Gisli Vikingsson

The North Atlantic Sightings Survey (NASS), the sixth in a series of surveys conducted between 1987 and 2015, was conducted in June/July 2015 and covered a large area of the northern North Atlantic. The Icelandic and Faroese ship survey component of the NASS covered the area between the Faroe Islands and East Greenland from latitude 52° to 72° N. The survey used 3 vessels and an independent double-platform configuration with each platform staffed by a minimum of 2 observers. Here we present both uncorrected abundance estimates derived using Multiple Covariates Distance Sampling, and corrected abundance estimates derived using Mark-Recapture Distance Sampling, for the following species: fin (Balaenoptera physalus), common minke (B. acutorstrata), humpback (Megaptera novaeangliae), blue (B. musculus), sei (B. borealis), sperm (Physeter macrocephalus), long-finned pilot (Globicephala melas) and northern bottlenose (Hyperoodon ampullatus) whales as well as white-beaked (Lagenorhynchus a...

In 1986 a large, pregnant, female balaenopterid whale was caught in Icelandic waters. The animal had morphological characteristics of both the blue and the fin whale. Molecular analyses of the whale showed that it was a hybrid between a female blue whale and a male fin whale. The descent of the species hybrid was established without access to either parental specimen. Analysis of the fetus showed that it had a blue whale father. The present report of species hybridization between the two largest cetacean species, the blue and the fin whale, documents the occurrence of cetacean species hybridization in the wild. It is also the first example of any cetacean hybridization giving rise to a fertile offspring.

The population structure of the highly mobile marine mammal, the harbor porpoise (Phocoena phocoena), in the Atlantic shelf waters follows a pattern of significant isolation-by-distance. The population structure of harbor porpoises from the Baltic Sea, which is connected with the North Sea through a series of basins separated by shallow underwater ridges, however, is more complex. Here, we investigated the population differentiation of harbor porpoises in European Seas with a special focus on the Baltic Sea and adjacent waters, using a population genomics approach. We used 2872 single nucleotide polymorphisms (SNPs), derived from double digest restriction-site associated DNA sequencing (ddRAD-seq), as well as 13 microsatellite loci and mitochondrial haplotypes for the same set of individuals. Spatial principal components analysis (sPCA), and Bayesian clustering on a subset of SNPs suggest three main groupings at the level of all studied regions: the Black Sea, the North Atlantic, an...

Ecosystem approaches to fisheries management have called for complicated models for multi—species interactions. However, data on many of these interactions are often limited as they require extensive analysis of stomach content data. Direct sampling is also fraught with difficulties both due to technical and political reasons. Changes in the environment can also play a role as the environmental changes may affect species differently. In the case of cod in Va one of the key uncertainties identified as the consumption of baleen whales, the common minke whales in particular. The common minke whales is the most abundant baleen whale species in Icelandic waters. As a possible response to climate change its abundance has decreased. A recent study on the feeding ecology suggested a high degree of gadoid consumption. The result from this survey were assimilated into a model of Cod­­Minke whales interactions in Gadget, a statistical framework for age – length based marine ecosystems models. ...

Background: this study is a part of a larger research programme on the biology and ecology of fin whales conducted in Icelandic waters in 1986–1989. The objective was to examine energetic strategies, seasonal fattening in particular, in the species using data on weight and chemical composition of different tissues. Methods: carcass analysis was used for estimating the allocation of energy

The distribution and abundance of blue whales (Balaenoptera musculus) was assessed from ship surveys conducted in the Central and Northeast Atlantic in 1987, 1989, 1995 and 2001. Blue whales were most commonly sighted off western Iceland, and to a lesser extent northeast of Iceland. They were very rare or absent in the Northeast Atlantic. Sightings were combined over all surveys to estimate the detection function using standard line transect methodology, with the addition of a covariate to account for differences between surveys. Total abundance was highest in 1995 (979, 95% CI 137-2,542) and lowest in 1987 (222, 95% CI 115-440). Uncertainty in species identity had little effect on estimates of abundance. There was a significant positive trend in abundance northeast of Iceland and in the total survey area.

ABSTRACT According to the IWC Schedule North Atlantic fin whales are divided into seven management stocks. This division originates in the 1970's and was mainly based on various types of indirect evidence such as distribution of catches, occurrence and length distributions of the catch. In this paper an attempt is made, to summarise the available data on stock structure of North Atlantic fin whales based on non-genetic methods. This includes a wide range of studies based on discovery marking, morphometry, earplug morphology, photo-identification, acoustics and biological parameters. Although each method is rather inconclusive by itself, collectively they indicate a separation between fin whales summering in the western, central and eastern North Atlantic. There also appears to be a more or less isolated stock in the Mediterranean Sea.

Background: Understanding the role of seascape in shaping genetic and demographic population structure is highly challenging for marine pelagic species such as cetaceans for which there is generally little evidence of what could effectively restrict their dispersal. In the present work, we applied a combination of recent individual-based landscape genetic approaches to investigate the population genetic structure of a highly mobile extensive range cetacean, the harbour porpoise in the eastern North Atlantic, with regards to oceanographic characteristics that could constrain its dispersal.

North Atlantic Sightings Surveys (NASS) is a series of large scale international cetacean line transect surveys, conducted in 1987, 1989, 1995 and 2001, that covered a large part of the central and eastern North Atlantic. Target species were fin (Balaenoptera physalus), common minke (B. acutorostrata), pilot (Globicephala melas) and sei (B. borealis) whales. Here we present new estimates of abundance for fin whales from the 2 most recent surveys and analysis of trends throughout the survey period. Fin whales were found in highest densities in the Irminger Sea between Iceland and Green-land. Abundance of fin whales in the survey area of the Icelandic and Faroese vessels (Central North Atlantic) was estimated as 19,672 (95% C.I. 12,083-28,986) animals in 1995 and 24,887 (95% C.I. 18,186-30,214) in 2001. The estimates are negatively biased because of whales diving during the passage of vessels, and whales being missed by observers, but these and other potential biases are likely small for this species. The abundance of fin whales increased significantly over the survey period. For all areas combined the estimated annual growth rate was 4%. An estimated annual increase of 10% in the area between Iceland and Greenland was responsible for most of this overall increase in numbers of fin whales in the area. Although high, the estimated rates of increase are not out of bounds of biological plausibility and can thus be viewed as recovery of a depleted population. However, the apparent pattern of population growth and the whaling history in the area indicate that fin whales made a significant recovery during the first half of the 20 th century and that the recent observed high growth rates cannot be explained solely by recovery after overexploitation.

The consumption of fish, cephalopods and planktonic crustaceans by cetaceans in Icelandic and adjacent waters was estimated. The estimates were based on (i) abundance estimates from recent sighting surveys (NASS-87,89,95); (ii) seasonal variation in abun-d a n c e e s t i m a t e d f r o m s i g h t i n g s a n d / o r c a t c h d a t a f r o m w h a l i n g v e s s e l s ; a n d (iii) consumption rates calculated from the estimated biomass of cetaceans in the area throughout the year. A large number of assumptions had to be made, and these calculations were mainly intended to give an idea of the possible magnitude of consumption as well as to be a guidance for further research in this field. The total food consumption was estimated as 6.3 million tons in a smaller area defined as Icelandic and adjacent waters, and 8.8 million tons in the larger area north of 60 o N. Considering total consumption, fin whales (Balaenoptera physalus) and minke whales (B. acutorostrata) were the largest consumers in the area, followed by long-finned pilot whales (Globicephala melas) and northern bottlenose whales (Hyperoodon ampullatus). Crustaceans comprise around 50% of the total consumption within the study area while finfish and cephalopods comprised 27% and 22%, respectively, in the large area. Minke whales were the largest consumers of finfish, consuming more than 1 million tons of fish in Icelandic and adjacent waters.

The 2004 Mid-Atlantic Ridge (MAR)-ECO expedition on the R.V. G.O. Sars provided the first opportunity to correlate oceanic distributions of cetaceans with synoptic acoustic (ADCP to 700 m depth, multi-beam echosounders) measurements of high-resolution, three-dimensional (3D) potential habitat (spatial scaleo100 km). The identified habitat features were tested with independent observations from the Icelandic combined cetacean and redfish cruises in 2001 and 2003 using data from a 3D ocean general circulation model of the MAR region (Regional Oceans Modelling System (ROMS) model 5 km resolution). The spatial autocorrelation of sampled encounter rates of sperm Physeter macrocephalus and sei whales Balaenoptera borealis indicated scale-dependent variability in the distribution of both species. Despite the large area surveyed, the observations of both species exhibited a strong small-scale structure (range parameter 20-50 km), indicating affinities to cross-seamount or cross-frontal structures. Potential cross-seamount and cross-frontal habitat structures were derived from the acoustic transect data by analysing fine-scale gradients in the 3D flow patterns and bathymetry, including interactions between frontal and topographic parameters. PLS regression was used to determine the potential habitat drivers of sperm and sei whales, both during the G.O. Sars cruise and during the Icelandic cruises in 2001 and 2003. The selected parameters, which reflected flow gradients interacting with the steep topography, were finally applied for modelling the habitat suitability of both target species along the northern MAR using Ecological Niche Factor Analysis. The results suggest aggregations of sperm and sei whales along the MAR are primarily associated with fine-scale frontal processes interacting with the topography in the upper 100 m of the water column just north of the Sub-Polar Front (SPF) and the Charlie-Gibbs Fracture Zone (CGFZ). As moderate and high habitat suitabilities were estimated only for areas downstream from the SPF, the findings suggest that the animals capitalise on secondary production maintained by enhanced primary production associated with the frontal processes in the upper part of the water column in the CGFZ and at the Faraday Seamounts. Further studies are encouraged to evaluate the importance of the bio-physical coupling, and the significance of small-scale frontal processes in the surface and subsurface waters north of the SPF for the transfer of energy to higher trophic levels in the North Atlantic. r