Editing Porbeagle (section)

{{Short description|Species of shark (Lamna nasus)}}
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{{Featured article}}
{{Speciesbox
| fossil_range = Upper miocene {{fossilrange|11.608|0}}
| image = Lamna nasus noaa.jpg
| image_alt = Side view of a gray torpedo-shaped shark with a pointed snout and a crescent-shaped tail
| status = VU
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=Rigby, C.L. |author2=Barreto, R. |author3=Carlson, J. |author4=Fernando, D. |author5=Fordham, S. |author6=Francis, M.P. |author7=Herman, K. |author8=Jabado, R.W. |author9=Liu, K.M. |author10=Marshall, A. |author11=Pacoureau, N. |author12=Romanov, E. |author13=Sherley, R.B. |author14=Winker, H. |date=2019 |title=''Lamna nasus'' |volume=2019 |page=e.T11200A500969 |doi=10.2305/IUCN.UK.2019-3.RLTS.T11200A500969.en |access-date=12 November 2021}}</ref>
| status2 = CITES_A2 
| status2_system = CITES 
| status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Lamna
| species = nasus
| range_map = Lamna nasus rangemap.png
| range_map_caption = 
{{leftlegend|#000080|Confirmed range|outline=gray}}{{leftlegend|#0080FF|Suspected range|outline=gray}}
| range_map_alt = World map with dark blue coloring in the northern Atlantic Ocean, around southern South America, east of South Africa, and around southern Australia and New Zealand, and light blue coloring along the southeastern U.S. coast and in a global band around the Southern Hemisphere
| authority = ([[Pierre Joseph Bonnaterre|Bonnaterre]], 1788)
| synonyms = ''Lamna philippii'' <small>Perez Canto, 1886</small><br/>
''Lamna punctata'' <small>Storer, 1839</small><br/>
''Lamna whitleyi'' <small>Phillipps, 1935</small><br/>
''Oxyrhina daekayi'' <small>Gill, 1861</small><br/>
''Selanonius walkeri'' <small>Fleming, 1828</small><br/>
''Squalus cornubicus'' <small>Gmelin, 1789</small><br/>
''Squalus cornubiensis'' <small>Pennant, 1812</small><br/>
''Squalus monensis'' <small>Shaw, 1804</small><br/>
''Squalus nasus'' <small>Bonnaterre, 1788</small><br/>
''Squalus pennanti'' <small>Walbaum, 1792</small><br/>
''Squalus selanonus'' <small>Leach, 1818</small>
}}

The '''porbeagle''' or '''porbeagle shark''' ('''''Lamna nasus''''') is a [[species]] of [[Lamniformes|mackerel shark]] in the [[family (biology)|family]] [[Lamnidae]], distributed widely in the cold and temperate marine waters of the [[North Atlantic]] and [[Southern Hemisphere]]. In the [[North Pacific]], its ecological equivalent is the closely related [[salmon shark]] (''L.&nbsp;ditropis''). It typically reaches {{convert|2.5|m|ft|abbr=on}} in length and a weight of {{convert|135|kg|lb|abbr=on}}; North Atlantic sharks grow larger than Southern Hemisphere sharks and differ in coloration and aspects of life history. Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow [[caudal peduncle|base of the tail]]. It has large [[pectoral fin|pectoral]] and first [[dorsal fin]]s, tiny [[pelvic fin|pelvic]], second dorsal, and [[anal fin]]s, and a crescent-shaped [[caudal fin]]. The most distinctive features of this species are its three-cusped teeth, the white blotch at the aft base of its first dorsal fin, and the two pairs of lateral keels on its tail.

The porbeagle is an opportunistic hunter that preys mainly on [[bony fish]]es and [[cephalopod]]s throughout the [[water column]], including the bottom. Most commonly found over food-rich [[bank (topography)|banks]] on the outer [[continental shelf]], it makes occasional forays both close to shore and into the [[open ocean]] to a depth of {{convert|1360|m|ft|abbr=on|-1}}. It also conducts long-distance seasonal [[fish migration|migrations]], generally shifting between shallower and deeper water. The porbeagle is fast and highly active, with [[endothermy|physiological adaptations]] that enable it to maintain a higher body temperature than the surrounding water. It can be solitary or gregarious, and has been known to perform seemingly [[play (activity)|playful]] behavior. This shark is [[aplacental viviparous]] with [[oophagy]], developing [[embryo]]s being retained within the mother's [[uterus]] and subsisting on [[trophic egg|non-viable eggs]]. Females typically bear four pups every year.

Only a few [[shark attack]]s of uncertain provenance have been attributed to the porbeagle. It is well regarded as a [[game fish]] by [[recreational fishing|recreational anglers]]. The [[shark meat|meat]] and fins of the porbeagle are highly valued, which has led to a long history of intense human exploitation. However, this species cannot sustain heavy fishing pressure due to its low reproductive capacity. Direct [[commercial fishing]] for the porbeagle, principally by [[Norway|Norwegian]] [[longline fishing|longliners]], led to [[Fish stocks|stock]] collapses in the eastern North Atlantic in the 1950s, and the western North Atlantic in the 1960s. The porbeagle continues to be caught throughout its range, both intentionally and as [[bycatch]], with varying degrees of monitoring and management. The [[International Union for Conservation of Nature]] (IUCN) has assessed the porbeagle as [[Vulnerable species|vulnerable]] worldwide, and as either [[endangered]] or [[critically endangered]] in different parts of its northern range.