Meeting Abstract
Many marine species form groups that exhibit schooling behavior in which conspecifics collectively perform directed movements. Squid and fish are hypothesized to have occupied similar niches over evolutionary time, and their resulting competition is reflected in convergent traits including collective social behavior. However, few quantitative measurements of schooling behavior have been made in squid, and the ability of squid to school in a manner similar to fish continues to be debated. We used cameras mounted inside a large pelagic net trawl to record the spatial organization of schools of the ecologically-similar California market squid, Doryteuthis opalescens, and Pacific sardine, Sardinops sagax. Our data suggest that schooling groups of market squid observed in situ exhibit similar spatial organization to those of sardine. To compare school formation in the two taxa, we examined how schooling groups reorganize after disruption by a strobe flash in a lab setting. We found that lab measurements of angular deviation for both species assessed in this manner were similar to those observed in situ. Despite the different types of startle-response behaviors (escape jet in squid vs. C-start in fish), groups of both species rapidly reorganized into a coherent school. As an assessment of how collective movements are coordinated in D. opalescens and S. sagax, we are currently working to compare the nature and extent to which movements of “influencers” predict movements of others within groups. Taken together, our results support the idea that groups of pelagic squid and fish exhibit convergent schooling behavior.
