Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas, United States of America.
PLoS One. 2019 Feb 19;14(2):e0211971. doi: 10.1371/journal.pone.0211971. eCollection 2019.
The Galveston Ship Channel (GSC) is a narrow, congested waterway that supports large-scale shipping, commercial fishing, dolphin tourism, and recreation. Human activity and common bottlenose dolphins (Tursiops truncatus) converge in the GSC with potentially negative consequences on the dolphins. Elevated land-based tracking and behavioral observation of dolphins and vessels were conducted along the GSC in June-August 2013 using a digital theodolite. Positional information was used to calculate dolphin movement patterns and proximity to vessels. Log-likelihood ratio and Chi-square contingency tests were used to assess behavioral states, and generalized additive models were used to analyze movement patterns (i.e., swimming speed, reorientation rate, and linearity) relative to endogenous and exogenous factors and vessel presence. Dolphins regularly use the GSC to forage (57% of observed behavioral states) and socialize (27%), and it is not a travel corridor for accessing other favorable sites (traveling = 5%). Dolphin behavior varied significantly based on time of day, group size, calf presence, and general boat presence. When boats were present, the proportion of time dolphins spent socializing and foraging was significantly less than expected by chance. Swimming speeds increased significantly in the presence of small recreational boats, dolphin-watching tour boats, shrimp trawlers, and when tour boats and shrimp trawlers were both present. Reorientation rate increased significantly in the presence of tour boats and trawlers. Dolphin behavioral responses to vessel presence may result in decreased energy consumption due to disrupted foraging activity. Without proper management, the observed behavioral changes may be detrimental to individuals within this population in the short term, with potential long-term consequences to health and survivorship.
加尔维斯顿航道（GSC）是一条狭窄、拥挤的水道，支持大规模的航运、商业捕鱼、海豚旅游和娱乐活动。人类活动和普通宽吻海豚（Tursiops truncatus）在 GSC 中汇聚，这可能对海豚产生负面影响。2013 年 6 月至 8 月，使用数字经纬仪在 GSC 沿线对海豚和船只进行了高空陆上跟踪和行为观察。利用位置信息计算海豚的运动模式和与船只的接近程度。对数似然比和卡方拟合优度检验用于评估行为状态，广义加性模型用于分析与内源性和外源性因素以及船只存在相关的运动模式（即游泳速度、转向率和线性度）。海豚经常在 GSC 觅食（观察到的行为状态的 57%）和社交（27%），而不是用于进入其他有利场所的通道（游动=5%）。海豚的行为因时间、群体大小、幼豚存在和一般船只存在而显著变化。当船只存在时，海豚用于社交和觅食的时间比例明显低于随机预期。当有小型休闲船、观豚游船、拖网渔船以及当游船和拖网渔船都存在时，海豚的游泳速度显著增加。当有游船和拖网渔船存在时，海豚的转向率显著增加。海豚对船只存在的行为反应可能会导致觅食活动中断，从而减少能量消耗。如果没有适当的管理，观察到的行为变化可能会对该种群中的个体在短期内造成损害，并可能对其健康和生存能力产生长期影响。
