This species is reef-associated and occurs in seagrass, coral reef, algal and rocky reefs and on algal beds at depths of one to 45 m. It exhibits a functional role in substrate use because it is an important excavator that often feeds on live coral.

There is no direct information on its life history to estimate generation length. However, based on sister species S. guacamaia, a generation of 7 to 10 years can be inferred.

Red List Category

Red List Criteria

Version

2010

Padovani-Ferreira, B., Floeter, S., Rocha, L.A., Ferreira, C.E., Francini-Filho, R., Moura, R., Gaspar, A.L. & Feitosa, C.

McIlwain, J. & Craig, M.T.

Justification

In 1996–1998, this species was the second most abundant species in Manoel Luis State Marine Park; it was present in 69% of underwater visual census (UVC) samples and had a mean length of 30 cm (Rocha and Rosa 2001). On the Abrolhos Bank, the largest coral reef area in the south Atlantic, this species represents 28% of total fish biomass, and has shown 50% decline in the past five years (Francini-Filho 2005, Francini-Filho and Moura 2008).

In the southeastern part of its range (Arraial do Cabo), the biomass has declined by 60–70% over the last 15 years based on UVC and fishermen interviews (B. Ferreira pers comm. 2008). Scarus trispinosus densities obtained with UVC (n=418 summer months at six areas) in shallow rocky reefs of less than 10 m depth in southeastern Brazil had a mean value of 0.00018/m² (A. Bertoncini pers comm. 2008). In the northeast of Brazil in Baixo-sul baiano, an UVC (n=713 at five reef areas) in shallow reefs from 10 to 25 m depth revealed mean density values of 0.0018/m² (A. Bertoncini and C. Sampaio pers comm. 2008).

Decreasing

This species is threatened by spearfishing throughout its range and also by net and trap fishing. Based on measured declines in at least two signicant parts of its range (Abrolhos Bank and the Arraial do Cabo), along with observations that large individuals have become very rare, it is estimated that at least 50% of the global population has declined over the past 20 to 30 years.

There are no species-specific conservation measures for this species. Significant differences can be seen in this species abundance inside and outside protected no fishing areas (Ferreira and Maida 2006). For example, in a study of this species in a no-take zone, it was abundant and recovered within 3-4 years from previous levels when fishing was allowed (Francini-Filho and Moura 2008).

A few populations are currently protected by reserves by no-take reserves along the coast, including some reefs in Abrolhos, in Costa dos Corais, and others where there is effective enforcement. However, the number of protected areas within its range does not include a large porportion of this species population or habitat.