D341: Porcupine Abyssal Plain cruise 2009


 D341



Cruise blog

Friday 7 August 2009

Wildlife at the Porcupine Abyssal Plain

Despite the name of the place we have not seen any porcupines but we have seen plenty of marine wildlife on the D341 cruise!

Pilot Whales
One of the first sightings we had was of a pod of small long finned pilot whales. These whales grow up to 6 metres in length and can weigh up to 3.5 tonnes. They occur only in the North Atlantic in the northern hemisphere. Although, they can also be spotted in other oceans in the southern hemisphere. Their diet consists of squid, octopus and fish and they are able to dive down to 600 metres. Their population around the world is unknown however sightings are common. Our picture shows a pod of around 10 pilot whales and from looking in our whale guide we think they are a mixture of males and females. You can tell this because they have different shaped dorsal fines. From the bridge of the ship you could see that the pod consisted of adult and younger whales. The more mature whales appeared to be guiding the young.

Blue Whale
We have been extremely lucky and had a sighting of a huge blue whale. These whales are extremely rare and are officially an endangered species. There are only a few thousand left in the world’s oceans. They are one largest animals to ever exist on earth and they can grow to more than 33 metres in length and weigh up to 190 tonnes. The whale we spotted was approximately 20 metres long and surfaced only 10 metres from the side of the ship.  The blue whale population was almost hunted to extinction through whaling in the 1800 and 1900’s. The mortality rates were so high it is now thought that some populations will never recover. They are found in all areas of the ocean apart from very far north in the Arctic. They dive to depths of 150 metres on average but they are thought to be able to go deeper. They can also swim at speeds up to 19 mph (30 km/h) which means that the ship we are aboard would not be able to keep up with one if it was swimming at its top speed. Considering how large blue whales are it is surprising that they only eat small krill and other crustaceans. However they eat these things in massive quantities. We were able to identify the whale as a blue whale from the small stubby looking dorsal fin which was a long way down its body. We have also had the sighting confirmed by the Sea Mammal Research Unit in St Andrews. The pictures that we were able to take do not do the experience of seeing one of these beautiful creatures justice. It really was an amazing and unforgettable experience.

Dolphins
As well as seeing whales we have also had a number of sightings of common dolphins. Common dolphins are extremely energetic and acrobatic. We have seen them riding the bow wave of the ship as we were steaming along as well as surfing the waves and fully breaching out of the water. We were lucky enough to get a picture of this. Dolphins are also very inquisitive and we saw three of them swimming around one of the PELAGRA’s as it was being recovered one night. They are often found in large active schools and they are highly vocal and sometimes their squealing can be heard above the surface. The common dolphin can grow up to 2.4 metres in length and have a weight of up to 110 kg. Their diet is mainly fish, squid and octopus. This species is threatened by entanglement in fishing nets, hunting and whaling, pollution and other human disturbance.  

Jellyfish
During the trip we have seen quite a lot of jelly fish. They have been mainly spotted at night time when we have been taking water from the CTD and the deck lights have been shining into the water. They occur in large swarms of 1000’s and make the water look a brown/red colour. We have also inadvertently captured some in the PELAGRA traps. We assume this is happening because the PELAGRAS are drifting through the swarms of jellyfish during the four days they are deployed. This allows the jellyfish to swim into the pots which are spiked with poison and then get trapped. The photograph shows some jellyfish which have been caught in the PELAGRA pots. 

Barnacles
Finally, we have also seen some barnacles attached to one of the moorings which were recovered. The mooring had been in the ocean for 2 months and during this time the barnacles had grown all over it. We think that these are a type of stalk barnacle which when they reach maturity can often attach themselves to ships and moorings.  The French research team onboard identified these as goose barnacles and said that they were good to eat. However, we decided that they smelt horribly bad and were not interested in cooking them up.

Jen and Charlotte


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