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An assessment Of Atlantic bluefin tuna
ELSEVIER
Fisheries Research 27 ( 19%) 275-277
Book review
An assessment of Atlantic bluefin tuna An Assessment Of Adantic Bluefin Tuna. Committee to Review Atlantic Bluefin Tuna (Chairman John J. Magnuson). National Academy Press, Washington, DC, 1994, price g23.95, ISBN o-309-05 18 1-9. This book provides a vivid insight into the scientific controversies surrounding the management of North Atlantic bluefin tuna. It is essentially a position paper presenting the views of fisheries scientists from one country (the USA) prior to the 1994 meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT). For students of fish biology the book carefully reviews the status of knowledge of this species. The arguments are presented very clearly and with an extensive bibliography makes this a very readable work of reference. ICCAT, based in Madrid has 22 member nations including the USA, Canada, Japan, Spain and France and is responsible for co-ordinating research on tuna in the Atlantic Ocean and proposing harvest protocols so as to obtain a maximum sustainable catch. There is considerable controversy surrounding the management of this species. The bluefin tuna from the North Atlantic spawn in two different areas, the Gulf of Mexico and the Mediterranean Sea. ICCAT management is based on the hypothesis that there are two separate stocks, the western and eastern stocks divided from one another by line at 45”W running down the centre of the Atlantic Ocean. Based on indices of catch per unit effort the western stock is severely depleted standing at a biomass of only 20% of that in the early 1970s. For US fishermen there are strict catch limits in force and fishing is prohibited in the spawning areas of the Gulf of Mexico. It must be particularly exasperating for them to observe that there is no quota in the eastern Atlantic and that there is a traditional fishery directed to interception of spawning fish in the Mediterranean. The National Research Council in the USA set up a committee of experts under the distinguished chairmanship of Dr. John J. Magnuson. He and his committee of 8 well-known US academics, Barbara A. Block, Richard B.Deriso, John R. Gold, William Stewart Grant, Terrance J. Quinn II., Saul B. Saila, Lynda Shapiro and E. Don Stevens are to be congratulated on producing this report within 6 months. Evidence was taken from individuals and organisations in the USA concerned with tuna management.
SSDl 0165-7836(95)00462-9
276
Book review
The report presents evidence that there is mixing between the bluefin tunas on the two sides of the Atlantic Ocean and therefore recommends that ICCAT should take this into account in future research and management. In particular a model is presented that shows that straying of young fish from the eastern Atlantic and Mediterranean can be very important for the stocks in the western Atlantic. The implication is that the two stock hypothesis should be rejected and that a one-stock management regime should be implemented. This would however create procedural problems in ICCAT since the western and eastern stocks are reviewed in alternate years. This means that data for both sides of the Atlantic are never considered together and adoption of a single stock hypothesis would require reorganisation of ICCAT. The NRC report was presented at the ICCAT meeting in the autumn of 1994. Broadly the research suggestions were accepted as commendable and indeed many were already being implemented. ICCAT however, did not accept that the two stock hypothesis is disproven. The problem is that the bluefin tuna is very widely dispersed throughout the world’s oceans and shows very little genetic variation throughout its range. It is difficult with DNA analysis to distinguish Atlantic from Pacific bluetins let alone fish from two sides of the same ocean. Even if genetic differences could be demonstrated straying of fish between stocks is not unusual and does not necessarily invalidate the use of two separate management regimes. It is important to distinguish between the management concept of fish stocks and the biological concept of genetically isolated populations. Fisheries for the bluefin tuna in the eastern stock are now dominated by catches in the Mediterranean. Traditional fixed-net fisheries that intercept spawning individuals are in decline and modem purse seiners now take a larger tonnage of juvenile fish. Catches in 1994 were exceptional with a 55% increase over 1993 to 28000 t compared with 8 t in the whole North Atlantic in 1994. The French fleet alone took 12000 tonnes with contributions from Italy, Spain, Turkey and Croatia. Such a sudden large increase in catch of any fish stock is inevitably likely to be followed by problems. It seems the concerns of the NRC report regarding tbe division of the Atlantic between east and west has been overtaken by events in the Mediterranean; will 25 000 to 30000 t from the Mediterranean be sustainable? In the 1950s the total Atlantic Bluefin tuna catch was 25 000-35 000 t, 80% of which came from the western Atlantic. The 1970s saw a decline to 15000 t but in 1994 the total catch was back up to 35000 t, but 80% came from tbe Mediterranean. It is easy to see why scientists from different nations might view the bluefin tuna problem in different ways. It would be particularly ironic if it is eventually demonstrated that the restrictions in the western Atlantic gave the French fishermen their bumper harvest in 1994. An important issue is that the quality of scientific work and advice is variable from county to country. Some Mediterranean and African countries cannot afford the scientific infrastructure necessary to participate effectively in fora such ICCAT. A further problem in fisheries science is that working documents and data often remain in the grey literature unavailable to the outsider. The publication of the NRC book is useful endeavour in publicising such material. Students will read it with interest but should be
211
Book reuiew
cautious, it does not tell the whole story but is the stuff of debate in fisheries and management.
research
I.G. Priede Department of Aberdeen University of Aberdeen Tillydrone Avenue Aberdeen, All9 2i’Y UK
Fisheries Research 27 ( 19%) 275-277
Book review
An assessment of Atlantic bluefin tuna An Assessment Of Adantic Bluefin Tuna. Committee to Review Atlantic Bluefin Tuna (Chairman John J. Magnuson). National Academy Press, Washington, DC, 1994, price g23.95, ISBN o-309-05 18 1-9. This book provides a vivid insight into the scientific controversies surrounding the management of North Atlantic bluefin tuna. It is essentially a position paper presenting the views of fisheries scientists from one country (the USA) prior to the 1994 meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT). For students of fish biology the book carefully reviews the status of knowledge of this species. The arguments are presented very clearly and with an extensive bibliography makes this a very readable work of reference. ICCAT, based in Madrid has 22 member nations including the USA, Canada, Japan, Spain and France and is responsible for co-ordinating research on tuna in the Atlantic Ocean and proposing harvest protocols so as to obtain a maximum sustainable catch. There is considerable controversy surrounding the management of this species. The bluefin tuna from the North Atlantic spawn in two different areas, the Gulf of Mexico and the Mediterranean Sea. ICCAT management is based on the hypothesis that there are two separate stocks, the western and eastern stocks divided from one another by line at 45”W running down the centre of the Atlantic Ocean. Based on indices of catch per unit effort the western stock is severely depleted standing at a biomass of only 20% of that in the early 1970s. For US fishermen there are strict catch limits in force and fishing is prohibited in the spawning areas of the Gulf of Mexico. It must be particularly exasperating for them to observe that there is no quota in the eastern Atlantic and that there is a traditional fishery directed to interception of spawning fish in the Mediterranean. The National Research Council in the USA set up a committee of experts under the distinguished chairmanship of Dr. John J. Magnuson. He and his committee of 8 well-known US academics, Barbara A. Block, Richard B.Deriso, John R. Gold, William Stewart Grant, Terrance J. Quinn II., Saul B. Saila, Lynda Shapiro and E. Don Stevens are to be congratulated on producing this report within 6 months. Evidence was taken from individuals and organisations in the USA concerned with tuna management.
SSDl 0165-7836(95)00462-9
276
Book review
The report presents evidence that there is mixing between the bluefin tunas on the two sides of the Atlantic Ocean and therefore recommends that ICCAT should take this into account in future research and management. In particular a model is presented that shows that straying of young fish from the eastern Atlantic and Mediterranean can be very important for the stocks in the western Atlantic. The implication is that the two stock hypothesis should be rejected and that a one-stock management regime should be implemented. This would however create procedural problems in ICCAT since the western and eastern stocks are reviewed in alternate years. This means that data for both sides of the Atlantic are never considered together and adoption of a single stock hypothesis would require reorganisation of ICCAT. The NRC report was presented at the ICCAT meeting in the autumn of 1994. Broadly the research suggestions were accepted as commendable and indeed many were already being implemented. ICCAT however, did not accept that the two stock hypothesis is disproven. The problem is that the bluefin tuna is very widely dispersed throughout the world’s oceans and shows very little genetic variation throughout its range. It is difficult with DNA analysis to distinguish Atlantic from Pacific bluetins let alone fish from two sides of the same ocean. Even if genetic differences could be demonstrated straying of fish between stocks is not unusual and does not necessarily invalidate the use of two separate management regimes. It is important to distinguish between the management concept of fish stocks and the biological concept of genetically isolated populations. Fisheries for the bluefin tuna in the eastern stock are now dominated by catches in the Mediterranean. Traditional fixed-net fisheries that intercept spawning individuals are in decline and modem purse seiners now take a larger tonnage of juvenile fish. Catches in 1994 were exceptional with a 55% increase over 1993 to 28000 t compared with 8 t in the whole North Atlantic in 1994. The French fleet alone took 12000 tonnes with contributions from Italy, Spain, Turkey and Croatia. Such a sudden large increase in catch of any fish stock is inevitably likely to be followed by problems. It seems the concerns of the NRC report regarding tbe division of the Atlantic between east and west has been overtaken by events in the Mediterranean; will 25 000 to 30000 t from the Mediterranean be sustainable? In the 1950s the total Atlantic Bluefin tuna catch was 25 000-35 000 t, 80% of which came from the western Atlantic. The 1970s saw a decline to 15000 t but in 1994 the total catch was back up to 35000 t, but 80% came from tbe Mediterranean. It is easy to see why scientists from different nations might view the bluefin tuna problem in different ways. It would be particularly ironic if it is eventually demonstrated that the restrictions in the western Atlantic gave the French fishermen their bumper harvest in 1994. An important issue is that the quality of scientific work and advice is variable from county to country. Some Mediterranean and African countries cannot afford the scientific infrastructure necessary to participate effectively in fora such ICCAT. A further problem in fisheries science is that working documents and data often remain in the grey literature unavailable to the outsider. The publication of the NRC book is useful endeavour in publicising such material. Students will read it with interest but should be
211
Book reuiew
cautious, it does not tell the whole story but is the stuff of debate in fisheries and management.
research
I.G. Priede Department of Aberdeen University of Aberdeen Tillydrone Avenue Aberdeen, All9 2i’Y UK