A Comparison of Size Structure, Age, and Growth of Red Snapper from Artificial and Natural Habitats in the Western Gulf of Mexico

Abstract

Red Snapper Lutjanus campechanus support economically important fisheries in the Gulf of Mexico (GOM) and have been classified as overfished since the first stock assessment was conducted in 1988. Although the stock is now showing signs of recovery, management could benefit from a better understanding of regional or even habitat‐level differences in stock demographics, as these dynamics ultimately determine overall stock productivity. From 2012 to 2014, we used a fishery‐independent vertical line survey to assess Red Snapper relative abundance, size and age structure, and growth parameters at standing oil and gas platforms, decommissioned platform artificial reefs, and natural banks in the western GOM. We captured 1,170 Red Snapper ranging from 275 to 855 mm TL. Vertical line CPUE data showed no differences among the three habitat types. Ages determined for 1,143 individuals ranged from 2 to 30 years; however, most (90%) were younger than age 8. Size and age frequencies revealed that natural banks supported a greater proportion of large and relatively old fish compared to standing platforms or artificial reefs, although this difference was heavily influenced by a single bank that had significantly larger and older Red Snapper than other sites. Mean age was not significantly different among habitat types. Among a suite of growth models fitted to size‐at‐age data, the logistic model provided the best fit and suggested that fish from artificial reefs reached larger sizes at age than fish from either standing platforms or natural banks. Our study provides the first estimates of habitat‐specific growth parameters for Red Snapper in the western GOM, and this information can benefit future stock assessments. This study also highlights the potential benefits of artificial reefs to Red Snapper and indicates that all habitats could contribute similarly to stock productivity on a per‐unit‐area basis. Received December 21, 2016; accepted March 14, 2017 Published online May 26, 2017

Habitat‐Specific Reproductive Potential of Red Snapper: A Comparison of Artificial and Natural Reefs in the Western Gulf of Mexico

“…; Streich et al. ). These implications should be considered in the Gulf to identify best practices for reefing efforts and the sustainable management of the Red Snapper fishery.…”

“…; Shipp and Bortone ; Streich et al. ). Many platforms in the Gulf are mandated for removal due to federal regulations such as “Idle Iron,” a recent regulation requiring inactive platforms to be decommissioned (U.S. Department of the Interior ).…”

“…There is evidence that in some locales, Red Snapper associate with artificial structures over long periods of time (Szedlmayer and Schroepfer 2005), whereas in other areas, Red Snapper exhibit low site fidelity to artificial structure (Peabody and Wilson 2006). One study also showed that larger, older fish inhabit natural banks in comparison to artificial reefs, including standing platforms, while fish on artificial reefs reach a larger size at age, which suggests a faster growth rate (Streich et al 2017b). Thus, platforms may influence Red Snapper biology, life history characteristics, and population dynamics.…”

“…One study also showed that larger, older fish inhabit natural banks in comparison to artificial reefs, including standing platforms, while fish on artificial reefs reach a larger size at age, which suggests a faster growth rate (Streich et al. ). Thus, platforms may influence Red Snapper biology, life history characteristics, and population dynamics.…”

“…Several authors have argued that artificial reefs do not provide suitable habitat and may also increase fishing pressure-factors that together create a sink in the population Walters et al 2008;Cowan et al 2011). However, other authors have suggested that artificial reefs do provide suitable habitat and may contribute to the recovery and maintenance of Red Snapper in the Gulf (Szedlmayer 2007;Gallaway et al 2009;Shipp and Bortone 2009;Streich et al 2017b). Many platforms in the Gulf are mandated for removal due to federal regulations such as "Idle Iron," a recent regulation requiring inactive platforms to be decommissioned (U.S. Department of the Interior 2010).…”