An Ecological Characterization of Tarpon Nursery Habitats in Texas

Picture yourself transported back to the 1930s, standing on a dock in Port Aransas, the “Tarpon Capital of the World.” The morning sun is just rising, casting a golden glow on the water as you prepare to embark on a thrilling angling adventure. Your guide's new Farley boat is waiting at the dock, a sturdy vessel designed for pursuing magnificent tarpon. Settling into a fighting chair on the boat, you watch as the town fades into the distance and the open gulf beckons. As you reach the south jetty, the perfect conditions reveal themselves – light southeast winds and a powerful incoming tide, setting the stage for an unforgettable encounter with tarpon.

Suddenly, your guide points excitedly, "There they are!" That’s when you witness multiple tarpon slashing through schools of mullet, sending them showering above the surface. With your heart pounding, you grab hold of a stout rod and reel, ready for the challenge. A live mullet is swiftly secured to your hook as the boat maneuvers into position. As you cast into the school of tarpon, the bait drops into the water and is met with a powerful strike, nearly yanking the rig from your grip. As you reel in and struggle to set the hook, you witness a breathtaking sight – a massive tarpon erupts from the water, its silvery form glinting in the morning light. For the next 20 minutes, you battle the powerful fish, feeling your muscles strain and the adrenaline pumping through your veins. Finally, the tarpon comes into view alongside the boat, pulling it closer your guide gaffs the tired fish and struggles to haul the mighty fish aboard. As you admire it, you can’t help but feel a sense of awe and accomplishment.

Sitting back in the chair, wiping the sweat from your brow, your guide grins and teases, "Ready for another one?" Despite the ache in your body, you can't help but stand up with determination, ready to take on another one.

Tarpon History in Texas

The Atlantic tarpon (Megalops atlanticus) is a synonymous species in the history of Texas sportfishing. From the 1920s to the 1940s, schools of tarpon numbering in the thousands would pass through not only Port Aransas but the entirety of the Texas coast. During this period, they supported an economically vibrant recreational fishery that drew in numerous tourists including a United States President, Franklin D. Roosevelt, who fished with the late Barney Farley. The scale from the five-foot tarpon he caught and many others from previous anglers are still displayed at the historic Tarpon Inn. A simple reminder of what we once had. However, by the late 1950s and early 1960s, it became a distant memory as the once prevalent tarpon populations dwindled to the point of the fishery collapsing. Since then, anglers and scientists alike have been trying to answer the question, “What caused the decline of tarpon in Texas?”

Declining Populations

Initially, the tarpon fishery collapse is primarily attributed to the overexploitation and mismanagement of adult fish. This is seen in historic photographs during the peak fishery where smiling anglers stand next to large tarpon hanging at the docks. Unless they were worthy of mounting, the majority were disposed of. In other countries, tarpon to this day, are still harvested to be sold in fish markets.

Although it occurred nearly 75 years ago, the state's severe drought during the 1950s set the stage for building damns and creating reservoirs to serve the needs of the people. It didn’t come without consequences that we still endure to this day. Simply put, freshwater is the lifeblood of Texas estuaries. Reducing freshwater inflow, nutrient reduction, and increased salinities affected important estuarine organisms like blue crabs and shrimp, which juvenile tarpon predate on. Throw in multiple years of development which have caused the loss of suitable habitat, and you can see where they can have a hard time recovering after all these years.

An examination of fishing records of tarpon caught between 1908 and 1998 in Port Aransas, Texas indicated a lack of small fish caught after 1960 while large fish were still present. Scientists have speculated that the collapse of the tarpon fishery in Texas was the result of recruitment failure to the area. In fact, Winemiller and Dailey (2002) modeled population dynamics of tarpon using life history data and determined that small declines in juvenile survival resulted in marked reductions in the abundance of adults. Thus, the collapse of the fishery in Texas appears linked to the quality and availability of nursery habitats used by juvenile tarpon during the early years of life. Unfortunately, our understanding of basic habitat requirements of juvenile tarpon in Texas is very limited, precluding our ability to assess population trends and develop sound conservation strategies. With a quickly growing human population in Texas and many people living in or moving to coastal counties, there is concern that juvenile tarpon and nursery habitats could be negatively impacted by increases in development activities. The first step to addressing these concerns and uncertainties is to improve our ability to identify nursery habitats for these species and provide new information on their ecology in these habitats. These needs are currently being addressed by a new study at the Sportfish Center.

Juvenile Tarpon Ecology

The purpose of the study is to provide new information on the ecology of juvenile tarpon occurring in nursery habitats along the Texas coast using standardized bimonthly field sampling, mark-recapture tagging, and validation of citizen science reports. The information provided by this project will fill severe knowledge gaps pertaining to the juvenile ecology and habitat needs of these species and provide managers with data needed to develop effective conservation plans for these important sportfish.

The specific objectives of the study are to:

1. Identify juvenile tarpon habitat, characterizing seasonal dynamics of the physical, ecological (e.g., community assemblage), and environmental (e.g., water quality) parameters of this habitat.
2. Document seasonal and interannual trends in the occurrence and abundance of juvenile tarpon within identified nursery habitats of coastal Texas.
3. Survey citizen scientists to identify juvenile tarpon habitats along the Texas Coast; ground truth a portion of these reports.
4. Collect fin clips and scales for future tarpon genetic and hatch date analyses.

The upcoming study will utilize bimonthly field sampling, PIT tag mark-recapture methods, and citizen science to gather new information about the ecology of juvenile tarpon and their nursery habitats in Texas. Sampling will take place at specific sites between Aransas Pass and Corpus Christi, Texas to identify and characterize nursery habitat. It will occur throughout the year to identify seasonal and interannual trends in the presence and abundance of juvenile tarpon. Bag seines and cast nets will be used to capture juvenile tarpon and characterize associated community assemblages in these habitats.

During each sampling event, habitat characteristics and water quality data will be recorded. Identified tarpon will be counted, measured, weighed, and tagged with PIT tags before being released. Additionally, potential prey items will be preserved, sorted, counted, identified, and measured on a monthly basis in the laboratory to determine what is available to these juvenile fish. The study will also attempt to estimate growth rates for this species from recaptures of tagged individuals. The estimated occurrence and abundance of tarpon will be associated with water quality measurements and sample site metrics using common fish-habitat modeling approaches.

To improve our understanding of juvenile tarpon nursery habitats, we will engage citizen scientists by conducting formal surveys, in-person interviews, and using message boards and social media to identify more nursery habitats across a wider geographic area. We have already created a survey for identifying juvenile tarpon habitats (https://bit.ly/3ISW9AF). Once we gather and summarize the survey data, we will verify a subset of these locations in each region of the Texas Coast (if reports come from each region) to confirm the presence of tarpon and to ensure that they are indeed juveniles, using the same seine protocols we use at our fixed sites near Corpus Christi.

Finally, additional tissues will be collected to improve our ecological understanding of this species in future studies. For every captured juvenile tarpon, a small portion of the anal fin will be clipped and preserved for optimal DNA preservation. Scales will also be collected to evaluate their use as non-lethal ageing structures. These tissues can be used for future genetic analyses (e.g., effective adult population size, comparing Texas relative population size to the eastern Gulf of Mexico, etc.).

This ecological characterization will provide novel information on these species’ seasonal residency, habitat use, and the physical, biological, and environmental characteristics of these habitats. This project will allow interannual comparisons of juvenile tarpon abundance and habitat use, and validation of citizen scientist-identified nursery habitats. These data will ultimately aid resource managers seeking to identify critical habitat and improve conservation measures for these important species in Texas.

In the prologue of Hart Stillwell’s book Glory of the Silver King, he states from his stories, “You might even become interested enough to go along with me when I say that the tarpon can be saved, even though no efforts along that line are being made now. Why? Because he is not considered a commercial species, such as the weakfish and flounder and striped bass and channel bass and shrimp and oysters that marine biologists are struggling to save. If the tarpon is saved, this happy event will take place as something of a byproduct of our campaign to save the creatures we eat.”

He didn’t know it at the time, but I feel like through all the trials and tribulations these fish have been through, anglers and scientists can help save future populations of tarpon. It may seem farfetched now, but one day, maybe you and I could have the opportunity to relive history as described in the Glory of the Silver King.