Article by Solving-FCB Work/Learn Student Duncan Murray, with assistance from Dr. Fresia Villalobos-Rojas and Dr. Christian Birkel.

Tucked inside a pristine, tropical peninsula on Costa Rica’s Pacific coast, the Gulf of Nicoya has been a source of sustenance, income, and connection for surrounding communities over many decades. Lush green forests mark the border of an idyllic aquatic environment, encircling fishermen seeking the catch upon which their livelihoods depend.
Recent years have seen the quantity of this catch fall dramatically, due to the effects of climate change and overfishing. This decline has harmed the Gulf of Nicoya ecosystem, leading to a fall in biodiversity and abetting a dangerous positive feedback loop: when either biodiversity, food security, or climatic stability are negatively affected, the result is that the other two face similarly adverse effects.
Solving-FCB researchers are partnering with local stakeholders and taking an interdisciplinary approach to understanding and addressing the threefold problem threatening the ecological health and socioeconomic viability of those who depend on the Gulf of Nicoya.
Challenges facing local fisheries in the Gulf of Nicoya
Because of illegal fishing and certain ambivalent policies, building a life on the Gulf of Nicoya has grown increasingly difficult for local fishermen. Concerns about sustainable fishing led the Costa Rican government to cease the administration of fishing licences in 2005, according to Fresia Villalobos-Rojas, Science Coordinator at MarViva, an environmental nonprofit and Solving-FCB partner organization that promotes the responsible use of marine products through resource management and science communication. Regardless, unlicensed fishermen have continued to fish in the region, despite the government forbidding such activity.
Illegal fishing of any variety is potentially damaging to the sustainability of the practice, but not all illegal fishing is the same. “There are a lot of fishermen that do not have licenses, but they could be using legal fishing gear, like hand lines, for example,” says Villalobos-Rojas.

Some non-licensed fishermen forego sustainable practices altogether. Fishing techniques like trolling are especially detrimental to the Gulf of Nicoya ecosystem. “Other fishing gear is really damaging to the fish and the habitat. Trolling is when fishermen use these nets with two boards that are really heavy, and they go down to the seabed and are pulled along, so the net catches everything that is in front of it. So, it catches small fish, big fish – everything. It is mainly targeting shrimp, but it catches a lot of other things,” explains Villalobos-Rojas.
Part of MarViva’s work in the Gulf involves partnering with local communities to create alternative means of economic support. For many Gulf of Nicoya communities, fishing has been one of the few industries upon which residents could build lives. If local people could build and sustain new ways of supporting themselves financially, dependence on small-scale fisheries – legal or otherwise – would likely decrease.
The Science at the Centre of Everything
Among the scientists studying the causes of declining fish populations and biodiversity in the Gulf of Nicoya is Dr. Christian Birkel, a hydrologist at the University of Costa Rica. Dr. Birkel began his studies focused on chemistry, but found that to be a little too detailed. “I’m more interested in doing measurements and seeing and being able to observe processes like rainfall, runoff, infiltration – hydrological processes that you can measure, that are tangible.”
Hydrology is a branch of science at the centre of a network of other sciences, relying on insights from chemistry, physics, geography, and geology to understand the role of water in a given interest area. “I study where water flows, how it gets to the ground, how it disappears into the ground and resurfaces in other places, such as the ocean. My interest is in understanding how much water we have in certain domains for planification purposes, to meet a certain demand from stakeholders,” says Dr. Birkel. “The [interest areas] could be, for example, drinking water, the energy sector, agriculture. All of this is connected, because your need water to produce, to generate income and societal well-being.”

As a member of the Solving FCB team, Dr. Birkel focuses on how terrestrial hydrology affects marine biodiversity and, consequently, small-scale fisheries in the Gulf of Nicoya. “When you have intense agriculture with lots of fertilizer application – lots of pesticides, some fungicides – they travel via stream flow of the rivers into the marine environment.” Dr. Birkel explains. The Gulf, however, is relatively shallow, and its mixing with the open ocean is quite limited. This means that the Gulf of Nicoya is particularly susceptible to the effects of agricultural runoff, which can cause eutrophication and declines in biodiversity.
Dr. Birkel says that a confluence of factors adversely affects the Gulf of Nicoya ecosystem, pushing coastal communities into an increasingly precarious position. “For two or three decades, the reported fish catch has been declining, which affects these communities that almost exclusively depend on fisheries. We are studying this chain of cause effects and how the coastal communities, in the end, are affected not only by climate change, but also by anthropogenic activities,” says Dr. Birkel. Based on the results of these studies, the group plans to create a model that can predict how communities will be affected by certain changes to the environment, and ultimately encourage policy action.
Between partnering with local fishermen, studying the effects of anthropogenic climate change, and trying to navigate the challenge of extralegal fishing operations in the region, the success of this case study rests on cooperation among a wide group of people, each with an important role to play. The interdisciplinary nature of inquiry that characterizes all Solving FCB case studies is perhaps nowhere better exemplified than in the Costa Rica case study.
See also:
To learn more about illegal fishing in the Gulf of Nicoya
Fish, Drugs, and Murder | Hakai Magazine
To learn more about eutrophication and its adverse effects
Eutrophication | Definition, Types, Causes, & Effects | Britannica