Tracking sharks through time: Long-term trends along the Texas coast

Sharks play a critical role in maintaining marine ecosystem resilience, yet many populations have declined due to overfishing and environmental change. In Texas, shark relative abundance trends across estuarine, nearshore, and offshore environments remain poorly understood. This study integrated three complementary fishery-independent surveys spanning ∼40 years (1983–2024), to improve understanding of cross-shelf shark assemblage structure and evaluate temporal and environmental drivers of relative abundance for 12 shark species, using Generalized Additive Mixed Models (GAMMs). This multi-dataset approach captured a broad range of environments and life stages, reducing bias associated with single-survey analyses. Of the 12 species examined, relative abundance of seven increased in at least one environment, three showed no directional change, and two declined consistently across environments. Blacktip Sharks (+149% [95% CI:101, 208] estuarine; +60% [95% CI:13, 125] offshore) and Bonnetheads (+481% [95% CI:366, 624] estuarine; +398% [95% CI:27, 1,855] offshore) exhibited the most consistent multi-environment increases. Bull Sharks (+128% [95% CI:106, 154]) and Scalloped Hammerheads (+373% [95% CI:224, 591]) increased significantly in estuaries, while Great Hammerheads increased in nearshore waters. In contrast, Lemon Sharks showed the most severe decline (−99% [95% CI:−100, −98]) in estuaries, and Atlantic Sharpnose Sharks declined consistently across environments (estuarine: −65% [95% CI:−79, −41]; nearshore: −79% [95% CI:−88, −65]). Overall, these findings support reported increases in shark encounters by fishers while also identifying species-specific declines that warrant concern. By establishing a unified baseline across environments, this study provides critical context for bycatch assessment and stock monitoring, and supports the development of adaptive, evidence-based shark management strategies in Texas waters.