Essential Fish Habitat Mapping: Monitoring vulnerable marine life
Grey Triggerfish are categorized as globally vulnerable by the International Union for the Conservation of Nature (IUCN). There is growing concern about the decline in the abundance of Grey Triggerfish which is a commercially valuable species, particularly in Southern Brazil, a region that relies heavily on its artisanal fishing industry.
The objective of this study is the identification of Essential Fish Habitat for several life history stages of the Grey Triggerfish in Southern Brazil. It is the hope that the data gathered contributes to the conservation of the species and to further improve the work undertaken to protect Grey Triggerfish.
Habitat mapping and species knowledge makes a major contribution to understanding the declining stocks of the highly valued Grey Triggerfish. This can be used to guide future marine spatial planning and sustainable management.
Grey triggerfish are relatively small fish, usually less than 2.3 kg found mainly in shallow waters up to a depth of 100 m. They are typically found near reefs and rocky areas. In terms of distribution, they are mainly located in the western Atlantic Ocean but have also been identified in West Africa, the Mediterranean and parts of Europe.
Grey triggerfish are currently one of Brazil's most commercially caught species, with the highest catch of 1,448 tonnes recorded in the 2000s. There is growing concern about the decline in abundance of the grey triggerfish, which is especially of high commercial value, as the Southern region of Brazil relies heavily upon its artisanal fishing industry and therefore species. As of 2024, the grey triggerfish is listed as an endangered species according to the IUCN, this was upgraded from its previously vulnerable status.
The project looked at species distribution modelling of grey triggerfish for both the adult and juvenile populations to help identify key areas for future stock enhancement work to try and protect this vital food source. A random forest algorithm was used to model the adult population. Several layers were input into the model with 10 environmental variables being identified as the most important. The juvenile population was modelled using a rule-based classification due to very little point data being available. Sargassum model was compiled using Google Earth engine and used 20 years' worth of data.
This work provides the baseline for future stock enhancement work taking place in Espírito Santo where these efforts are being concentrated by IFES. Stock enhancement in the case of Brazil, is defined as increasing the productivity of a fishery by augmenting the natural supply of juveniles and optimising harvesting. Looking at areas where juveniles can be reintroduced into the ocean to help bolster populations. The project's first phase successfully reached its aim of better understanding this species.
Key Highlights
- The success of BORA Blue Ocean Research Alliance®, as shown by phase one of the grey triggerfish project, is further emphasised with phase two currently in the planning stage.
- The results from the project have been presented at international conferences with a scientific paper being internally reviewed before publication.
- The collaboration between IFES and NOC and the exchange of knowledge between the institutions has been a fantastic demonstration of industry and science collaboration. This will be further strengthened during further phases of the project.
- This project also highlights the need for science and industry partnerships like BORA Blue Ocean Research Alliance® to facilitate industry and research collaborative efforts, as well as NOC's emerging role in the space of food security.
