LDWF’s Fishery-Independent Trawl Sampling Program Has Gathered Vital Information For More Than 50 Years
story by TREY ILES, LDWF Public Information

Jeff Marx longs for the days when he was out on the open waters of coastal Louisiana pulling routine shrimp samples. It didn’t matter that the Louisiana summers were vexing because of the oppressive heat and humidity or that cold fronts in the winter blew in bone-chilling temperatures enhanced by unrelenting north winds.

Marx, the Louisiana Department of Wildlife and Fisheries interim Director of Marine Fisheries, had a zeal for gathering data vital to monitoring Louisiana’s shrimp, blue crab and bottom fish that inhabit the state’s inshore and offshore waters.

“I loved being out on the water,’’ Marx said. “Now I look at trees from my office. There were tough days going out because of the weather. But I always enjoyed the work.’’

He’s certainly not the first LDWF biologist to do this job and won’t be the last. It’s the passion shown by many of the field biologists that has helped LDWF’s fishery-independent trawl sampling program produce sustainable harvests and allow for profitable fisheries for more than 50 years.

In fact, the program, birthed in 1967, celebrated its 50th anniversary in 2017. And the data collected during that time has been critical for the state. That’s important considering Louisiana accounts for more than 25 percent of annual landings of shrimp in the United States and more than 40.8 million pounds of blue crabs were landed in the state in 2016. No state supplies more domestic shrimp or blue crab than Louisiana.

The dockside value of shrimp in 2016 was appraised at $140.4 million and the blue crab at $50.2 million.

“This is one of the most important programs conducted by marine fisheries,’’ Marx said. “And a reason for its success is the people who do it and have done it through the past 50 years. They have a passion for it. They like what they do and managing the resource is so important to them.

“Many of our biologists having been doing this for a long time and that experience is important. Paul Cook, one of our managers in New Iberia, has been here for more than 35 years. When you have someone who argues that he’s been shrimping for 30 years, well, Paul has been sampling these waters for 35 years.’’

The process for retrieving the samples is fairly simple. Using LDWF vessels that range from 20 to 35 feet, biologists deploy 16-foot trawls into the water and tow them for 10 minutes. After that, the biologists raise the trawls, retrieve the samples – shrimp, blue crab and fish – and place them in plastic bags and transfer them to ice chests. The samples are then taken to the labs located in the LDWF regional offices for workup and analysis.

The program data is vital in setting annual shrimp seasons, monitoring size and abundance over the course of the season, viewing long-term trends and monitoring fisheries resources before and after natural disasters.

“Our sample process is the biggest thing for setting the opening and closing of (shrimp) seasons, both fall and spring season,’’ Marx said. “ For blue crabs, the samples feed into the stock assessments and the stock assessments are what we’re using to base our management actions on.’’

The dedication of LDWF’s marine fisheries staff has given the department the ability to acquire 50 years’ of fishery-independent trawl data. The diligence is shown through the amount of effort it takes to collect both fisheries independent and dependent samples. On an annual basis, the marine fisheries staff is responsible for completing more than 3,600 individual dredge and square meter samples, 2,400 inshore and offshore trawl samples, 2,100 gill, trammel and seine samples, 1,600 dockside creel surveys and the collection of the target of more than 11,000 otoliths through LDWF’s biological sampling program.

That sounds like a lot of samples, but consider that when those samples are collected, they’re compared to that historic set of samples. Since 1967, more than 41,000 6-foot trawl samples and more than 75,000 16-foot trawl samples have been taken – more than 116,000 trawl samples with those two gears combined. That historic data provides a solid basis to compare any current information to, in order to develop management recommendations.

Basing management decisions on this consistent data has allowed Louisiana to have the first and only certified sustainable blue crab fishery and a healthy shrimp resource with good economic value. This is the longest continuous monitoring program in Louisiana fisheries. Since the establishment of this program, additional fishery-independent monitoring programs have been established to monitor finfish and oyster populations to provide similar perspective on changes in those populations.

To augment the samples, LDWF biologists take input from commercial and recreational fishermen.

“We get calls, which is another added benefit,’’ Marx said. “All of our area personnel who actually take the samples are coastal study area managers. They have the data for their basin and they get phone calls from commercial fishermen, local recreational fishermen requesting information on the best places to go fishing or shrimping. They know what it looks like on the water because they are out there, often several times during a week.’’

When LDWF began the sampling program back in 1967, it was done so with an eye on protecting the resources. Shrimp boats were numerous on the inshore and offshore waters and LDWF knew it was time to get a handle on how those resources were being managed before it became a problem.

Louisiana’s inshore waters and marshes are certainly different from back then thanks to coastal erosion. The shrimping industry today isn’t as large as it once was because of hurricanes, foreign shrimp flooding the market and other factors.

The changing landscape makes the 50-year-old program that much more valuable. The 50-year data set and the constantly adapting fisheries independent sampling directly addresses the LDWF goal to enhance the collection of biological and environmental data associated with fish and habitat resources from state waters.

“The one thing that has always gone on during that time is we sample,’’ Marx said. “We’ve changed the frequency some times when economics require us to do so. If we’re having a budget crunch we may not go as much. But we still try to get it as a routine.’’

The program proved its worth recently when a decline in the blue crab population was noted. The Louisiana Wildlife and Fisheries Commission enacted a 30-day ban on take of blue crab in March of 2016 to help the resource recover. This year, a two-month ban on the take of female blue crab will be in place.

“We saw from the stock assessment that we were having an issue,’’ Marx said of the decline. “The data showed that there was a problem. We had heard from fishermen there was a problem. Our data backed that up. It didn’t necessarily drive what we did but it did drive us to take action.’’

The future of the sampling program will prove valuable in a way that probably was unimaginable in the middle 1960s. With Louisiana working to restore coastal land loss, the program will be in an important tool for measuring the health of a fishery in areas where diversion projects will be implemented.

“We’re going to have the data that shows what was going on in that particular area before they open a diversion or create a marsh or whatever the case may be,’’ Marx said. “(Louisiana’s Coastal Protection and Restoration Authority) is working with us closely to get some of this data. It’s useful for them to use in their models because it’s a long term data set.’’

Louisiana dynamic fishing industry has undergone many changes since the middle 1960s and continues to evolve. Because of LDWF’s sampling program, that evolution can take place with the benefit of science and trusted data that has been around for 50 years and continue to help Louisiana’s seafood industry to thrive.