Comparing Shallow Seagrass Versus Fringing Marsh Habitat Use by Nekton Juvenile Recruits with “Incomparable” Fishing Gear in the Northern Gulf of Mexico

Shallow coastal systems act as nursery habitat for many species of fish and macroinvertebrates. Juveniles of these species may show selective use of certain habitat types over others, but the degree of such selectivity is not well studied for many species. Analysis of habitat selectivity is often hindered by inherently different gear types used in the habitats examined, which may not allow for direct comparison between the habitats. Here, we carry out nekton catches in the fringing marsh, using fyke nets, and in the adjacent seagrass habitat, using trawls, in the northern Gulf of Mexico to assess the relative use of the two habitats by the juveniles of six widespread important species. To resolve issues of gear comparability between fyke nets and trawls, we develop a habitat use index (HUIS)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$({HUI}_{S})$$\end{document}. The results reveal a consistent trend where, in relation to pinfish, speckled sea trout shows slightly higher (from 8.4 to 66.9 times); American silver perch and brown shrimp show moderately higher (from 2.3 to 369.4 times); and blue crab and white shrimp show greatly higher (from 90.6 to 2366.4 times) use of marsh over seagrass habitat. Thus, while similar in direction, differences in the use of marsh over seagrass habitat in relation to pinfish were more pronounced in some sites. We propose an index that can resolve issues of gear comparability and improve our understanding of coastal habitat selectivity by fish and macroinvertebrates.