Spatial and temporal occurrence of fin whales ( Balaenoptera physalus ) and euphausiids ( Nyctiphanes simplex ) in the Ballenas Channel, Gulf of California, Mexico
Fin whales ( Balaenoptera physalus ) are observed year-round in the B allenas Channel and Bahía de los Ángeles region, Gulf of California, where their main food item is the euphausiid Nyctiphanes simplex . This investigation was desi gned under the hypothesis that the spatial and temporal occurrence...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2015 |
| País: | México |
| Institución: | Centro de Investigación Científica y de Educación Superior de Ensenada |
| Repositorio: | Redalyc-CICESE |
| OAI Identifier: | oai:redalyc.org:48039202004 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=48039202004 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias de la Tierra fin whale euphausiids Gulf of California Nyctiphanes simplex Balaenoptera physalus |
| Sumario: | Fin whales ( Balaenoptera physalus ) are observed year-round in the B allenas Channel and Bahía de los Ángeles region, Gulf of California, where their main food item is the euphausiid Nyctiphanes simplex . This investigation was desi gned under the hypothesis that the spatial and temporal occurrence of whales and euphausi ids coincides. The aim was to establish the geographic, seasonal, and interannual changes in the abundance of the fin whale and its main prey in the region during 2003 and 2004. F our field trips were carried out per year. Surveys to search for whales and carry out horizontal surface t ows were conducted from small boats . Fin whales and euphausiids were mainly observed off the coast of Baja California and in the southern B allenas Channel. The ir abundance varied significantly from one season to another in both years. The highest rel ative abundance of whales occurre d in July (warm season), followed by June (cold–warm transition period) and March–April (cold season), and th e lowest in October (late warm season). Euphausiid abundance wa s significantly higher in June (cold–warm transition period), followed by July (warm season). There was n o direct correlation between week ly abundances of both species, probably because whale peak abundance occu rred four weeks later than eup hausiid peak abundance. Fin whal e relative abundance was signif icantly higher in 2004 than in 2003 (2.22 and 0.46 whales h –1 , respectively), but euphausiid abundance remained almost the s ame (geometric means 255 and 174 ind/1000 m 3 ). Even though there wa s no weekly correlati on between both spe cies, their geographic di stribution did overlap. |
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