[Animals] Sawfish

[WilkerCSBD]

At first glance it draws attention. His appearance from another age stands out from the rest of the fish and his long saw full of sharp teeth instills fear and keeps those who see him at bay.

The sawfish inhabits the waters of the Pacific, the Caribbean and the main rivers of the northern zone of Costa Rica. They are active at night and sleep during the day, they can reach up to eight meters and feed very close to the bottom of the water on crabs, shrimp and other fish, in fact they use their saw to hit their prey.

These animals are not very reproductive because they have to spend approximately 10 years to reach sexual maturity, their gestation periods are very long (more than nine months) and when they have young, between two and eight individuals are born.

These specific characteristics of reproduction, added to fishing, the deterioration and destruction of its habitat and climate change have caused the distribution of the animal to be experiencing a reduction of more than 95%.

This is why, with the intention of determining the current status of the species in Costa Rica, Jorge Valerio Vargas and Mario Espinoza Mendiola started a research project in 2016 to find out how it is distributed in Costa Rica and what its main threats are.

"We were very concerned that this species would disappear in Costa Rica without anyone doing anything about it," said Espinoza.

 The study
The objective that both researchers had was to try to talk to the po[CENSORED]tion so that they would give them as much information as possible about the sawfish. They mainly focused on fishermen, but also included other people in the community. This survey led them to travel for two years along the Pacific and Caribbean coasts, as well as the main rivers in the northern part of the country.

“We knew from historical reports that the species was distributed in all these environments. We asked the fishermen how much they knew about this fish, if they had caught it, when and where, if they had released it or if it had died, if they sold it, if they ate it, ”said Espinoza.

Out of a total of 275 interviews conducted in 42 communities, they were able to confirm 206 encounters with the long-toothed sawfish (Pristis pristis) and only two with the small-toothed sawfish (Pristis pectinata).

The data collected reveals that these individuals have experienced a substantial decrease, as the number of sightings or captures went from 89 historical records more than 20 years ago to 24 in the last five years.

Many of the interviews gave them information about where the species was two or three decades ago and where it is now. This helped them rebuild the redistribution and begin to settle where the species is currently seen.

“It filled us with hope to know that there are still many reports and that there are two 'hot' areas (Térraba-Sierpe National Wetland and in the north of the country in several of the large rivers that flow into the San Juan) in which we have to work with the community so that the species can last ”, added the researcher.

The study was developed based on a total of 275 interviews carried out in 42 communities. ...
The study was developed based on a total of 275 interviews carried out in 42 communities. Photo: courtesy of Mario Espinoza.
 
Two places, two problems
Despite the fact that the Térraba-Sierpe National Wetland is located in a region of importance for tourism, the expansion of areas destined for monocultures is affecting the habitat of the sawfish.

In the north the story is different. The problem of the fish is linked to the socioeconomic and bordering condition of the place. Many of the reports indicate that, due to harpoon fishing and by confusing it with real shad - commonly consumed by the inhabitants of the area - people kill it.

Illegal trafficking in the mountains is also very present in the country. These parts are used as ornaments, trophies and, recently, it was discovered that the teeth of the saw are intended for the manufacture of spurs, which are used in illegal cockfights in several Latin American countries.
 

What's next?
Although the study by Valerio and Espinoza is recent (it was published in November 2019), since 2017 actions have been implemented to protect the species present in Costa Rica. At the end of this last year, several articles were approved in the Legislative Assembly to prohibit sea hunting and the capture of sawfish.

In 2017, a social projection work was also started at the UCR that consists of educating, raising awareness and sensitizing the Costa Rican po[CENSORED]tion about the species, through urban advertising campaigns in the Greater Metropolitan Area. Likewise, trainings were carried out in schools and colleges in the areas where they have seen the sawfish.

In addition, a phase of fishing expeditions began in Sierpe de Osa to be able to capture the species and study it better, mark it and measure it, which has not yet been achieved. Most of the catches and reports of sightings of the fish have been by local fishermen.

The next steps that the researchers propose are to continue with the explorations, not only concentrated in Sierpe, but also in Corcovado, in the Osa peninsula, in the north and in Barra del Colorado, in the Caribbean, in order to “be able to carry the sawfish to people's houses ”. The idea is that there is a rapprochement between this animal and the communities in order to make the conservation message bigger and bigger.

In 2019, a study called Global Sawfish Search (led by James Cook University, Australia) was started, which seeks to improve global conservation efforts targeting sawfish through the use of environmental DNA techniques.

Through this methodology, it is about detecting the species through water samples that are analyzed to obtain small traces of DNA and thus be able to locate a species without the need to have seen an individual.

Based on the interviews conducted, Valerio chose a series of sites and collected water samples. At the end of the previous year, he traveled to Australia to examine these water samples and identify if there are traces of the sawfish.

The results of the environmental DNA study will be overlaid with the information collected in the interviews to definitively determine which are the most important areas where this species is found, and then organize expeditions to try to observe it.

Everything that biologists have been doing during these years has been an initial phase to prepare a later stage that deserves much scientific evidence necessary for the conservation of sawfish.