Photo: Ken O’Sullivan filming Blue Sharks in Ireland
Sharks, skates and rays (collectively known as Elasmobranchs) are found all along the Irish coast. Many people don’t realise, but there are actually 72 different species of elasmobranchs documented in our waters, primarily due to the wide range of marine habitats along our coasts and our island’s position on the continental shelf. Our productive waters offer these animals great feeding opportunities, so many highly migratory species will pass through during the summer months but we also have many species which call Irish waters home all year round!
Blue Shark – Madradh Gorm/ Famaire/ Beathach Gorm
Blue sharks are the world’s most wide-ranging sharks and can be found in nearly all global oceans. They are usually seen in Irish waters usually from June to October.
Blue sharks are the highest species caught as bycatch from longliners which are targeting tuna and other billfish. Due to this and other reasons they are listed as ‘near threatened’ on the IUCN Red list for cartilaginous fish. Unfortunately due to a lack of data on discards, the number of blue sharks actually caught as bycatch could be much higher.
- These animals are one of the most eye-catching species in the water due to their luminous blue colouration.
- They can reach over 3 metres in length and have a slender streamlined body shape.
- They are viviparous which means they give birth to live young and can have litters with over 100 pups although the average is usually around 35.
- They sexually mature at around 6 years of age and can live up to 20 years.
Climate change is having a negative impact on these beautiful animals. There are areas in the ocean which are losing oxygen and these are called oxygen minimum zones (OMZs). These OMZs are typically at depths around 200 – 800m and it is thought they will have an effect on ocean species which need high levels of oxygen in the water such as predatory fish.
Blue sharks can dive down to depths of 1600m in search of squid one of their prey species. Research has shown that blue shark diving behaviour is being affected by these OMZs and is forcing the animals to spend reduced time at depth and more time near the surface.
This means they are in the depth range where huge fishing boats soak their longlines and so they are more vulnerable to being caught. Research such as this points towards the importance of having MPAs with adaptable management plans and being able to introduce emergency measures such as time-area closures when vulnerable species are at risk due to climate change or other pressures.
Marine Protected Area legislation is being developed by the Irish government however the process needs to move more quickly if we are to effectively meet our targets and turn the tide on biodiversity loss in the ocean. Fair Seas is campaigning to ensure the ocean, our greatest source of biodiversity and most powerful climate ally, is given the protection it urgently needs.
Fair Seas hosted the inaugural World Ocean Day conference in June 2023. We welcomed ocean advocates, government, industry and key stakeholders together, to map out the next steps for Marine Protected Areas (MPAs) in Irish waters. If you missed it or would like to revisit the sessions which took place, our conference recordings are now available to view on our Youtube channel.
Help us spread the word - please share!
