Resources, fishing and biology of the tropical tunas of the Eastern Central Atlantic
FAO FISHERIES TECHNICAL PAPER 292
| Resources, fishing and biology of the tropical tunas of the Eastern Central Atlantic |
| Table of Contents |
Edited by
A. Fonteneau
ORSTOM
Centre de recherches océanographiques
Dakar, Senegal
and
J. Marcille
Division of Marine Resources and Environment
FAO Fisheries Department
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M-43
ISBN 92-5-102652-1
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PREPARATION OF THE DOCUMENT
In this document the FAO Fisheries Department synthesized available information on tuna resources and fisheries. The purpose of this document is to summarize the current knowledge of fishing and the biology of tropical tunas in the eastern central Atlantic. The document was prepared by scientific team of the Institut Francais de Recherche Scientifique pour le Développement en Coopération (ORSTOM), the Centre de Recherches Océanographiques de Dakar Thiaroye, the Centre de Recherches Océanographiques d'Abidjan, and the Fisheries Research Unit of Tema during the years 1985 to 1987.
The eastern central Atlantic tuna fishery is very large and has developed over a period of some thirty years. Voluminous information is available which needs to be presented in a synthetic form. The document is intended not only for young researchers of the countries of the region but also for the officials responsible for fishing in these countries in order to provide them with a general view of the existing fisheries, the available resources, the biology of the principal species exploited, and of the methods currently developed for estimating the status of the stocks.
The following authors have collaborated in this work (in alphabetical order):
J.B. Amon Kothias, Centre de Recherches Océanographiques, B.P. V-18, Abidjan, Côte d'lvoire
F.X. Bard, (ORSTOM) Centre de Recherches Océanographiques, B.P. V-18, Abidjan, Côte d'lvoire
P. Cayré, ORSTOM, 213, rue La Fayette, 75480 Paris Cedex 10, France
T. Diouf, Centre de Recherches Océanographiques, B.P. 2241, Dakar, Sénégal
A. Fonteneau, (ORSTOM) Centre de Recherches Océanographiques, B.P. 2241, Dakar, Sénégal
T. Gouriou, ORSTOM, 213, rue La Fayette, 75480 Paris Cedex 10, France
J. Marcille, Fishery Base, P.O. Box 499, Sorico Biak, Irianjaya, Indonesia
M.A. Mensah, Fisheries Research Unit, P.O. Box B-62, Tema, Ghana
J.M. Stretta, ORSTOM, 213, rue La Fayette, 75480 Paris Cedex 10, France
Alain Fonteneau and Jacques Marcille coordinated the compilation and editing of this document.
Distribution
FAO Fisheries Department
FAO Regional Fisheries Officers
Regional Projects
Authors
| Fonteneau, A.; Marcille, J. (eds). Resources, fishing and biology of the tropical tunas of the Eastern Central Atlantic. FAO Fisheries Document Paper. No. 292. Rome, FAO. 1993. 354p. |
| ABSTRACT |
| The tuna resources of the eastern central Atlantic have been the object of an intensive fishery for over thirty years, and have been the object of numerous studies conducted under the coordination of the International Commission for the Conservation of Atlantic Tunas. This document presents a summary of current knowledge of the biology of the principal species of tuna in the eastern tropical Atlantic, the oceanographic environment of tunas and the influence of environmental conditions on production. A detailed description of the principal fisheries of the region and the history of their development is presented as well as the methods of population dynamics used to assess the abundance of the stocks and to estimate changes in the level of their exploitation. |
ACKNOWLEDGEMENTS
The production of this collective work would not have been possible without the dedication of the authors, the spirit of collaboration which stimulated the researchers of the oceanographic research centres of the African coast, and the support of the CECAF project of ORSTOM.
Alain Fonteneau was the prime mover of this work. Although the various chapters are the responsibility of the respective authors, we owe this document on tropical tunas to his persistency, his profound knowledge and his capacity to rapidly prepare a document of this quality.
We thank him for his dedication.
S. Garcia
Director, Fishery Resources and Environment Division
Institut sénégalais de recherches agricoles
French Institute of Scientific Research for Cooperative Development
Fishery Committee for the Eastern Central Atlantic
Food and Agriculture Organization of the United Nations
Rome, 1993 © FAO
Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.
This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.
II. SYSTEMATIC PRESENTATION AND GEOGRAPHICAL DISTRIBUTION OF SPECIES
(by T. Diouf and J.B. Amon Kothias)
2.1.2. Large tunas (Figure 2.2)
2.1.2.1. Thunnus albacares (Bonnaterre, 1788)
2.1.2.2. Thunnus obesus (Lowe, 1893)
2.1.2.3. Katsuwonus pelamis (Linnaeus, 1758)
2.1.2.4. Thunnus alalunga (Bonnaterre, 1788)
2.1.2.5. Thunnus thynnus (Linnaeus, 1758)
2.1.3 Small tunas and related species (Figure 2.3)
2.1.3.1. Euthynnus alletteratus (Rafinesque, 1810)
2.1.3.2. Auxis spp. (Cuvier, 1829)
2.1.3.3. Sarda sarda (Bloch, 1973)
2.1.3.4. Scomberomorus tritor (Cuvier, 1831)
2.1.3.5. Acanthocybium solandri (Cuvier, 1831)
2.1.3.6. Orcynopsis unicolor (Geoffroy St. Hilaire, 1871)
2.1.3.7. Scomber japonicus (Houtuyn, 1780)
2.2. ISTIOPHORIDAE AND XIPHIIDAE
2.2.1. Xiphias gladius (Linnaeus, 1758)
2.2.2. Istiophorus albicans (Latreille, 1804)
2.2.3. Makaira nigricans (Lacépède, 1802)
2.2.4. Makaira indica (Cuvier, 1831)
2.2.5. Tetrapturus albidus (Poey, 1860)
2.2.6. Tetrapturus pfeurgeri (Robins and de Sylva, 1963)
III. THE ENVIRONMENT IN THE EASTERN TROPICAL ATLANTIC
(By Y. Gouriou)
3.2. CLIMATE AND DYNAMICS OF THE SYSTEM
3.2.4. The wind field and its variability
3.3. THE OCEANIC CIRCULATION IN THE INTERTROPICAL ATLANTIC
3.4.3.1. The Senegalese Upwelling (figure 3.5)
3.4.3.2. The Gulf of Guinea Upwelling
IV. TUNA FISHERIES IN THE EASTERN TROPICAL ATLANTIC
(by A. Fonteneau, T. Diouf and M. Mensah)
4.2. PRINCIPAL METHODS OF FISHING
4.2.1. Pole and Line or Baitboat fishing
4.3 CHANGES IN CATCH BY SPECIES AND GEAR OF LARGE TUNA IN THE EASTERN TROPICAL ATLANTIC
4.3.2. The development of fisheries in the eastern tropical Atlantic
4.3.2.1. Historic artisanal exploitation
4.3.2.2. Live bait pole and line boats
4.3.3. Exploitation of large tuna (yellowfin, skipjack and bigeye), in the eastern tropical Atlantic
4.3.4. Assessment of average catches by zone and device in the zone and by device in the study zone during the recent period for yellowfin, skipjack and bigeye
4.3.4.3. Average catches 1978 – 1982
4.4. THE EXPLOITATION OF SMALL TUNA AND RELATED SPECIES IN THE EAST TROPICAL ATLANTIC
4.4.3. Size structure of catches
4.5. EXAMINATION BY COUNTRY OF THE CHANGES IN TUNA BOAT FLEETS EXPLOITING MAJOR TUNA IN THE EASTERN TROPICAL ATLANTIC
4.5.1.2. Boats and fishing methods
4.5.1.3. Fishing zones and seasons
4.5.3.2. Boats and fishing methods
4.5.3.3. Fishing zones and seasons
4.5.4. Taiwan (Province of China)
4.5.4.2. Boats and fishing methods
4.5.4.3. Fishing zones and seasons
4.5.7.3. Fishing zones and seasons
4.5.8.2. Boats and fishing methods
4.5.8.3. Fishing zones and seasons
4.5.9.2. Boats and fishing methods
4.5.9.3. Fishing zones and seasons
4.5.10.2. Boats and fishing methods
4.5.10.3. Fishing zones and seasons
4.5.11.2. Boats and fishing methods
4.5.11.3. Fishing zones and seasons
4.5.11.6. Catch rates by Korean fleets
4.5.17.2. Boats and fishing methods
4.5.17.3. Fishing Zones and Seasons
4.5.18.3. Fishing zones and seasons
4.5.19.2. Boats and fishing methods
4.5.19.3. Fishing zones and seasons
V. MIGRATIONS (by F.X. Bard, P. Cayré and T. Diouf)
5.1. GENERALITIES AND STUDY METHODS
5.1.1. Introduction: Definition and importance of studies on migration
5.1.2.1. Direct methods: tagging
5.2. MIGRATIONS OF MAJOR TUNA (yellowfin, skipjack and bigeye)
5.2.1.2. Migrations of juveniles
5.2.1.5. Determinants of yellowfin migrations
5.2.1.6. Yellowfin migration model
5.2.2.4. Comparison of tagging and fisheries data
5.2.2.5. Determinants of skipjack migrations
5.2.2.6. Migratory model of skipjack in the Eastern Atlantic
5.2.3.2. Juvenile migrations (1.5 to 8 kg)
5.2.3.3. Preadult migrations (8 to 20 kg)
5.2.3.4. Adult bigeye migrations
5.2.3.5. Determinants of bigeye migrations
5.2.3.6. Migration model of Atlantic bigeye
5.3. SMALL TUNA AND RELATED SPECIES
5.3.2. Spotted tunny (Euthynnus alletteratus)
5.3.2.1. Geographic distribution by stage of development
5.3.2.2. Migrations and fishing seasons
5.3.3.1. Geographic distribution by stage of development
5.3.3.2. Fishing migrations and seasons
5.3.4. Atlantic bonito (Sarda sarda)
5.3.4.1. Geographic distribution by stage of development
5.3.4.2. Migration and fishing seasons
5.3.5. Western African Spanish Mackerel (Scomberomorus tritor)
5.3.5.1. Geographic distribution by stage of development
5.3.5.2. Migrations and fishing seasons
5.3.5.3. Ecological factors linked to distribution
5.3.6.1. Migrations and fishing seasons of the plain bonito (Orcynopsis unicolor)
5.3.6.2. The Wahoo (Acanthocybium solandri)
5.3.7. Conclusion on migrations of small tuna
VI. BIOLOGY OF TUNA (by P. Cayré, J.B. Amon Kothias, T. Diouf and J.M. Stretta)
6.1. MAJOR TUNA: YELLOWFIN, SKIPJACK, BIGEYE
6.1.1. Reproduction of major tuna: yellowfin, skipjack, bigeye
6.1.1.2. Study methods for east tropical Atlantic tuna reproduction
6.1.1.3. Sexuality and fertilization
6.1.1.4. Size at first maturity
6.1.1.6. Spawning (zones, periods, frequency) and fecundity
6.1.2.1. Definition and expression
6.1.3.2. Determination and expression methods of results
6.1.4. Diet and feeding behaviour of yellowfin, skipjack and bigeye
6.1.4.2. Methods used for the study of tuna feeding
6.1.5. Tuna and thermoregulation
6.1.5.2. Description of the vascular heat exchange system
6.1.5.3. Classification of tuna based on the heat exchange system
6.1.5.4. Advantages and mechanisms of tuna thermoregulation
6.1.6. Dissolved oxygen and distribution of Atlantic tuna
6.1.6.2. Tolerance thresholds of yellowfin, skipjack and bigeye
6.1.6.3 Levels of dissolved oxygen in the Atlantic and distribution of the species 203
6.1.7. Associations of tuna schools with other large pelagic animals or various floating objects
6.1.7.2. Data and methods of analysis
6.1.7.3. Frequency of free and associated schools
6.1.7.4. Tuna and pelagic animals
6.1.7.5. Tuna and natural debris
6.1.8. Parasites of major tuna (yellowfin, skipjack and bigeye)
6.1.9. Mixtures of species within tuna schools
6.1.9.2. Pole and line boats of Tema
6.1.9.4. Discussion of results
6.2. Small tuna and related species
6.2.2. Spotted tunny (Euthynnus alleteratus)
6.2.2.4. Nutrition and feeding behavior
6.2.2.7. Physiology and responses to stimuli
6.2.2.8. Association with flotsam
6.2.3.4. Nutrition and feeding behavior
6.2.4. Atlantic bonito (Sarda sarda)
6.2.4.4. Nutrition and feeding behavior
6.2.5. Spanish mackerel (Scomberomorus sp.)
6.2.5.4. Nutrition and behavior
6.2.6.1. Plain bonito (Orcynopsis unicolor)
6.2.6.2. Wahoo (Acanthocybium solandri)
6.3.1. Definition of measurements utilized
6.3.2.1. Length (fork length) - weight relation
6.3.2.2. Predorsal length (DL1) - length (fork length:FL) relation
6.3.2.3. Eviscerated weight (EW) - total live weight (W) relation
6.3.3. Length-weight relation of skipjack
6.3.4. Size-weight relation of small tuna and related species
6.3.4.1. Spotted tunny (Euthynnus alleteratus)
6.3.4.2. Auxids (Auxis thazard and Auxis rochei)
6.3.4.3. Atlantic bonito (Sarda sarda)
6.3.4.4. Western African Spanish Mackerel (Scomberomorus tritor)
6.3.4.5. Plain bonito (Orcynopsis unicolor)
VII. ENVIRONMENT AND TUNA FISHING IN THE EASTERN TROPICAL ATLANTIC
(by J.M. Stretta)
7.2.2. Spatio-temporal divisions
7.3. Relations between tuna and environmental parameters
7.3.1. Relation between tuna catches and surface temperature
7.3.2. Relation between tuna catches and dissolved oxygen
7.3.3. Relation between tuna catches and the surface salinity
7.3.4. Relation between tuna catches and thermocline
7.3.5. Relation between tuna and productivity of the seas
7.3.5.1. Productivity of intertropical waters
7.3.6. Food chain and tuna food
7.3.7. Ecological conditions for reproduction
7.4. Analysis of catches within spatio-temporal strata
VIII. MODELING, MANAGEMENT AND DEVELOPMENT OF TUNA FISHERIES IN THE
EASTERN CENTRAL ATLANTIC
(by A. Fonteneau)
8.1.1. Exploitation of migrating stocks by multi-gear fisheries
8.1.2. General review of models
8.1.2.2. Age-structured models: vectors of fishing mortality (F) and underlying ages (N)
8.1.2.3. Yield per recruit analysis
8.1.2.4. Stock recruitment relationships
8.1.3. The problem of species composition:
8.2. MODELING AND STATUS OF STOCKS
8.2.1.2. Age structured analysis: Recruitment and rate of fishing mortality as a function of age.
8.2.1.5. Simulation models of the yellowfin fishery
8.2.2.2. Age-structured analysis: Recruitment and fishing mortality as a function of age
8.2.3.2. Age-structured analysis: Recruitment and fishing mortality rates as a function of age
8.2.4. Multiple gear and multiple species simulations