一个用来将嫌疑犯放入罪案场景的犯罪调查工具如今正在被用来追踪海洋中的凶猛杀手——大白鲨。在连环犯罪的侦破过程中，地缘剖绘技术通过评估犯罪现场的位置从而确定罪犯最有可能的出没地域。如今，一个研究小组第一次利用这项技术对在南非海岸附近捕捉南非海豹的鲨鱼进行了研究。
尽管有的是力气，但捕猎对于鲨鱼而言也不是一件容易事儿。作为鲨鱼的主要猎物，海豹在水中能够迅速转向，并且成Z字形曲折前进。美国佛罗里达州迈阿密大学的鲨鱼研究人员Neil Hammerschlag表示：“鲨鱼不得不依靠完美的伏击来捕捉海豹。”
但鲨鱼是否一直在漫无目的地游水直到它们偶然遇到一只海豹，抑或它们拥有一套更为复杂的捕猎策略呢？为了回答这个问题，Hammerschlag和同事记录了发生在南非海豹岛——这里大约生长着64000只南非海豹——附近的340起鲨鱼袭击海豹事件。当研究人员发现一条大白鲨追赶一只海豹时，他们利用全球定位系统确定了这条鲨鱼的位置，评估了鲨鱼的大小，并记录了环境状况，其中包括水深和水温，以及海底地形学特征。研究人员同时记录了这只海豹最终是逃脱了，还是被吃掉了。
接下来，研究小组利用一套数学模型计算出上述袭击最有可能发生的基本条件。结果显示，他们所观测的鲨鱼会将自己驻扎在特定的地点，但这里不一定就是捕获海豹几率最高的地方。实际上，这些地点能够在发现猎物的能力、与同类鲨鱼之间的竞争，以及捕获一只海豹的可能性之间提供一个最有利的平衡。研究小组同时发现，更小一些的年轻鲨鱼往往会在一个更大且更分散的区域内寻找猎物，而它们的成功率则较低。这可能意味着鲨鱼学会了通过经验在一些区域浓缩它们的努力，从而提供最佳的捕猎条件，或者是大一些的鲨鱼会将小一点儿的同类排除在最好的狩猎点之外。研究小组在最新出版的《动物学杂志》上报告了这一研究成果。
美国佛罗里达州萨拉索塔市穆特海洋实验室的海洋生物学家Robert Hueter表示：“地缘剖绘技术是一个新的方法，使得研究人员能够分析食肉动物的运动与它们的猎物之间的关系。”但是Hueter指出，这项研究得出的结论只适合于鲨鱼群体的捕猎模式，而非鲨鱼个体的捕猎行为。（生物谷Bioon.com）
生物谷推荐原始出处：
Journal of Zoology 22 Jun 2009
Hunting patterns and geographic profiling of white shark predation
R. A. Martin 1 , D. K. Rossmo 2 & N. Hammerschlag 3
1 Fish Museum, Zoology Department, University of British Columbia, Vancouver, BC, Canada
2 Center for Geospatial Intelligence and Investigation, Department of Criminal Justice, Texas State University-San Marcos, San Marcos, TX, USA
3 Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
Predators can play important roles in structuring their communities through top-down effects on the distribution and abundance of their prey. Sharks are top predators in many marine communities, yet few studies have quantified those factors influencing their distribution and hunting behaviour. Here, we use location data from 340 predatory interactions between white sharks Carcharodon carcharias (Linnaeus), and Cape fur seals Arctocephalus pusillus pusillus (Schreber), data on associated environmental factors, and spatial analysis, including a novel application of geographic profiling – a tool originally developed to analyse serial crime – to investigate spatial patterns of shark attack and search behaviour at Seal Island in False Bay, South Africa. We found that spatial patterns of shark predation at this site are nonrandom. Sharks appear to possess a well-defined search base or anchor point, located 100 m seaward of the seal's primary island entry–exit point. This location is not where chances of intercepting seals are greatest and we propose it may represent a balance among prey detection, capture rates, and competition. Smaller sharks exhibit more dispersed prey search patterns and have lower predatory success rates than larger conspecifics, suggesting possible refinement of hunting strategy with experience or competitive exclusion of smaller sharks from the most profitable hunting locations. As many of the features of this system will be common to other instances of foraging, our conclusions and approach employed may have implications and applications for understanding how large predators hunt and for studying other predator–prey systems.
