Kingdom: Animalia Phylum: Chordata
2. Biological data The large, highly migratory and aggregating, warm-blooded porbeagle shark (Lamna nasus) occurs in temperate North Atlantic and southern ocean waters. It is relatively slow growing, late maturing, and long-lived, bears small litters of pups and has a generation period of 20–50 year...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.548.9737 http://www.cms.int/bodies/COP/cop9/Proposals/Eng/II_10_Rev1_Lamna_nasus_porbeagle_EC_E.pdf |
| Summary: | 2. Biological data The large, highly migratory and aggregating, warm-blooded porbeagle shark (Lamna nasus) occurs in temperate North Atlantic and southern ocean waters. It is relatively slow growing, late maturing, and long-lived, bears small litters of pups and has a generation period of 20–50 years and an intrinsic rate of population increase of 5-7 % per annum. It is a high value species, whose aggregations may be targeted by fishers, and is therefore highly vulnerable to over-exploitation in fisheries. L. nasus is an apex predator, occupying a position near the top of the marine food web (it feeds on fishes, squid and some small sharks, but not on marine mammals [Compagno 2001, Joyce et al. 2002)]. It has few predators other than humans, but orcas and white sharks may take this species (Compagno 2001). Fisheries and Oceans Canada (2006) considers that the abundance of NW Atlantic population is now too low for this species still to have any indirect value through its role in ecosystem function or regulation. Stevens et al. (2000) warn that the removal of populations of top marine predators may have a disproportionate and counter-intuitive impact on trophic interactions and fish population dynamics, including by causing decreases in some of their prey |
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