Hard Freeze Threatens Fill Kill

 Those who have lived down here for most of their lives will remember the historic freezes of 1983 and 1989. I believe that 1983 has been the most serious freeze in my lifetime, when nearly the entire bay froze over, and the tall fan palms and most of the citrus tree population, died. Following 1983, big trout were few and far between. But they repopulated quickly, and it only takes 6-8 years or so before a female trout reaches 27-28 inches. Then, again in 1989 that bay froze in places, and huge numbers of trout came to the surface, stunned and dying along shorelines, asphyxiating from the low oxygen context of the freezing saltwater. Unconscionable people gathered to snag, hook or net them in their most vulnerable state. Game wardens intervened to keep opportunistic SPI guides from making multiple runs to areas filled with the dying fish.

The freeze we just experienced--with nighttime temps in the low-to-mid 20s--and will suffer again tonight to a lesser extent, may not have had the devastating impact on the lower Laguna that it apparently has had on the waters around Rockport. Pictures of shorelines covered with big trout have been showing up among anglers who have made early visits to the bay's edge. And yet, the rumors among guides and serious fly fishers 100 miles south in the Rio Grande Valley are cautiously optimistic, as reported by my son Ryan, who always has his ear to ground, and networks with several area guides.

From the warmth of my arm chair (after going without electric heat for two days!), I have nothing definitive to say. But the mortality levels among trout, and usually to a much lesser extent among relish, are starting from historically high populations of both species. Indeed, the big trout population has had 32 years to prosper to unprecedented levels of larger fish since the last serious or "hard" freezes of 1989, defined by subfreezing temperatures over a long period of time. A flash frost normally poses no threat. But a sustained 8-12-hour period of subfreezing temperatures quickly transforms the bay from a normally temperature tolerant ecosystem, to a body of water that eventually "catches up" with the  air temperature. The available oxygen in the water plummets and the larger fish, which normally gravitate toward shallow water for feeding advantage, get caught unable to thrive in the low O2 frigid conditions. 

Reds can tolerate temps from the low 50s to the upper 80s before they have to relocate, but the "optimal temperatures for spotted seatrout are between 69° - 80°F. They will seek out cooler(deeper) water when it is warmer than 88°. Likewise, when the water is colder, they may hold in deeper channels or holes where the water may be warmer. They may die at temperatures below 48 degrees. (http://recon.sccf.org/sport-fishing/spotted-seatrout)

Another reputable source summarizes as follows:

• Above 60 degrees Specks are happy
• 50-60 degrees Specks live a normal life. Moving towards areas with deep channels and shallow flats.
• Under 50 degrees metabolisms begin to slow dramatically. Movement and feeding is reduced.
• Somewhere in the 40-degree range, the threat of fish kills begins.(https://www.wafb.com/story/37469520/bigfish-speckled-trout-fishing-heats-up-as-water-temperatures-rise/

And yet another source sets the lower survival limit at 37%:

"If spotted seatrout are trapped for an extended period in water below 41 F or the water temperature changes too quickly for the fish to escape, then the fish may become stunned. Most fish seen stunned do not survive. Spotted seatrout have an absolute minimum water temperature of around 37 F, below which there is very little chance of survival.

And another source, https://www.westernbass.com/article/spotted-sea-trout-management-after-cold-stun

summarizes the trout's adaptation to cold as follows:

"Like all species, spotted seatrout select habitats within a water temperature range optimal for survival. If water temperatures fall below 45 degrees Fahrenheit , spotted seatrout will begin to experience stress and try to move to warmer water. If spotted seatrout are trapped for an extended period in water below 41 F or the water temperature changes too quickly for the fish to escape, then the fish may become stunned. Most fish seen stunned do not survive. Spotted seatrout have an absolute minimum water temperature of around 37 F, below which there is very little chance of survival.'

In the next few days, I hope to report a visual and more definitive scientific assessment of the impact of the "Freeze of 2021," which it will surely be called.

Meanwhile, the freeze has not greatly dampened my enthusiasm for flyfishing the bay just as soon as it returns to normal. And "normal" this time of year is wet wading during a warming trend in the seasonally low tides. February is better than March, weather permitting, for big trout, because the tides remain low enough to sight cast for the trophy fish.

But if that doesn't happen on my "available days," I've already planned a four-day retreat on the water in April with my son Ryan and good friend Henry Bone of Austin, and his shown Ethan. And then during the first week in May, I have the privilege of guiding one of my favorite client teams of Tony Woodward and Scott Minnich. Mid-April to early June has to be the "sweet spot" of the early season, with October to mid-November being my other favorite period, during which I will be guiding another "legacy" pair of clients from Virginia--Ted Thomas and Dennis Matt. Meanwhile, Ryan will be guiding new clients this season, COVID and schedules permitting.

In summary, Nature does its thing. Hard freezes were more common in the 50-80s, and then climate change seems to have significantly warned our winters. Those who live here have witnessed the migration of flounder north, and the explosion of black mangroves along the shorelines--both indications of sustained higher temperatures overall. But now they are saying that the warming of the ice caps will result in a more frequent spillover of the "Arctic Vortex" to the southern lands, a paradoxical effect of overall rising temperatures. Go figure. Regardless, the occasional hard freeze has been a part of southern Texas life for as long as anyone can remember. And take heart; The flora and fauna of our subtropical ecosystem recovers quickly. The temperatures and fertility of our terrestrial and aquatic ecosystems are resilient and responsive. We will surely see Nature adjust to this latest event, and leave only those who have carefully tracked the rhythms of their home waters with any member of her most dramatic moods.