Stock enhancement is a fisheries management tool used around the world to help supplement wild fish populations by introducing hatchery-reared fish into the wild. Texas Parks and Wildlife Department (TPWD) operates three marine fish hatcheries to spawn, rear and stock (release) Red Drum, Spotted Seatrout, and Southern Flounder fingerlings (~1.5 inches total length) into Texas bays and estuaries. Between the three hatcheries, an average of 24 million fingerlings are released into the Texas coastal waters annually. You may say, “That is a lot of fish! But where do all the fingerlings come from?” Well, they come from a few fish, a few wild-caught fish.
The process of stocking fingerlings into the bays and estuaries starts with the critical step in any hatchery program, collecting broodstock (sexually mature fish) from the wild. Each year, the hatcheries rotate 25% of the Red Drum brooders out of the program and back into the wild. To replenish the broodfish that are phased-out, TPWD uses a variety of methods to collect replacement Red Drum and Spotted Seatrout. One approach used by hatchery personnel is the traditional hook and line method via shoreline or by boat. Another avenue to source brooders is longline sampling, a method used by our TPWD coastal management groups, especially effective for Red Drum in offshore waters. Not all our collection efforts are done by hatchery personnel. There are groups of individuals up and down the Texas coast, such as local guides and avid anglers, that enjoy volunteering their time assisting the hatcheries by collecting broodstock. We arrive with a fish hauling unit to meet up with our volunteers and, in a matter of hours, dozens of Spotted Seatrout are loaded up and transported to a designated hatchery to be added to the program. The same goes for Southern Flounder brooders, but they can be a little trickier to land. With a makeshift holding tank on pontoons (Figure 2), local guides and hatchery personnel use hand nets to collect the flounder broodfish and minimize injuries. We receive a lot of help from the angling community and we really appreciate their time spent volunteering with the collection efforts. We have one individual that has logged an astonishing 2,123 volunteer hours assisting the hatcheries by collecting fish!
For over two decades, TPWD has also utilized live weigh-in fishing tournaments to collect broodfish. From the Texas Gulf Coast Roundup in late 90s to the Coastal Fisheries Bay Team in the mid-2000s and today, these tournaments have been an excellent source for collecting brooders and benefit the agency in saving manpower and money. From these tournaments, fish are loaded into a fish hauling unit and transported to one of our fish hatcheries to be integrated into the program. If you are interested in seeing a local tournament weigh-in, check your local newsstand for upcoming events as they are enjoyable and family-friendly!
For these fish to successfully integrate as TPWD broodstock, it is essential that they are properly handled and cared for during the collection process. When hatchery personnel collect broodstock, the fish are handled as little as possible to minimize stress. Using barbless hooks, for easier hook removal, fish are landed as quickly as possible to avoid exhaustion. A rubber-mesh landing net (nylon nets can be abrasive) is used to transport the fish from the water to the hauling unit. Once in the transport container, the hook is removed using a hook removal tool and rubber gloves are worn in case the fish need handling. Less handling means less mucus removal and less opportunity for bacterial infections to develop. Each hauling unit is equipped with compressed oxygen that is trickled into the water using a diffuser (the smaller the bubbles the better they dissolve). If an exhausted fish needs resuscitation, it is gently moved back and forth in the current, moving water into the month and over the gills. Water parameters such as temperature and dissolved oxygen are routinely monitored throughout the collection process and during transportation back to the hatchery.
Once back at the hatchery, the newly acquired fish are placed into quarantine tanks. During the quarantine process, fish are rid of ectoparasites and transition from feeding on live bait to cut bait. Once habituated to tank life and free of pathogens, the new brooders are added to spawning tanks and placed on a 150-day photoperiod and temperature maturation cycle. At the end the cycle, the broodfish routinely start spawning and fertilized eggs are collected by staff and incubated. Three days after hatching, the larval fish are moved to outdoor culture ponds and reared to fingerling size. Once they have reached target size, the ponds are harvested, and the fingerlings are stocked into the wild.If you want to see the broodstock fish in action and want to learn more about the Coastal Fisheries stock enhancement program, Sea Center of Texas in Lake Jackson provides hatchery tours to the public. For more information go to Sea Center’s website at www.tpwd.texas.gov/fishing/sea-center-texas. Hatchery tours are also available at the CCA Marine Development Center in Corpus Christi by appointment only. For more information go to CCA Marine Development Center’s website at https://tpwd.texas.gov/fishboat/fish/management/hatcheries/ccacpl.phtml