Family Hemigaleidae The Weasel Sharks

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Family HemigaleidaeThe Weasel Sharks

• Sara McCutcheon

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General Characteristics

• Small to medium sized sharks
• Horizontal, oval eyes w nictitating eyelids
• Long labial furrows
• Spiral intestinal valve
• Strong ventral lobe of caudal fin
• Wavy dorsal edge of caudal
• Upper teeth large and saw-edged
• Lower hooked teeth protrude from mouth

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Taxonomy8 species in 4 Genera

• Chaenogaleus (1 sp.)
• Hemipristis (1 sp.)

• Hemigaleus (2 spp.)
• Paragaleus (4 spp.)

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Taxonomy

• 1 Chaenogaleus macrostoma Hooktooth shark
• 2 Hemigaleus microstoma Sicklefin weasel shark
• 3 Hemigaleus australiensis Australian weasel
  shark
  
• 4 Hemipristis elongatus Snaggletooth shark
• 5 Paragaleus leucolomatus Whitetip weasel
  shark
  
• 6 Paragaleus pectoralis Atlantic weasel shark
• 7 Paragaleus randalli Slender weasel shark
• 8 Paragaleus tengi Straighttooth weasel shark

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Habitat

• Continental and insular shelves
• Tropical and subtropical waters
• Depths range from shallow to 170 m
• Demersal
• Benthopelagic
• Coastal

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Distribution

• Indo-West Pacific for 7 species
• East Atlantic for Paragaleus pectoralis

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Reproductive Biology

• Viviparous with yolk-sac placenta
• Minimum population doubling time more than 14
  years
  
• Fecundity ranging from 1-19
• Gestation time of 6 months to one year
• Biennial or triennial reproductive cycles Mate in
  March-May and parturition in May-June

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Diet

• Varied diet
• Feed on cephalopods, crustaceans, and small fish
• Some are specialist feeders of cephalopods,
  especially octopus
  
• Hemipristis elongatus also feeds on sharks and
  rays
  
• Some live in reefs and weedy areas for prey

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Fisheries

• Common and important in fisheries
• Taken regularly in inshore artisanal fisheries
• Intensive and largely unmanaged net and trawl
  fisheries occur throughout most of the sharks
  range (except for Australia)
  
• Hemigaleus microstoma is fished in high numbers
  in SE Asia

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Status

• Used for human consumption, the liver is
  processed fro vitamins, fins for oriental shark
  fin trade, and by-products for fishmeal
  
• Thought to have a very low resilience to fishing,
  with a maximum population doubling time of more
  than 14 years
  
• Most are considered harmless to humans
• Hemipristis elongatus is considered potentially
  dangerous because of large teeth and shallow
  habitat

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IUCN Red List

• Hemigaleus microstoma listed as least concern
• Hemipristis elongatus is listed as vulnerable
  except in Australia (Least Concern)
  
• Chaenogaleus macrostoma, Paragaleus leucolomatus,
  Paragaleus pectoralis, Paragaleus randalli, and
  Paragaleus tengi are not in IUCN Red List

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Bibliography

• Bass, A.J., Heemstra, P.C., and Compagno, L.J.V.
  1986. Carcharhinidae. P. 67-87. In M.M. Smith and
  P.C. Heemstra (ed.s) Smith's sea fishes.
  Springer-Verlag, Berlin.
• Carrier, J.C., Musick, J.A., and Heithaus, M.R..
  2004. Biology of Sharks and their Relatives. CRC
  Press, Boca Raton, FL. pp. 51, 73.
  
• Compagno, LJV. 1984. FAO Species Catalogue, Vol
  4. Sharks of the World. An annotated and
  illustrated catalogue of shark species known to
  date. Part 2 Carcharhiniformes. FAO Fish.
  Synop. 125 (4/2)251-655.
• Compagno, L, M. Dando, and S. Fowler. 2005.
  Sharks of the World. Princeton University Press,
  Princeton, NJ. pp. 283-287.
  
• Nelson, J.S. 2006. Fishes of the World, 4th ed.
  John Wiley and Sons, Inc, NJ. p. 62.
  
• Simpendorfer, CA, 2003. Hemigaleus microstoma.
  In IUCN 2007. 2007 IUCN Red list of Threatened
  Species. www.iucnredlist.org. Downloaded on 24
  October 2007.
• White, W.T. 2003. Hemipristis elongatus. In IUCN
  2007. 2007 IUCN Red List of Threatened Species.
  www.iucnredlist.org. Downloaded on 24 October
  2007.
• White, W.T., Last, P.R., and Compagno, L.J.V.
  2005. Description of a new species of weasel
  shark, Hemigaleus australiensis n.sp.
  (Carcharhiniformes Hemigaleidae) from Australian
  waters. Zootaxa 107727-49.
• Capape C, Diatta Y, Diop M, Reynaud C, Guelorget
  O. New data on the reproductive biology of the
  Atlantic weasel shark, Paragaleus pectoralis
  (Chondrichthyes Hemigaleidae) from the coast of
  Senegal (eastern tropical Atlantic). CYBIUM 29
  (4) 363-371.