A rare guest

by firmm Team

Northern Minke Whale (Balaenoptera acutorostrata)

Text: Brigitte, photo: firmm, drawing: wale.info

Today we would like to dedicate a blog post to a rare guest.

On July 19th at 20.35 on the last trip of the day we had the rare luck to see a Minke Whale (Balaenoptera acutorostrata). This does not happen very often here in the Strait of Gibraltar. so far only 27 times in the 25-year history of firmm.
Some years we saw no animal of this species at all, sometimes one and only one year they visited us 4 times (2003) and in three years 3 times (2013, 2014 and 2018). They always swam in a westerly direction, except for 2 times in an easterly direction, 1 time in a south-easterly direction and 6 times there is no information about the direction. Once one whale turned around briefly on its way towards the Atlantic and swam half a mile towards the Mediterranean Sea, only to make another 180° turn and continue its way west. Minke and Fin Whales do not feed in the Strait of Gibraltar, we only see them passing through.

The Minke Whale can reach a size of 8-10 metres and a weight of 10 tonnes. Its body is slender with a pointed head.

It has a dark-coloured back and a pale belly. At birth it is 2.8-3.5 metres long and weighs 450 kg, it can live up to 60 years. The two white bands around the flippers (pectoral fins) of Northern Minke Whales (Balaenoptera acutorostrata) are characteristic and could be used to identify them but are rarely seen on the water surface. The Southern Minke Whale (Balaenoptera bonaerensis) has no such white bands.

Minke Whale October 2015

At sea, it can easily be mistaken for a young Fin Whale (for comparison: these can grow up to 22 metres long. The birth dimensions of them are 6.5 metres and 1.5 tonnes). When identifying species in the ocean, length is a good guide, because a young Fin Whale does not usually swim alone. Therefore, at this size, the first assumption is that it is a Minke Whale. In addition, he sometimes shows its "nose" when surfacing, which the Fin Whale does not. The line of its upper jaw is also sharper than that of the Fin Whale.

The animal we observed did not swim in a straight line but was rather restless and changed course frequently. This made it even more difficult for us to find it again after it had dived for a few minutes at a time. (Minke Whales can dive for at least 15 minutes, usually coming to the surface every 6 to 12 minutes).

It is the smallest of the rorquals. The rorquals are a family of baleen whales (the others are the right whales, the grey whales, and the pygmy right whales, the latter two consisting of only one species). Depending on the species, they have 10-100 throat folds (furrows) that are 2.5-5 cm deep and help them hold a lot of water with food in their throat pouch. What distinguishes them from toothed whales is that they do not have teeth, but baleen, which hang from the upper jaw and function like a filter and have two blowholes in the middle of the head. In contrast, toothed whales have only one blowhole. (Minke Whales have 230 to 360 short, white/cream-coloured baleen plates on each side of the mouth and 50 to 70 throat folds. Their blow is bushy and between 2 and 3 metres high. (Source: NOAA)

According to Marc Carwardine's book (Whale Watching in Britain and Europe), the Minke Whale is the baleen whale most hunted by commercial whalers in Norway, Iceland, and Japan.
In this year's whaling season, the number of these whales that may be killed has been increased to 1000 in Norway, Japan has committed to 167 and Iceland to 217. The good news is that Iceland will not extend these current fishing quotas and intends to end whaling completely from 2024.

According to the IUCN (International Union for Conservation of Nature), the current endangerment status of the Minke Whale is «Least Concern». The population trend is reported as unknown and the number of adult individuals in the world is estimated at 200,000.

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