught during the spawning season (May through September).

“Most saltwater recreational anglers in South Carolina complied, and began releasing spotted seatrout that they could have otherwise kept. Surprisingly, just over a year later, sampling efforts showed a gradual increase in abundance. The voluntary release of spotted seatrout by recreational anglers almost certainly contributed to a more rapid recovery of the stock.”

They noted spotted seatrout rarely move from the estuaries where they were spawned. As a result, their abundance may also be affected by fishing mortality. Simply put, an increase in fishing pressure can cause a decrease in abundance.

“We have no control over the weather or how it affects our fisheries, but we can easily adjust our actions to become more conservative if and when the need may arise.”

That is a good thought to end with on this subject. There are lots of potential outcomes for a freeze event but if anglers abide by the laws and if necessary use voluntary restraint in the aftermath of a freeze events, fisheries can and will recover.

Anglers and coastal residents can report any freeze-related fish kills or large numbers of sluggish or cold-stunned fish by contacting TPWD’s Upper Coast Regional Office at (281) 534-0100 or the Lower Coast Regional Office at (361) 729-2328.

 

 

— TF&G Staff Report

 

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