Report on Fin Whales (Balaenoptera physalus)

The Fin Whales (Balaenoptera physalus) we encounter on our trips show clear migratory behaviour. In summer, most of them swim from the Mediterranean towards the Atlantic. Only very few swim into the Mediterranean during this time.

Position Finnwale 1999–2015
Positions of Fin Whales from 1999 to 2015

During their migrations through the Strait of Gibraltar, the Fin Whales use the more favourable current for them: they swim towards the Atlantic with rising water and towards the Mediterranean with sinking tide.

According to our projections 48 to 122 Fin Whales swim every summer direction west from the Mediterranean Sea into the Atlantic Ocean. However, we can observe individual Fin Whales, which swim atypically to the east in the summer. Perhaps they belong to the last survivors of a former population that lived off Gibraltar, which was practically extinguished between 1920 and 1960. Skin samples and genetic analyses would be necessary to test this hypothesis.

Keydata from annual reports

2006

According to a first evaluation of recorded data, 100–250 Fin Whales leave the Mediterranean through the Strait every season.

2008

  • Sighted mainly in July
  • Detection of groups of up to 5 animals
  • Four groups of 5 animals in July
  • All leaving the Mediterranean

2009

  • Fin Whales accounting for 2 % of the sightings
  • Mainly in June, when 22 Fin Whales were spotted
  • 39 Fin Whales in total, two of them being calves
  • Only one group of 5
  • July: 11 Fin Whales did leave the Mediterranean

2010

  • Mainly in July and August
  • 23 Fin Whales in 14 sightings
  • They accounted for 1% of the sightings
  • Largest group of 3 animals
  • May: one calf with two adults

2011

  • Spotted throughout the whole season (April 23rd to November 2nd)
  • 32 Fin Whales in 21 sightings
  • Largest group of 3 animals
  • April and June: each month with sighting of a mother-calf pair

2012

  • 34 Fin Whales in 23 sightings (Mai 17th to September 21st)
  • Largest groups of 3 animals
  • September 14th: one adult with calf

2013

  • 32 Fin Whales in 31 sightings (April 11th to October 15th)
  • Sightings distributed over a longer period of time
  • Individuals or in groups of up to 4 animals
  • July 29th: a calf with 3 adults

2014

  • 27 Fin Whales, distributed over 19 sightings (April 29th to October 20th)
  • Mostly single animals
  • 4 calves sighted
  • June 5th: two calves accompanied by 3 adult Fin Whales
  • 2 sightings of single adult animals swimming east in the middle of summer
  • October: single Fin Whale also swam east (probably already on its way to its winter quarters in the Mediterranean Sea; the whale temporarily turned west, in order to follow a pod of Striped Dolphins chasing a shoal of fish)

There seems to be a constant number of Fin Whales migrating from the Mediterranean to the Atlantic in summer. However, taking into account the 2014 increase in trips and the constant number of Fin Whales observed, there may have been a slight decrease in their migration through the Strait of Gibraltar.

2015

  • 54 Fin Whales distributed over 37 sightings (April 18th to October 31st)
  • Considerably more animals than during the last 3 seasons
  • A total of 5 calves, three of which in July
  • Mostly individually migrating whales
  • 5 sightings of groups of two
  • 3 sightings of groups of three
  • 1 sighting of a group of four and another of five
  • Summer: migration from the Mediterranean to the Atlantic
  • End of April to beginning of August: five Fin Whales heading east
  • September, October: two Fin Whales heading east (possibly on their way back to the Mediterranean where they spend the winter)

2016

  • 34 Fin Whales destributed across 25 sightings (May 22nd to October 6th)
  • Mostly single animals
  • Exception: group of 3 migrating towards the Atlantic at March 30th, four sightings of groups of two
  • Summer: leaving the Mediterranean towards the Atlantic
  • 3 calves in total (all in July)
  • 4 sightings of single adults towards the East:
    three in September and October (possibly on their migration back into the Mediterranean) and one at May 22nd

2017

  • 36 Fin Whales, distributed over 25 sightings (April 25th to October 30th)
  • Mostly individually migrating whales
  • 2 sightings of groups of three
  • 7 sightings of groups of two
  • Only 1 calf sighted (June 9th) accompanied by 2 adults
  • Summer: migration from the Mediterranean to the Atlantic

This season there were 2 sightings of single animals swimming east and one observation of an animal that did not follow a defined direction. One of them was possibly on its way back to the Mediterranean Sea in September, where the Fin Whales spend the winter. But two swam towards the Mediterranean at the end of April and beginning of August.

2018

  • 40 Fin Whales distributed across 23 sightings (April 16th to October 21st)
  • Mostly individual animals
  • Ten sightings of groups of 2-5
  • Four calves
    • Two mother calf pairs in April and July
    • Two acompanied by two adults respectively in July and October
  • Migrating towards the Atlantik during summer
  • One adult towards the East at August 7th

For firmm reports sorted by years (in German) check out firmm-education.