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Resource and habitat use of northern bottlenose whales in the Gully: Ecology, diving and ranging behaviour.

机译：沟谷北部宽吻鲸的资源和栖息地利用：生态，潜水和测距行为。

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Northern bottlenose whales (Hyperoodon ampullatus) show a concentrated distribution within the Gully, a submarine canyon off the coast of eastern Canada. Using data collected between 1988 and 1998, I have analysed the potential function of this local abundance in terms of foraging behaviour, movements and distributional preferences of these whales in the Gully.; Stomachs of northern bottlenose whales, which stranded in Nova Scotia and Quebec, contained a high proportion of the squid Gonatus steenstrupi . Fatty acid and stable isotope analysis of biopsy samples collected from free-ranging whales in the Gully were compared to results for samples of Gonatus fabricii. Results suggested that squid of this genus could form the bulk of bottlenose whale diet in the Gully. Isotopic nitrogen values suggest that bottlenose whales (mean 15.3% delta 15N) occupy a trophic level of approximately 4.4.; The abundance and distribution of bottlenose whales varied between years, with yearly distribution shifting primarily along the main axis of the canyon. Bottlenose whale distribution was investigated in relation to fixed physical parameters (depth and slope), surface environmental characteristics (sea surface temperature and water clarity), and mid-water environmental characteristics (sub-surface biomass, depth and thickness of deep scattering layer). The distribution of bottlenose whales was found to show strongest correlation with water depth and deep-water biomass.; Two deployments of suction-cup attached time-depth recorder/VHF radio tags on bottlenose whales demonstrated the whales' exceptional diving ability, with dives approximately every 80 min to over 800 m (maximum 1453 m), and up to 70 min in duration. Sonar traces of non-tagged, diving bottlenose whales suggested that such deep dives are not unusual. Many of the recorded dives were to, or close to, the sea floor.; Photo-resightings and radio-tracking follows were used to investigate the pattern and scale of whale movements within the Gully over time intervals up to their residency period (approximately 10 days). Bottlenose whales showed little daily movement (∼4 km/day) and maintained ranges of ∼20 km 2 for time intervals between hours to days. This relative lack of movement is unusual for oceanic odontocetes and suggests that the canyon supports a profitable and stable food source for these whales. Geographic positions of individuals showed significant variation between years, but no range difference between whale age-sex classes. Within years, individuals showed some range separation particularly in years of highest whale abundance. Mature males showed consistent spatial orientation between years suggesting preferred relative locations.; Regular ultrasonic foraging clicks were recorded while whales were diving, and lower frequency, rapid and variable clicks were heard while whales were at the surface. The inter-click interval (0.4 s) and frequency (24 kHz) of clicks heard during dives were consistent with foraging at ranges of ∼300 m on objects of diameter greater than 6 cm.; The estimated level of primary production required to support bottlenose whales in the Gully was much greater than could be produced within this area, suggesting that there must be significant energetic influx to the system. Identification of this input will aid in the development of a comprehensive conservation plan for bottlenose whales. The benthic nature of bottlenose whale foraging suggests that this foodweb would be especially sensitive to threats to the seafloor in the Gully.
机译：北部宽吻鲸（Hyperoodon ampullatus）在加拿大东部沿海海底峡谷Gully内集中分布。利用从1988年至1998年收集的数据，我从沟壑中这些鲸鱼的觅食行为，运动和分布偏好方面分析了这种局部丰度的潜在功能。在新斯科舍省和魁北克搁浅的北方宽吻鲸的胃中含有高比例的鱿鱼Gonatus steenstrupi。比较了从沟壑中自由放养的鲸鱼采集的活组织检查样品的脂肪酸和稳定同位素分析结果，并与Gonatus fabricii的样品结果进行了比较。结果表明，该属的鱿鱼可以构成沟壑中大部分的宽吻鲸鱼饮食。同位素氮值表明宽吻鲸（平均15.3％三角洲15N）占据大约4.4的营养水平。宽吻鲸的丰度和分布在不同年份之间变化，年度分布主要沿峡谷的主轴线移动。研究了宽吻鲸的分布与固定的物理参数（深度和坡度），地表环境特征（海表温度和水的净度）以及中层水环境特征（地下生物量，深层散射的深度和厚度）之间的关系。发现宽吻鲸鱼的分布与水深和深水生物量之间的相关性最强。在宽吻鲸鱼上两次部署带有吸盘的时深度记录仪/ VHF无线电标签，证明了鲸鱼具有出色的潜水能力，大约每80分钟潜水一次至800 m以上（最大1453 m），潜水时间最长为70分钟。声纳中未标记的潜水宽吻鲸的痕迹表明，这种深度潜水并不罕见。记录的许多潜水都在或接近海床。下面的照片监视和无线电跟踪用于调查居留期间（直至居住时间（约10天））内鲸鱼在鲸鱼内的运动方式和规模。宽吻鲸每天运动很少（约4 km /天），在数小时至数天之间的时间间隔内保持在约20 km 2的范围内。这种相对缺乏运动对于大洋鲸科来说是不寻常的，这表明峡谷为这些鲸鱼提供了有利可图的稳定食物来源。个体的地理位置在几年之间显示出显着的变化，但是在鲸类年龄性别类别之间没有范围差异。在数年之内，个体表现出一定的距离分离，尤其是在鲸鱼丰度最高的年份。成熟的雄性在年间表现出一致的空间方向，表明了相对的位置。鲸鱼潜水时会记录规律的超声觅食滴答声，而鲸鱼在水面时会听到较低频率，快速且可变的滴答声。潜水过程中听到的喀嗒声间隔（0.4 s）和频率（24 kHz）与直径大于6 cm的物体在〜300 m范围内觅食一致。支撑沟壑中的宽吻鲸所需的初级生产水平估计要比该区域内的生产水平高得多，这表明该系统必须有大量的能源涌入。确定这一投入将有助于制定宽吻鲸的综合保护计划。宽吻鲸觅食的底栖性质表明，这种食物网对沟壑中海底的威胁特别敏感。

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