Acta Ichthyologica et Piscatoria 42(1): 21-30, doi: 10.3750/AIP2011.42.1.03
Biology, feeding, and habitat preferences of Cadenat’s rockfish, Scorpaena loppei (Actinopterygii: Scorpaeniformes: Scorpaenidae), in the Balearic Islands (western Mediterranean)
expand article infoF. Ordines, M. Valls, A. Gouraguine
Open Access
Background. Scorpaena loppei Cadenat, 1943 is a small benthic scorpion fish, distributed in the eastern Atlantic from the Bay of Biscay to Mauritania and the Mediterranean Sea. This work constitutes the first complex attempt to study aspects of biology, feeding, bathymetric distribution, and habitat preferences of S. loppei. Materials and methods. The biological samples of S. loppei, as well as the data on its abundance and distribution, were collected during the annual bottom trawl survey series BALAR-MEDITS carried out from 2005 through 2010. The biological sampling included: weighing and measuring the fish, gonad weighing, determination of sex and maturity stage, age estimation through otolith readings, and stomach content analysis. Results. The sampled individuals ranged from 5.5 to 12.8 cm in total length (TL). The females predominated in the smaller size classes, and males being more abundant in the larger ones. All females sampled were mature (or approaching maturity). The age determined ranged from 0 to 5 years and from 1 to 5 years, for females and males, respectively. The estimated values of the von Bertalanffy asymptotic length L∞ (cm) and growth coefficient k (year–1) for females and males were 10.9 and 0.53 and 12.4 and 0.49, respectively. According to the age–length key, all females of S. loppei should be attaining their first maturity during their first year of life.  The diet of S. loppei consisted predominantly of crustaceans (mysids and decapods) followed by teleosts fishes. A specialized feeding behaviour was indicated by the Levin’s index for numerical composition and frequency of occurrence assuming values  of 0.18 and 0.28, respectively. The presence of S. loppei was restricted to sandy-mud deep continental shelf bottoms from 90 to 180 m depth. This distribution did not overlap with that of other small scorpion fish species inhabiting the area. Conclusion. Unlike its congeners, S. loppei demonstrated specialised feeding habits and habitat requirements. Being the only small scorpion fish inhabiting this benthic habitat in the study area might have reduced the interspecific competition, facilitating feeding and growth and allowing an early achievement of sexual maturity.
Scorpaena loppei, small scorpion fish, deep continental shelf, bottom trawl surveys, biological traits, distribution, Balearic Islands, western Mediterranean