The morphology of euphausiid mandibles used to assess selective predation by blue whales in the southern sector of the California Current System

TitleThe morphology of euphausiid mandibles used to assess selective predation by blue whales in the southern sector of the California Current System
Publication TypeJournal Article
Year of Publication2018
AuthorsNickels C.F, Sala L.M, Ohman MD
JournalJournal of Crustacean Biology
Volume38
Pagination563-573
Date Published2018/09
Type of ArticleArticle
ISBN Number0278-0372
Accession NumberWOS:000456690400006
Keywordsbody-size; Crustacea; daytime surface swarms; dependence; Euphausiacea; fecal-sample analysis; gulf; Krill; Marine & Freshwater Biology; prey selection; zoology
Abstract

We describe the mandibular morphology of the eight most abundant euphausiid species in the California Current and report regression relationships between mandible size and body total length. We applied these species-specific characters to the mandibles recovered from fecal samples of 18 blue whales (Balaenoptera musculus (Linnaeus, 1758)) collected between 1998 to 2015 off Southern California to test for selective feeding on the euphausiid assemblage. The diets of blue whales were consistently and overwhelmingly dominated by the large neritic euphausiid Thysanoessa spinifera Holmes, 1900, even when other species were present or dominant in closely collected net samples. More than 99% of the ingested euphausiids were longer than 10 mm, indicating that blue whales in this region are highly selective by prey species and size class, and dependent upon aggregations of juveniles or adults of a limited number of coastally associated euphausiid species.

DOI10.1093/jcbiol/ruy062
Short TitleJ. Crustac. Biol.
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