Minke whales (Balaenoptera acutorostrata) are abundant on the south-west coast of Iceland, in Faxaflói Bay, and on north-east coast, in Skjálfandi Bay. Sightings of large numbers of Minke whales generally begin at the end of March and continue until the beginning of November, with highest numbers encountered from July to August in Faxaflói Bay (Salo, 2004; Bertulli, 2010).
In the Faxaflói area, the first photo-identification catalogue of Minke whales has been established in 2007 and until now it counts over 200 different individuals (Bertulli et al., in prep). Photo-identification surveys have been covering an area of approximately 10–12 nm west from Kollafjörður and the Garður area where both species were sighted especially during spring and summer months.
Aerial surveys conducted to estimate Minke whale abundance, under the North Atlantic Sighting Survey (NASS), has yielded a population estimate of 43.633 (95% CI:30.148–63.149) individuals in Icelandic shelf waters in 2001 and 10680 individuals in 2007 (95% CI:5873–17121) (Borchers et al., 2009; Pike et al., 2009; 2008).
Current research objectives
- Determine the abundance of Minke whales in the Faxaflói population
An intensive photo-identification study designed to minimize violation of mark-recapture assumptions can help to minimize bias and maximize precision of population estimates
- Determine patterns of residency of Minke whales in the Faxaflói populations
Using the photo-ID data for each year, it is possible to examine the number of days individual whales and dolphins are re-sighted; minimum residency time (the number of days between first and last sightings within the same season); and re-sighting rate (the proportion of individual whales/dolphins identified on more than one day within the same season)
- Establish sex ratio estimates using genetic and/or hormone level data
For most species, sex determination relies on the observation of the ventral region, which is a rare event in situ. The impracticality of morphological sex determination hinders a thorough understanding of important biological factors. Molecular sexing can close this gap and can be coupled with low impact sampling such as biopsy darting, which has proved to be safe and minimally invasive for free-ranging cetaceans
- Investigate the prevalence of cutaneous disorders in Minke whales of Faxaflói Bay
Skin diseases in free-ranging whales and dolphins have been studied using a variety of research methods including photographic identification (photo-id) surveys. Thus, photo-identification techniques can be extended to record the prevalence of certain signs of disease in whales and dolphins, and suggests that these methods could be used to complement other studies of disease in wild cetacean populations
- Investigate the foraging behaviour of Minke whales and their association with seabirds during feeding bouts
The feeding patterns displayed by the minkes whales can be divided into two types: (1) Entrapment manoeuvres in which component behaviours serve to intercept, contain, or compress the prey, which comprises of sub-surface and near-surface movements, and (2) engulfing manoeuvres, in which the prey is consumed or swallowed. These manoeuvres occur at the surface. A third category (3) comprising near-surface movement with elements of surface movements also exists although its function is unclear. These movements are used on occasion for entrapment and engulfing and are thus termed entrapment/engulfing manoeuvres (Curnier, 2005; Tscherter, unpublished). A Minke whale bird-association forager exploits concentrations of fish fry that have been ‘prepared’ by flocks of feeding gulls and diving birds from above and often by predatory fish and sharks from below. The bird association feeder takes advantage of a concentrated prey resource but that is, however, ephemeral and consequently difficult to locate. The ‘line fishing ’involves engulfing mouthfuls of prey scattered along a line (which is akin to the principals of bird-associated foraging) involves a higher threshold of feeding activity within a confined area