TABLE F-1  Estimates of mixing between the two stocks based on discriminant function analysis using jackknife probabilities of group membership of adult bluefin tuna sampled from a variety of locations and at different times.

 

Estimated % mixing

Source of tuna

Analyzed 1983

Analyzed 1984

Western Atlantic Ocean

  Massachusetts (1980)

12.7

10.8

  Massachusetts (1982)

11.9

  Gulf of Mexico (1983)

4.2

Eastern Atlantic Ocean

 

 

  Gibraltar (1982)

11.3

90.0

  Gibraltar (1983)

4.3

  Tyrrhenian Sea (1982)

12.9

60.0

  Tyrrhenian Sea (1983)

5.2

  Ionian Sea (1982)

14.3

100.0

A summary of some other problems is presented in Table F-1 (adapted from Calaprice, 1983, Table 2). Estimated mixing varies from 4 to 100%, depending on when it was analyzed and on the source of the material.

Although there are new pattern recognition techniques that could be applied to the data collected by Calaprice, the committee does not recommend such analysis. A better approach would be to apply new analytical techniques to new samples.

REFERENCES

Calaprice, J.R. 1983. X-ray fluorescence of stock variation in bluefin tuna, status report. pp. 1-42.

Calaprice, J.R. 1984. X-ray fluorescence study of stock variation in bluefin tuna, Third quarterly report. pp. 1-25.

Calaprice, J.R. 1985. Chemical variability and stock variation in northern Atlantic bluefin tuna. ICCAT SCRS/85/36. pp. 222-252.



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