Forage Fish and 2021 Texas Winter Storm Uri
The 2021 Texas winter storm Uri was truly an unprecedented event that not only impacted the lives of thousands of Texans, but it also impacted our sensitive natural resources. Following the storm, quick actions were taken by the TPWD Coastal Fisheries (CF) division in a coastwide effort to rescue cold stunned sea turtles and protect recreational fish by implementing freeze closures. In addition to these efforts, fish kill assessments were conducted to estimate the number of fish killed by the storm. The final tally estimated that 61 species were impacted by the freeze and around 3.8 million fish were killed by the prolonged frigid temperatures. These numbers included recreationally important species such as the Spotted Sea Trout (SST), whose population was greatly impacted by the freeze event. Emergency actions in the form of a reduced bag limit and changes to the minimum and maximum size limits were implemented to counter the high mortality in SST in Lower and Upper Laguna Madre. These actions were taken to protect this valuable species and encourage its recovery so Texans can continue to enjoy it for years to come.
An estimated 91% (approximately 3.5 million fish) of the fish kill total were non-recreational species such as Silver Perch, Pinfish, Striped Mullet, Atlantic Croaker, Spot, Gulf Menhaden, and more. These species are examples of forage fish, small schooling species lower in the marine food web that serve as prey or bait for larger commercially and recreationally important fish, mammals, and sea birds. The six bait fish species mentioned above are a biological indicator of the health of the coastal ecosystem. For example, these species are commonly predated on by SST, therefore, a decrease in their availability can reduce the health and availability of SST for Texas anglers. By analyzing data from the TPWD CF Division’s routine long-term monitoring program, TPWD can gauge the condition of the ecosystem pre- and post-freeze by looking at how forage fish populations were impacted and how that change could impact predatory fish populations like SST. The data collected from the monitoring program derives from sampling done by the CF Division in Texas bay systems using three gear types: gill nets, bay trawls, and bag seines. Gill nets target adult fish while bay trawls and bag seines target the sub adult and juvenile fish, respectively. Catch rates from these gear types over the most recent 10-year period along the Texas coast were compared to catches in 2021 to assess the effects of the freeze event (Figures 1-3). No gill net data was collected in 2020 due to COVID restrictions.
What did we find? Of all the non-recreational fish mortalities caused by Uri, 52% were composed of the six species of forage fish investigated here. The catch rate from the bag seine data revealed coast wide catch rate for juvenile Sliver Perch, Striped Mullet, Gulf Menhaden, and Atlantic Croaker remained at or under the 10-year pre-freeze average, although there was a 75% catch rate increase above the 10- year average for Pinfish (Figure 1). Ongoing decreased catch rates in both Gulf Menhaden and Atlantic Croaker cannot be directly linked to the freeze event as they were already decreasing in 2020. Bay trawl data showed a post freeze coast wide catch rate increase for sub-adult Pinfish (53% increase), Striped Mullet (38% increase), Spot (144% increase), Gulf Menhaden (70% increase), and Atlantic Croaker (66% increase) above the 10-year average. Sub-adult Sliver Perch showed a slight decrease in 2021 but remained above the 10-year average (Figure 2). Gill nets in part mirrored the trends in the bag seine data where most of the coast wide catch rates remained at or slightly below the 10-year average, with the exception of Pinfish. The coast wide catch rate of adult Pinfish showed a 75% decrease from the 10-year average in 2021, the lowest within the previous 10 years (Figure 3).
Despite the large number of non-recreational fish killed during the 2021 freeze event, our most recent data indicates the event had little impact on the six fish populations examined here. Silver perch yielded the highest mortalities of all the forage fish species with a loss of approximately 1,190,782 individuals, but no major decreases were observed in 2021 compared to their 10-year average for all three gear types. Moreover, the bay trawl data indicates an increase in juvenile to sub-adult Atlantic Croaker, Gulf Menhaden and Spot. This could be attributed to the loss of predatory fish and adult fish of the same species that compete for similar resources. The only forage species that appeared to be negatively impacted by the freeze is Pinfish, as indicated by the gillnet data. However, these decreases were not seen in the bag seine or bay trawl data, meaning only adult Pinfish were heavily impacted. Therefore, the surviving juvenile and sub-adult Pinfish should replenish the adult populations in coming years.
It has only been a little over a year since the freeze event of 2021, and while it killed millions of fish within Texas waters, data indicates the impacted fish species are showing their resilience. Similar freeze events occurred in 1983 and 1989 and the Texas fisheries have endured and recovered. TPWD will continue to closely monitor trends along the Texas coast using data from the long-term monitoring program to assess the health of our fishery resources for future generations. The resiliency of these forage fish is a good indicator that our coastal ecosystems are thriving and that they will continue to provide a steady and plentiful food source to promote the recovery of species like the Spotted Seatrout that were impacted by the freeze.
A special thanks to the Coastal Fisheries Kill and Spills Team and Resource Management Teams that assisted in the rapid coast wide fish kill assessment after the freeze event.