In the field with Luke Johnson

Luke Johnson (R) & Francisco Manera, forest ranger

Meet Luke Johnson,  a fish researcher working with us for six months to understand the biology of juvenile Atlantic Tarpon in freshwater streams.

After a few years spent touring salmon streams gathering data for fisheries studies in the Pacific Northwest, Luke is exploring the riverbanks, streams, and shores of Lake Nicaragua and the Rio San Juan.

The project Luke set out to undertake is outlined below, but with dry riverbeds and no sightings of the targeted species yet this season, his current focus is on establishing protocol for monitoring streams, water quality, and fish populations.

These new baseline assessments and research methods will expand our biodiversity monitoring in the Paso del Istmo, and our work with  Nicaragua's fishermen.

Background:
Throughout the Caribbean and South coastal United States, Atlantic Tarpon have proven to be an invaluable fishery for means of subsistence, for eco-tourism and local economies, and ecologically. Fossil research shows that Atlantic Tarpon have inhabited warm ocean waters since prehistoric times, which is a testament to the historic role these fish have had in our global oceanic ecosystems. Their Atlantic range is expansive; all throughout the Caribbean and Gulf coast, from the coasts of Virginia to central Brazil in the west and along the coast of Africa to the east. Upwards of 8 feet long and 280 pounds, these fish have a monster presence in the estuaries and coasts of the Atlantic through their 80 year lifespan. As a result of their size and agility, Atlantic Tarpon are one of the most sought after sport fish in the Atlantic ocean. The appeal of Tarpon as large fighting fish attracts sport fishermen from all over the world and the fishery has an estimated worth of more than $6 billion annually.

In addition to the value of Atlantic tarpon as a sport fishery, these fish are known to provide an important source of protein for those who live a subsistence farming lifestyle in rural parts of Latin America. Tarpon are a catadromous species, which means they spawn in open saltwater and live at least a part of their life in freshwater. Before the fish grow to be a large carnivore, sometimes known as the “Silver King”, Atlantic Tarpon are known to feed on a variety of crustaceans and insects in their juvenile stage. During this period of development Atlantic Tarpon swim up estuaries and into rivers, streams, and lakes to bolster their diet. The rainy season is the most common time of year for the young Tarpon to migrate up these perennial and often times seasonal streams. During this migration the fish become more available to harvest for Latin Americans who live inland and people fish for Atlantic Tarpon with large nets and eat them in a variety of ways for a vital source of protein.

Although these fish play a large role in people’s livelihoods, local economies, global eco-tourism, and marine ecology, much of the Atlantic Tarpon’s life cycle is shrouded in mystery. There have been a number of studies on Atlantic Tarpon genetics, diet, habitat, and migration. However, these studies have not been extensive in their geographic area (primarily in Florida) and have not been repeated to provide substantiation. There remains much to be learned about the Atlantic Tarpon life cycle including an accurate estimate of the current population and/or stocks.

Paso Pacifico and Atlantic Tarpon:
Paso Pacifico, an NGO that works on conservation biology and environmental education in the Paso del Istmo in Nicaragua, has been working closely with foresters and local Nicaraguans to manage lands with a holistic perspective. During their work to reforest and reconnect habitat of a variety of wildlife species, the organization has determined that integrating the nearby freshwater systems, lakes and streams, should naturally be component of the management plan. Much of the nearby seasonal streams flow directly through conservation sites and foster young Atlantic Tarpon populations for part of the year. Paso Pacifco aims to integrate Tarpon monitoring and habitat restoration into their work in order to continue the holistic approach to environmental education and wildlife conservation.

Objective:
Very little is known about the life cycle of Atlantic Tarpon and, in particular, the Atlantic Tarpon population that emigrates through El Rio San Juan and Lake Nicaragua. As a result Paso Pacifico will conduct a baseline study to begin to learn about the number of fish occupying these streams, their size and stage of development, and the number of fish harvested annually.