Journal article Open Access

Decadal variation in the trans-Pacific migration of northern bluefin tuna (Thunnus thynnus) coherent with climate-induced change in prey abundance

Polovina, Jeffrey J.

Northern bluefin tuna, Thunnus thynnus, apparently spawn only in the western Pacific and a portion of the juveniles migrate to the eastern Pacific. During the past decade, catches of northern bluefin in the eastern Pacific have declined. One possible cause for this decline, proposed by bluefin stock assessment studies, is a decline in the proportion of bluefin that migrate out of the western Pacific. This hypothesis is examined with several indices of the relative abundance of bluefin tuna in the western and eastern Pacific. These indices suggest a decline in the proportion of bluefin migrating to the eastern Pacific since 1977. This period of reduced bluefin migration coincides with a period when a prey of bluefin, Japanese sardine, Sardinops melanosticta, were abundant off Japan. It is hypothesized that in years when sardines are abundant off Japan, a higher proportion of bluefin stay in the western Pacific compared with years when sardines are scarce. Currently, the adun‐dance of sardines off Japan is declining. If this decline continues, this hypothesis predicts an increase in bluefin migrating north of Hawaii and into the eastern Pacific.

Files (406.4 kB)
Name Size
article.pdf
md5:83fa11d19c5e83afa12262c484219440
406.4 kB Download
44
83
views
downloads
Views 44
Downloads 83
Data volume 33.7 MB
Unique views 44
Unique downloads 81

Share

Cite as