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Porbeagle shark (Lamna nasus)

Status | Species Description | Habitat | Distribution | Population Trends | Threats | Conservation Efforts | Regulatory Overview | Taxonomy | Key Documents | More Info

Status

CITES Appendix II - throughout its range

Species Description

Weight:
about 300 pounds (135 kg)
Length:
up to 11.5 feet (3.5 m)
Appearance:
dark bluish-grey backs with a white belly, they have a cylindrical body, conical head, and crescent-shaped tail
Lifespan:
around 65 years
Diet:
small fishes, sharks, squid
Behavior:
females give birth to live young that are nourished in utero with egg yolk for about 8-9 months

Porbeagle sharks are moderately large, spindle-shaped sharks. They are characterized by a cylindrical body, conical head and crescent-shaped tail. A distinctive white patch on the lower trailing edge of the first dorsal fin is used to identify fins in trade. They are warm-blooded, relatively slow growing and late maturing, long-lived, and bear only small numbers of young.

In the northwest Atlantic, males mature at approximately 8 years and 5.5 feet (1.5 m) length while females mature at 13 years and 6.4 feet (2 m) length. Life history characteristics vary between stocks. Northeast Atlantic porbeagle sharks are slightly slower growing than the northwestern stock. Both northern stocks are much larger, faster growing, and have a shorter life span than the smaller, longer-lived (~65 years old) southern porbeagles. They are ovoviviparous (that is, they give birth to live young that are nourished in utero with egg yolk), and females produce an average of four young per year. Gestation is thought to last 8 to 9 months.

Habitat

The porbeagle shark is a coastal species found in the upper pelagic zone from the surface to 200 m deep (occasionally to 350 m-700 m). They are most commonly reported on continental shelves and slopes from close inshore (especially in summer), to far offshore (where often associated with submerged banks and reefs). They are apparently less abundant in the high seas. Stocks segregate (at least in some regions) by age, reproductive stage, and sex. They undertake seasonal migrations within their stock area.

Mature females tagged off the Canadian coast appear to migrate 1,240 miles (2,000 km) south to give birth in deep water in the Sargasso Sea in the Central North Atlantic. Pups seem to follow the Gulf Stream to return north.

Distribution

Porbeagle sharks are found worldwide in a band between ~30° and 60°S in the Southern Hemisphere and mostly between 30° and 70°N in the North Atlantic Ocean and Mediterranean. Genetic studies identified two isolated populations, in the North Atlantic and the Southern oceans.

Population Trends

In 2005, the Northwest Atlantic population size was estimated to be about 190,000.

North and Southwest Atlantic stocks have identified marked declines to significantly less than 30% of historic baseline, according to the joint assessments by the Standing Committee on Research and Statistics of the International Commission for the Conservation of Atlantic Tunas and the International Council for the Exploration of the Seas.

Mediterranean catch per unit effort has declined to less than 5% of baseline.

More limited data from other Southern Hemisphere stocks--also a high value target and secondary catch of longline fisheries, but biologically less resilient to fisheries than North Atlantic stocks--also suggest declining trends.

Threats

This species is highly desired for the shark meat trade in Europe and some other areas. Fins are also moderately desirable in trade. They are caught in a variety of fisheries, including artisanal and small-scale commercial fisheries and commercial longline, gill net, drift net, and trawl fisheries. Sports fisheries exist in the U.S., New Zealand, and in some European Union Member States.

Conservation Efforts

In October 2012, a number of countries agreed to sponsor a proposal to add all manta rays to Appendix II of CITES to provide further protections from the high demand in international trade. The proposal was passed at the CITES meeting in March 2013 and was effective as of September 14, 2014. Export of their fins requires permits that ensure the products were legally acquired and that the Scientific Authority of the State of export has advised that such export is not detrimental to the survival of the species.

Regulatory Overview

On January 20, 2010, we received a petition from WildEarth Guardians requesting that we list porbeagle sharks (Lamna nasus) throughout their entire range, or as Northwest Atlantic, Northeast Atlantic, and Mediterranean Distinct Population Segments (DPS) under the ESA, as well as designate critical habitat for the species. We also received a petition from the Humane Society of the United States (HSUS), dated January 21, 2010, requesting that we list a Northwest Atlantic DPS of porbeagle sharks as endangered in the North Atlantic under the ESA. On July 12, 2010, we published a notice that listing porbeagle sharks under the ESA is not warranted. We were challenged in court on this 90-day finding and have re-evaluated the information in the petitions as well as other new information readily available in our files since 2010 regarding porbeagle sharks globally. In March 2015, we published a positive 90-day finding that listing porbeagle sharks under the ESA may be warranted.  We conducted a status review of the species and based on the best available scientific and commercial information available, and taking into account ongoing efforts to protect the species, we have determined that porbeagle sharks do not warrant listing at this time.

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Lamniformes
Family: Lamnidae
Genus: Lamna
Species: nasus

Key Documents

(All documents are in PDF format.)
Title Federal Register Date
Not Warranted 12-Month Finding on Petitions to List Porbeagle Sharks under the ESA 81 FR 50463 08/01/2016
Status Review n/a 2016

Positive 90-Day Finding on Petitions to List Porbeagle Sharks under ESA

80 FR 16356 03/27/2015
CITES Appendix II Proposal   10/04/2012
90-Day Finding on Petitions to List the Porbeagle Shark; ESA-Listing Not Warranted 75 FR 39656 07/12/2010

More Information

Updated: August 22, 2016