kidney stones and how to remove themsta.ie/perch/resources/lessons/a4bs-lesson11th-edition.pdf ·...

Kidney stones and how to remove them

KidneysPain is part of human consciousness and is an invaluable aid to survival. It tells us when something is wrong with our body. All pains are different; back pain, toothache, bruising or headache. There are even phantom pains where people who have had limbs amputated feel pain in the limb even although it is no longer there. One of the worst pains is that associated with kidney stones. It is described as similar to being stabbed with a knife, agonising or excruciating. However, a vivid description is ‘exquisitely painful’, as it gives an indication of the uniqueness of the pain.

The Greek physician Hippocrates first described the symptoms of kidney stones in 400 BC as follows:

‘...an acute pain is felt in the kidney, the loins, the flank and the testis of the affected side. With the urine sand is passed; as the sand passes along the ureter, it causes severe pain which is relieved when it is expelled; then the same sufferings begin again.’

What are kidney stones? Kidney stones, sometimes called renal calculi, are lumps of hard, crystalline mineral material that form within the kidney or urinary tract. The medical term for having them is nephrolithiasis. About one in every 20 people will be affected at some time in their life, usually between the ages of thirty to fifty. They are more common in Asians and Caucasians than in Africans or African Americans.

Causes of kidney stonesKidney stones form for three main reasons:

1. The urine may contain more crystal-forming substances than the fluid in it can dissolve.

2. The urine may lack the substances that prevent crystals from sticking together.

3. In response to a urinary tract infection.

Dehydration is probably the most important risk factor for kidney stone formation. The two most likely causes of dehydration are taking lots of strenuous exercise or living in a hot climate and not drinking enough water. Dietary factors also play a part. For example, people who take large doses of vitamin C, often in the belief that it will prevent disease, have a 20% higher risk of developing stones. Eating foods rich in oxalates such as rhubarb can also be a contributory factor.

A family history of kidney stones is also a significant risk factor, especially in this part of the world. People with certain medical conditions (e.g. gout), or those who take some medications, such as those used in chemotherapy, are also at an increased risk of developing stones.

Diagnosis Initial diagnosis is based on symptoms but this may be followed by X-ray, ultrasound scans, intravenous pyelogram (IVP) or even a CT scan to give a more detailed picture of the size, number and location of the stones. This is always carried out prior to surgical intervention.

Types of kidney stonesKnowing the type of kidney stone helps determine the cause and may give clues on how to reduce the risk of getting more kidney stones. Types of kidney stones include:

Calcium stones make up the majority of kidney stones usually in the form of either calcium oxalate or calcium phosphate.

Struvite stones form in response to a urinary tract infection where bacteria produce ammonia which builds up in the urine and causes the formation of magnesium ammonium phosphate which forms the stone. These stones can grow quickly and become quite large, blocking the ureter and causing it to distend. It is the swelling of

the ureter that causes the sudden pain, sometimes with little warning.

Uric acid stones can form in people who don’t drink enough fluids or who lose too much fluid, eat a high-protein diet, or those who have gout. Certain genetic factors may also increase the risk of developing uric acid stones.

Cystine stones form in people with a hereditary disorder that causes the kidneys to excrete too much of certain amino acids especially cysteine. This type of stone is not very common.

Other, rarer types of kidney stones can also occur.

Treatments Most kidney stones pass on their own with time, and only a small proportion need surgical intervention.

The initial treatment is to give analgesics (pain killers) and significantly increase the volume of water consumed. In some cases medication is given to increase the amount of urine produced; these are called diuretics. Other drugs, called alpha-blockers, relax the muscles of the ureter allowing the stone to pass through more easily and with less pain.

If this is not sufficient to cause the stone(s) to pass though the ureter, to the bladder and out through the urethra then surgical techniques may be used. Open surgery may be required but this can cause prolonged pain and has a long recovery time. Nowadays the two most common procedures are considerably less invasive.

ESWL (Extracorporeal shock wave lithotripsy) is a non-invasive treatment of kidney stones using sound waves to break up the stone. Somewhat like the opera singer hitting just the right note and causing the wine glass to shatter. There are various arrangements of the apparatus but in general the patient, dressed in a hospital gown, lies on a water-filled cushion. High energy shock (sound) waves are focused on the stone for about an hour and these break the stone into small pieces. This is non-invasive, apart from the possible use of a catheter to help remove the debris, but there can be a certain amount of bruising and bleeding caused by the shock waves. The patient is normally conscious and, if there are no complications, can go home shortly afterwards.

RIRS (retrograde intrarenal surgery) which is a procedure for performing surgery within the kidney using a viewing tube called a fibre-optic endoscope. The scope is passed through the urethra and bladder and then through the ureter into the pelvis of the kidney, depending on the location of the stone(s). The stone is viewed through the scope and can then be manipulated, crushed by an ultrasound probe, evaporated by a laser probe or grabbed by small forceps or in a basket and removed.

If the stone is causing a blockage this will cause urine to back up into the kidney where it will cause pain. More importantly it will damage the kidney, and in severe cases can lead to the loss of the kidney. In this case a stent is put in place to bypass the stone and allow the urine to escape before permanent damage is done. These procedures are carried out by a specialist urologist under general or spinal anaesthesia. The recovery time with both these methods is very short.

Some ‘home remedy’ advocates suggest that lemon juice drinks are an effective preventative and cure. It is more probably the increased intake of water with the lemon juice that produces the effects. Find this and other lessons on www.sta.ie

Boston Scientific has supported the production of this lesson.

We are a leading innovator of medical solutions that improve the health of patients around the world. Our products and technologies are used to diagnose or treat a wide range of medical conditions, including heart, digestive, pulmonary, vascular, urological, women’s health, and chronic pain conditions. We continue to innovate in these areas and are extending our innovations into new geographies and high-growth adjacency markets.

With approximately 23,000 employees and 12 manufacturing facilities around the world and market presence in 100 countries, Boston Scientific is dedicated to transforming lives through innovative medical solutions that improve the health of patients around the world.

With corporate headquarters in Marlborough, Massachusetts and major operations in North and South America, Boston Scientific has established three key strategic sites in Ireland — Clonmel, Cork and Galway — employing in excess of 3,500 employees across the broad range of activities in which the company is involved.

Boston Scientific in Clonmel

The Clonmel operation is responsible for the production of implantable pacemakers and defibrillators that offer life-saving therapy for patients suffering from cardiac arrhythmias and heart failure. It currently employs more than 900 people, many of whom specialise in a range of engineering disciplines e.g. Electrical, Mechanical, Biomedical, Material Science, Quality, R&D and Industrial along with other functional areas such as Supply Chain, Human Resources, Finance, Process Development, IT and Manufacturing.

Boston Scientific Clonmel actively promotes and participates in the local community through initiatives such as their Schools Programme where BSC facilitates local students on work experience and sponsors a Student of the Year Award in local schools, culminating in an opportunity for summer work. BSC is actively involved in Junior Achievement activities, with over 19 employees delivering programmes in the region.

Find out more about Boston Scientific at www.bostonscientific.com


Find this and other lessons on www.sta.ie

BIM is the Irish State agency responsible for developing the Irish seafood industry. It was established under the Sea Fisheries Act 1952.BIM’s mission is to grow a thriving Irish seafood industry; expand the raw material base, add value and develop efficient supply chains that together deliver on the Government’s Food Harvest 2020 targets for seafood and create sustainable jobsWe help to develop the Irish seafood industry by providing:

• technical expertise• business support• funding• training and • by promoting responsible environmental practices.

The industry contributes about €700 million annually to national income and employs 11,000 people, mainly in coastal counties from Donegal to Louth. The four main activities in the Irish seafood industry are covered by:

• Fishing – The top fishing ports in Ireland are Killybegs, Castletownbere, Dingle, Dunmore East and Kilmore Quay, but fishing vessels also land into numerous small ports around the coast.

• Fish farming - Aquaculture activity includes growing finfish, such as salmon and trout and shellfish farming, including the cultivation of mussels, oysters and scallops.

• Processing - Seafood companies produce high value products from salmon, whitefish, shellfish and pelagic fish species (e.g. herring, mackerel and horse mackerel) all of which generate substantial export earnings to the sector.

• Marketing - Irish seafood is sold at home (€340 million) and in international markets (Europe, Africa and the Far East) where exports are valued at €375 million.

BIM’s clients are fishermen, fish farmers, processors and anyone involved in marketing Irish seafood. But it also works with students, educators, the media, seafood consumers and the general public to spread the word about the quality and potential of the Irish seafood industry.BIM offers a range of training programmes for the Irish Fishing Industry. Training programmes include: marine engineering, radio, safety and aquaculture. The training programmes are accredited by the Department of Transport, Tourism & Sport & Quality and Qualifications Ireland. BIM has five training centres in Ireland and entry to BIM’s training courses is directly to their colleges, as BIM is not part of the CAO system.

For further information visit: www.bim.ie

What is sustainable fishing?The seafood industry in Ireland supports about 10,000 jobs directly, between fishing, aquaculture and processing. The table below shows the approximate breakdown of the numbers.

Full time Part time TotalFishing 40% 10% 50%

Aquaculture 8% 12% 20%

Processing 23% 7% 30%

Total 70% 30% 100%

About another 1,000 people are involved in ancillary industries such as the supply and repair of engines, boats, nets, sonar, navigation equipment, refrigeration facilities etc.

The long term sustainability of these jobs depends on:

1. an appropriate level of pay for those involved, taking account of the difficulty of the work, the long and often unsocial hours and the risks involved

2. reliable market conditions and demand

3. and the protection and sustainability of the fish stocks.

Balancing conflicting requirementsA population of fish will remain stable if the rate of harvesting, natural mortality and predation is equal to the rate of reproduction. This is true regardless of the size of the population; a small population can sustain only a low level of harvesting. It follows that the greatest rate of harvesting (i.e. the maximum sustainable yield (MSY)) can be achieved when the population growth rate is a maximum.

When the population is small the growth rate is also small. As the population increases, so does its rate of growth. However, the limited supply of food reduces the growth rate. When the population is as big as the food supply can sustain, further growth leads to food shortage and a decrease in the population. At the maximum carrying capacity the growth rate is zero.

It turns out that the maximum growth rate typically occurs at 50% of the carrying capacity. This is the level which produces the maximum sustainable yield.

It is therefore important to keep fish populations as large as their environment can sustain in terms of food. Once the population falls below that level, the rate of harvesting must be reduced proportionately — otherwise the population will continue to decline, with no chance of recovery. In fact, harvesting should be reduced further to allow stocks to recover.

The wrong responseIf the population of a particular species drops significantly then it becomes increasingly difficult to catch the amount of fish that was previously consumed. As the catch decreases the price tends to increase and this can encourage the fishing industry to expend more effort in order to increase the catch. This response only accelerates the decline of the fish stock. To restore the fish numbers the fishing effort must be reduced until the population returns to the maximum growth rate.

Increased ‘fishing effort’As the world’s population increases so does the demand for food, including fish. In order to meet this growing need, the number and size of fishing vessels increased dramatically after 1950. In the EU the fishing effort is now ten times bigger than it was in 1950 but the catch is about five times

bigger. In other words, the increase in the catch is only half as large as the increase in fishing effort in kW days. For each fishing vessel this is found by multiplying its power (in kilowatts) by the number of days it is at sea.

Some numbersThe European Commission reported in June 2015 (see: http://europa.eu/rapid/press-release_IP-15-5082_en.htm ) that in the Northeast Atlantic area, the North Sea and the Baltic Seas more than 50% of fisheries were at sustainable levels in 2014. This is a significant improvement on the situation in 2009 when only 14% of the fish stocks in the area were at sustainable levels. (Of the 62 stocks studied 32 were at sustainable levels.)

This change was brought about by:• Limiting the EU total allowable catch (TAC) of various fish stocks.

Each member state is allocated a portion or ‘quota’ from the TAC and aggregate size for fishing vessels in each state or region

• Setting an aggregate total allowable engine power (measured in kW) and aggregate size for fishing vessels in each state or region

• Managing the fishing effort by limiting the number of fishing days with respect to engine power (kW days)

• Prohibiting the fishing of some stocks during certain months of the year The Commission bases its proposals on the best available scientific advice provided by independent bodies.

There is a particularly urgent need for more concerted international effort to prevent overfishing in the Mediterranean where only 7% of fish stocks in are currently at sustainable levels.

Who does what?EU fisheries controls are implemented by the individual states through their own inspectors. In order to encourage collaboration and best practice, inspectors from different states agree joint controls. The EU Commission has its own inspectors. They do not inspect individual fisheries but work with the national authorities and inspectors to ensure that the EU regulations are consistently enforced.

If the European Commission finds that national authorities are not enforcing fisheries rules properly:

• it first tries to resolve issues through consultation • it may temporarily withhold EU funds • it may close a fishery until the issue is resolved• if national quotas are exceeded then the excess is deducted

from future quotas • the Commission can take the member state concerned to the

EU Court of Justice.

Overfished fish stocksA fish ‘stock’ is a sub-population of one species that is more or less independent of the total population found in a particular area. Some stocks are regarded as ‘overfished’ in the seas around Ireland.

If a stock is severely overfished it can be termed ‘outside safe biological limits’ where there is a high chance the population will collapse because there are insufficient adult fish left to spawn and ensure that sufficient juvenile fish replace those that were caught. All overfished stocks are below the level that would give the maximum sustainable yield.

Where a stock is overfished specific ‘Recovery Plans’ are put in place. Such Recovery Plans have been successful in rebuilding the mackerel and hake stocks to levels above MSY in recent years. A Recovery Plan is currently also in place for a number of Irish cod stocks. In addition to these some stocks of whiting, sole and herring in Irish waters are regarded as overfished at present and restrictive TACs have been applied.

It is important to note that a fish stock might be within ‘safe biological limits’ while being far below the maximum sustainable yield.

EU fisheries policy aims to return fish stocks to maximum sustainable yield by 2020.

How do TACs work?The health of fish stocks varies from place to place. A fish species that is depleted in one area may be close to its maximum growth rate in another area. For this reason TACs are linked to specific fishing areas.

For each EU fishing area an annual total allowable catch (TAC) is set and each country is allocated a certain percentage or quota from the TAC.

The table shows some examples of the TAC for particular demersal species (species that swim close to the sea bed) in specified fishing areas (not listed here).

In order to allow overfished stocks to recover the TAC for some species in specific areas is zero.

Other measuresMany fish stocks have not been thoroughly studied and so their status is unknown. Of those that have been studied more than half are below MSY and in danger of being depleted. Measures to make the fishing industry sustainable in the long term include the following:

• Setting limits on the aggregate ‘size’ of the fishing fleet for each state. • Specifying the type of nets that are used for different species to ensure

juvenile fish escape• Limiting fishing of certain species to particular times of the year • Developing aquaculture.

Although some of these measures have a short term negative effect on local fishing communities there is no other way to ensure the fishing industry is sustainable in the long term.

Demersal Species

EU TAC (tonnes)

Irish % of EU TAC

Saithe 5,631 7%

Monkfish 4,432 10%

Megrims 4,074 13%

Haddock 3,988 16%

Haddock 1,210 8%

Plaice 658 40%

Pollack 397 14%

Whiting 277 30%

Cod 74 22%

Common sole 57 81%

time

popu

latio

n

maximum growth rate

Growth of a fish population

maximum sustainable yield

carrying capacity

A school of mackerel

Sustainability in Irish Fisheries


Syllabus ReferencesThe main syllabus references for the lesson are:

Leaving Certificate Biology• Ecology: Definition of “ecology”.• Ecosystem: Definition and diversity of “ecosystems”. (p.11) • Ecological Relationships: Factors that control populations.

Definition and one example of the following control factors: competition, predation, parasitism, symbiosis.

• Population Dynamics: Outline of the contributory factors or variables in predator and prey relationships (p.12)

Leaving Certificate Geography• Economic activities have an environmental impact: Sustainable

economic development so as to control environmental impact. National settings: role of EPA, depletion of fish stocks, mining sites.(p.26)

Science and Technology in Action is also widely used by Transition Year classes.

• Student Activities1. The table shows Ireland’s 2015

quota (tonnes) for some species in different sea areas. Investigate one of these species under the following headings and display your findings in a poster or a computer presentation:• description• its place in the marine food web• its life cycle• its commercial importance• its current status (in terms

of sustainability) (Different groups of students could

focus on different species.)

2. Fish stocks can be compared to an investment account that returns some interest every year. If the interest is withdrawn every year then the amount (or capital) remains the same. If the interest is not withdrawn the capital increases every year, by increasing amounts. If more than the interest is withdrawn every year then eventually nothing is left. Make a poster to illustrate this analogy.

3. Design a poster or computer presentation to illustrate the kinds of steps that can be taken to make the fishing industry sustainable.

Did You Know?The fishing industry contributes about €700 million annually to national income and employs 11,000 people, mainly in coastal counties.

The four main activities in the Irish seafood industry are covered by:



• Processing - Seafood companies produce high value products from salmon, whitefish, shellfish and pelagic fish species (eg. herring, mackerel and horse mackerel) all of which generate substantial export earnings to the sector.


Biographical NotesResponsible Irish Fish (founded by Frank Fleming from West Cork)

A new label for fish and shellfish has been introduced to the Irish market called “Responsible Irish Fish”. The main aims of the group behind the label are to assist vessel owners achieve certification for their fish/shellfish, to develop a brand to allow Irish fishermen differentiate their products in the market place and to promote Irish fish caught in a responsible manner.

The development of an Environmental Management System (EMS) by BIM, with the fishing industry, forms the basis for this new label. The EMS system can be used as a stepping stone to various forms of certification depending on the fishery a vessel is involved in. The system implemented by the vessels is based on three main pillars of

• quality (ensuring good practice during handling and storage), • provenance (the fish are fully traceable back to an Irish vessel), and • responsibility (harvested in an environmentally responsible way).

Learning OutcomesOn completion of this lesson, students should be able to:

• Explain what is meant by ‘maximum sustainable yield’ (MSY). • Describe the relationship between the ‘maximum growth rate’

of a particular fish stock and the maximum sustainable yield.• Outline the factors that affect the size of fish stocks• Outline how fishing quotas are specified• Describe what is meant by ‘outside safe biological limits’ • Distinguish between ‘within safe biological limits’ and MSY• Describe measures that can be taken to restore fish stocks to MSY

General Learning Points These are additional relevant points which are used to extend knowledge and facilitate discussion.

• A sustainable fishing industry requires sustainable fish stocks and appropriate financial reward for effort and investment

• More than half the fish stocks for which data are available are overfished and declining. No data is available on many more and so it is important to avoid depleting them through thoughtless exploitation. Declining catches (for the same effort) are the first indicators of overfishing.

• A distinction is usually made between ‘maximum sustainable yield’ and ‘optimum sustainable yield’. When a fish stock is very abundant then the fish are caught more easily. As the stock declines more effort is required to achieve the same ‘harvest’. The ‘optimum sustainable yield’ (or maximum economic yield) is less than the ‘maximum sustainable yield’ but it gives the best economic return for the effort involved. Managing fish stocks in this way is better for the fish and better for the fishing community.

True/False Questions

a) The seafood industry in Ireland supports about 110,000 jobs directly. T F

b) Aquaculture accounts for 20% of jobs in the fishing industry. T Fc) The long term sustainability of these jobs depends only on

the fish stocks. T Fd) The greatest rate of harvesting can be achieved when the

population growth rate is a maximum. T Fe) It turns out that the maximum growth rate typically occurs at

half the carrying capacity. T Ff) When a fish stock declines then more fish can be caught for

the same effort. T Fg) Fishing effort in the EU is now ten times what it was in 1950. T Fh) All EU fish stocks are below sustainable levels. T Fi) The EU sets annual quotas for each fishing area and each

country is given a specified fraction of each quota. T Fj) In the Mediterranean 70% of fish stocks are at

sustainable levels. T F

Check your answers to these questions on www.sta.ie.

Revise The TermsCan you recall the meaning of the following terms? Revising terminology is a powerful aid to recall and retention.

ancillary industries, aquaculture, demersal species, fish stock, fishing effort, gigatonne, harvesting, kilowatt, maximum carrying capacity, maximum sustainable yield, outside safe biological limits, overfished, predation, quota, rate of reproduction, seafood, sustainability

Check the Glossary of terms for this lesson on www.sta.ie

Examination Questions Leaving Certificate Biology (OL) 2010, Q. 10 c

‘The great pressure put on wildlife by the growing human population has caused many species to become extinct. Habitat destruction, over-exploitation and environmental pollution have been the main causes. There is a clear need for conservation if such a trend is to be halted. Conservation has many practical outcomes from which humans will benefit in future years.’ (Adapted from Advanced Biology, 3rd Edition, J. Simpkins, J. I. Williams)

(i) Explain the underlined words from the passage.(ii) State the effect of any one named pollutant.(iii) Outline one conservation measure carried out by one of the following

industries: agriculture or forestry or fisheries.(iv) Name one problem associated with waste disposal.(v) State one role of microorganisms in waste management.

Leaving Certificate Biology (HL) 2013, Q. 13 c

Using your knowledge of ecology, suggest why caution is advised regarding each of the following practices.

(i) The release of non-native animals into the Irish countryside.(ii) Using fishing nets of very small mesh size.(iii) Hedgerow cutting in spring and summer.(iv) Spreading slurry on farmland.

Leaving Certificate Geography (OL) 2007, Q. 9 CThere are a number of environmental issues which are causing concern in Ireland at present. These include over fishing in Irish waters

Examine the concerns caused by overfishing.

Leaving Certificate Geography (OL) 2009, Q. 8 A

Examine the table showing the top 10 fishing nations in the North-East Atlantic and answer the questions which follow in your answer book.

(i) Which country had the highest catch in 2006?

(ii) Name one country which had an overall increase between 2000 and 2006?

(iii) By how much did Ireland’s catch fall between 2000 and 2006?

(iv) Did Norway’s catch rise or fall between 2000 and 2006?

(v) Which country had the highest catch in 2000?


Catches in NE Atlantic (000 tonnes live weight)

COUNTRY 2000 2002 2004 2006

Denmark 1534 1442 1087 864

France 491 497 467 423

Germany 178 194 236 259

Iceland 1990 2138 1742 1340

Ireland 275 242 246 211

Netherlands 336 350 391 357

Norway 2693 2725 2511 2243

Spain 417 323 303 373

Sweden 337 294 269 268

UK 738 679 650 604

Mackerel 89,222

Boarfish 36,830

Herring 13,527

Norway lobster 7,740

Whiting 5,328

Megrims 2,878

Monkfish 2,540

Albacore 2,511

Haddock 2,106

Saithe 1,491

Cod 1,030

Pollack 1,030

Syllabus ReferencesThe main syllabus references for the lesson are:

Leaving Certificate Biology• Ecology: Definition of “ecology”.• Ecosystem: Definition and diversity of “ecosystems”. (p.11) • Ecological Relationships: Factors that control populations.

Definition and one example of the following control factors: competition, predation, parasitism, symbiosis.

• Population Dynamics: Outline of the contributory factors or variables in predator and prey relationships (p.12)

Leaving Certificate Geography• Economic activities have an environmental impact: Sustainable

economic development so as to control environmental impact. National settings: role of EPA, depletion of fish stocks, mining sites.(p.26)

Science and Technology in Action is also widely used by Transition Year classes.

• Student Activities1. The table shows Ireland’s 2015

quota (tonnes) for some species in different sea areas. Investigate one of these species under the following headings and display your findings in a poster or a computer presentation:• description• its place in the marine food web• its life cycle• its commercial importance• its current status (in terms

of sustainability) (Different groups of students could

focus on different species.)

2. Fish stocks can be compared to an investment account that returns some interest every year. If the interest is withdrawn every year then the amount (or capital) remains the same. If the interest is not withdrawn the capital increases every year, by increasing amounts. If more than the interest is withdrawn every year then eventually nothing is left. Make a poster to illustrate this analogy.

3. Design a poster or computer presentation to illustrate the kinds of steps that can be taken to make the fishing industry sustainable.

Did You Know?The fishing industry contributes about €700 million annually to national income and employs 11,000 people, mainly in coastal counties.

The four main activities in the Irish seafood industry are covered by:



• Processing - Seafood companies produce high value products from salmon, whitefish, shellfish and pelagic fish species (eg. herring, mackerel and horse mackerel) all of which generate substantial export earnings to the sector.


Biographical NotesResponsible Irish Fish (founded by Frank Fleming from West Cork)

A new label for fish and shellfish has been introduced to the Irish market called “Responsible Irish Fish”. The main aims of the group behind the label are to assist vessel owners achieve certification for their fish/shellfish, to develop a brand to allow Irish fishermen differentiate their products in the market place and to promote Irish fish caught in a responsible manner.

The development of an Environmental Management System (EMS) by BIM, with the fishing industry, forms the basis for this new label. The EMS system can be used as a stepping stone to various forms of certification depending on the fishery a vessel is involved in. The system implemented by the vessels is based on three main pillars of

• quality (ensuring good practice during handling and storage), • provenance (the fish are fully traceable back to an Irish vessel), and • responsibility (harvested in an environmentally responsible way).

Learning OutcomesOn completion of this lesson, students should be able to:

• Explain what is meant by ‘maximum sustainable yield’ (MSY). • Describe the relationship between the ‘maximum growth rate’

of a particular fish stock and the maximum sustainable yield.• Outline the factors that affect the size of fish stocks• Outline how fishing quotas are specified• Describe what is meant by ‘outside safe biological limits’ • Distinguish between ‘within safe biological limits’ and MSY• Describe measures that can be taken to restore fish stocks to MSY

General Learning Points These are additional relevant points which are used to extend knowledge and facilitate discussion.

• A sustainable fishing industry requires sustainable fish stocks and appropriate financial reward for effort and investment

• More than half the fish stocks for which data are available are overfished and declining. No data is available on many more and so it is important to avoid depleting them through thoughtless exploitation. Declining catches (for the same effort) are the first indicators of overfishing.

• A distinction is usually made between ‘maximum sustainable yield’ and ‘optimum sustainable yield’. When a fish stock is very abundant then the fish are caught more easily. As the stock declines more effort is required to achieve the same ‘harvest’. The ‘optimum sustainable yield’ (or maximum economic yield) is less than the ‘maximum sustainable yield’ but it gives the best economic return for the effort involved. Managing fish stocks in this way is better for the fish and better for the fishing community.

True/False Questions

a) The seafood industry in Ireland supports about 110,000 jobs directly. T F

b) Aquaculture accounts for 20% of jobs in the fishing industry. T Fc) The long term sustainability of these jobs depends only on

the fish stocks. T Fd) The greatest rate of harvesting can be achieved when the

population growth rate is a maximum. T Fe) It turns out that the maximum growth rate typically occurs at

half the carrying capacity. T Ff) When a fish stock declines then more fish can be caught for

the same effort. T Fg) Fishing effort in the EU is now ten times what it was in 1950. T Fh) All EU fish stocks are below sustainable levels. T Fi) The EU sets annual quotas for each fishing area and each

country is given a specified fraction of each quota. T Fj) In the Mediterranean 70% of fish stocks are at

sustainable levels. T F

Check your answers to these questions on www.sta.ie.

Revise The TermsCan you recall the meaning of the following terms? Revising terminology is a powerful aid to recall and retention.

ancillary industries, aquaculture, demersal species, fish stock, fishing effort, gigatonne, harvesting, kilowatt, maximum carrying capacity, maximum sustainable yield, outside safe biological limits, overfished, predation, quota, rate of reproduction, seafood, sustainability

Check the Glossary of terms for this lesson on www.sta.ie

Examination Questions Leaving Certificate Biology (OL) 2010, Q. 10 c

‘The great pressure put on wildlife by the growing human population has caused many species to become extinct. Habitat destruction, over-exploitation and environmental pollution have been the main causes. There is a clear need for conservation if such a trend is to be halted. Conservation has many practical outcomes from which humans will benefit in future years.’ (Adapted from Advanced Biology, 3rd Edition, J. Simpkins, J. I. Williams)

(i) Explain the underlined words from the passage.(ii) State the effect of any one named pollutant.(iii) Outline one conservation measure carried out by one of the following

industries: agriculture or forestry or fisheries.(iv) Name one problem associated with waste disposal.(v) State one role of microorganisms in waste management.

Leaving Certificate Biology (HL) 2013, Q. 13 c

Using your knowledge of ecology, suggest why caution is advised regarding each of the following practices.

(i) The release of non-native animals into the Irish countryside.(ii) Using fishing nets of very small mesh size.(iii) Hedgerow cutting in spring and summer.(iv) Spreading slurry on farmland.

Leaving Certificate Geography (OL) 2007, Q. 9 CThere are a number of environmental issues which are causing concern in Ireland at present. These include over fishing in Irish waters

Examine the concerns caused by overfishing.

Leaving Certificate Geography (OL) 2009, Q. 8 A

Examine the table showing the top 10 fishing nations in the North-East Atlantic and answer the questions which follow in your answer book.

(i) Which country had the highest catch in 2006?

(ii) Name one country which had an overall increase between 2000 and 2006?

(iii) By how much did Ireland’s catch fall between 2000 and 2006?

(iv) Did Norway’s catch rise or fall between 2000 and 2006?

(v) Which country had the highest catch in 2000?


Catches in NE Atlantic (000 tonnes live weight)

COUNTRY 2000 2002 2004 2006

Denmark 1534 1442 1087 864

France 491 497 467 423

Germany 178 194 236 259

Iceland 1990 2138 1742 1340

Ireland 275 242 246 211

Netherlands 336 350 391 357

Norway 2693 2725 2511 2243

Spain 417 323 303 373

Sweden 337 294 269 268

UK 738 679 650 604

Mackerel 89,222

Boarfish 36,830

Herring 13,527

Norway lobster 7,740

Whiting 5,328

Megrims 2,878

Monkfish 2,540

Albacore 2,511

Haddock 2,106

Saithe 1,491

Cod 1,030

Pollack 1,030


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