Tagging whales and mapping prey

Hi everyone,

My name is Elliott Hazen and I currently work for the National Oceanic and Atmospheric Association’s Environmental Research Division’s lab. Before that, I worked at Duke with Ari Friedlaender which is where I became involved with marine mammals and tagging. I am leading a small research project measuring prey and oceanographic variables around the tagged whales, before and after acoustic playbacks. The main task of my job is to understand which physical features are correlated with denser prey, and how these factors influence the whale behavior measured by the tag. These data can be used to inform our understanding of how baleen whales respond to the simulated SONAR.

I use a fisheries echosounder made by SIMRAD to measure the distribution and density of prey in the water column. The picture of the metal towfish has two orange echosounders, one operating at a high frequency (120 kHz) and one at a lower frequency (38kHz). Each echosounder emits a pulse of sound, similar to a dolphin echolocating, and measures the sound properties when it returns to the echosounder. We can figure out how deep layers of prey are, the shape of any detected schools, and how these prey patches change over time without a large impact to the prey. Our main limitation is that we cannot identify the species we are looking at acoustically. Luckily for us, in the case of a blue whale, we know they are eating krill. The screen shot shows an echogram from the 120kHz echosounder with higher acoustic densities in orange and red, and lower densities in blue to green, and the bottom shows up as a dark red. The echograms show time on the horizontal axis and depth shown vertically. This image is a good sample of what we’ve seen, specifically that the krill schools are denser near shelf breaks, such as where the bottom depth drops quickly from 100 to 180 meters. It also confirms what a colleague, Dr. Jarrod Santora has found for krill at a broader scale along the California coast. We hope this project will give us more information on how blue whales are making foraging decisions as we collect more fine scale measurements and more tag data from these large whales.

 

Comments

[jobs in writing]

I saw like this in Discovery channel I am so empress how they tagged the whale in just a little time.

[economics help]

interesting and detailed description of an experiment

[fectdiqueft]

проекты по окружающему миру


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[Majella McGonagle]

Interesting post. My 11 year old son loves all wide life documentaries especially about whales and sharks.

[Justice]

Surprisingly well-wirtten and informative for a free online article.