Alligator Gars in Texas Coastal Bays: Long‐Term Trends and Environmental Influences

Abstract

AbstractRecognition of the recreational and conservation value of the Alligator Gar Atractosteus spatula has spurred efforts to understand its biology, ecology, and status in river–reservoir systems throughout their range. However, Alligator Gars have also been found in the coastal bays that link these rivers to the Gulf of Mexico. Little is known about the species in saltwater environments or their potential role in coastal fish communities. For that reason, we analyzed 37 years (1975–2012) of standardized gill‐net catches of Alligator Gars in 10 Texas bays to characterize spatiotemporal trends in abundance and size structure and identify influential environmental covariates. Over 28,000 Alligator Gars (113–2,040 mm TL) were collected during 24,756 net‐nights of effort. The species was generally omnipresent both spatially and temporally; however, catch per unit effort varied by two orders of magnitude and was both cyclical and synchronous among bays. Trends in catch and size structure were consistent in most bays, which is indicative of stable abundance and dynamic rates. Current salinity and freshwater inflows, as well as catch rates, salinity, and freshwater inflows during the previous sampling year, explained significant proportions of the variation in catch in all but one system. Generally, periods of increased catch were associated with lower salinity and higher freshwater inflow, though Alligator Gars continued to be collected at salinities over 35‰. Analyses revealed that Alligator Gar catches in Texas bays were similar to or considerably greater than those of Bull Sharks Carcharhinus leucas, which are considered the most abundant top predator in these systems. The broad distribution of the Alligator Gars along the coast, coupled with its high relative abundance, highlight the need to understand the species’ role in coastal food webs and ecosystem function, with the ultimate goal of improving our ability to manage both Alligator Gar populations and coastal communities.