The franciscana (Pontoporia blainvillei) is endemic to coastal waters from Brazil to Argentina. The species is regarded as one of the most threatened cetaceans in South America due to high bycatch levels. Four management units (FMAs) were defined throughout the species’ range. FMA II includes states along southeastern and southern Brazil, and represents one of the least known units. Recently, genetic analysis proposed that FMA II comprises two distinct populations and its range should be divided into FMA IIa and IIb. In December 2008 and January 2009 aerial surveys were conducted to assess the distribution and to estimate abundance of franciscanas off FMA II. A total of 54 groups were seen (average group size = 2.76, SE = 0.17) in shallow (mean depth = 7.15 m, SE = 7.08) coastal habitats (average distance from the shore = 6.48 km, SE = 6.28). Abundance corrected for perception and availability bias was estimated at 6,827 (CV = 0.26) franciscanas in FMA II, and at 1,915 (CV = 0.32) and 4,353 (CV = 0.24) franciscanas in FMA IIa and FMA IIb, respectively. This study indicates that, at least during the summer, franciscanas aggregate in shallow coastal habitats. Current estimates of incidental mortality in FMA II correspond to 4.4%–7.3% of the estimated stock size, suggesting high, likely unsustainable bycatch.

中文翻译：

---

巴西东南部和南部濒临灭绝的方济各会的分布，栖息地利用和丰富度

方济各会（Pontoporia blainvillei）是从巴西到阿根廷的沿海水域特有的。由于兼捕水平高，该物种被认为是南美最受威胁的鲸类之一。在整个物种范围内定义了四个管理单位（FMA）。FMA II包括巴西东南部和南部的州，是鲜为人知的单位之一。最近，遗传分析提出FMA II包含两个不同的种群，其范围应分为FMA IIa和IIb。在2008年12月和2009年1月进行了航测，以评估FMA II外的方济各会的分布并估计其数量。在浅处（平均深度= 7.15 m，SE）总共观察到54个组（平均组大小= 2.76，SE = 0.17）= 7.08）沿海栖息地（距海岸的平均距离= 6.48 km，SE = 6.28）。FMA II中校正后的感知和可用性偏差的丰度估计为6,827（CV = 0.26），而FMA IIa和FMA IIb分别为1,915（CV = 0.32）和4,353（CV = 0.24）。这项研究表明，至少在夏季，方济各会聚集在浅海沿海生境中。目前对FMA II的偶发性死亡率的估计占估计种群数量的4.4％–7.3％，表明存在较高的，可能是不可持续的兼捕物。