“Another Kid on the Block”: Testing the Effects of Artificial Substrates on the Recruitment of Juvenile Fishes in the Northwestern Gulf of Mexico

Abstract

Most artificial reefs (ARs) in the Gulf of Mexico are considered intermediate to high vertical relief structures which have recruited large predatory species indicating a lack of juvenile habitat. Small, inexpensive ARs, standard monitoring units for the recruitment of reef fishes (SMURFs), were deployed at eight treatment stations at −20 m as habitat for juvenile fishes to understand and determine the effects of substrate type on the recruitment of juvenile fishes. Each treatment station contained four SMURFs with four treatments: small and large concrete rubble (~10 and ~20 cm), oyster shells, and bare. Surveys conducted from July 2017 to July 2019 yielded 39 different juvenile species, including one of the most economically important species, Lutjanus campechanus, present across all replicates. There were 5238 individual fishes collected, and the family Lutjanidae accounted for ~49% of these. The highest species richness and diversity occurred in SMURFs containing oysters or small concrete rubble while bare treatment had the lowest. Both concrete rubble and oyster shells might offer shelter to numerous body shapes and sizes of juvenile fishes as a result from a variety of crevice sizes. This study suggests that the deployment of low-relief structures with different substrate materials might affect recruitment of select species and provide further information useful to designing ARs, aiding fisheries production. Because enhancing fisheries is one of the goals of the Texas Parks and Wildlife Department Artificial Reef Program it is here recommended to continue developing other designs of low-relief to be allocated in between existing high-relief ARs that should serve as stepping stones for the survival of species of fisheries interest (e.g., L. campechanus).