Marine Life & Conservation Blogs
Western Ecology Tour: Notes from the Field – Pembrokeshire
Scubaverse blogger, Donovan Lewis, is currently on the Western Ecology Tour. The aim of the expedition is to travel to the northern reaches of Scotland, along the West Coast to the Llŷn Peninsula in North Wales, and finally onto Pembrokeshire, diving the best the west has to offer. The expedition is looking to live life in a minimalist way, camping and cooking out in the open air.
The teams aim is not just to dive sites, but to tackle conservation issues and shed light on projects up and down the UK, they have three projects which the trip will be focusing on. These projects include the Shark & Skate Citizen Science Scotland, Project Seagrass, and Neptune’s Army of Rubbish Cleaners (NARC). The team will be accompanied with a Biologist or expert that works on each of the 3 projects to aid and guide the team, but also help shed extra light on the critical conservation work being carried out.
Here are Donovan’s notes from the third and final leg of the trip:
Hello once more the final field report from expedition WET, as the expedition reach es its final leg its amazing to see how much we’ve done as a team. In our final leg we we’re in Pembrokeshire where we were covering NARC (Neptune’s Army of Rubbish Cleaners) with Lloyd Jones.
Our first dive was at Hobbs Point at Pembroke Dock. This dive was a sad one, NARC had been called to the area due to a report of several oil drums and other rubbish that had been thrown in the water. We were able to lift four oil drums, nets, a scooter, and much more. There was also a huge amount of fishing gear tangling around the kelp and seabed and even when we were in the water there were anglers on the wall above the dive site.
The next dive lead by Lloyd was at Martins Haven a mere five-minute drive from where we were staying at West Hook Campsite, this site is part of the Skomer Marine Nature Reserve. Here we saw lobster, mating Spider Crabs, a Pink Sea Fan and Moon Jellyfish.
The Final Dive which was also led by Lloyd as he was determined to find us huge amounts of catsharks was at Stackpole Quay on the South Pembrokeshire Coast, This site was a shallow dive at no more 7.5 metres but the dive was full of life with once again loads of mating Spider Crabs, lobster, Pollock, Sand Eel and huge amounts of catsharks.
As the expedition was ending, we found out there were some spaces on the Saturday and Sunday on Celtic Deeps Puffin and Seal snorkel Trips and some of us booked on to go out with them. Let’s just say that day was incredible, but you’ll have to wait for the images in the full trip report.
If you’d like any further information on the Expedition Western Ecology Tour check out the webpage https://andythenortherndiver.com/expedition-wet/
Marine Life & Conservation Blogs
Creature Feature: Dusky Shark
In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.
This month we’re taking a look at the Dusky Shark, a highly migratory species with a particularly slow growth rate and late age at maturity.
Dusky sharks are one of the largest species within the Carcharhinus genus, generally measuring 3 metres total length but able to reach up to 4.2 metres. They are grey to grey-brown on their dorsal side and their fins usually have dusky margins, with the darkest tips on the caudal fin.
Dusky Sharks can often be confused with other species of the Carcharhinus genus, particularly the Galapagos Shark (Carcharhinus galapagensis). They have very similar external morphology, so it can be easier to ID to species level by taking location into account as the two species occupy very different ecological niches – Galapagos Sharks prefer offshore seamounts and islets, whilst duskies prefer continental margins.
Hybridisation:
A 2019 study found that Dusky Sharks are hybridising with Galapagos Sharks on the Eastern Tropical Pacific (Pazmiño et al., 2019). Hybridisation is when an animal breeds with an individual of another species to produce offspring (a hybrid). Hybrids are often infertile, but this study found that the hybrids were able to produce second generation hybrids!
Long distance swimmers:
Dusky sharks are highly mobile species, undertaking long migrations to stay in warm waters throughout the winter. In the Northern Hemisphere, they head towards the poles in the summer and return southwards towards the equator in winter. The longest distance recorded was 2000 nautical miles!
Very slow to mature and reproduce:
The Dusky Shark are both targeted and caught as bycatch globally. We already know that elasmobranchs are inherently slow reproducers which means that they are heavily impacted by overfishing; it takes them so long to recover that they cannot keep up with the rate at which they are being fished. Dusky Sharks are particularly slow to reproduce – females are only ready to start breeding at roughly 20 years old, their gestation periods can last up to 22 months, and they only give birth every two to three years. This makes duskies one of the most vulnerable of all shark species.
The Dusky Shark is now listed on Appendix II of the Convention on the Conservation of Migratory Species (CMS), but further action is required to protect this important species.
Scientific Name: Carcharhinus obscurus
Family: Carcharhinidae
Maximum Size: 420cm (Total Length)
Diet: Bony fishes, cephalopods, can also eat crustaceans, and small sharks, skates and rays
Distribution: Patchy distribution in tropical and warm temperate seas; Atlantic, Indo-Pacific and Mediterranean.
Habitat: Ranges from inshore waters out to the edge of the continental shelf.
Conservation status: Endangered.
For more great shark information and conservation visit the Shark Trust Website
Images: Andy Murch
Diana A. Pazmiño, Lynne van Herderden, Colin A. Simpfendorfer, Claudia Junge, Stephen C. Donnellan, E. Mauricio Hoyos-Padilla, Clinton A.J. Duffy, Charlie Huveneers, Bronwyn M. Gillanders, Paul A. Butcher, Gregory E. Maes. (2019). Introgressive hybridisation between two widespread sharks in the east Pacific region, Molecular Phylogenetics and Evolution 136(119-127), https://doi.org/10.1016/j.ympev.2019.04.013.
Marine Life & Conservation Blogs
Creature Feature: Undulate Ray
In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.
This month we’re looking at the Undulate Ray. Easily identified by its beautiful, ornate pattern, the Undulate Ray gets its name from the undulating patterns of lines and spots on its dorsal side.
This skate is usually found on sandy or muddy sea floors, down to about 200 m deep, although it is more commonly found shallower. They can grow up to 90 cm total length. Depending on the size of the individual, their diet can range from shrimps to crabs.
Although sometimes called the Undulate Ray, this is actually a species of skate, meaning that, as all true skates do, they lay eggs. The eggs are contained in keratin eggcases – the same material that our hair and nails are made up of! These eggcases are also commonly called mermaid’s purses and can be found washed up on beaches all around the UK. If you find one, be sure to take a picture and upload your find to the Great Eggcase Hunt – the Shark Trust’s flagship citizen science project.
It is worth noting that on the south coasts, these eggcases can be confused with those of the Spotted Ray, especially as they look very similar and the ranges overlap, so we sometimes informally refer to them as ‘Spundulates’.
Scientific Name: Raja undulata
Family: Rajidae
Maximum Size: 90cm (total length)
Diet: shrimps and crabs
Distribution: found around the eastern Atlantic and in the Mediterranean Sea.
Habitat: shelf waters down to 200m deep.
Conservation Status : As a commercially exploited species, the Undulate Ray is a recovering species in some areas. The good thing is that they have some of the most comprehensive management measures of almost any elasmobranch species, with both minimum and maximum landing sizes as well as a closed season. Additionally, targeting is entirely prohibited in some areas. They are also often caught as bycatch in various fisheries – in some areas they can be landed whilst in others they must be discarded.
IUCN Red List Status: Endangered
For more great shark information and conservation visit the Shark Trust Website
Image Credits: Banner – Sheila Openshaw; Illustration – Marc Dando
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