Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1996

Erin A. Baker
University of Toronto
Toronto, Canada

Bruce B. Collette
Supervising Scientist
Department of Vertebrate Zoology
Division of Fishes

"The opportunity to work in such an exciting environment, on such a challenging project is one of the greatest learning experiences I have ever had."

Systematic status of the Red Sea-northern Indian ocean Scomber, including an evaluation of morphological characters used to distiguish between S. japonicus and S. australasicus

ABSTRACT
The genus of mackerels, Scomber, shows the typical adaptations for high speed swimming that characterize the family Scombridae, which also includes the tunas, Spanish mackerels and bonitas. Because various adaptations allow for more efficient swimming, the genus is highly conservative in morphology. Distinction of two closely related species of mackerel, Scomber japonicus and S. australasicus has been based on only four morphological characters. This study evaluates these, as well as other morphometric and meristic characters for reliability in identification. Two characters often used, colour patterns and dorsal groove to dorsal interspace ratios, were not reliable enough to use for purposes of identification. The other two characters, number of dorsal spines and number of interneural bones, can be used simultaneously for accurate identification of 100% of all specimens. Though reliable, this method of identification is impractical to use in the field because determining interneural bone counts requires either dissection, which is time consuming, or radiography, which is costly. Unfortunately, other morphometric and meristic characters studied here did not reveal alternative methods for diagnosis of species. The inability to identify species accurately and efficiently has profound implications for the study and management of mackerels specifically, but also of Scombrids in general.

This research was supported by a grant from the Smithsonian Women's Committee.

Letter of Gratitude