Scientists develop new method to estimate seal breeding frequency

NOVEMBER 21, 2019 

by University of St Andrews

New research, led by the Sea Mammal Research Unit (SMRU) at the University of St Andrews, develops method to better record breeding histories of seals, allowing for improved fecundity calculations. 

Fecundity is a defining feature of the population dynamics of long-lived animals. Adult female seals typically give birth to single pups in most years so recording how often seals breed is a vital stage in estimating population size. However, some seals appear to "skip" breeding in some years and determining how often individuals breed is then complicated by observability; is a 'missing' year a failure to breed or a failure to record a breeding event? 

Researchers have used the pattern of sequential changes in a seal mother's body mass over several years to reconstruct incomplete breeding histories. 

The new approach, developed in collaboration with the University of Edinburgh, and published in the Journal of Animal Ecology (Thursday 21 November) allows missing years to be assigned as breeding or non-breeding, producing complete breeding records for each seal and fecundity of all seal mothers to be estimated. 

The new method relies on understanding the mass changes that mothers experience in the course of rearing a pup. Rearing offspring is costly, and a seal mother must be in good condition to breed successfully. Grey seals in the UK are true capital breeders, that is, a mother fasts during the brief but demanding period of pup-rearing, so that all the costs of rearing a pup, including nursing the offspring with high fat milk and sustaining the mother's own requirements are met from body reserves accumulated before breeding. If food is scarce before breeding takes place or the mother experiences other difficulties, breeding in that year may be sacrificed as a trade-off against her future survival and breeding. 

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Drones warning over breeding seals in Pembrokeshire

6 September 2019

Breeding seals are being disturbed by drones flying near them, experts have warned.

The grey seal population in Pembrokeshire breeds from August to November, but a lack of awareness has led to them being scared into the water with the potential not to return.

Research by Swansea University has so far found drones with four propellers are most likely to cause problems.

It has prompted calls for users to learn about flying them near wildlife.

Paul Renfro, who works with the Pembrokeshire Coastal Forum, said a ban would be difficult to enforce but "acting responsibly" would make a difference.

"Plan ahead, know where the sensitive areas are and keep your distance," he said. "If the seals are starting to notice you, then you're too close.

"Their eyes almost bulge and you can see the stress in their face. When they are starting to look at you then that's close enough."

Pembrokeshire has one of the biggest breeding colonies of grey seals in south west Britain.

While numbers have been struggling in other areas, one of the highest ever annual birth rates was recorded for seals pups last year in west Wales.

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Antarctic biodiversity hotspots exist wherever penguins and seals poop

Date:  May 9, 2019

Source:  Cell Press

Scientists have found that on the desolate Antarctic peninsula, nitrogen-rich poop from colonies of penguins and seals enriches the soil so well that it helps create biodiversity hotspots throughout the region. Their work, appearing May 9 in the journal Current Biology, finds that the influence of this excrement can extend more than 1,000 meters beyond the colony.

Researchers braved the wicked cold of the Antarctic and maneuvered through fields of animal waste and groups of clamoring elephant seals, gentoo, chinstrap, and Adélie penguins to examine the soils and plants surrounding these colonies. "What we see is that the poo produced by seals and penguins partly evaporates as ammonia," says Stef Bokhorst, a researcher in the Department of Ecological Sciences at Vrije Universiteit Amsterdam. "Then, the ammonia gets picked up by the wind and is blown inland, and this makes its way into the soil and provides the nitrogen that primary producers need in order to survive in this landscape."

In fact, this process allows ammonia to enrich an area up to 240 times the size of the colony. And the results of this enrichment: a thriving community of mosses and lichens, which in turn supports an incredible number of small invertebrates, like springtails and mites. "You can find millions of them per square meter here, but in grasslands in the US or Europe, there are only about 50,000 to 100,000 per square meter," says Bokhorst. "It took months and months of sitting in the lab counting and IDing them under a microscope," he says, and he notes that trekking through the bitter temperatures of the Antarctic was far preferable to that task.

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Lions have adapted to hunt seals and seabirds in Namibia, study finds

Desert lions learning to hunt marine life to survive Skeleton Coast’s harsh conditions

Niki Rust

Mon 28 Jan 2019 10.04 GMTLast modified on Mon 28 Jan 2019 15.53 GMT

Lions in Namibia have turned to hunting seabirds and seals in the face of scarce food resources in the desert landscape, research has found.

The desert lions, which are found exclusively within the country’s Skeleton Coast region, are the only lions known to target marine life. Among the creatures they have been recorded eating are fur seals, flamingos and cormorants.

The conservationist Flip Stander, the author of the study published in the Namibian Journal of Environment, said the discovery showed the big cats have learned diet adaptability is key to survival in this unforgiving terrain.

The Skeleton Coast spans the coastal backbone of Namibia and is the driest place in sub-Saharan Africa, receiving as little as 5mm (0.2in) of rain a year. The desert lion’s usual prey of oryx and ostriches are thin on the ground there. The neighbouring ocean, however, is rich in life, sustaining nearly 1m Cape fur seals that breed on the shoreline, and a multitude of seabirds.

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Australian study into how seals react to boats prompts new ecotourism regulations

Date:  December 20, 2018

Source:  Pensoft Publishers

Unable to differentiate between a predator and a tourist boat carrying humans curious to view a colony of seals while resting in their natural habitat, pinnipeds are quick to react defensively as soon as they sense what they perceive as a potential life threat. The closer the vessel approaches, the more likely it is for the animals to rush into the sea in an attempt to escape and the greater the risk of injury and even death in the event of a stampede, or predation once they are in the water. In fact, just the act of remaining alert comes at potentially high energetic costs for the animals.

"Although the purpose of ecotourism is to give patrons the opportunity to observe animals in the wild engaging in typical behaviors, ecotourism-based human interactions may insteadalter pinniped behavior by initiating responses indicative of predation avoidance," explain the scientists.

Read on 

Eleven seal species narrowly escaped extinction

Date:  November 16, 2018

Source:  Bielefeld University

Their fur was used as a raw material for coats; their fat was used for oil lamps and cosmetics: right up to the end of the nineteenth century, millions of seals were being hunted and killed every year worldwide. The consequences of this episode of commercial hunting for today's seal populations is the subject of a study published today (16.11.2018) in Nature Communications. Population geneticists at Bielefeld University and the British Antarctic Survey have found that eleven seal species only narrowly escaped extinction. The scientists managed to include nearly all of the species alive today in their research. The study nevertheless reveals that most species survived the heyday of seal hunting in sufficient numbers to retain most of their genetic diversity.

'Hunting, epidemics, and climate change all have the potential to reduce the number of individuals in a population to the point where genetic diversity is lost,' says Professor Dr Joseph Hoffman, head of the Molecular Behavioural Ecology research group at Bielefeld University and sub-project manager in the Transregio Collaborative Research Centre NC³ that is studying animals and their individual niches. 'These extreme population reductions are known as bottlenecks and can affect a species' potential to survive'.

'When a species lacks genetic diversity, it has a lower chance of adapting to changing environmental conditions or protecting itself against parasites or pathogens. You can compare the gene pool with a toolbox: the fewer tools you have, the less well-equipped you are for different situations,' says Hoffman.

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Biologists show that female seals have consistent personalities

Whether bold or shy, seal personalities are steady over time, study says

Date: June 27, 2018

Source: University of Alberta

Summary:

Female seals don't change their spots, according to a new study. In fact, individual differences in boldness remain consistent over time. The study is among the first to examine boldness in wild marine mammals in the burgeoning field of animal personality. Animal personality influences many ecological processes, like how individuals interact with other species or respond to changing environmental conditions.

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Stress test: New study finds seals are stressed-out by sharks

Researchers test the effects predators have on their prey's cortisol levels in the wild

Date:  December 6, 2017

Source:  University of Miami Rosenstiel School of Marine & Atmospheric Science

Summary:

While a little added stress may be helpful to flee a dangerous situation, or to meet an approaching deadline, it's no secret that prolonged exposure to the stress hormone cortisol is linked to health problems. So, what effects does stress have on animals in the wild that need to navigate the same waters as the ocean's top predator -- great white sharks?

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Seals, birds and humans compete for fish in the Baltic Sea

Date:  November 13, 2017

Source:  Stockholm University

In Sweden and in other parts of Europe there are concerns that seals and birds compete with humans for fish resources. For the Baltic Sea, an international study now shows that this competition is a reality.

"Because fish is nutrient-rich food and angling provides valuable recreation, the increased populations of seals and fish-eating birds in the Baltic have resulted in a sometimes contentious debate over the effects of these animals on the fish stocks. The debates are often based on assumptions, which is why I took the initiative to look at the problem from a scientific viewpoint," said Sture Hansson, Professor of Ecology, Environment and Plant Sciences at Stockholm University.

Together with four researchers from the Swedish University of Agricultural Sciences (SLU) and seven other colleagues from countries around the Baltic, Hansson has estimated birds' and seals' fish consumption. Seals are the primary fish-eating mammals, and their consumption is about the same as that of all birds together. Humans catch 3 to 4 times more fish than seals and birds combined.

Small-scale coastal fishing most impacted by wildlife

The fishing grounds most impacted by competition from wildlife are the coastal areas with species like perch, pike, pikeperch, brown trout, salmon, whitefish and vendace. Seals and cormorants consume similar amounts as humans. Because we know that these fish are impacted by human fishing activities, it's reasonable to conclude that they are also impacted by predation from seals and birds. Wildlife thus competes with humans for these fish resources.

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Seals are deafened in noisy shipping lanes, say scientists

Urbanisation of marine environment impacts on seal hearing and is comparable to noise pollution of inner cities

Seals are being temporarily deafened by underwater noise in the UK’s busy shipping lanes, a new study suggests. Researchers compared the experience of the seals to that of people living amid the din of inner cities.

Dr Esther Jones, an ecologist from the University of St Andrews, said: “Like humans living in busy, noisy cities, some seals live in areas where there is a lot of shipping traffic and associated noise.

“The UK has some of the busiest shipping lanes in the world, and underwater noise has been increasing over the last 30 years.”

Her team drew up maps showing the extent to which grey and harbour seals around the UK were affected by shipping traffic. The scientists then investigated noise levels that individual animals were likely to be subjected to in Moray Firth on the north-east coast of Scotland.

For 20 of the 28 seals studied, the predicted noise from shipping was loud enough to cause temporary hearing loss. The maps showed that 11 of 25 special areas of conservation may contain seals affected by shipping.

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El Niño ocean warming 'causing havoc' for seals off California coast

Unprecedented numbers of dead or starving seals washing ashore as Pacific Ocean warms, with experts saying they are ‘preparing for the worst’ in 2016

Oliver Milman

Wednesday 30 December 2015 16.52 GMTLast modified on Wednesday 30 December 201516.59 GMT

The warming of the Pacific Ocean caused by the El Niño climate event is “causing havoc” among marine animals off California’s coast, with unprecedented numbers of dead or starving seals being washed ashore.

The San Francisco-based Marine Mammal Center said it has rescued 106 emaciated northern fur seals so far in 2015 – three times greater than the previous record year for rescues. The center said the seals are victim of the exceptionally strong El Niño, which has brought a surge of warm water species, such as red tuna crabs and hammerhead sharks, to California’s coast.

Mothers of seal pups born on California’s channel islands, found west of Los Angeles, are finding it difficult to find their usual prey of sardines and anchovies, which are moving to cooler areas further north to escape sea temperatures that are 2-4C warmer than average.

This means that pups, initially reliant on their mother for nutritious milk, are underweight and understrength when they have to find their own food.

“They can’t dive as deep, they can’t hold their breath as long,” said Dr Shawn Johnson, director of veterinary science at the Marine Mammal Center. “We have been rescuing four-month-old pups weighing 4-5kg, which is typically their birth weight. They should be double that. We are finding pups at record low weights. It’s really worrying for us.

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3D-printed seal whisker helps scientists understand how they use them to hunt

OCTOBER 16, 2015

by John Hopton

Seals' impressive ability to track prey has long intrigued marine biologists, so Engineers at MIT wanted to investigate how seals can be such master hunters.

Seals can follow the path of prey that passed by up to 30 seconds before, due to the antennae-like qualities of their whiskers. Engineers at MIT fabricated and tested a large-scale model of a harbor seal’s whisker in order to investigate how this talent works.

Each whisker is wavy rather than straight, with an elliptical cross-section that varies in size along its span.

“It’s marvelous to see this intricate pattern, it’s not just a straight antenna — it’s a perfect sinusoid,” said Michael Triantafyllou, the William I. Koch Professor in MIT’s Department of Mechanical Engineering. Together with former graduate student Heather Beem, whose PhD thesis formed the basis of the work, he published the results of the study in the Journal of Fluid Mechanics.

Whereas most long, thin rods tend to create large vortices, or eddies, as they move through water, Beem found that the wavy pattern of the whisker’s geometry created much weaker vortices, enabling the whisker to move silently. This, the researchers suggest, may help the seal block out its own disturbance as it moves.

“It’s like having the ability to stick your head out of a car window, and have there be no noise, so that your ears don’t ring: It’s a quieting effect,” Triantafyllou said.

Whiskers that ‘slalom’ like a skier

With minimal water disturbance assured, the seals can follow the wake left by the prey because of a ‘slaloming’ motion in the whiskers, the scientists found.

The team observed that once their own synthetic whisker entered the wake left by a passing object, it started to vibrate at the same frequency as the wake’s passing vortices. Close inspection showed that the whiskers ‘slalom’ among the vortices, like a skier zigzagging between flags.

Read more at

Bottlenose Dolphins and seals are being harassed in Cornwall

Some water users around Cornwall’s north coast, particularly in the St Ives Bay area, have been repeatedly harassing Bottlenose Dolphins and other marine life, such as seals, in recent weeks.

This disturbance ranges from seals being flushed from their rocks into the sea by kayakers and rock climbers, and dolphins being chased by wildlife day trip boats.

Disturbing wildlife in this way is not only illegal, but also can result in distress to the animals, make them change their natural behaviour and, in the worst case, can lead to serious injuries, amputations and even death due to propeller strike. 

Abby Crosby, Marine Conservation Officer for Cornwall Wildlife Trust says: "We are lucky enough to get 17 species of whales, dolphins and porpoises as well as basking sharks and turtles visiting the South West.

"The last thing we want to do is to drive these beautiful animals away from our coast and their feeding grounds."

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Baby seals that practice in pools make better divers

Date: July 1, 2015

Source: Society for Experimental Biology

Summary: Being able to dive is what matters most for seal pups, but how do they learn to do it? Grey seal pups that can play in pools may have better diving skills once they make the move to the sea, and this could increase their chance of survival. Researchers have found that spending time in pools of water helps seal pups hold their breath for longer.

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Shell’s US Arctic drilling will harass thousands of whales and seals

Exploratory drilling, seismic testing and ice-breaking activities threaten to expose whales to damaging sounds, and ‘a deaf whale is a dead whale’

Rose Hackman in New York

Friday 5 June 2015 17.46 BSTLast modified on Friday 5 June 201520.00 BST

Royal Dutch Shell’s plans for exploratory drilling in the US Arctic this summer will involve the harassment of whales and seals by the thousands, an application document filed by Shell to the National Marine Fisheries Service (NMFS) reveals.

Most notably, Shell estimates its Arctic activities will expose more than 2,500 bowhead whales, more than 2,500 gray whales and more than 50,000 ringed seals to continuous sounds and pulsed sounds, deemed damaging enough to constitute harassment.

The bowhead whale is listed under the US Endangered Species Act. By Shell’s own estimate, 13% of the overall population of bowhead whales still alive are potentially harassed .

The number of gray whales potentially harassed also constitutes 13% of the overall population, while the number of ringed seals potentially harassed amounts to 16%. Under the ESA, the ringed seal is classified as threatened.

Under the Marine Mammal Protection Act, the government may allow for the “taking” or “harassment” of marine mammals, so long as the number taken is small and the impact on the species negligible.

But environmental groups argue the numbers affected by the Shell plans are not small, nor will the impact on species be negligible.

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Offshore wind turbine construction could be putting seals' hearing at risk

Date: May 19, 2015

Source: British Ecological Society (BES)

Summary: Noise from pile driving during offshore wind turbine construction could be damaging the hearing of harbour seals around the UK, researchers have found. They say more research is needed on how noise affects marine mammals' hearing and into engineering solutions to reduce noise levels.

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More seals saved from the threat of ghost fishing nets

Posted on May 7, 2015 by Sarah Dickinson

Many marine wildlife groups working in Cornwall often get calls about sighting of seals who are injured, or entangled in fishing gear, or marine litter. 

Over the last month, British Divers Marine Life Rescue (BDMLR) and the National Trust received several calls about a seal entangled in lost fishing gear but despite repeated search attempts by BDMLR, the seal in question could not be found. A concern to all as injuries from entanglement are known to end the life of a seal prematurely. 

On Saturday 25 April another trip was undertaken to find the stricken seal and when the groups arrived at the beach they found not one, but two entangled seals, one on the beach at the West Cornwall haul out and another out to sea. 

Despite facing rain and slippery rocks, the team from BDMLR, Cornwall Seal Group and a rope safety adviser abseiled down a 45m cliff to the beach in order to save the seals, whose injuries would have certainly lead to their premature death. 

Seals are spooked by humans very easily and can move incredibly fast over land, so the rescuers waited cautiously until both seals were on the beach, out of sight from the abseil point and in a position that they could be reached before the seals were aware of human presence. 

With years of experience in handling marine mammals, the team were able to free both the seals from the dangerous netting and rope and after assessing their condition they were able to release them safely back into the sea. 

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Pup numbers boom at English seal colony

Blakeney Point becomes the biggest breeding site for grey seals in England thanks to remote, sheltered beach

Press Association

Monday 19 January 2015 10.01 GMT

A grey seal colony has seen the number of pups born each year increase a hundred-fold in just 14 years to become the biggest breeding site for the animals in England.

North Norfolk’s Blakeney Point, managed by the National Trust, saw 2,426 seals born this year, almost double the number born there two years ago.

National Trust experts put the success of the colony, which has grown exponentially since the first 25 pups were born there 14 years ago, down to the remote, sheltered beach which is safe from predators and other disturbances.

To prevent walkers disturbing the seals, which can increase the chance of fighting among the adults and lead to the pups being crushed, National Trust rangers and volunteers have fenced off part of the beach and dunes and introduced viewing areas.

National Trust rangers monitor the colony, tracking and recording seal pups born throughout the winter from November. The young seals are expected to be on Blakeney Point until the end of January.

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Heart arrhythmias detected in deep-diving marine mammals

Date:

January 16, 2015

Source:

University of California - Santa Cruz

Summary:

A new study of dolphins and seals shows that despite their remarkable adaptations to aquatic life, exercising while holding their breath remains a physiological challenge for marine mammals. The study found a surprisingly high frequency of heart arrhythmias in bottlenose dolphins and Weddell seals during the deepest dives.

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Fish fitted with electronic tags act like a 'dinner bell' for hungry seals

By Auslan Cramb, Scottish Correspondent

4:31PM GMT 19 Nov 2014

Scientific attempts to track fish are being thwarted by seals treating the pinging noise that comes from their electronic tagging devices like a “dinner bell”.

Grey seals are thought to have skewed the results of studies by chasing down the sound and eating the fish fitted with acoustic tags

Biologists said the noise that allowed scientists to follow shoals of fish was being linked by predatory seals with the availability of a meal.

They added that the discovery could have a "profound effect" on research designed to monitor fish stocks.

Projects studying the movements of salmon and lingcod are said to have suffered disproportionate losses and scientists fear further research could be compromised unless a different type of tag is used.

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