Searching for sawfish in northern Peru
Alejandra is sampling environmental DNA to scour the coast of northern Peru for largetooth sawfish. Although the species was long thought to be extinct here, two individuals were caught in the Tumbes Region in 2016. The finding has sparked some dedicated sleuthing from Alejandra, who will be interviewing fishers to find out about ancestral fishing grounds in the hope that the insights she gains will help to narrow down her search. Reports from fishers using the Cancas and Caleta La Cruz landing sites suggest that once-abundant sawfish were overfished for the value of their teeth, which were traditionally used as spurs on the feet of prize birds in cockerel fights.
Alejandra Mendoza Pfennig
I grew up by the sea in Lima, the capital of Peru. When I was little, I used to spend my summers camping with my parents on a beach where there were no houses, only fishing camps. I would wake up early to wait for the fishermen to return in their boats and then watch them disentangle the fish from the nets and ask them the names of the different species. Although I was very young, I soon recognised all the species and learned to remove the scales and clean the fish on the rocks with sea water....
Searching for the largetooth sawfish using fishing ancestral knowledge and eDNA tools in northern Peru
To determine whether there is a remnant population of sawfish in northern Peru so that regulations for the conservation of the species can be implemented.
Sawfish have been fished since ancient times for their ‘teeth’, which have been used as spurs in cockfights. Today there are few records of them and we do not know whether there is still a population in Peruvian waters and what habitat it is using. Environmental DNA will be employed to search for sawfish in potential refuge or nursery areas, generating information to improve management and raise awareness about the species’ conservation.
The largetooth sawfish Pristis pristis was for a long time considered extinct in Peruvian waters, but in 2016 two individuals were caught as bycatch on the Tumbes coast. The area where they were caught includes two mangrove systems that are fed by the Tumbes and Zarumilla rivers. As we know, sawfish usually live in shallow coastal waters, usually at depths of up to 20 metres (65 feet) but sometimes as deep as 122 metres (400 feet). They can tolerate a wide range of salinity and thus can be found in inland waters and in estuaries. They are also known for using fresh-water bodies as nursery grounds in northern Australia and Florida in the USA.
According to fishermen from the Tumbes region (Cancas and Caleta La Cruz landing areas), sawfish used to be abundant along the north coast of Peru, but due to overfishing they have now almost disappeared. The overfishing was driven by the high value of sawfish teeth, which were used in cockfighting as artificial spurs fitted to the birds’ feet to give them a competitive advantage. In addition to the two individuals caught in 2016, the following year a third specimen was captured in a gill net and landed dead in Mancora, a few kilometres south of Tumbes. These three reports of sawfish are from the same area where scientists had recorded the species earlier. It appears that this region is still part of the largetooth sawfish’s range, and since sighting or monitoring individuals in open water is difficult because the area is so large, using eDNA to locate a nursery ground in the vicinity of shallow waters is likely to be the most successful method of finding sawfish.
- To conduct interviews with fishermen and use their ancestral knowledge to search for sawfish in the sites with the most chances of success.
- To search for sawfish DNA in these sites.
- To promote the conservation of the species by holding workshops to help fishermen identify sawfish correctly and to inform them how to avoid catching sawfish by accident.