Irish Marine Life
inshore offshore play science coral-reefs crabs ag snámh news think imeachtaíLutra lutra
The sea is cold and quiet these weeks; a freshening visit to the shore seems for many unnecessary with endless icy weather streams from the North. Marine life is consulted and found through other means in spells such as these. One such mammal which is represented in more than its fair share of poetry and literature is the otter whose scientific name is the musical Lutra lutra and occasionaly better known in the West as the not very wild sounding water-dog. West Mayo’s sometimes resident Michael Longley highlighted some of its ecology to conclude a poem about mortality when he wrote:
I watched a dying otter gaze right through me
At the islands in Clew Bay, as thought it were only
Between hovers and not too far from the holt.
The holt being its home constructed in the river bank and a hover a resting place for passing a part of the day. Lutra lutra is one of our most intriguing marine animals perhaps because it is not marine at all. It has a cousin which is restricted to the sea, the Californianotter, but Ireland’s otter is as terrestrial as we are. Its forays to the shore are a consequence of living beside the tide and if it is born to an inland holt it will only know the bog runs and freshwater streams of that area. Its diet is also as varied as ours and will switch from fish to shellfish and urchins if availability is low which increasingly happens due to coastal pollution. A study of otter spraints (droppings) in Clare Island in 2007 by a student of NUIG’s department of Zoology suggested seaweed may even be a part of diet at times.
Their mystery and strong lore may also stem from their impressive elusiveness. I can count with two sightings: one jumping in the kelp on a sheltered shore; another running bravely along an exposed beach and ultimately into the small waves where it faced us and mocked my curious dog.
If the halting northeasterlies turn back to the southwest quarter and the shore is welcoming again, look for the otter in areas where freshwater comes close to the sea. The otter needs to rinse the salt from its dense fur after a fishing session to maintain the fur’s insulation property, so the low duachs west of Louisburgh or townlands beginning with Barna- (Barna means passage to the sea as Gaeilge) are good places to catch one returning from the tide at sunset.
The Eurasian Otter (Lutra lutra) is a semi-aquatic mammal from the family Mustelidae. Otters are usually territorial solitary mammals, except in the case of a family group consisting of a nurturing female and cubs. They grow to over 1m in length, and a large adult can weigh as much as 12kg. They have five webbed toes on each foot and a powerful, rudder-like tail which aids swimming. Their claws are sharp and strong for gripping food such as eels and they have especially powerful jaws. The home range of otters is 3-4Km in coastal populations. The Otter has undergone a decline in Europe throughout the 20th century and is extinct in much of central Europe. TheOtter is protected in Ireland by both the Wildlife Act 1976 and the Wildlife Amendment Act 2000.
This article appeared in the Mayo News edition 02-03-10
Monsters and Mermaids
Image credit: Louise Duignan
Placed high and dry upon the clean blue pebbles by a spring tide, the mermaid’s purse I found last week was not hard to spot. Another purse some months ago was easier to miss, dark and unlovely as they are and cast as it was amongst the deposited kelp of similar leathery brown shades. That relationship of camouflage was once so necessary underwater, when the four pronged purse held a tiny shark, skate or ray and the kelp held to the rock and provided cover for the purse until its inhabitant was ready to leave. How curious that now, far from those dynamic undersea worlds, they defiantly continue this relationship as they desiccate together on the still shore, the kelp now concealing the purse from the eyes of hurried beach walkers.
The purses, egg cases which once protected a fertilised embryo, are the unremarkable reproductive clue to species such as the dogfish, our smallest and most common shark. But not all sharks reproduce like this. Mayo’s legendary basking sharks, which once entertained enough mystery in their labelling as a sea monster as Gaeilge (An Liabhán Mór) are still almost a mystery to scientists in this regard. It is believed the sharks give birth to live young, but a pregnant female has only ever been seen once and nobody knows when or where or how many young are born. Porbeagle sharks which have been landed in Clew Bay definitely do give birth to live young, usually four at a time. And although they won’t be found in Clew Bay anytime soon, its worth noting the female hammerhead shark which gave birth in a zoo in The U.S. in 2001 – despite no male contact in three years. Sharks are apparently capable of such immaculate feats, but only in extreme circumstances and it’s bad for genetic diversity.
The un-immaculate mermaids’ purses are not so dramatic. And the almost blind dogfish, which spends 23 hours a day dozing on the seafloor, is no hammerhead, but there is still useful information to be gleaned from them. Compiling records of their distribution can provide valuable information on the location of nursery areas of sharks, skates and rays. Many of these are severely threatened such as the common skate, which was once found throughout European waters, now ironically titled as it is only found in a few select locations. Purse Search Ireland are one group who have undertaken the task of compiling this info, and provide a user-friendly online form at www.marinedimensions.ie for you to log your report.
Sharks, skates and rays are related and together make up the Elasmobranch class of fish, a very ancient class dating back 400 million years. They are different to other fish having cartilage skeletons instead of bone. The Dogfish (Sycliorhinus canicula) is found all around our coastline in sandy bays and off-shore. It feeds mostly on prawns, crabs and occasionally fish. They breed annually, and nine months after mating, the female lays approximately 25 eggs which develop inside mermaid’s purses for nine months. The Basking Shark (Cetorhinus maximus) is a filter feeder, passively filtering small fish, invertebrates and zooplankton near the surface with its gaping mouth open. Recent satellite tagging studies have confirmed that the some sharks undertake huge migrations in winter. They were almost fished to extinction in the west of Ireland until the 1970s but are now believed to be making a recovery.
The violence of our peaceful seas
Normal North Atlantic order has restored itself after a most remarkable 4 weeks in Ireland’s recent meteorological history. It will be hard now to discern any surface goings-on between shore and horizon with wind and swell likely to run for weeks on end as they often do in January and February, driven to us by lows sweeping across from Newfoundland in our general direction.
These lows stopped for that extraordinarily Siberian month, blocked by a strong high pressure air- mass to our North which made for a very still Atlantic allowing me one evening to sharply define the space between caudal fin and ocean and see through the burst of spray between dorsal fin and sky. It could be September but for the 10 degree water I thought as the three dolphins surged powerfully high out of a flat sea and all of this silhouetted by a low cloudless sunset over Renvyle.
Such acrobatic behaviour, in particular whirling vertical leaps is more noted of the smaller common dolphin which is usually found far offshore over the continental shelf in great numbers. They are only occasionally seen inshore and that’s usually in the southwest of the country. There was not enough light to be sure but these were most likely bottlenoses, which do from time to time leap and spin like this, and bow ride and surf of course too. But then the bottlenoses are continuously surprising us. Reports of porpoises with great shark-like chunks taken from them a hundred miles or so south of here this summer led to the surprising discovery of research, mostly from Britain, on violent bottlenose attacks on porpoises.
Where the two species occur together, the most common cause of washed up porpoises’ death was attacks from bottlenose dolphins according to The British Environment Ministry. They don’t compete for food and scientists are guessing that it is a simple territorial aggression, with serious costs for the muc mhara (the porpoise is the pig of the sea in Irish). Damage recorded to porpoises includes broken ribs, internal organ rupture as well as bite marks. Have some of the many that wash up on Mayo’s shores experienced the same underwater violence? Probably, but data and studies could say for sure.
The bottlenose is not the indifferent play seeker we may have thought and neither does the muc mhara dip from cuain to cuainín in Clew Bay as carefree as it could appear.
The bottlenose dolphin (Tursiops truncatus) is grey to black above and light grey on the underside. They have a tall fin and a long, rounded beak with a curved mouth-line giving the familiar smiling expression. They are usually seen in small groups and frequently inshore where they are engaging and playful. The common dolphin (Delphinus delphis) is smaller than the bottlenose with a distinctive ‘hourglass’ colour pattern on its sides; yellow to the front and light grey to the back. Above this hourglass shape is black and below is white. They have a tall fin and a long black beak. They are more commonly seen in deeper waters in large numbers, but are sometimes seen off coastal headlands in summer. Report your dolphin sightings to The irish Whale and Dolphin Group at www.iwdg.ie
This piece appeared in The Mayo News 02/02/2010 edition
Humpback breaching – footage
A huge congragulations to everyone in The Irish Whale and Dolphin Group who was involved in getting the incredible footage seen by so many last night on the RTE News. Anyone who had not previously heard of the iwdg have now, and Ireland’s profile as a country that is aware of its stunning marine life has been raised considerably. Here is the video footage…
Remarkable weekend for whale watchers in Ireland
Image credit:RTE Website
The Hook Head area was the location last week for some of the most remarkable large marine life activity ever witnessed in Ireland. These pictures from RTE.ie show a humpback whale breaching, with common dolphins, harbour porpoises and fin whales also present in the area. The activity was witnessed by the Irish Whale and Dolphin Group who also succesfully recovered a sample of whale flesh which will allow genetic analysis of the whale’s gender. Such information is of exceptional value given the humpbacks’ threatened status.
Read more about the event on the iwdg.ie website.
Shellfish on Bettystown Beach
Irishmarinelife received a report today of thousands of shellfish washed up on Bettystown Beach, Meath around the 12th of January. The observer was at a loss to identify the species, a light coloured and relatively large bivalve, smooth and unlike a scallop or oyster species.
After some researching it is probably the Otter Shell that she saw (Lutraria lutraria) which burrows in sand and mud substrates and is found mostly in The Irish Sea and also parts of Connemara.
There was a period of sustained easterly gales leading up to the 12th which led to the extraordinary disturbance of its habitat and its displacement onto the shore. We did not receive any photos of the event; if you have any, please send them to irishmarinelife@gmail.com.
The Irish Times – North Donegal Basking Shark Hotspot
The Irish Times today reports on the identification of North Donegal as a basking shark ‘hotspot’. The article reports on increased activity observed by the Irish Whale and Dolphin Group and notes that reports of humpback whale breaching may actually be sharks.
Tiny Marine Birds, Big Migrations – Irish Times Article
Photo credit: Casrsten Evegang/PA Wire, The Irish Times
Least we forget that our marine life is limited to the terrestrial and aquatic zones, we host an impressive selection of birds who live out their lives, or parts of them along our coasts.
They can be big like the sometimes coastal winter migrant whooper swan, 2 of which beat a low flightpath past me last week as I waited for waves outside Doughmakone Strand. They can also be tiny and impressively migrant as the Irish Times reports today of The Arctic Tern. They make a round trip of 44,000 miles, pole to pole to be comprehensively global, spending months between March and Septmeber on our shores.
Similar to The Common Tern, but smaller, it is considered to have the longest migration of all birds, as The Irish Times reports, making journeys over the course of its lifetime equal to three trips to the moon. Read the article here.
Read Birdwatch Ireland’s species profile here.
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Wild November, Mild December, New Year
Photo credit: Andrew Butler
In the glassy December stillness after a high energy November, traces of this stormy and violent month made themselves apparent in our marine ecosystem.
The legacy of swell after swell which finally ceased a week into December to a calm orderliness groomed by light easterlies revealed itself if you bore the cold and looked carefully enough over the Christmas holidays. At the north end of the beach waves broke in a place they normally don’t; enough sand had been displaced by the wave action and its accompanying rip currents to form a shallow sandbar just far enough outside the beach to be notable. The sand had been scoured deep around it, focusing the wave energy on the centre, a powerful and perfect wave for those lucky enough to access it.
Such events have a capacity to unearth, to claw at our moveable shores and reveal, more sometimes than is at first apparent. Inside the new sandbar, the beach had lost a few feet of its sand rudely exposing a bed of rocks from their summer covering. Scattered amongst these new additions to the shore’s topography were small rods and fragments of kelp, our perennial indicator of what is happening in the elusive offshore kelp-beds. Contrary to what is often thought (and sometimes taught) the presence of sea rods on the shore is usually determined more by the plants’ life cycle than the action of the ocean. In this instance however, the masses of short, thin fragments littered on the shore implied that the juvenile Laminaria and Alaria species which should be hanging on in their unknown strongholds between Carrownisky and Inishturk for a few more years were interrupted by an extraordinary month.
And not only the deep, but the past was evoked by the legacy of November 2009. A little further down the shore and sand again was divulging its secrets. A section of the cliff bluff, which is nothing more than sediment held in place by resolute marram grass, had given way to incessant westerlies undermining its base. Here, 20 feet above the high tide mark, crumbling out of the cliff face were periwinkles and bairneachs. Many winters ago, somewhere between mesolithic and medieval, these mollusks of the low tide rocky shore made their way to someone’s mealplace by hand. The people who identified a shellfish which would ultimately be harvested and sell well in France (the periwinkle, the bairneach’s taste never found popular favour) laid down their rubbish in a shell-midden for us to consider our past months with as we turn on a New Year. The January sea continues December’s theme steadily bringing us a newer, colder agenda from the north. The winkles and bairneachs make their way back down to the ocean and the sediment as new legacies are deposited and secrets are covered up again by the stealthy sands.
Bairneach is the local name for in English what is called the common limpet (Patella vulgata). It is a marine Gastropod related to periwinkles and land snails all belonging to the Mollusca phylum. It grazes algae when the tide is high and its feeding trails can be seen on the rocks it inhabits in the intertidal. Bairneachs clamp themselves to the rock with remarkable force if disturbed and are presently been studied in Ireland for their bio-adhesive properties. Bairneachs were commonly eaten in coastal areas until recent times.
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lenny antonelli
