FLANAGAN and HENDRICKSON: FISHERY AND REPRODUCTIVE BIOLOGY OF TOTOABA 



former size, and catch events have become spo- 

 radic and undependable. The span of the breeding 

 period has been reduced from several months to a 

 period of only 18 days within the open season of 

 1972. Of those 18 days, a majority of the catch 

 occurred on 21 and 22 March. Although data are 

 scarce, the average size of adult fish is reduced and 

 in recent years most commercially caught in- 

 dividuals have probably been first- or second-year 

 spawners. These harsh facts are indications of a 

 fish population struggling unsucessfully for sur- 

 vival under pressure. 



The future of the species is uncertain. Until the 

 recent action of the Mexican Government in 

 establishing a total closed season, the outlook was 

 bleak, indeed. While the commercial fishery was 

 ready to crash before its legal cancellation (a 

 number of financial failures were reported to us), 

 and would presumably never have hunted down 

 and eliminated the last reproductive pair of these 

 magnificent animals, the continued rising prices 

 for totoaba in a seller's market would have guar- 

 anteed continued maximum pressure. If there are 

 behavioral elements in the reproductive pattern of 

 the species which require mutual stimulation in 

 large schools for reproductive success, a threshold 

 may have already been crossed which will drive the 

 totoaba the way of the passenger pigeon. The 

 trends produced by irreversible change of the 

 spawning ground may prove more important than 

 we have speculated. In either of the last two 

 circumstances, the ability of the stocks to rebound 

 upon release of fishing pressure may be critically 

 impaired. 



We suggest three meaningful measures at this 

 stage: 1) Continuation of the total closed season 

 which has been imposed, until intensive studies 

 document a strong and vigorously increasing 

 population. We suggest an enforcement period of 

 about IV2 times our estimated 6-yr minimum 

 recruitment age, or 10 yr. 2) Action by the U.S. 

 Government (the major market area) com- 

 plementing the Mexican action by declaring the 

 totoaba an endangered species, to facilitate en- 

 forcement of the neighbor country laws by 

 removing much of the stimulus for poaching and 

 smuggling. 3) Intensive scientific investigation to 

 provide knowledge of the species' autecology and 

 behavior with potential application to all facets of 

 management, ranging from environmental ma- 

 nipulation to hatchery techniques. Failing these, 

 we conclude that the probability of extinction of 

 Cynoscion macdonaldi by the year 2000 is high. 



ACKNOWLEDGMENTS 



Various research grants and contracts con- 

 tributed to the support of this work and are here 

 gratefully acknowledged: International Union for 

 the Conservation of Nature and Natural Re- 

 sources/World Wildlife Fund Project No. 623; 

 National Science Foundation Grants GB29101 and 

 GB34675; National Aeronautics and Space Ad- 

 ministration Contract NAS5-21777; and a special 

 University of Arizona Foundation Grant. We 

 acknowledge with sincere appreciation the sup- 

 port and professional participation of Mexican 

 authorities and scientists in this work. Luis Ka- 

 suga Osaka, Director of the National Institute of 

 Fisheries, Mexico, and Pedro Mercado Sanchez of 

 the Subsecretariat of Fisheries, Ministry of In- 

 dustry and Commerce, helped us obtain neces- 

 sary permits (3977, 5344, 8202, and 12183) for work 

 in the field and in other ways provided important 

 support and encouragement. Among the many 

 members of the National Institute of Fisheries 

 who gave freely of their time and efforts, special 

 mention must be made of Joaquin Arvizu and 

 Humberto Chavez, who cooperated in field work 

 and data analysis. We are particularly indebted to 

 Biologist Chavez, Head of the Institute's Depart- 

 ment of Fisheries Resources, for important con- 

 tributions and professional advice from inception 

 of field work to manuscript preparation. The 

 Fishery Inspectors of San Felipe, Baja California 

 Norte, and Puerto Penasco, Sonora, rendered 

 valuable assistance in making contacts with 

 fishers and made date available. Francisco 

 Aguilera Grijalva, Fishery Inspector at Golfo de 

 Santa Clara, Sonora, made particular efforts on our 

 behalf and was of invaluable assistance in collec- 

 tion of detailed catch data. We thank all the 

 students of the University of Arizona who ren- 

 dered assistance on field trips, and all the staff and 

 students of the Institute of Oceanologic Inves- 

 tigations, Autonomous University of Baja 

 California, who have been such productive 

 partners in most of our work in the northern Gulf 

 of California. Special recognition is due L. T. 

 Findley for his field and museum contributions 

 and enthusiastic interest. We greatly appreciate 

 the time spent by D. A. Thomson, J. Tash, and G. 

 Pyke who read the manuscript critically and 

 consulted on matters of data analysis and inter- 

 pretation (all responsibility for errors is ours). It is 

 impossible to overvalue the contribution of Lupe 

 P. Hendrickson in clerical, translation, and edi- 



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