couchii is an intermediate host. This host-parasite relationship indicates that fin whales probably also feed on N. couchii in the NEA (Gregori et al. 2012). The diet of humpback whales in the NEA is poorly studied, although they are known to be generalists feeding on amphipods, capelin, clupeids and krill (Piatt et al. 1989, Skern-Mauritzen et al. 2011). They have been observed foraging in association with fin whales in the CS (Whooley et al. 2011). In the CS, fin and humpback whales associate with a seasonal inshore movement of spawning herring (Clupea harengus) (Whooley et al. 2011). These herring comprise

two stocks targeted by a single fishery. Historically, these stocks have collapsed possibly as a result of a combination click here of over-exploitation and environmental factors (Lynch et al. 2011, Harma et al. 2012). Sprat (Sprattus sprattus) is a major bycatch component of other fisheries in the CS (e.g., for groundfish and herring), but there is also a targeted fishery that is not currently managed or assessed by the Intergovernmental Counsel for the Exploration

of the Seas (ICES) for which there is an open quota (Enever et al. 2007). Moreover, sprat are recognized as an important prey for several predators in the CS ecosystem (Trenkel et al. 2005, Chivers et al. 2012). In order to effectively conserve fin and humpback whales in the CS, their basic requirements and roles in the ecosystem must be identified, so that threats to their habitat, survival, CH5424802 and population

http://www.selleck.co.jp/products/CAL-101.html growth can be identified and alleviated. Towards achieving this goal, the present study aims to estimate relative contributions of krill and clupeid fish in the diet of fin whales and humpback whales that occur sympatrically in the Celtic Sea (CS) using stable isotope Bayesian mixing models. It is hoped that this information may aid the development of ecosystems based approach to fisheries management. The study area comprised the CS and coastal waters to the south of Ireland (Fig. 1). A literature review and photographic evidence of surface active feeding were used to identify a priori the most likely prey (sources) contributing to the diet of both fin and humpback whales (mixture) in the CS. Herring (C. harengus) and sprat (S. sprattus) were caught by pelagic trawl during dedicated herring fisheries surveys and plankton samples were collected in a ring net (1 m diameter, 360 μm mesh) using vertical tows. Plankton samples were collected during February 2010 and fish samples were collected on 18 October 2010 from the RV Celtic Explorer. Skin biopsies were collected from whales between November 2009 and July 2011. Species identification of zooplankton was carried out under the microscope. Skin biopsies were collected from fin and humpback whales from small boats (5–12 m) using modified bolts (CETA-DART) fired from a crossbow (150 lb draw-strength).