story by Brett Falterman, LDWF Program Manager
In Louisiana, we take our fishing and seafood seriously. We also understand that if we want to pass along this great legacy, we need to keep a close eye on these valuable resources.
At the Louisiana Department of Wildlife and Fisheries (LDWF) Fisheries Research Lab in Grand Isle, La., biologists are conducting offshore research and monitoring projects critical for gathering the information needed to effectively manage a wide range of fisheries resources throughout the Gulf of Mexico.
The state-of-the-art facility opened in 2009 after Hurricane Katrina demolished the old LDWF lab on Grand Terre Island. The Grand Terre lab had been in use since the early 1950s. The new lab on Grand Isle is located on Louisiana’s only inhabited barrier island providing the opportunity to conduct research and monitoring right off of Louisiana’s coast. Below is a list of some of the current research programs being conducted at the Fisheries Research Lab.
Partnering with SEAMAP
The Southeast Area Monitoring and Assessment Program (SEAMAP) is one of the Lab’s flagship programs designed to monitor offshore fisheries. Through SEAMAP, LDWF works with other states, federal agencies and universities to conduct fisheries independent surveys, sample fish populations and gather abundance and biological data used to assess the status of marine fish stocks. SEAMAP partners conduct these surveys throughout the Atlantic Ocean, Caribbean Sea and the Gulf of Mexico. Partners follow standardized protocols to ensure collections are consistent and accurate across areas.
LDWF began conducting Gulf of Mexico SEAMAP surveys in the 1980s and has continued to expand these surveys throughout the years. Today, the lab participates in four SEAMAP surveys:
Shrimp/Groundfish – a bottom trawl survey which collects information on the abundance and distribution of shrimp and groundfish.
Vertical Line – a reef fish survey conducted using commercial bandit gear at natural and artificial reef habitats .
Bottom Longline – a survey which collects information on coastal sharks and finfish associated with open bottom habitats.
Plankton – a survey which uses small mesh nets to collect information on eggs, larvae and small juvenile fish.
Biologists also record environmental parameters, such as temperature, salinity and dissolved oxygen for the entire water column at every site, resulting in a comprehensive, long-term data set.
“Conducting standardized, large-scale surveys such as these would not be possible without the partnerships created through the SEAMAP program,” said Chloe’ Dean, Louisiana’s SEAMAP Coordinator. “The greatest aspects of the program are that information is gathered on all levels of the food chain, from tiny plankton to top predators and that this information is available to researchers and members of the public upon request.”*
The Lab also houses a cutting-edge histology lab. Histology, literally translated as “tissue science,’’ is the study of tissues and cells at a microscopic level. At the Fisheries Research Lab, biologists study the microscopic anatomy of fish ovaries to understand the reproductive biology of commercially and recreationally important species.
They dissect fish that are captured during surveys and take the reproductive organs back to the lab for further analysis. To start, they infuse a piece of the ovary with wax so it can be sliced into tiny slivers and mounted on a slide. They then soak the slide in a series of chemical stains so that when they examine the ovary piece under a microscope they can easily distinguish the different parts of the ovary.
“What we’re really looking for are indicators of spawning that tell us how often the fish spawns while we count the eggs to figure out how many eggs are released during each spawn,” biologist Erik Lang explained. “We also try to discern the age at which most of the population sexually matures or is able to spawn. Just like humans, not every fish within the same species matures at the same time.”
The Grand Isle histology lab has previously helped gather information on red snapper and red drum reproduction. Current projects focus on assessing Louisiana’s spotted seatrout stock and managing greater amberjack in the Gulf of Mexico and along the U.S. coast in the Atlantic Ocean in cooperation with researchers from the University of Florida.
With information on when, where, and how often fish reproduce, coupled with results from age and growth studies, managers at both the state and federal level are able to set fishing seasons and size limits that allow fish a chance to reproduce prior to potentially being harvested.
On the Half Shell
At the Lab’s Michael C. Voisin Oyster Hatchery, which opened in 2015, biologists from both LDWF and Louisiana Sea Grant work to produce oyster larvae for restoration, research and industry purposes. Oysters are important to both Louisiana’s economy and ecology. Larvae from the hatchery help enhance natural oyster production. At the hatchery, biologists spawn fertile, sexually mature oysters and rear the larvae until they develop a foot, at which time they are called a pediveliger larvae. The larvae are ready to set, which is where they go from being mobile larvae to immobile spat, or a baby oyster.
“My favorite days in the hatchery are spawning days,’’ hatchery supervisor Erin Leonhardt said. “It’s exciting when the oysters start to spawn and you know your next larval brood is on their way.”
The hatchery is designed to produce one billion pediveliger larvae in a season. To accomplish this, the hatchery is equipped with a series of water filtration technologies, an algal production system, a high-density larval rearing system, a boiler system, a warm and cold broodstock holding system and a recirculating system.
Each of these components is critical for successfully rearing oyster larvae. For example, the boiler system and warm broodstock holding system allow the hatchery to expand the larval production outside the typical wild oyster spawning season. The algal production system grows algae specifically selected for optimal oyster larval growth and survival.
Leonhardt also attributes the success of the hatchery to her team. “Our well-trained staff does an excellent job at operating and maintaining these systems,’’ she said. “With them, the world is our oyster.”
Tank and Tag Research
The Lab has multiple tank systems configured for recirculation and filtration of the water. This allows biologists to conduct controlled experiments to observe what happens beneath the water’s surface and help guide research conducted on state managed inshore and offshore species. Biologists have used the tank systems to conduct a variety of projects, including a study comparing two different types of conventional tags used by volunteer anglers to tag spotted seatrout.
“The tank trials on spotted seatrout demonstrated good survival and retention rates for both tag types, so we have deployed this into a comparative field study using some of the elite volunteer taggers that tag over 100 fish per year,” said program manager Craig Gothreaux.
Based on the success of the tank trial with speckled trout, a similar tank trial is currently being planned for southern flounder. Although it is in the very early stages, the objective of this tank study is to compare the survival and tag retention rates for southern flounder marked with two types of conventional tags, with the hope that results will determine the most suitable tag type moving forward on potential mark-recapture research on a state-wide basis. Such a project would be one of several ways that LDWF biologists are working to collect additional data in an effort to improve stock assessments conducted by LDWF on state managed species.
Another research study monitored the recovery of red drum that underwent surgery to implant acoustic tags for a telemetry tagging project in Lake Pontchartrain. “We were able to continually observe the red drum in our tanks and document the rapid recovery rate at the incision site, and are happy to report 100 percent survival,’’ Gothreaux said. Controlled tank studies such as these help biologists advance new fishery management tools, while also developing better estimates for models that would otherwise have to rely on assumptions about survival and long-term tag retention rates.
Some research projects are done in collaboration with universities, like the current electronic tagging study LDWF is participating in with Texas A&M Galveston and USM’s Gulf Coast Research Lab. This project aims to compare the survival of blacktip sharks to the level of stress indicators in their blood just before they are released.
In addition to the significant research and monitoring work being done at the lab, the facility also serves as a significant department asset for public outreach. The Lab has hosted a number of events over the past year including the Grand Isle Migratory Bird Festival, ‘Wetshop,’ Womens’ Fishing Workshops, Volunteer Instructor Program (VIP) Trainings, Louisiana Master Naturalist Program, LWF Commission meetings, and Enforcement Cadet training. Tours of the facility are also available to the public and the lab has worked closely this year with Second Hand Harvesters Food Bank, donating fish from sampling projects to the tune of about 1,500 meals.
With leading expertise, innovative methods and great access to fisheries resources, LDWF strives to stay ahead of the game when it comes to providing data for fisheries management in the Gulf of Mexico. Whether you are a Louisiana resident, a visitor enjoying the state’s fisheries resources or a consumer of Louisiana seafood, you can be proud of the state’s responsible and proactive approach to monitoring and managing the extensive fisheries resources off the coast of Louisiana and beyond.
*The Gulf States Marine Fisheries Commission coordinates Gulf-wide surveys like SEAMAP. For more information on SEAMAP programs and data requests, go to www.gsmfc.org or contact the Commission directly at 228-875-5912.
- YOUNG GUNKindal Tonn Is Already A Natural With All Aspects Of
- A GRAND DAYHunting With His Grandfather, Seth Gottardi Harvested
- 2017 YOUTH HUNTER OF THE YEARThe Louisiana Department of Wildlife and Fisheries
- SPOTLIGHTChicot Lake Size: 1,642 acres Maximum Depth: 14 feet
- NIGHT PATROLLDWF Enforcement Agents Take Aim At Illegal Night