Kinematics and energetics of foraging behavior in Rice's whales of the Gulf of Mexico

The endangered Rice's whale (Balaenoptera ricei) is endemic to the Gulf of Mexico (GOM) and has a small population of fewer than 100 individuals. Little is known about their foraging ecology. Suction cup tags were attached to two Rice's whales to collect information on their diving kinematics and foraging behavior. The tagged whales primarily exhibited lunge-feeding near the sea bottom and to a lesser extent in the water column and at the sea surface. During foraging dives, the whales typically circled the prey before executing one or two feeding lunges. Longer duration dives and dives with more feeding lunges were followed by an increase in the breathing rate. The average lunge rate of both animals was much lower than expected based on comparative research on other lunge-feeding baleen whales, which may be related to differences in prey or inter-specific differences, or may be an indication of different foraging conditions. Overall, these data show that Rice's whale foraging behavior differs from other lunge-feeding rorqual species and may be a significant factor in shaping our understanding of their foraging ecology. Efforts to mitigate threats to the Rice's whale will benefit from improved understanding of patterns in habitat use and fine-scale ecology within the population.

濒危莱斯鲸（Balaenoptera ricei）为墨西哥湾（Gulf of Mexico, GOM）特有物种，种群规模不足100头。目前学界对其觅食生态学的认知仍较为有限。研究人员通过吸盘式生物标记标签（suction cup tags）对两头莱斯鲸进行标记，以采集其潜水运动学与觅食行为相关数据。被标记的个体主要在近海底区域开展冲刺摄食（lunge-feeding），仅在少量场景下于水层中或海面完成摄食。在觅食潜水中，鲸类通常会环绕猎物，随后执行1至2次冲刺摄食动作。时长更长的潜水，以及伴随更多冲刺摄食次数的潜水结束后，鲸类的呼吸频率会显著升高。相较于其他以冲刺摄食为生的须鲸类的同类研究，两头被标记个体的平均冲刺摄食频率远低于预期，这一现象或与猎物种类差异、物种间生态位差异相关，亦可能反映了不同的觅食环境条件。总体而言，本数据集表明莱斯鲸的觅食行为与其他冲刺摄食的鳁鲸类（rorqual）存在显著差异，这或将重塑学界对莱斯鲸觅食生态学的认知。若能进一步明晰该种群的栖息地利用模式与精细尺度生态学特征，将有助于开展针对莱斯鲸的生存威胁减缓保护工作。