title: Conservation Status of Killer Whales, Orcinus orca, in the Strait of Gibraltar.
abstract: Killer whales (Orcinus orca) in the Mediterranean Sea are currently restricted to the Strait of Gibraltar and surrounding waters. Thirty-nine individuals were present in 2011, with a well-differentiated social structure, organized into five pods. Killer whale occurrence in the Strait is apparently related to the migration of their main prey, Atlantic bluefin tuna (Thunnus thynnus). In spring, whale distribution was restricted to shallow waters off the western coast of the Strait where all pods were observed actively hunting tuna. In summer, the whales were observed in the shallow central waters of the Strait. A relatively new feeding strategy has been observed among two of the five pods. These two pods interact with an artisanal drop-line fishery. Pods depredating the fishery had access to larger tuna in comparison with pods that were actively hunting. The Strait of Gibraltar killer whales are socially and ecologically different from individuals in the Canary Islands. Molecular genetic research has indicated that there is little or no female-mediated gene migration between these areas. Conservation threats include small population size, prey depletion, vessel traffic, and contaminants. We propose the declaration of the Strait of Gibraltar killer whales as an endangered subpopulation. A conservation plan to protect the Strait of Gibraltar killer whales is urgently needed, and we recommend implementation of a seasonal management area where activities producing underwater noise are restricted, and the promotion of bluefin tuna conservation.
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain. Electronic address: ruthesteban@gmail.com.
authors: R
authors: R
authors: Esteban
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain.
authors: P
authors: P
authors: Verborgh
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain.
authors: P
authors: P
authors: Gauffier
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain.
authors: D
authors: D
authors: Alarcón
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain.
authors: J M
authors: JM
authors: Salazar-Sierra
authors: Estación Biológica de Doñana (EBD-CSIC), Sevilla, Spain.
authors: J
authors: J
authors: Giménez
authors: CMPG, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
authors: A D
authors: AD
authors: Foote
authors: CIRCE (Conservation, Information and Research on Cetaceans), Pelayo-Algeciras, Cádiz, Spain.
authors: R
authors: R
authors: de Stephanis
mesh_terms: D063147:Animal Distribution; D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D008522:Mediterranean Sea; D011157:Population Dynamics; D050685:Whale, Killer / Q000502:physiology*
keywords: Drop-line fishery; Genetics; Killer whale; Matrifocal; Orcinus orca; Social structure; Strait of Gibraltar