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Balaenoptera physalus (Mediterranean subpopulation)

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CETARTIODACTYLA BALAENOPTERIDAE

Scientific Name: Balaenoptera physalus (Mediterranean subpopulation)
Parent Species:
Common Name(s):
English Fin Whale
French Rorqual Commun
Spanish Rorcual Común
Taxonomic Notes: Genetic analyses based on both mitochondrial and nuclear DNA indicated differences between the Mediterranean population, which is thought to be resident, and Fin Whales in Atlantic coastal waters of Canada, Greenland, Iceland and Spain (Bérubé et al. 1998). Further genetic analyses (Palsbøll et al. 2004) predicted that Mediterranean Fin Whales would prove to be largely resident in the basin, although limited but recurrent gene flow was detected in the data. Palsbøll et al. (2004) estimated the effective number of female migrants between the Mediterranean Sea and the Eastern North Atlantic to be 0.33 migrant/year, a value that is consistent with the IUCN definition for subpopulation (i.e., less than about one migrant/year). Direct evidence supporting this prediction was later provided through satellite tagging (Guinet et al. 2005) and fatty acid analysis, suggesting that Fin Whales summering in the Ligurian Sea may spend the winter in Spanish Atlantic waters, returning during spring and summer to the Mediterranean Sea (Ruchonnet et al. 2006).

Assessment Information [top]

Red List Category & Criteria: Vulnerable C2a(ii) ver 3.1
Year Published: 2012
Date Assessed: 2011-07-07
Assessor(s): Panigada, S. & Notarbartolo di Sciara, G.
Reviewer(s): Taylor, B.L. & Perrin, W.F.
Justification:
The Red List assessment for the Mediterranean subpopulation of Fin Whale requires the following considerations:
  • The Mediterranean subpopulation, which is genetically distinct from Fin Whales in the Atlantic, contains fewer than 10,000 mature individuals;
  • The subpopulation experiences an inferred continuing decline in number of mature individuals;
  • All mature individuals are in one subpopulation.
No population estimates exist for the entire region. However, line-transect surveys in 1991 yielded Fin Whale estimates in excess of 3,500 individuals over a large portion of the western Mediterranean (Forcada et al. 1996), where most of the basin’s Fin Whales are known to live. It is reasonable to assume that a realistic estimate for the total basin would not exceed 5,000 individuals, so the threshold of <10,000 mature is easily met.

Human-induced mortality from vessel collisions and bycatch in fishing gear (Panigada et al. 2006), together with the potential effects of the disturbance caused by growing whale watching activities, lead to the inference that the subpopulation is declining. Fin Whales have been described as particularly abundant during the summer months in the Corso-Ligurian-Basin, which is considered their major feeding ground in the Mediterranean Sea. A sharp decrease in Fin Whale abundance has been observed in the Pelagos Sanctuary over the last decade, with estimates of 900 individuals reported from the western Ligurian Sea in 1992 (Forcada et al. 1995), declining to significantly lower numbers (N=147; CV=27.04%; 95% CI=86–250) in 2009 (S. Panigada and G. Lauriano pers. comm). While the sharp decrease of Fin Whales in the Pelagos Sanctuary may be due to whales relocating elsewhere within the Mediterranean, their decrease in prime Fin Whale habitat must be addressed with precaution, and a population decline in the Mediterranean cannot be discounted at this time.

Fin Whales in the Mediterranean are a subpopulation based on the IUCN definition (less than about one migrant/year; Palsbøll et al. (2004) suggested an estimation of 0.33 migrant/year between Mediterranean and Atlantic). Genetic data from a sample of Fin Whales from the Mediterranean have not provided evidence for within-region population structure (Bérubé et al. 1998); Fin Whales, known as a highly mobile species, are thought to roam widely across the Mediterranean, and the assumption that they form a single subpopulation within the basin is the most parsimonious. Should future research reveal that Fin Whales in the Mediterranean are structured into a western and an eastern subpopulation, this would involve the splitting of the current subpopulation into two even smaller designatable units, possibly subjected to higher levels of vulnerability and threats.
History:
2012 Vulnerable

Geographic Range [top]

Range Description: The Fin Whale is the most common large whale species in the Mediterranean Sea. It is found mostly in deep, offshore waters of the western and central portion of the region, from the waters north and east of the Balearic Islands to, and including, the Ionian Sea, and less frequently elsewhere. The Corso-Ligurian Basin and Gulf of Lyon are the Mediterranean areas where Fin Whale abundance is highest by far (Notarbartolo di Sciara et al. 2003). Cotté et al. (2009) reported on the satellite tracking of eight whales, all of which remained in the Mediterranean over a period of 10 months, except one which moved into the Atlantic; spatial modelling results by the same authors confirmed year-round presence of Fin Whales in the north-western Mediterranean, with lower levels during winter.

Fin Whales are regularly encountered throughout the western and central basins, with seasonal summer concentrations in highly productive portions of the Corsican, Ligurian and Tyrrhenian seas, where they apparently feed on a single euphausiid species, Meganyctiphanes norvegica (Orsi Relini et al. 1998). Limited evidence exists of similar feeding activities in the eastern Ionian Sea (Notarbartolo di Sciara et al. 2003). Seasonal (late winter) feeding aggregations of Fin Whales have also been observed recently in the Sicily Channel (Canese et al. 2006).

Acoustic detections, using seafloor autonomous recording units, monitored Fin Whale presence off the eastern and southern Mediterranean coasts of Spain, providing evidence of transit between a summer ground in the Corso-Ligurian Basin and a possible winter ground off southern Spain and the North African coast (Castellote et al. 2008). Movements thorough the Strait of Gibraltar assessed acoustically revealed a limited seasonal exchange of Fin Whales from the North Atlantic Ocean towards the Alborán Sea, with eastern movements recorded in the early winter and western ones in the early summer (Castellote et al. 2009). Evidence of acoustically different populations or stocks has been presented, with songs recorded in the Alborán Sea during the winter attributed only to the North-East North Atlantic (NENA) population; no evidence of songs attributed to the Mediterranean subpopulation have been recorded (Castellote et al. 2009). Laran et al. (2008) used bathymetry, Chl-a, and SST to predict Fin Whale habitats in the northwestern Mediterranean, underlining favourable areas in the Tyrrhenian Sea, between the mainland of Italy and the Island of Sardinia, off the Pelagos Sanctuary borders. Presence of Fin Whales in this area has also been demonstrated by Arcangeli et al. (2009) and by opportunistic sightings (http://med09-expedition.blogspot.com/).

Photo-identification data imply a high degree of site fidelity in Fin Whales summering in the Ligurian Sea (Zanardelli et al. 1998). Breeding and calving grounds have yet to be identified (Notarbartolo di Sciara et al. 2003). Fin Whales are extremely rare in the Adriatic and Aegean Seas and in the Levantine Basin.
Countries:
Native:
Algeria; Cyprus; Egypt; France; Gibraltar; Greece; Israel; Italy; Lebanon; Libya; Malta; Monaco; Morocco; Spain; Syrian Arab Republic; Tunisia; Turkey
FAO Marine Fishing Areas:
Native:
Mediterranean and Black Sea
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: No population estimates exist for the entire region. However, line-transect surveys yielded estimates of 3,583 Fin Whales (S.E. 967, 95% C.I. 2,130–6,027) over a large portion of the western Mediterranean in 1991 (Forcada et al. 1996) and 901 (S.E. 196.1, 95% C.I. 591–1,374) in the Corsican-Ligurian-Provençal Basin in 1992 (Forcada et al. 1995). Further line-transect survey effort in the same area yielded a strikingly consistent density estimate of 0.015 individuals km-2 (Gannier 1997).

A survey carried out in the entire Pelagos Sanctuary area yielded an estimate of 715 individuals (%CV 31.2, 95% C.I. 421–1,215), with highest values in the Ligurian-Provencal area (Gannier 2006). Two aerial surveys organized in winter and summer 2009 in the whole Pelagos Sanctuary area yielded 0 and 17 Fin Whale sightings, respectively, resulting in an estimate of Fin Whale abundance for the summer of 147 individuals (%CV=27.04; 95% CI=86–250) (S. Panigada and G. Lauriano pers. comm.). This indicates that Fin Whales in this area may be less abundant than previously reported (Forcada et al. 1995, Gannier 2006).

A sharp decrease in Fin Whale abundance has been observed in the Pelagos Sanctuary over the last decade, with estimates of 900 individuals reported from the western Ligurian Sea in 1992 (Forcada et al. 1995), declining to significantly lower numbers (N=147; CV=27.04%; 95% CI=86–250) in 2009 (S. Panigada and G. Lauriano pers. comm.). While the sharp decrease of Fin Whales in the Pelagos Sanctuary may be due to whales relocating elsewhere within the Mediterranean, their decrease in prime Fin Whale habitat must be addressed with precaution, and a population decline in the Mediterranean cannot be discounted at this time.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Fin Whales in the Mediterranean are most common in deep waters (400 to 2,500 m), but they can occur in slope and shelf waters as well, depending on the distribution of their prey (Gannier et al. 2002; Laran and Gannier 2008; Notarbartolo di Sciara et al. 2003; Panigada et al. 2005, 2008). They favour upwelling and frontal zones with high zooplankton concentrations, their main prey in the region. Habitat-use results show that cetacean distribution in the western Ligurian Sea may change in response to climate variability, with Fin Whales avoiding areas with extreme sea surface temperature (SST) values (different from the monthly average) (Azzellino et al. 2008).
Systems: Marine

Use and Trade [top]

Use and Trade: In the Mediterranean Sea, this species is not utilized.

Threats [top]

Major Threat(s): Although each impacting factor may not be considered a major threat when considered alone, the number of cumulative effects in a semi-enclosed basin heavily affected by human presence, such as the Mediterranean, is interpreted in a precautionary manner to amount to potentially large and detrimental effects on both birth and death rates, and might explain the observed localized decline. Incidental mortality of Fin Whales in fishing gear (pelagic driftnets) is uncommon (Podestà and Magnaghi 1989) and its effect on the population is therefore considered low but not negligible (International Whaling Commission 1994). Ship strikes also cause mortality and are a concern particularly in areas of heavy vessel traffic (Cagnolaro and Notarbartolo di Sciara 1992, Panigada et al. 2006, Weinrich et al. 2006). The increasing use of high-speed ferries requires further investigation in this regard. Shipping noise and vessel disturbance, particularly from the unregulated whale watching that has recently begun in the area (Airoldi et al. 1999), is another source of concern. Other vessel traffic may cause additional acoustic stress. Seismic airguns can deter Fin Whales from feeding or breeding grounds (Castellote et al. 2009), with potential detrimental effects on the population. There is no competition between Fin Whales and fisheries in the Mediterranean because in this region Fin Whales are almost exclusively planktophagous (Notarbartolo di Sciara et al. 2003). Fossi et al. (2003, 2007) described high levels of contamination by organochlorines, trace elements and DDT metabolite values in Mediterranean Fin Whales, and suggested that their estrogenic and anti-androgenic effects may negatively influence the population. Fossi et al. (2007) presented evidence of endocrine disrupting chemicals (EDCs) in Fin Whale biopsy samples from the western Ligurian Sea, which may adversely affect the reproductive functions of these whales. The potential effects of global climate change or ocean acidification on this subpopulation, largely dependent for feeding on euphausiids species such as M. norvegica, N. couchii, (Notarbartolo di Sciara et al. 2003), possibly susceptible to climate changes, are currently unknown, but cannot be neglected and need further investigation.

Conservation Actions [top]

Conservation Actions: A large international protected area (approx. 90,000 km²), the Pelagos Sanctuary for Mediterranean Marine Mammals, was recently established and listed among SPAMIs (Barcelona Convention SPA Protocol) and encompasses a key Fin Whale feeding area in portions of the Provençal, Corsican, Ligurian, Tyrrhenian and northern Sardinian Seas (Notarbartolo di Sciara et al. 2008). Whale-watching regulations are likely to be incorporated into national legislation in the near future. The species is listed in Appendix I of CMS, in Appendix II of the Bern Convention, in Appendix I of CITES, and in Annex 2 of the Protocol on Specially Protected Areas and the Biological Diversity in the Mediterranean of the Barcelona Convention. For the present at least, Mediterranean Fin Whales are protected by the International Whaling Commission’s moratorium on commercial whaling that came into force in 1986.

Citation: Panigada, S. & Notarbartolo di Sciara, G. 2012. Balaenoptera physalus (Mediterranean subpopulation). The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 November 2014.
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