一個(gè)用來(lái)將嫌疑犯放入罪案場(chǎng)景的犯罪調(diào)查工具如今正在被用來(lái)追蹤海洋中的兇猛殺手——大白鯊,。在連環(huán)犯罪的偵破過(guò)程中，地緣剖繪技術(shù)通過(guò)評(píng)估犯罪現(xiàn)場(chǎng)的位置從而確定罪犯最有可能的出沒(méi)地域,。如今,，一個(gè)研究小組第一次利用這項(xiàng)技術(shù)對(duì)在南非海岸附近捕捉南非海豹的鯊魚進(jìn)行了研究,。
盡管有的是力氣,，但捕獵對(duì)于鯊魚而言也不是一件容易事兒。作為鯊魚的主要獵物,，海豹在水中能夠迅速轉(zhuǎn)向,，并且成Z字形曲折前進(jìn)。美國(guó)佛羅里達(dá)州邁阿密大學(xué)的鯊魚研究人員Neil Hammerschlag表示：“鯊魚不得不依靠完美的伏擊來(lái)捕捉海豹,。”
但鯊魚是否一直在漫無(wú)目的地游水直到它們偶然遇到一只海豹,，抑或它們擁有一套更為復(fù)雜的捕獵策略呢？為了回答這個(gè)問(wèn)題,，Hammerschlag和同事記錄了發(fā)生在南非海豹島——這里大約生長(zhǎng)著64000只南非海豹——附近的340起鯊魚襲擊海豹事件,。當(dāng)研究人員發(fā)現(xiàn)一條大白鯊追趕一只海豹時(shí)，他們利用全球定位系統(tǒng)確定了這條鯊魚的位置,，評(píng)估了鯊魚的大小,，并記錄了環(huán)境狀況，其中包括水深和水溫,，以及海底地形學(xué)特征,。研究人員同時(shí)記錄了這只海豹最終是逃脫了，還是被吃掉了,。
接下來(lái),，研究小組利用一套數(shù)學(xué)模型計(jì)算出上述襲擊最有可能發(fā)生的基本條件。結(jié)果顯示,，他們所觀測(cè)的鯊魚會(huì)將自己駐扎在特定的地點(diǎn),，但這里不一定就是捕獲海豹幾率最高的地方。實(shí)際上,，這些地點(diǎn)能夠在發(fā)現(xiàn)獵物的能力,、與同類鯊魚之間的競(jìng)爭(zhēng)，以及捕獲一只海豹的可能性之間提供一個(gè)最有利的平衡,。研究小組同時(shí)發(fā)現(xiàn)，更小一些的年輕鯊魚往往會(huì)在一個(gè)更大且更分散的區(qū)域內(nèi)尋找獵物,，而它們的成功率則較低,。這可能意味著鯊魚學(xué)會(huì)了通過(guò)經(jīng)驗(yàn)在一些區(qū)域濃縮它們的努力，從而提供最佳的捕獵條件,，或者是大一些的鯊魚會(huì)將小一點(diǎn)兒的同類排除在最好的狩獵點(diǎn)之外,。研究小組在最新出版的《動(dòng)物學(xué)雜志》上報(bào)告了這一研究成果。
美國(guó)佛羅里達(dá)州薩拉索塔市穆特海洋實(shí)驗(yàn)室的海洋生物學(xué)家Robert Hueter表示：“地緣剖繪技術(shù)是一個(gè)新的方法,，使得研究人員能夠分析食肉動(dòng)物的運(yùn)動(dòng)與它們的獵物之間的關(guān)系,。”但是Hueter指出,，這項(xiàng)研究得出的結(jié)論只適合于鯊魚群體的捕獵模式，而非鯊魚個(gè)體的捕獵行為,。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
