MURPHY and SHOMURA: PRE-EXPLOITATION ABUNDANCE OF TUNAS 



APPENDIX A 



VALIDITY OF YELLOWFIN TUNA AS AN INDEX OF THE TUNA-SHARK 



TROPHIC LEVEL 



Throughout this paper we have compared the 

 distribution of tuna with the distribution of cer- 

 tain biological and physical properties of the 

 environment. We have examined these environ- 

 mental properties in relation to the number of 

 yellowfin and other tuna captured per 100 hooks. 



This procedure could lead to misinterpretation, 

 if the size of the individuals taken varies sig- 

 nificantly or if the relative abundance of species 

 within a trophic level changes with respect to 

 time or space. 



Ideally, we wish to ascertain the relative 



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2' 4« 6° 8* 10* \2' 14" N S 4* 2° 0° 2° 4" 6° 8° 10' 12* 14° N 



LATITUDE LATITUDE 



Appendix Figure 1.— Latitudinal distribution of longline-caught fish on long 150°W during August-September 

 1951, a period of good fishing success. A. Number of fish per 100 hooks. B. Weight (in kilograms) per 100 hooks. 



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