Working Groups

Introduction

Much shorebird habitat has been altered for commercial shrimp farms on the coasts of Mexico, Central, and South America, but shorebirds often use these farms and their natural and modified habitats for opportunistic foraging and roosting. Between 20 – 27 shorebird species and tens of thousands individuals have been observed using a single shrimp farm (e.g., at the Gulf of Fonseca, Morales et al. 2019, and in Mexico, Navedo and Fernández 2018). Willets, American Oystercatchers, Western Sandpipers and Black-necked Stilts are among the species which make use of the shrimp farms for roosting and foraging in the drained shrimp ponds between production cycles. There lies an opportunity for the shrimp farm industry and shorebird conservation practitioners to work together towards improved conditions for shorebirds.

Background

Shrimp farming is an aquaculture production method that yields high-quality shrimp for human consumption. Shrimp farming in Latin America began in the 1970s and gained momentum in the 1990s with improvement in production practices and capital investments from international development funds. Shrimp farms operate in different ways, but semi-intensive farms are a complex of human-made ponds and dikes, developed primarily within tidal mangrove estuaries with freshwater sources to aid production.

As of 2016, there were approximately 60,000 hectares (ha) in production in Central America (Guatemala to Panama), another 60,000 ha in Mexico, 19,000 ha in Brazil and 220,000 ha in Ecuador (Figure 1. ARAP 2008, SENASA 2016, INPESCA 2016, El Salvador Ministry of the Environment 2016, FAO 2018, Global Aquaculture Alliance 2018). Within Latin America, the nations with the largest volume of production are Ecuador, Mexico, Brazil, Honduras, and Nicaragua. Mexico and Brazil primarily produce shrimp for domestic markets, but other countries, like Nicaragua, export their products.

Threats and opportunities related to shrimp farm development

During the 1990s, international lending institutions and national governments promoted the expansion of shrimp aquaculture in Latin America as an important industry for rural economic development (Queiroz 2014). As a result, shrimp aquaculture development has contributed to the loss of 38% of mangrove habitats in the Americas (Valiela et al. 2001). However, within mangrove ecosystems the specific habitat frequently converted to shrimp farms are salt flats (Berlanga-Robles et al. 2011). The adjacent maps illustrate how shrimp farming has expanded in Honduras and Nicaragua between 1985 and 2015, converting natural salt flats habitats into shrimp ponds (Figure from Morales et al. 2019).

Shrimp aquaculture can directly impact shorebird habitats by destroying or reducing habitat quality in salt flats and marshes, seasonal freshwater wetlands, and mangrove estuaries. Shorebirds also make use of the shrimp farms’ dikes for roosting, and the daily farming operations can disturb birds. Once farms are developed, they also tend to encourage other infrastructure and activities including: 1) building of dams, roads, and utility lines; 2) extraction of mangroves for wood; 3) alteration of nursery fish habitat; 4) modification of wetlands 5) compounded conflicts of water management; and 6) increased industrial pollution (Benessaiah and Sengupta 2014).

Studies suggest that once semi-intensive shrimp farms ponds are established, they may benefit migratory shorebirds during the non- breeding season. For example, one of the benefits of shrimp farms ponds is that they provide feeding habitat after the shrimp harvest. The farms also offer supra-tidal roosting areas on the dikes, particularly those that do not have vegetation. Negative impacts can be minimized and positive benefits can be enhanced through the development of sustainable best management practices that reduce damage to natural and human-modified habitats that surround the shrimp farms (Navedo and Fernández 2018).

How shorebirds make use of natural and shrimp farm habitats

Shorebirds make use of a variety of coastal habitats for foraging, roosting and breeding. Daily tidal cycles regulate the availability of shorebird food: Mudflats and shorelines are exposed during low tides and invertebrates are within the reach of probing shorebird beaks, whereas the flooding of high tides makes food unavailable. Shorebirds make use of these daily cycles to forage rapidly during low tides and rest when tides are high and food is unavailable.

Shorebirds feed in ponds at shrimp farms when water levels are low after a harvest of shrimp, usually for a 3- to 4-day period. More frequently, shorebirds can be found roosting on the farm’s dikes or other non-production areas during high tides (Morales et al. 2019).

Conservation need and goals

Coastal mangrove habitats and adjacent salt flats are productive ecosystems that benefit human wellbeing through the delivery of ecosystems services, such as subsistence agriculture, artisanal fisheries, and provision of building materials and fuels (Lacerda 2002). Mangrove estuaries are vital nursery habitats for subsistence and commercial fisheries (Hutchinson et al. 2015). Given the importance of mangrove ecosystems, including salt habitats, people working to protect shorebirds and their habitats while maintaining economic opportunities have identified the following goals:

• Limit the impact of shrimp aquaculture by discouraging development in sensitive areas of high importance to birds and fish.
• Mitigate the impact of shrimp farms on shorebird populations by implementing best management practices and market-driven valuation.

Conservation Strategies

In 2018, a Shorebirds and Shrimp Farm Working Group was created to more effectively build expertise and resources to support, guide, and encourage efforts by shrimp farmers to adapt production practices to increase their value for shorebirds and other wildlife. The Working Group is comprised of shorebird and wetlands biologists, research scientists, and shrimp farm industry representatives. If you are interested in joining the Working Group, please contact Salvadora Morales, WHSRN Conservation Specialist, smorales@manomet.org.