Robbie Schallert:
I recently joined the exciting TRCC team in the spring of 2003 with the opportunity to work with some of the most incredible species of pelagic fish (tuna, billfish, shark) I also have the privilege of rubbing elbows with a group of scientists that is second to none in the world. Besides maintaining a daily assortment of data, my job allows me to delve into cutting edge physiology and biochemistry. More specifically, my colleagues and I are currently looking at how the cardiovascular system of tunas is capable of maintaining function across a wide range of temperatures.
Jason Blank-
My PhD research addresses the cardiac physiology of tunas. Tunas are endothermic (warm-blooded) fishes with high metabolic rates, which require a high rate of blood flow to their tissues. Tuna hearts are larger, can beat faster, and can pump more blood than the hearts of other fish. Although tunas are endothermic throughout their swimming muscle, viscera and heads, their hearts operate at the temperature of the surrounding water. This creates a challenge when a tuna dives into cold water, as the cold heart must still pump enough blood to supply the warm, active muscles with oxygen. I am interested in finding out how tuna hearts are affected by such temperature changes and how tunas have evolved high-performance hearts compared to those of other fishes. Using fish from the TRCC, we have measured the effects of temperature change on heart rate, stroke volume, and cardiac output in yellowfin and bluefin tunas, as well as the pacific mackerel. One of our major findings so far is that bluefin hearts are less sensitive to temperature change and beat faster at low temperatures than yellowfin tuna hearts. This difference may help explain how bluefin can tolerate a much wider range of water temperatures in the wild than yellowfin can. Currently, we are focused on discovering the biochemical basis for the extraordinary performance of tuna hearts and the different temperature-tolerances of different tuna species.
Andreas Walli-
In May 2000 I started as a Research Technician in the Tuna Research and Conservation Center team at Stanford University. Generally my job involves working with the huge amount of data obtained from electronic tags and remote sensing techniques (Gigabytes of binary files). I visualize and analyze the data to show the great variety of exciting natural phenomena we are observing in our electronic tagging studies. One way of lightening up the spatiotemporal complexity of such datasets is to combine them with other oceanographic data layers obtained by remote sensing and analyze it through GIS techniques; by this mean it is possible for a human brain to synthesize and understand the patterns and relationships which would otherwise stay undetected. In this case we are not only able to visualize movement patterns of many pelagic over time but also to determine the causative factors and physical environmental patterns, which govern the life of these animals. Currently I am a research assistant to Prof. Barbara Block and have a organizational and management function on the operational side of research projects like TOPP. In autumn 2003 I will start a PhD. with Prof. Block on habitat modeling of Atlantic Bluefin Tuna for the development of a satellite based system that will allow the implementation of dynamic area/time closures based on ecosystem parameters that change the migration pathways and aggregation of these highly mobile species. The advantages of such novel management approaches are the protection of a critical population size, the improvement of fisheries efforts as well as decreasing the long-term financial risks of such a fishery.
Kevin Weng-
I am a PhD student interested in the habitats of pelagic animals, their movements within these habitats on daily, seasonal and ontogenetic time scales, and the effects of physiological specializations on habitat breadth. I am studying the lamnid sharks, focusing on the habitats and migrations of the salmon shark and the white shark. My aims are to define the regions of the ocean that are important to these species; determine the oceanographic conditions that define their habitat; learn of their movement patterns within these areas; and investigate potential ecological implications of their endothermic physiology.