Greg Lutz and Mark Shirley

Aquaculture production is one of Louisiana’s major animal industries, and its $609 million contribution to the state’s economy makes it an important part of Louisiana’s agriculture. Crawfish production typically accounts for more than 60% of the farm-gate value of Louisiana aquaculture, and water quality in crawfish ponds is probably the most important factor influencing survival and growth of the popular crustacean. For as long as people have been farming crawfish in south Louisiana, the cure for most water quality problems has been to simply pump water, either from irrigation wells or surface sources. This is necessary to flush out stagnant or “bad” water (with low oxygen content and high levels of ammonia, nitrite and hydrogen sulfide) that can result from the breakdown of the vegetation that fuels the crawfish food chain. Because of this, water quality in production ponds impacts the surrounding watershed, and vice versa.

While replacing bad water in a crawfish pond with fresh, oxygenated water usually helps maintain satisfactory conditions, the term “water quality” refers to a number of different parameters. Dissolved oxygen is by far the most important consideration for crawfish farmers and, generally speaking, if oxygen can be maintained at good levels, other components of water quality will be satisfactory.

Origins of AgCenter Crawfish Best Management Practices

In 1989, the Natural Resources Defense Council Inc. and Public Citizen Inc. jointly filed an action against the Environmental Protection Agency alleging that the agency had failed to comply with certain responsibilities under the Clean Water Act. Under a consent decree agreed to in 1992, EPA’s administrator was required to propose an effluent discharge rule for the U.S. aquaculture industry by August 2002 and to take final action on that proposal by June 30, 2004. The final rule resulted in no new regulatory burdens on Louisiana’s crawfish industry, largely because the AgCenter participated in the task force that interacted with EPA during the rule-making process. By 2003 the AgCenter had published its first set of recommended best management practices for all aquaculture producers, and in 2011 these recommendations were updated with a new set of best management practices specifically for the crawfish industry. In addition to water quality considerations, these included many other practices that impact environmental and economic sustainability.

Current Recommended Best Management Practices

Water quality in crawfish ponds is influenced by many factors, including the type of vegetation planted, when the vegetation is planted, how the vegetation is managed prior to flooding and when the pond is flooded. Because of this, many of the best management practices developed for crawfish production relate to one or more of these factors. Even if the impact on water quality is only indirect, the result is improved environmental conditions both within and around crawfish ponds.

Crawfish producers have been surveyed on many occasions over the past two decades (most recently in 2018) to determine their understanding and adoption of recommended practices. Economic assessments of many of these practices have also been developed over the years based on AgCenter budgets and research results, as well as field observations in commercial operations. Differences in net returns based on ignoring or adopting certain practices, individually, were extrapolated on a per-acre basis in relation to total costs and projected yields. Many of these potential impacts are not necessarily additive within an operation, although some clearly could be. The results of the most recent evaluation are presented here.

The most recent AgCenter data from 2020 indicates 172 million pounds of crawfish were harvested from 283,000 acres of ponds in Louisiana, with a farm-gate value of $230 million. The overall economic impact of each of the practices listed here is clearly significant, and many are still being adopted more widely. For example, if the practice of measuring oxygen on a regular basis were adopted by an additional 20% of producers, the economic benefit to the industry would be approximately $10 million. AgCenter personnel demonstrated early on in the development of best management practices for crawfish production that it is more cost-effective to drain a portion of bad water from a pond and subsequently pump oxygenated water to replace it than it is to drain and pump at the same time. This practice alone has greatly reduced both pumping costs and effluents industry-wide.

All indications are that crawfish aquaculture will continue to grow in Louisiana. As markets, input costs, government regulations and environmental conditions such as water availability continue to change, the AgCenter will continue updating best management practices for the industry.

Greg Lutz is a professor and specialist in the School of Renewable Natural Resources. Mark Shirley is a regional aquaculture specialist in the Southwest Region. Both have worked with crawfish producers for more than 30 years, and both hold joint appointments with Louisiana Sea Grant.

This article appears in the winter 2023 edition of Louisiana Agriculture.

Regular monitoring of dissolved oxygen levels is essential. This allows producers to respond to deteriorating water quality and to avoid unnecessary pumping costs. LSU AgCenter file photo

Aeration greatly improves cost effectiveness when filling and flushing ponds. LSU AgCenter file photo

Costs associated with harvesting crawfish include bait, fuel, labor and depreciation of equipment such as boats, engines and traps. Efficient harvesting practices can make the difference between profit and loss. LSU AgCenter file photo