The data used were for the years 1964, 1965, 

 and 1967. The data were aggregated by vessel 

 for the whole year. For each vessel, the following 

 information was produced: 



1. Days at sea 



2. Days fishing 



3. Total trips 



4. Days at sea by calendar quarter 



5. Days fishing by calendar quarter 



6. Trips to major areas: offshore, inshore, 

 off Canada 



7. Pounds caught, by major species 



8. Value, by major species 



9. Total pounds caught 



10. Total value 



This information was augmented by the 

 addition of information from the Merchant 

 Vessels of the United States (1965), including: 



11. Gross tons 



12. Horsepower 



13. Hull construction 



14. Year built 



Information from National Marine Fisheries 

 Service files was added on: 



15. Crew size 



16. Home port 



Vessels with total landings valued at less 

 than $10,000 were excluded from the sample; 

 we made the assumption that these were casual 

 fishermen. There were about 120 vessels excluded 

 per year, accounting for 3% of New England 

 landings. Otherwise, no editing was done; 

 therefore, the sample contains all trips, in- 

 cluding brokers. Thus, the estimates have built 

 into them all conditions that vessels from this 

 fleet experience on the North Atlantic. The total 

 sample consisted of about 383 vessels per year 

 or 1,149 vessel years. 



The Tropical Tuna Purse 

 Seine Fleet 



The Inter-American Tropical Tuna Commis- 

 sion (lATTC) kindly let us transcribe landings 

 data from their files for the years 1966,1967, 

 and 1968. The data were for the whole year 



for the full-time purse seiners. The data trans- 

 cribed were as follows: 



1. Official number 



2. Days at sea 



3. Landings by species 



4. Major area fished: Atlantic or Pacific 



This information was supplemented by the 

 addition of information from the Merchant 

 Vessels of the United States (1965) including: 



5. Gross tons 



6. Horsepower 



7. Length 



8. Year built 



Finally, the following information was added: 



9. Capacity (American Tunaboat 

 Association) 



10. Crew size (NMFS files) 



The total sample consisted of 89 vessels per 

 year or 267 vessel years. The data were divided 

 into two periods: (1) when there was unrestricted 

 fishing for yellowfin and (2) when yellowfin was 

 restricted to 15% of the total catch. The data 

 from the restricted season were not used in the 

 analysis because of the different conditions 

 following the season closure. 



THE STATISTICAL RESULTS 

 Overall Results 



The statistical results of these experiments 

 are quite encouraging. It is possible to explain 

 very high variations in catch with a minimum 

 of information. In the tropical tuna fishery we 

 can explain approximately 70% of the variation 

 in the dependent variable, and in the New 

 England trawl fishery, approximately 84% . 



Tests for heteroscaedasticity showed that it 

 existed in the linear equations. When it is 

 present, we have inefficient estimators. Log- 

 arithmic transformation of the variables in both 

 fisheries removed this problem. Results in both 

 forms are reported, but only the logarithmic 

 results are suitable for analytical work. 



Several regression experiments were run 



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