Category Fisheries

Sea-grey shadows under a Cornish sea

© 2018 Duncan Greenhill

High water on a September spring tide reduces Gwithian beach to a sliver. Dark wet sand curves upwards on the ramparts of the most seaward dunes where we dodge to keep feet dry from the more persistent waves. In the surf, aground, something sizeable appears to writhe. Something grey and smooth. Something that glistens where the sunlight catches it as the sun slumps lower to the horizon. We approach closer and see that it is a dead seal, the waves rolling and animating the corpse. My trousers wick seawater to the knee as I wade in and bend over it to get a closer look. It is a young grey seal, this year’s brood. How it died I don’t know. There are no wounds, there have been no recent storms, and it appears to be well fed. Yet here it is, carrion in a Cornish sea.

Death is part of every species’ life-history. Not all pups will become adults; it’s one of the central principles of evolution that more must be born than can survive to reproduce. We know this as an abstract fact, but not as a physical reality where a young corpse floating at your feet is not so easy to reason away.

But what if this pup had not died? What would her life have held? Where would she and us have come together, and what would that have meant for both of our species? What would our shared story look like if we could return to her birth, and follow her down a different path?

A head appears between her mother’s hind flippers, a membrane stretched over it, and then one final surge and tear and there are two seals on the sand, one breathing air for the first time. Blood from the placenta leaves a jagged trail across the sand as the mother shuffles around to check her pup. Soft white fur is slicked down to the pup’s body, while around her are more females with their own pups. The mother bares her teeth and snorts if the others come too close, warning them away, maintaining ownership of her own patch of beach as effectively as a towel placed amongst regiments of sun loungers.

The males arrived first in these coves, a few days before the females, and displayed to each other with mouths agape, marking territory and asserting dominance. When dominance fails, they fight, trying to pin down their challengers and bite them. Blood marks the necks on both, overlaying the deep scars from previous years where the failure to deter meant an obligation to fight. The bigger males, at least a decade old, are the more frequent winners of these conflicts. These contests for dominance continue after the females have given birth as the males protect their right to mate, a right they will soon exercise. The males can be up to two metres long and 230 kilograms in weight. The females are shorter and much lighter – up to 180 centimetres and 160 kilograms – and they scatter from these brawls for safety, their pups shuffling after them.

Fourteen kilograms at birth, our pup increases in size as if inflated. Seal milk is rich in fat, at around 60 per cent, and with this calorie-packed nutrition her birth weight doubles in nine days. She lays down blubber under her skin for her seaborne future to come. Her mother feeds her from her own body’s reserves. For around three weeks she will feed our pup, and only in the later stages will she leave the pup to briefly feed herself. Then comes separation.

Our pup is alone. How likely she is to survive her first year depends partly on how well her mother has fed her. She already has an advantage in that she is female; males, the bigger risk-takers, are less likely to reach their first birthday.

She fasts. She must replace the white fur of her birth with her adult coat before she can go to sea, in much the same way that a baby bird must grow its adult feathers before it can leave the nest and fly. She fasts for anywhere from a week and a half to almost six weeks while she moults, losing perhaps up to a quarter of her body weight. As an adult, she will return to this site every year to moult again but for now, she must go to sea and learn to fend for herself. There is no parental instruction – her mother has gone – and her prey is scattered in the coastal waters like the first spots of rain on pavement. She is still substantially smaller than an adult, and her size means she cannot dive for as long. Time is limited. She must learn to search for, find, and catch her prey before her protein and blubber reserves fall too low for her to survive. She undertakes an extended hunting trip of many days at sea, like an apprenticeship but without a master, gradually extending the depth and duration of the dives. She will learn.

At the surface she prepares herself to dive and then she does something strange and unexpected: she breathes out. Her nostrils close naturally as she relaxes the muscles holding them open. Her ribcage and lungs will collapse as the water pressure increases. Any air that remains in them is pushed up into the bronchi and trachea, the tubes that carry air from the mouth to the lungs, and away from the parts of the lung where gases could be exchanged with the blood. We might think that evolution took a wrong turn, lost an opportunity to take more oxygen on board, but it is we who are wrong. In seals, oxygen is stored primarily not as a dissolved gas, but within the muscles, where it is bound to a molecule called myoglobin. Her muscles are rich in this molecule, containing between ten and thirty times more than a mammal living on land. More oxygen still is stored in the bloodstream, where it is bound to a molecule called haemoglobin. Both avoid the need for gas under pressure to enter the bloodstream directly from the lungs. We would fill our lungs before venturing underwater; our seal breathes out. Her physiology is exquisitely evolved to diving underwater; ours is not. Our seal, once adult, could easily descend to over 250 metres in a dive lasting up to half an hour.

She dives. Her heart rate slows. Some blood vessels constrict, concentrating the flow of oxygen-rich blood to those organs that need it the most. She will feed at the bottom, although in around a third of her dives a chance encounter on the descent will mean she will feed in mid-water. She is not a fussy eater. She will eat what she can catch, and what she catches will depend mostly on what prey is available and in what numbers. Sand eels are a favourite; small, long and thin like knife blades. Silver slivers that disappear as one into the sand at the approach of a predator. She will learn to find these. Another popular choice is cod and its close relatives: whiting, haddock, saithe, pollack and ling. Flatfish such as plaice and lemon sole are another favourite. But she has a competitor for many of these species: humans. And competitors can be dangerous.

A seal may compete with us for fish in two ways. They may damage the fishing gear or they may take fish before we can catch them. Fishing gear can be active or passive. A trawl net is active gear. A boat tows a net through the water either close to the seabed or in mid-water. Mid-water, or pelagic, trawls are the ones that pose the risk to seals as they swim around the net picking off fish as the trawl is towed. Nets that are left to hang in the water are passive gear. Gill nets catch fish in a single ‘hole’ of the net as they swim into it and become snagged by their gills, but there is another, more deadly type. Tangle nets are more loosely hung than gill nets, like net curtains in a window, with perhaps 300 metres of netting making a 100 metre wall of fishing net. As the name suggests, fish do not need to be held by the gills to be caught by this net. Fish caught here offer an easy meal, but our seal must be wary; a careless seal may find that their prey are not the only animals entangled. If a seal cannot break free, they drown. Dead seals hauled onto the deck of fishing boats with the nets are often juveniles, often male. Whether this is from the curiosity of the young not yet tempered by experience, or a lack of strength to break free remains unknown. Those that do break free tear the nets. Some seals may eat the fish and escape without being tangled. The end result is a spoiled catch and damaged gear. The fishers are not happy.

One species of fish links fishers and seals more than any other: cod. Cod live close to the seabed and are caught by trawls that fly just above the bottom. Cod is a totemic fish in the U.K. with a special place in British culture. It is the fish of fish and chips on a bleak rain-lashed seafront promenade, the fish of fish fingers from childhood meals, of brave British trawlers facing down Icelandic gunboats in stormy sub-arctic seas in the 1970s. But the amount, the stock, of cod in the sea is low, and staying low, especially in the Irish Sea and the West of Scotland, although the stocks are recovering in the North Sea. Who to blame for this situation? The seals of course.

The truth is more subtle, as it so often is. Seals eat some cod, but the fall in fish stocks has come not from the seals but from our greed of catching too many fish, of politicians setting catch limits year after year above those that scientists recommend. And year by year the stocks have fallen. Seals have played their part, not in the decline, but by slowing the recovery. Seals eat young cod, small cod, too small to be caught and landed by the fishers. Seals take the cod before they grow large enough for the fishers to legally catch, and before the fish reach an age and size to spawn.

Fisheries scientists have an acronym to describe the part of the fish population that can breed and contribute to the next generation: the SSB or spawning stock biomass. The number of fish reaching a size to be legally landed is called the recruitment. Recruitment is kept lower by the seals eating the young fish, and with recruitment lower any increase in the SSB is much slower. Imagine you’re trying to save money for something special, a holiday perhaps. Your salary is like the fish born each year. You pay your bills and expenses and the amount left over is your disposable income. The bills and expenses are like the natural mortality of the fish, those that die or are eaten by something other than seals, and the disposable income – the amount left over – corresponds to the recruitment. But this month there has been an extra expense. Perhaps something went wrong with the car, or an extra household expense became due. This extra expense that reduces the disposable income is like the extra mortality from the seals. This extra mortality slows down the growth of the population in the same way that the car breakdown slows how fast you can build your savings.

Some fishers say that there are too many seals, but perspective matters. The UK has over a third of the world’s population of grey seals, but over 95% of the European population. We have a responsibility for their conservation, both morally and legally. The legal responsibility is one given to us through the habitats directive of the European Union. If a plant or animal is unique to one country it’s easy to recognise the obligation to protect it. If a plant or animal is common and found in many countries that obligation is much weaker. Grey seals fall into an uneasy middle ground; nationally common but globally relatively rare.

The oceans, especially our coastal waters, are polluted places. Much originates from the land. Sewage pipes discharge directly into the water, and although treated, the discharges can remain high in nutrients and bacteria. Rivers carry litter seawards. More nutrients are washed from fertiliser applied to agricultural fields, and feed blooms of algae off the mouth of estuaries. And some problems come from the sea such as lost fishing nets – ‘ghost’ gear – that continues to fish. The large pieces kill immediately through entanglement and drowning. The smaller pieces, and the thin nylon line from anglers, kills more slowly and painfully. The pieces wrap themselves around flippers or encircle the neck, gradually tightening, constricting, cutting in. The wounds deepen. In 2004 around one in every twenty seals in a single Cornish seal colony had some form of entanglement with debris, the majority of it originating from the fishing industry. For a seal entangled around the neck the options are not good: starvation, strangulation, or death through blood loss or infection. In rare cases, there is another option – capture, rehabilitation and release by conservationists.

Conservation can be a benefit to more than the seals themselves. They are good business, one of the charismatic megafauna – the big beasts that engage our imagination – that live or visit Cornish seas. Others are whales and dolphins, basking sharks, sunfish, and perhaps a leatherback turtle on passage northwards to feast on the jellyfish in Cardigan bay. One of the largest leatherbacks ever recorded washed ashore dead on Harlech beach in Wales in 1988. Three metres long, one hundred years old, and almost a tonne in weight, it died from entanglement in fishing lines.

There are wonders in our waters, but seals have the advantage of being predictable. They haul out on rocks and sandbars as the tide falls to rest and sleep. They use the same sites again and again, making it easy for a boat to bring tourists to see them. Predictability is good for business. After all, no one wants a wildlife watching trip that fails to find any wildlife.

Sometimes the seals come to you. Around St. Ives harbour tourists sit on benches trying to guard chips from seagulls that can swoop and snatch them between lap and mouth. High tide approaches. As the fishing boats return the tourists rise and make their way around the harbour to gather on the quay. The seals arrive and wait for the boats to discard some of their catch. There is one large male and two smaller females. One of them could be our seal; Gwithian beach is only a short swim across the bay. The tourists crowd the edge of the quay, trying to capture them on smartphones and cameras looking for the sea-grey shadows below the water, judging where they will surface. Signs on the harbour office warn against swimming with the seals, warning that they are wild animals. The seals feed as dusk falls and the crowd thins, photographs taken.

Wildlife tourism brings people and money to an area, but fishers see the seals, look at their catches, and place the blame. Calls for culls or other controls may follow. The income from the wildlife boats may offset some of the losses, real or otherwise to the local economy, but this is of little use. Those that benefit are not the same as those that lose, and even if they were, viewing the seals in terms of their contribution to the community coffers is pure arrogance. It’s an arrogance that humans are frequently guilty of, one that views an animal as enigmatically beautiful as our seal primarily in terms of their contribution to our economic well-being. We are part of, not apart from, the ecosystems in which we reside. We should not think that we are above them simply because we are a more sophisticated tool builder than most animals.

Our seal is four years old, and an adult now. She has learned the intricacies of catching prey. She has avoided the hazards of fishing net and line. It is spring and she is hauled out to moult, when the previous year’s fur is replaced by new growth. The juveniles have already moulted, and now it is the turn of the adult females. Last autumn our seal returned to the beach where she was born and mated, but her pup is not yet growing. Birth is an annual affair, with mating on the same beach shortly afterwards. The problem is that seal pregnancies only last for thirty-five weeks. Grey seals solve this problem by pausing the development for fifteen weeks before the pup actively starts growing inside her. In this way, births can be tied to an annual cycle, and with all the pups being born around the same time there is protection from predators through numbers. Moulting is complete, the creamy brown old hairs have been replaced by pristine black and grey fur, the pattern or pelage unique to her, a fingerprint to identify her with. She returns to the sea building up her blubber that will be used to feed her pup.

It is autumn again, the fifth since our seal first drew breath on this beach. She stakes her claim to a patch of beach and gives birth to a single pup. He has soft white fur and weighs fourteen kilograms. Many hazards await him, but first, he suckles.

What future for wild sea bass?

There are many things that can cause problems for a species. Sometimes it’s some aspect of the biology that makes them vulnerable. Sometimes it’s human pressures. And sometimes it all comes together to really cause problems for an animal. Sea bass are a popular fish for commercial fishermen and anglers, and are a popular fish for eating. Despite the fact that most of the sea bass consumed in the EU is farmed wild sea bass populations are in trouble. While assessments of the stock are not easy, ICES, the intergovernmental organisation that gives advice on sustainable fishing to the EU has said that the losses from the population due to fishing have consistently been above sustainable levels1 and also recruitment of young fish has been very poor since 20081.

Swimming Sea Bass

Sea Bass by Bjoertvedt is licensed under creative commons (CC-BY-SA 4.0)

Sea bass grow slowly and mature relatively late. They mature between four and seven years old when the males are around 35 cm long and the females are around 42 cm2. Before the 1st September 2015 the minimum size for landing was 36cm nationally2, although some regions such as Cornwall had a slightly larger size3. Not surprisingly, having a minimum size where the female fish could be landed before they had had a chance to breed is not the best route to a sustainable fishery. Sea bass behaviour also increases their vulnerability to over-exploitation. The juveniles congregate in groups in estuaries, and as adults migrate offshore to spawn (where they are targeted by trawlers4) and then return to the same coastal sites year after year5. This site fidelity means that once local populations are overfished recovery is slow, especially if there are cold winters that can kill juveniles, reducing the number of new individuals recruited to the population5. All these factors mean that the breeding population has dropped from around 16,000 tonnes in 2009 to less than 7,000 tonnes in 2015. ICES state that the ability of the population to reproduce successfully is seriously compromised below 5,000 tonnes.

So what has been the response? The minimum landing size has been increased to 42cm6 and is now called the minimum conservation reference size, which at least gives the females a chance to breed but comes at a cost for the fishermen. The fish that are above 35cm now and could have been caught under the old rules are now not available to be caught until they grow large enough to exceed the new minimum. There is also to be a closed season for six months of the year between January and June to allow the fish to spawn. For the other six months of the year recreational anglers will be allowed to land one bass per day, while commercial fishers are restricted to catch limits of one tonne per month. The EU proposes that catch limits should fall from 2,656 tonnes in 2015 to 1,449 tonnes in 2016, a reduction of around 45%7. The problem is, though, that ICES has said that the limit should be set at 541 tonnes for 20168, which would be a reduction of 80% on the 2015 figures. In other words, the limit set by the EU is nearly three times larger than what the scientific assessment says it should be. This may be an attempt to spread the impact on fishermen over a longer period, but with the stock at such a low level this may backfire. A collapsed fishery supports no one.

What else could be done? Save Our Sea Bass suggest that the lower landings limit (the ICES figure) should be adopted as a matter of urgency, and that both anglers and commercial fishermen should only be allowed to catch sea bass by rod and line or hand lines. They also suggest that the share in the 541 tonnes should be distributed in line with article 17 of the common fisheries policy, which means based on environmental criteria and economic benefits to coastal communities. The idea behind using lines to catch sea bass is that line-caught sea bass fetches higher prices. The marine conservation society has a good fish guide, and currently (November 2015) lists wild-caught sea bass as a fish to avoid. Farmed sea bass are a more acceptable alternative to wild-caught fish.

You can keep up to date with sea bass issues either from the Marine Conservation Society or Save Our Sea Bass site.

References

1,8 ICES Advice on fishing opportunities, catch, and effort Celtic Seas and Greater North Sea Ecoregions 2015
2 European sea bass (Dicentrarchus labrax) exploited around Welsh waters – preliminary results: December 2013.
3Cornwall Inshore Fishery and Conservation Association new minimum size for bass
4Protecting Sea Bass
5Parliamentary briefing on sea bass.
6Bass fishing: catch limits, minimum size, and where you can fish (Gov.uk)
7Commission proposes fishing opportunities in the Atlantic and North Sea for 2016

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No limits, no future

Recently, I volunteered with the Shark’s Trust at the Dive Show in Birmingham helping to raise awareness about their ‘no limits no future‘ campaign to stop uncontrolled shark fishing. Shark and ray populations worldwide are under increasing pressure, and the total number of sharks caught annually may be over 100 million. One study1 published earlier this year (2014) estimated that up to a quarter of shark and ray species are threatened if assessed using the IUCN red list criteria. If we think about risks to shark populations we might think about shark finning in the Pacific, or sharks being caught as part of longline fisheries for tuna2 but the problem is actually a lot closer to home.

Originally, sharks were an unwanted part of the catch (bycatch) as fishermen pursued species such as cod and tuna, but now there is an increasing trend for the targeting and retention of these bycatch sharks. They are caught for their meat, their fins and their liver oil. Unfortunately, the life-history and behaviour of sharks makes them vulnerable to overfishing and populations are declining. Sharks reach maturity late and have relatively few young compared to other fish. In addition, they often congregate in groups of individuals that are either all a single sex, or are very close in age. Should a fisherman catch these sharks it has a bigger effect than catching the same number of sharks at random from the population.

In 2012 there were 280,000 tonnes of reported shark landings worldwide, with EU vessels landing 40% of this world total, the majority of which came from the Atlantic ocean and Mediterranean sea. One issue in that this is reported landings – the true level of landings is thought to be three to four times higher3. Worse still, most of this European catch from the Atlantic and Mediterranean is concentrated on just five species4.

These five species are:

97% of all sharks caught and landed from the Atlantic and Mediterranean in 2012 are no limits species, which has been estimated to amount to 6,400,000 individuals. This is why although some of the species above are currently listed as of ‘least concern’ it’s important to make the fisheries sustainable before the populations crash due to overfishing. Once overfished, there is no guarantee that populations will recover as demonstrated by the collapse of the cod fishery on the grand banks off the eastern coast of Canada. In addition, sharks are important components of ecosystems as top-level predators. The shark trust is campaigning for science-based catch limits. Please sign the petition, and see the ‘get involved‘ page for other ways to contribute.

References

1http://elifesciences.org/content/3/e00590
2http://www.sciencedirect.com/science/article/pii/S2351989414000055
3 4http://www.nolimitsnofuture.org/wp-content/uploads/2014/07/no_limits.pdf

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This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.