Biomass evaluation

Biomass evaluation

Nortek is the only technology provider that combines the measuring capabilities of traditional ADCPs (current speed and direction) with those of a scientific echo sounder. This opens up new research opportunities for those trying to understand the abundance or dynamics of ocean biomass, enabling oceanographers and biologists to collaborate more closely on research projects. It also offers cost savings by reducing the number of equipment purchases and installations.

Researchers at the Institute of Marine Research in Norway using an ADCP for biomass evaluation (through echo measurements).

Highlights

  • Current profiles at multiple levels in the water column
  • Concurrent measurement of high-resolution acoustic signal strength
  • Biomass abundance and vertical distribution in the deep ocean
  • Long-term deployments under the Arctic or Antarctic ice cap

What and why

What is biomass evaluation and why is it useful?

Biomass evaluation at sea is a survey of the total quantity or weight of organisms, such as fish or krill, in a given area or volume. This is of great value for resource management and helps support sustainable fisheries.

Being able to combine the documentation of biomass with data on the speed and direction of currents can add considerable value to a research project. For example, having precise information on currents may help researchers more accurately calculate the size and weight of schools of fish or swarms of krill.

Living organisms also make a biological imprint on physical ocean processes and can reveal details of layered flow patterns that are undetectable using classic ADCP technology. The way in which living creatures react with the physical processes in the ocean can be analyzed, while observing the biological imprint can help researchers study physical processes on a much smaller scale, and with greater precision.

The desired end result is a clear understanding of the volume and dynamics of biomass in the ocean’s ecosystem, and how this biomass varies over time. For example, biomass surveys can help find types of fish in waters where they were previously unknown. Nortek’s solutions can also help researchers monitor biomass far from land, where it would be impractical and expensive to use boats to continuously conduct surveys. Furthermore, Nortek’s technology enables researchers to deploy monitoring instrumentation at greater depths, beyond the range of echo sounders mounted on ships.

This is of great value to the scientific community, as we have limited knowledge about the nature of marine life at depths of over 500 m.

Who it's for

Solutions for biomass evaluation are most relevant for fishery scientists and marine biologists. Nortek’s instrumentation enables such researchers to work together with oceanographers studying ocean currents and researchers investigating sediment transportation.

Biomass evaluation has traditionally been done mainly with echo sounders mounted on moving vessels. Researchers now see the need to supplement this data with biomass evaluation based on measurements taken from one or more fixed positions over a longer period.

Technical considerations

Instrumentation for evaluation of biomass is deployed in the same way as a regular ADCP. This means that operators must be able to deploy the instrument in the ocean, and provide a structure where the instrument can be affixed. Such a structure may be a frame on the bottom of the sea, or a subsurface buoy.

Data presentation

OceanContour is a standalone, interactive desktop application that provides data visualization and processing capabilities for acoustic Doppler systems, such as ADCPs for biomass evaluation. Data can also be exported by using other software, such as specialized biomass estimation tools.

Data presentation

Choice of instrument

Nortek is the only technology provider that combines the measuring capabilities of traditional ADCPs (current speed and direction) with those of a scientific echo sounder in just one instrument. This saves researchers the need to buy two instruments to cover these capabilities – a unique advantage that makes research simpler and cheaper.

Most ADCPs have a resolution so low that it is difficult to precisely identify the constituents that scatter the acoustic pulse. The high resolution of Nortek’s ADCPs, on the other hand, enables very precise measurements at a vertical resolution never before seen in commercial instrumentation.

The Signature100 offers a 3–400 m range from its deployment depth (this range applies to the echo sounder function only). It is the ultimate specialized tool for high-resolution measurements of biomass in the water column. This instrument is tailor-made for fishery scientists and marine biologists.

The Signature500 is the right tool for biomass surveys that require a maximum 50 m range, while the Signature1000 has a capacity for surveys requiring a range less than 30 m. The Signature500 and Signature1000 would be the instruments of choice for researchers focusing primarily on the physical attributes of the ocean (current speed and direction), while collaborating with marine biologists to add value to their research project.

  • Signature1000

    CURRENT PROFILER

    Signature1000

    High-performance mean currents and turbulence, wave height and direction
  • Signature500

    CURRENT PROFILER

    Signature500

    Mean currents and turbulence, plus wave height, direction and ice tracking
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