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> Advantages vs. Disadvantages for Hydroacoustic Echo Sounder Systems

 
 

   Hydroacoustics have several key advantages over other fisheries assessment techniques, including:

 
 
Cost-effective
Hydroacoustics offers a cost-effective method of monitoring fish over a large area, for extended periods of time. This is primarily due to the relatively low field man-hours required. Due to the high sample power of hydroacoustics, more data can be collected in a given amount of time than with virtually any other fisheries evaluation technique. In fixed-location evaluations, hydroacoustics is routinely used to collect fisheries data 60 min/hr, 24 hr/day, for up to a year at a time.
Unobtrusive
Hydroacoustics does not harm the fish it monitors, or the surrounding environment. At the operating frequencies commonly used, it doesn’t even alter fish behavior (with rare exceptions). Other fisheries evaluation techniques invariably affect fish behavior, and some direct sampling techniques inflict injury or death.
Non-selective
Hydroacoustics is not selective in what it monitors, minimizing bias. It monitors fish of all sizes, and is generally not limited by fish size, range or behavior. It also provides independence from net avoidance and other net bias problems. An analogy to netting would be a gill net with infinitely variable mesh sizes.
Established and Defensible
Quantifiable hydroacoustics has been used extensively throughout the world for nearly 40 years. Hydroacoustic results have been successfully defended in court proceedings, before government legislatures, and in United States FERC (Federal Energy Regulatory Commission) relicensing hearings.
For many fisheries agencies around the world, hydroacoustics has become an important tool for
evaluation fisheries questions and for managing stocks.
Real-time Results Available
Hydroacoustic data can be analyzed as they are collected, permitting retrieval of real-time estimates of fish abundance (or biomass), distributions, and behavior.
Collects Large Quantities of Data
The ease of acquisition of large quantities of data improves statistical comparisons.
 
 

 
 

   Hydroacoustics may not be a good fit for your study, depending on your objectives. Here are the
   principal disadvantages or limitations of hydroacoustic techniques:

 
 
Collects Large Quantities of Data
In addition to the advantage of rapidly collecting large quantities of data, hydroacoustics collects so much data that it may present a challenge to store and analyze, depending on your systems. Fortunuately, several helpful database and analysis tools are available - making the large amounts of data more manageable.
Lack of Definite Species Identification
While there has been some limited success in the laboratory with fish species identification, hydroacoustics cannot reliably identify species directly. It can estimate fish size, and this information coupled with multi-frequency and distributional information (e.g., depth or diel distributions) or behavioral data (e.g., swimming path, velocity) frequently aids partitioning of fish abundance estimates by species.
Monitoring Fish Near Boundaries
Hydroacoustics has difficulty monitoring fish very close to boundaries, such as near the very bottom or the surface. Difficulties can be minimized by careful specification of hydroacoustic system capabilities, and in the case of fixed-location studies, by proper siting and deployment.
Initial Investment
Scientific hydroacoustic equipment capable of reliable quantification of fisheries parameters requires a significant initial investment. However, like other innovative technologies, over the last two decades costs have steadily decreased while capabilities have increased.
Requires Training in Hydroacoustic Concepts
Hydroacoustic techniques are relatively complex compared to other fisheries techniques. Proper application requires more training and experience than required for most fisheries assessment techniques (e.g., netting, mark-recapture, electroshocking). While most fisheries professionals should have little difficulty grasping hydroacoustic concepts, most have little or no training in hydroacoustics, and may be initially unfamiliar with the mathematical, electrical, and physical concepts involved.
 

> Would hydroacoustics be the best fit
   for my study?

Is hydroacoustic equipment best for the needs of your study? Click here and find out. up  
 
 

Hydroacoustics is an extremely powerful and effective fishery assessment tool when properly applied under appropriate conditions. However, the technique is not a panacea for all fisheries assessment challenges, and is not applicable in many cases. To find out if the objectives for your study would be best addressed with hydroacoustics, take this quick questionnaire.

> What are hydroacoustic systems?

> How does it work?

> Advantages vs.  Disadvantages?

> Would this be the best fit for my study?
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