Conservation Status of Killer Whales, Orcinus orca, in the Strait of Gibraltar.

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.

Conservation Status of Long-Finned Pilot Whales, Globicephala melas, in the Mediterranean Sea.

Mediterranean Sea long-finned pilot whales (Globicephala melas) are currently classified as Data Deficient on the International Union for the Conservation of Nature (IUCN) Red List. Multiple lines of evidence, including molecular genetic and photo-identification mark-recapture analyses, indicate that the Strait of Gibraltar population (distributed from 5.8°W longitude to west of Djibouti Bank and Alborán Dorsal in the Alborán Sea) is differentiated from the Mediterranean Sea population (east of Djibouti Bank and the Alborán Dorsal up to the Ligurian Sea). There is low genetic diversity within the Mediterranean population, and recent gene flow with the Strait of Gibraltar population is restricted. Current total abundance estimates are lacking for the species in the Mediterranean. Pilot whales in the Alborán Sea region were negatively affected by a morbillivirus epizootic from 2006 to 2007, and recovery may be difficult. The Strait of Gibraltar population, currently estimated to be fewer than 250 individuals, decreased by 26.2% over 5 years after the morbillivirus epizootic. Population viability analyses predicted an 85% probability of extinction for this population over the next 100 years. Increasing maritime traffic, increased contaminant burdens, and occasional fisheries interactions may severely impair the capacity of the Strait of Gibraltar population to recover after the decline due to the pathogen.

Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants.

Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended.

Bioaccumulation and biomagnification of classical flame retardants, related halogenated natural compounds and alternative flame retardants in three delphinids from Southern European waters.

Occurrence and behaviour of classical (PBDEs) and alternative (HNs, HBB, PBEB, DBDPE and HBCD) flame retardants, together with naturally produced MeO-PBDEs, were studied in short-beaked common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus) and long-finned pilot whale (Globicephala melas) in two sampling locations from Southern European waters. PBDEs, Dec 602, Dec 603, DP, α-HBCD and two MeO-PBDEs were detected in all three species. ∑PBDEs were between 17 and 2680 ng/g lw; ∑HNs were between 1.1 and 59 ng/g lw; α-HBCD levels ranged between 3.2 and 641 ng/g lw; ∑MeO-PBDEs were between 34 and 1966 ng/g lw. Bottlenose dolphins were the most contaminated species and some individuals could present health risk for endocrine disruption since levels found were above the reported threshold (1500 ng/g lw). Stable isotope analysis was used to evaluate the biomagnification capacity of these compounds. PBDEs, MeO-PBDEs and Dec 602 showed a significant positive correlation with trophic position.