The new state of the art Fisheries Research Lab located in Grand Isle is an important tool of the LDWF in monitoring the health of Louisiana’s recreational fisheries.
The Fisheries Research Lab opened on July 1, 2009, on the north shore of Grand Isle, Louisiana. The 35,000 square foot, state-of-the-art facility is home to a range of projects including monitoring and research programs, and the dedicated staff works around the clock to protect the state’s diverse marine resources.
Biologists based out of Grand Isle study a variety of marine species including finfish, crab, shrimp, sharks and oysters and their associated habitat, which are all crucial to the economy of Louisiana.
The LDWF Fisheries Research Laboratory is a vital asset when it comes to ensuring the safety of recreational anglers, studying game fish, community outreach and working with the nation’s top research institutions.
Protecting the state’s marine resources is an ongoing effort, and the Fisheries Research Laboratory is up to the challenge. Whether it’s conducting important research on offshore and inshore species, educating the public or assisting in recovery efforts, this dedicated program is geared up with the scientists, boats, personnel and facilities to make it happen.
SEAMAP is one of the lab’s flagship monitoring programs run in conjunction with the federal agencies in charge of assessing the status of the ocean. LDWF has four main sampling programs that generate the information used to determine the health status and fish populations throughout the northern Gulf of Mexico. These four methods consist of plankton surveys, bottom long-line surveys, ground-fish sampling and vertical line sampling. With these four techniques LDWF scientists and federal partners can paint a picture of the diversities and biomass of Louisiana’s Gulf waters.
Plankton surveys are conducted by towing two specific types of nets with standards for size, mesh and “soak-time.” Plankton is the collective name for the many larval fish, crustaceans and microscopic creatures that live adrift in the ocean currents. Many of these strange larvae are not recognizable until they transform into the classic adult forms that we know well. These samples are sorted for fish counts and water is sampled for various parameters including chlorophyll, which is a good measure of the abundance of this microscopic environment. It is crucial to know these amounts, as they are the basis of the entire food chain in the oceans. There is a specific room in the lab know as the “chlorophyll” room, and it houses the sensitive equipment needed to separate and quantify or count the levels of chlorophyll in the samples. The chlorophyll is degraded by natural light, and the entire lab is illuminated with a green light that does not alter the chlorophyll during the tests. Though tedious to work with, these microscopic counts are extremely important in knowing the overall health of an area.
Bottom long-lines are another method used to sample the diversity of much larger animals along the bottom of the ocean. This sampling regime enables biologists to sample adult fish the state regulates. Biologists deploy a mainline with baited dropper-lines along randomly selected areas of the Gulf’s muddy bottom. Again, standard protocols are strictly monitored, and after a set amount of time the mainline is retrieved and the fish are measured, weighed, tagged and mostly released. Sharks of varying species make up the bulk of the catch, but red snapper, grouper and other bottom dwellers occasionally make a showing. The short duration of the “soak-time” ensures the likelyhood that released fish will survive. Some fish are retained to sample age and growth parameters. Hook size, bait type and “soak-time” are all standard factors that allow samples to be compared over time and amongst other participating Gulf States.
Age and growth studies are important aspects to fisheries management. Otoliths are the name for a fish’s ear bones. They are found in the head of the fish and are collected from many of the fish that are sampled. Otoliths have growth rings on them similar to the rings of a tree and can be used to determine the age of a fish. The otoliths are sliced super thin with a special saw and mounted on a slide to view under the microscope. Once research has determined a base line for age of a particular fish, LDWF scientists can determine the age of a sampled fish by counting the rings.
Reproductive organs are also collected and studied in the lab. For example, ovaries from a fish are sampled, infused with wax, chilled in special trays, finely sliced and then mounted on a slide. They are then put in a machine that “stains” the specimen by dunking it in a sequence of chemicals to make the tissues more visible under the microscope. From these samples, biologists can determine the sexual maturity level of the fish in comparison to its age and size. These factors help managers know what size fish can be harvested without negatively effecting the overall population.
Another sampling technique modeled after the commercial fishing method is the vertical line sample. Bandit reels are large spooled, commercial fishing reels used to deploy a string of hooks suspended above a large weight. They are used to lower the fishing rig to the bottom around selected structures like oil rigs. They allow the sampling of fish of various sizes in the moderate range. Hook sizes are varied in a standardized way to allow different sizes of fish to be caught. Again, baits and “soak-time” are standard, and all aspects of the catch are documented for analysis later. Red snapper are one of the most common catches with this method, but many other types are encountered too.
Again using standard commercial gear, the fourth sampling method utilizes a shrimp trawl and catches an assortment of juvenile fish and invertebrates by dragging a net across the muddy bottom. All of the specimens are sorted, measured, weighed and cataloged for present and future uses. Samples are preserved and labeled to go back to the lab for more detailed studies. This method of collection is used to sample the juvenile size classes of important species that cannot be caught on the larger hooks of the previous methods. Shrimp counts are also an important aspect of this sample because commercial and recreational shrimping is a huge aspect of Louisiana’s seafood based economy.
These four methods of sampling help biologists paint a more accurate picture of the present state of the fisheries. Each one targets a different size of various species and gives researchers a sample across the age classes. These statistics are then shared with the federal agencies that are monitoring the Gulf, but much of the science stays here in Louisiana to help promote public access to these fisheries and ensure that the fisheries are healthy for all generations that follow.
