Advances in Obtaining Environmental Data by Tracking Free-Swimming Sharks

Friday, 14 February 2014
Acapulco (Hyatt Regency Chicago)
Kim N. Holland , University of Hawaii, Manoa, Manoa, HI

Knowledge of the environment (depth, temperature, oxygen concentration, etc.) experienced by free swimming fishes is important for advancing our understanding of their physiological ecology and habitat preferences. However, these same data could also be useful for improving oceanographic models (e.g., regional and local circulation patterns, upwelling events, etc.). Our research has demonstrated that even ‘coastal’ sharks make frequent dives between the surface mixed layer and a depth of several hundred meters and thereby repeatedly ‘sample’ ocean structure.  However, obtaining these data in a timely manner (for example, in near real time) and with sufficient precision and geographic accuracy presents significant challenges because these species come to the surface infrequently and/or for short periods of time. This situation is exacerbated in areas with minimal satellite coverage.  For instance in Hawaii, Argos satellite coverage is only approximately 20% of any 24 hour period.

To improve methods for obtaining environmental data from free swimming fishes and to assess the quality and utility of these data, we are tagging sharks in the PacIOOS arena around Oahu, Hawaii. The PacIOOS array has a suite of “traditional” oceanographic sensors that contribute to a data base against which we can compare our animal-derived data and to which, potentially, we can add our own results.   In order to acquire both the desired environmental data (e.g., temperature, oxygen saturation) and get accurate estimates of the animal’s location, we are tagging sharks with combinations acoustic, satellite and pop-off satellite tags.  One new avenue of inquiry is whether land based receivers can significantly augment the data being acquired via satellite transmissions. This presentation will briefly review the progress being made in these various lines of investigation.