Writer's Monthly Tips!
Subscribe!
CCA Marine Development Center
Incubation room.
The CCA Marine Development Center (MDC) in Corpus Christi is the mother hatchery of Texas's marine stock enhancement program. Built in 1982, it was the first full-scale production hatchery for red drum, which was the first marine fish species in Texas to be stocked in mass quantities. They have since expanded to include spotted seatrout in 1992 and, just four years ago, southern flounder. Let's take a walk through, and I'll show you what makes this hatchery tick.
Spawning Rooms
Here's where the magic happens, complete with mood lighting and adjustable thermostat (for turning up the heat). There are ten spawning rooms; seven of them have four spawning tanks and three of them have two tanks. Each tank holds 3200 gallons of water from the Upper Laguna Madre. Tank water is exchanged twice a week.
Most of the spawning rooms are reserved for redfish. A warm water species, redfish require the water temperature to be almost 80F for spawning. Temperature is checked and manually adjusted three times a day by staff. Lights inside each tank simulate daylight and are controlled by computer. Due to the controlled environment, redfish in these tanks have a 150-day spawning cycle, half the time of redfish in the wild. This guarantees two spawns per year, one on March 15th, and another on October 15th. Redfish in the wild spawn once a year in the fall. There are five redfish per tank: 2 males and 3 females. They are fed three percent of their body weight three times a week. Through trial and error, hatchery staff have discovered that these are the conditions that induce redfish to spawn.
All brood fish are tagged upon entry and exchanged with wild stock every four to five years, to preserve genetic diversity. Redfish spawn at night, typically around 9 or 10pm, amidst a resonance of passionate drumming (or at least, very LOUD drumming). Eggs float to the top, are sucked into collection bins, and are collected from the bins every morning by staff. The eggs are briefly put in graduated cylinders to measure amounts. One milliliter equals about 1000 redfish eggs, or 1700 trout eggs, or 1700 flounder eggs.
Redfish and trout have similar spawning processes, both being of the drum family. The biggest difference is that there are ten trout per tank: five males, five females. Flounder, on the other hand, are still a big mystery. They're a cold water species, to start. There are typically 50-60 flounder per tank, and while, optimally, there would be two males for every female, there is an unfortunate shortage of males. Hatchery researchers still haven't quite found the right mix of conditions for natural spawning in flounder. For now, hormone injections take the place of magic.
Incubation Room
Eggs are transferred from the collection bins in the spawning rooms to very small (comparatively) tanks in the incubation room (IR). Each incubator tank can easily hold half a million fry. For reds and trout, the incubation tanks are open. For flounder, the system has to be enclosed, so the IR gets turned upside down for flounder season (aka winter). The drum eggs hatch in 18-24 hours, and the newly hatched fry live for three days in the IR, feeding off their yolk sac. They grow about a millimeter a day. Flounder eggs take 3-5 days to hatch, and the larva spend a much longer time in the IR. After their yolk sac days, the young flounder are fed a rotifer slushy that looks suspiciously like a college cafeteria green drink.
Grow Out Ponds
After their stint in the IR, the larval drum and flounder are stocked into grow out ponds (segregated, of course; no interspecies mixing; the flounder spawn later anyway). There are 34 grow out ponds on site: 14 one-acre ponds, 10 two-acre ponds, and 10 half-acre ponds. A one-acre pond takes one and a half days to fill, and ponds take 7-10 days of fertilization before they are ready for stocking. (You can see how all the cogs have to be turning at the right time for this to come together.) Fry are stocked in the ponds at a density of 400,000 fry per acre of pond. Sometimes, the water from the Upper Laguna is more saline than desired. The spawning and incubation tanks can have fresh water added from two on-site reservoirs, but for the ponds, there's no such luck.
Fingerling drum are harvested for release when they reach 35-40 mm, which takes roughly 30-40 days, depending on temperature. Harvests occur Wednesday through Friday at midnight. No, not because the hatchery is staffed with vampires. Nighttime harvests are cooler (temperature-wise), the fish can't see in the dark, and there's no bird predation at night. Ponds are drained into kettles, and fish are harvested by the bucketful from the kettles. Buckets are pre-weighed with just water and post-weighed with the fish. The weight difference is all fish, baby.
From egg to fingerling, there's a 10-40 percent release rate for drum, on average. Fifteen million redfish and eight million seatrout fingerlings are released annually. The current flounder goal is 50,000 (3,823 were released last year). Fingerlings are released all along the Texas coast. There are two wild genetic stocks of redfish, the upper coast and the lower coast, with San Antonio Bay being the midpoint. The MDC handles the lower coast stock. Trout and flounder stocks are bay-specific, so whatever bay the brood stock comes from, that's where the fingerlings have to be released. If something disrupts production at the MDC (construction, hurricane, alien attack, etc), the fish can be shipped to and raised at either of the other two marine hatcheries (Sea Center or Perry R. Bass), and vice versa. Release sites for the specific stock don't change though. Even if lower coast reds are raised at an upper coast hatchery, they are still released on the lower coast.
Personal History of the MDC
The MDC sits on the edge of the largest King Ranch in Texas; it was initially intended to be a buffer between the public and the ranch. Thanks to this, even though it's right on the edge of a big city, it seems like it's out in no man's land. This gives the sixteen staff members extra time with nature. Deer are a given, lots of them, pretty much all the time. During fawn season, the does can be seen, not infrequently, chasing off coyotes and a bobcat or two. Hogs aren't usually a surprise, though one was, when he was found ear deep in the alfalfa stash one morning (used to fertilize the ponds). Even a mountain lion is seen occasionally. Once, a mama mountain lion was seen with her cubs. The man doing the seeing was unfortunately between mama and said cubs. A hasty retreat into the truck was required This job really requires a respect, if not a love, of wildlife.
Besides stock enhancement, the MDC also conducts scientific research and is active in public outreach. There are two kid fishing ponds stocked with big, native fish. (Ospreys love these ponds, too.) Many kids have caught their first fish in those ponds. There is a small visitor's center, and people are always welcome to come for a tour (by appointment). It's all much more impressive in person, so I recommend you drop in if you're in the area.
Sources
Rodney Gamez, NRS - Facility Manager, CCA Marine Development Center
Michael Robertson, Fish & Wildlife Technician III, CCA/AEP Marine Development Center
Spawning Rooms
Here's where the magic happens, complete with mood lighting and adjustable thermostat (for turning up the heat). There are ten spawning rooms; seven of them have four spawning tanks and three of them have two tanks. Each tank holds 3200 gallons of water from the Upper Laguna Madre. Tank water is exchanged twice a week.
Most of the spawning rooms are reserved for redfish. A warm water species, redfish require the water temperature to be almost 80F for spawning. Temperature is checked and manually adjusted three times a day by staff. Lights inside each tank simulate daylight and are controlled by computer. Due to the controlled environment, redfish in these tanks have a 150-day spawning cycle, half the time of redfish in the wild. This guarantees two spawns per year, one on March 15th, and another on October 15th. Redfish in the wild spawn once a year in the fall. There are five redfish per tank: 2 males and 3 females. They are fed three percent of their body weight three times a week. Through trial and error, hatchery staff have discovered that these are the conditions that induce redfish to spawn.
All brood fish are tagged upon entry and exchanged with wild stock every four to five years, to preserve genetic diversity. Redfish spawn at night, typically around 9 or 10pm, amidst a resonance of passionate drumming (or at least, very LOUD drumming). Eggs float to the top, are sucked into collection bins, and are collected from the bins every morning by staff. The eggs are briefly put in graduated cylinders to measure amounts. One milliliter equals about 1000 redfish eggs, or 1700 trout eggs, or 1700 flounder eggs.
Redfish and trout have similar spawning processes, both being of the drum family. The biggest difference is that there are ten trout per tank: five males, five females. Flounder, on the other hand, are still a big mystery. They're a cold water species, to start. There are typically 50-60 flounder per tank, and while, optimally, there would be two males for every female, there is an unfortunate shortage of males. Hatchery researchers still haven't quite found the right mix of conditions for natural spawning in flounder. For now, hormone injections take the place of magic.
Incubation Room
Eggs are transferred from the collection bins in the spawning rooms to very small (comparatively) tanks in the incubation room (IR). Each incubator tank can easily hold half a million fry. For reds and trout, the incubation tanks are open. For flounder, the system has to be enclosed, so the IR gets turned upside down for flounder season (aka winter). The drum eggs hatch in 18-24 hours, and the newly hatched fry live for three days in the IR, feeding off their yolk sac. They grow about a millimeter a day. Flounder eggs take 3-5 days to hatch, and the larva spend a much longer time in the IR. After their yolk sac days, the young flounder are fed a rotifer slushy that looks suspiciously like a college cafeteria green drink.
Grow Out Ponds
After their stint in the IR, the larval drum and flounder are stocked into grow out ponds (segregated, of course; no interspecies mixing; the flounder spawn later anyway). There are 34 grow out ponds on site: 14 one-acre ponds, 10 two-acre ponds, and 10 half-acre ponds. A one-acre pond takes one and a half days to fill, and ponds take 7-10 days of fertilization before they are ready for stocking. (You can see how all the cogs have to be turning at the right time for this to come together.) Fry are stocked in the ponds at a density of 400,000 fry per acre of pond. Sometimes, the water from the Upper Laguna is more saline than desired. The spawning and incubation tanks can have fresh water added from two on-site reservoirs, but for the ponds, there's no such luck.
Fingerling drum are harvested for release when they reach 35-40 mm, which takes roughly 30-40 days, depending on temperature. Harvests occur Wednesday through Friday at midnight. No, not because the hatchery is staffed with vampires. Nighttime harvests are cooler (temperature-wise), the fish can't see in the dark, and there's no bird predation at night. Ponds are drained into kettles, and fish are harvested by the bucketful from the kettles. Buckets are pre-weighed with just water and post-weighed with the fish. The weight difference is all fish, baby.
From egg to fingerling, there's a 10-40 percent release rate for drum, on average. Fifteen million redfish and eight million seatrout fingerlings are released annually. The current flounder goal is 50,000 (3,823 were released last year). Fingerlings are released all along the Texas coast. There are two wild genetic stocks of redfish, the upper coast and the lower coast, with San Antonio Bay being the midpoint. The MDC handles the lower coast stock. Trout and flounder stocks are bay-specific, so whatever bay the brood stock comes from, that's where the fingerlings have to be released. If something disrupts production at the MDC (construction, hurricane, alien attack, etc), the fish can be shipped to and raised at either of the other two marine hatcheries (Sea Center or Perry R. Bass), and vice versa. Release sites for the specific stock don't change though. Even if lower coast reds are raised at an upper coast hatchery, they are still released on the lower coast.
Personal History of the MDC
The MDC sits on the edge of the largest King Ranch in Texas; it was initially intended to be a buffer between the public and the ranch. Thanks to this, even though it's right on the edge of a big city, it seems like it's out in no man's land. This gives the sixteen staff members extra time with nature. Deer are a given, lots of them, pretty much all the time. During fawn season, the does can be seen, not infrequently, chasing off coyotes and a bobcat or two. Hogs aren't usually a surprise, though one was, when he was found ear deep in the alfalfa stash one morning (used to fertilize the ponds). Even a mountain lion is seen occasionally. Once, a mama mountain lion was seen with her cubs. The man doing the seeing was unfortunately between mama and said cubs. A hasty retreat into the truck was required This job really requires a respect, if not a love, of wildlife.
Besides stock enhancement, the MDC also conducts scientific research and is active in public outreach. There are two kid fishing ponds stocked with big, native fish. (Ospreys love these ponds, too.) Many kids have caught their first fish in those ponds. There is a small visitor's center, and people are always welcome to come for a tour (by appointment). It's all much more impressive in person, so I recommend you drop in if you're in the area.
Sources
Rodney Gamez, NRS - Facility Manager, CCA Marine Development Center
Michael Robertson, Fish & Wildlife Technician III, CCA/AEP Marine Development Center