GRAY WHALE MORTALITY AT OJO DE LIEBRE AND GUERRERO NEGRO LAGOONS, BAJA CALIFORNIA SUR, MEXICO: 1984–1995
GRAY WHALE MORTALITY AT OJO DE LIEBRE AND GUERRERO NEGRO LAGOONS, BAJA CALIFORNIA SUR, MEXICO: 1984–1995
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墨西哥南下加利福尼亚州奥霍德利布雷和格雷罗内格罗泻湖的灰鲸死亡率：1984-1995 年
DOI：
10.1111/j.1748-7692.1998.tb00699.x
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发表时间：
1998
影响因子：
2.3
通讯作者：
JoseAngel Sanchez Pacheco
中科院分区：
文献类型：
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作者：
JoseAngel Sanchez Pacheco
灰鲸每年都会从白令海和楚科奇海的北部觅食地迁徙到墨西哥下加利福尼亚州海岸的冬季繁殖和产仔地。 Swartz 和 Jones (1983) 估计，一年中 5.4% 的灰鲸幼崽死于泻湖附近或泻湖内，另外 31% 的幼鲸死亡发生在它们向北迁徙的第一阶段到达加利福尼亚中部时。泻湖外幼崽死亡率的增加强调了沿海泻湖栖息地对于该物种繁殖成功的明显优势。在繁殖和产犊泻湖中发现的多种因素的结合可能会提高小牛的存活率（Rice 和 Wolman 1971，Jones 和 Swartz 1984，Sanchez 1991）。本研究的目的是（1）确定泻湖内和附近的搁浅位置，（2）确定冬季繁殖季节的死亡率高峰期，（3）确定搁浅鲸鱼的性别比例，（4）确定搁浅鲸鱼的年龄和性别类别，以及（5）确定和描述可能影响泻湖内和附近灰鲸死亡率的关键因素。从Ojo de Liebre泻湖入口南端向北的外海岸除 1986 年和 1994 年外，从 1984 年到 1995 年，每年冬天都会对曼努埃拉泻湖最北端的竞技场岛进行调查。我们拍摄、测量、确定性别并记录遇到的每头死鲸的位置。此外，我们还根据腐烂尸体的状态、海岸上的位置以及自上次搜索以来经过的时间估计了死亡日期。记录下任何独特的标记或疤痕。每具尸体都用一条绑在鳍周围的线进行标记，以防止重复计数。总共发现了191头鲸鱼。确定了 176 头鲸鱼的长度，确定了 146 头鲸鱼的性别，估计了 117 头鲸鱼的死亡时间。竞技场岛西南海岸搁浅死鲸的发生率最高（34%）（图 1）。洋流、盛行西北风以及进出泻湖的潮汐流之间的相互作用可能是导致该地区漂浮尸体沉积的原因。 Rice 等人 (1981) 注意到在同一地点有类似数量的搁浅鲸鱼。这些作者
Gray whales migrate annually from their northern feeding grounds in the Bering and Chukchi Seas to their winter breeding and calving grounds along the coast of Baja California, Mexico. Swartz and Jones (1983) estimated that 5.4% of gray whale calves of the year die near or in the lagoons, and an additional 31% of calf mortality occurs by the time they reach central California in the first part of their northward migration. This increase in calf mortality outside the lagoons emphasizes the apparent advantage of the coastal lagoon habitats to reproductive success of this species. Calf survival may be enhanced by the combination of factors found in the breeding and calving lagoons (Rice and Wolman 1971, Jones and Swartz 1984, Sanchez 1991). The objectives of this study were to (1) identify stranding locations within and adjacent to the lagoons,(2) determine periods of peak mortality during the winter reproductive season,(3) determine the sex ratio of stranded whales,(4) determine the age and sex class of stranded whales, and (5) identify and describe key factors that may influence the mortality of gray whales in and adjacent to the lagoons.The outer coasts from the southern end of the entrance to Ojo de Liebre Lagoon north along Arena Island to the northernmost portion of Manuela Lagoon were surveyed each winter from 1984 to 1995 except for 1986 and 1994. We photographed, measured, sexed and noted the location of each dead whale encountered. In addition, we estimated date of death from the state of the decomposing carcass, location on the shore, and time elapsed since our previous search. Any unique markings or scars were noted. Each carcass was marked with a line tied around a flipper to prevent double counting. A total of 191 whales were found. Length was determined for 176 whales, sex was determined for 146, and time of death was estimated for 117. The southwest coast of Arena Island had the highest incidence (34%) of stranded dead whales (Fig. 1). Interactions among ocean currents, prevailing northwest winds, and tidal flow into and out of the lagoon are likely responsible for depositing floating carcasses in the area. Similar abundance of stranded whales at this same location was noted by Rice et al.(1981). These authors