Report on Sperm Whales (Physeter macrocephalus)

Sperm Whales (Physeter macrocephalus) can be seen in the Strait of Gibraltar throughout the season, but are more common in spring and autumn than in midsummer. This is probably due to varying food availability.

Position Pottwale 1999–2015
Positions of Sperm Whales from 1999 to 2015

We sight most Sperm Whales at the beginning of the season until about June, the second half of the summer they remain predominantly in the Mediterranean according to our observations.

Altogether, there are good and bad years for watching them. Fluctuations in the occurrence of large squids could be responsible for this. When comparing "good" and "bad" years, it is noticeable that the Sperm Whales leave the Strait of Gibraltar earlier in the summer season in bad years and only return later.

We have investigated the question of whether little wind is accompanied by a large occurrence of Sperm Whales (and probably squids) in the Strait of Gibraltar. Our data until 2014 show that less the wind force than the wind direction seems to have an influence on the presence of Sperm Whales: years with westerly winds attract more Sperm Whales. (However, there was hardly any easterly wind in 2015, yet only a few Sperm Whales showed up. 2016 had some strong wind phases from the east, nevertheless the Sperm Whales were quite frequently present.)

Using the number of Sperm Whales per sighting as a measure of group size, they seem to "move closer together" when they are present in smaller numbers. They may need to spread more if they are many to share the limited food resources of the Strait.

Keydata from annual reports

2006

  • Many Sperm Whales, also at "uncommon" locations
  • Spring: up to 3 Sperm Whales in the Bay of Gibraltar
  • Beginning of October: rare observation of 4 Sperm Whales, close to the Island of Tarifa, accompanied by 13 Pilot Whales

2007

  • Many Sperm Whales, also at "uncommon" sites in the northern border of the Strait of Gibraltar
  • August: Sperm Whale in the Bay of Gibraltar
  • Mating at July 8th
  • Seem to be staying throughout the whole season, no larger breakes in sighting probabilitiy from April to the end of October

Maybe the Sperm Whales stay longer than initially observed in the Strait of Gibraltar and not only from March to August, when they are supposed to use the Strait as a feeding ground. This might be important to consider when it comes to regulate shipping and to define the biological importance of the Strait.

2008

  • Sperm Whales present almost during the complete season, even during the hottest months.
  • Highlight – September 1st: 9 Sperm Whales in one trip. They were respotted more and more westerly during further trips that day, suggesting they were leaving the Strait towards the Atlantic

2009

  • Only 27 sightings
  • Mainly in April, May and July
  • Only 2 % of all sightings, in good years from 9-16 %

2010

  • Only 17 sightings
  • Mainly in April, May and June
  • Only 1 % of all sightings (worst Sperm Whales season since firmm started to record)

2011

  • Sperm Whales continue to be almost absent
  • Only 15 Sperm Whales at 9 sightings
  • Mainly in June, August, September and October
  • Another season with only 1 % of the sightings being Sperm Whales (second worst season since firmm started its recordings in the Strait)

2012

  • June and July: 5 Sperm Whales in the Strait of Gibraltar; at least two of them youngsters who liked to jump
  • The other months of the season scarce sightings
  • 130 sightings in total (great improvement compared to the last two seasons, but never as good as 2008)

Together with the port “Tanger Med” and its noise, the fluctuating availability of prey might be the main reason for good and bad Sperm Whale years in the Strait of Gibraltar.

2013

  • April and May: up to 4 Sperm Whales in the Strait of Gibraltar
  • Rest of months only scarce sightings
  • 73 sightings in total

News about a dead stranded Sperm Whale, with the stomach packed with plastik rubbish (German article at Spiegel Online), give a hint about the threats they have to face in the Mediterranean.

2014

  • Good Sperm Whale season
  • Sighting period: from April to November
  • June and July: most of the sightings (up to 4 Sperm Whales per trip)
  • June 1st: 9 Sperm Whales in one trip, one of them a calf
  • June 7th: another calf
  • 342 sightings in total

2014 was en exceptionally good Sperm Whale season, the calm weather allowed to carry out many trips. The question arose, wether less wind accounts for more Sperm Whale prey (large squid) in the Strait of Gibraltar?

2015

  • Bad Sperm Whale season
  • Sighting period: from April to mid of September
  • Mainly in May and June (most being individual animals, ocasionally 3-5 Sperm Whales per trip)
  • No calves
  • 110 sightings in total

2016

  • Good Sperm Whale season
  • Sighting period: end of March to beginning of November
  • Mainly in April and May (one month earlier than 2015)
  • Mostly individual animals, except some groups of 3-9 animals
  • April 23rd and 24th: one group of 9 - and another of 7 animals respectively
  • Calves present
  • 280 sightings in total

2017

  • Good Sperm Whale season
  • Sighting period: from start of April to end of September
  • 197 sightings in total
  • Most of the sightings in April, May and June: (confirms our observation, that they stay in the Mediterranean during the hottest months)
  • Mostly individual animals (groups of 2-3 animals only at 13 trips)
  • September 25th and 26th (two last days of Sperm Whale sightings): group of more than 10 animals (although sightings of this species in the Strait are normally scarce at this time of the year)
  • No calves

2018

  • Mediocre Sperm Whale season
  • Sighting period: from start to end of season
  • 128 sightings in total
  • Mainly in May and June
  • Mostly individual animals (groups of 2–3 animals only at 13 trips)
  • 9 sightings of groups with 2–4 animals, one mother calf pair at October 22nd

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