Electricity in Fish Research and Management

Theory and Practice

W. R. C. Beaumont

• Publisher: Wiley-Blackwell
• Year: 2016
• ISBN:
  9781118935569
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Fisheries & Aquaculture
• Index: Technology & Engineering

Electricity in Fish Research and Management, 2nd Edition provides a comprehensive discussion of the uses of both electricity and electrical principles in fishery management and research. It covers electric fishing (including theory, equipment, data analysis and practical factors affecting efficiency), fish barriers, fish counters and fish welfare issues.

The book concentrates on Electric Fishing (or Electrofishing); an internationally accepted and widely used procedure for sampling fish. Over the past 50 years electric fishing has become a standard method for fishery studies and management e.g. establishing population densities and abundance. However, due to the potential hazards of the method (both to operators and fish) there is a continuing need to develop and promote best practice guidelines.

The author has studied fish ecology for 40 years and understands the need for information that reaches out to all levels of understanding in the field. Previous books on this subject have either been collections of scientific papers and/or technical reports or very simple instruction manuals. In this book theory and practice is explained using non-technical language and simple equations. It brings depth as well as breadth in both information and principles behind the methods and should be an invaluable tool to both fisheries managers and researchers.

Although the book is aimed at undergraduates, the clear explanation of the factors means that the book is suitable for all levels of practitioners.

CHAPTER 1
Introduction

Over the past 100 years, electricity, or he use of electrical theory, has become a vital tool for fishery research and management. It is used to divert fish from hazards, capture them for research or husbandry, count them as they migrate within rivers and anaesthetise/sedate them for easier handling or tagging. Due to the potential hazards associated with using ‘free’ electricity in an aquatic environment (to both operators and fish), there is a continuing need to develop and promote Best Practice Guidelines for its use. Also, recent advances in electronics have resulted in new equipment that allows far greater control and selection of the output from the equipment. This new availability of output settings makes the need for improved understanding and guidance on how the method works and suitable output settings even more necessary. Probably the commonest use for electricity in fish research and management is for capturing them; this is called electric fishing (or electrofishing). Even for this methodology, books about the method tend to be either too simplistic or collations of scientific papers. The aim of this book is to give comprehensive information about the technical and theoretical aspects of using electricity but in easily understood language and format. In addition, practical guidance gained from over 40 years of experience of using electricity for a variety of uses in a wide range of locations and conditions is also given. The book will concentrate on electric fishing but in doing so will explain the fundamental concepts that govern other uses of electricity in fish research and management.

There has recently been a greater awareness and concern for fish welfare while electric fishing, and this book emphasises the concept of promoting fish welfare above fish capture. Information on basic electric circuit theory, choice of equipment, output characteristics and use should enable adequate fish capture efficiency with minimum incidence and severity of fish damage. Information and guidance that enable users to have a good understanding of the factors that influence efficient equipment set-up and benign fish capture are fundamental to achieving these goals. The work presented in this document is intended to give the above guidance and is based on an earlier document on Best Practice Guidelines for electric fishing (Beaumont et al. 2002) prepared for the UK Environment Agency. When Beaumont et al. (2002) was being written, it was hoped that it would be possible to lay down definitive rules and settings for use under a standard set of conditions and equipment specifications. Unfortunately, due to the wide variety of gears in use, water bodies in which they are used and range of operational requirements, it is not easy to categorically state what to use and where. Instead, it was decided that operators should have a good understanding of equipment and of the basic theory behind technique; this would allow them to set gear and output according to circumstances. This book is yet a further step along that road.

Overviews of electric fish screens, fish counters and the use of electricity to anaesthetise and sedate fish are also given.

The book is aimed at all who undertake sampling using electric fishing: professional practitioners such as government research scientists, under and post-graduate students and lay operators (water keepers etc.). Contrary to the comments of Smolian (1944) that ‘at all costs electrofishing should not be allowed to develop into a method that allows any errand boy to be a fisherman’, I hope that all who read this book will gain an understanding of at least the basic principles.

Recommendations from this work will include guidance on:

1. Output type and waveform
2. Frequency and power output
3. Anode size and shape, and cathode size and shape
4. Choice of options available regarding gear configuration (single anode, multi-anode, boom-mounted etc.)
5. Practical advice on using the equipment
6. Post-capture fish care.

Only core health and safety issues specifically associated with electric fishing will be addressed, as national, regional or local Codes of Practice or guidelines should deal with issues such as lifting and working near water, and so on.

Whilst this book is based on equipment and practice commonly used in Europe, the electrical principles described are universal and will apply to whatever type of equipment is being used.

CHAPTER 2
The history of electricity in fish research

In nature, certain fish have been using electricity for millennia, using it for defence (electric ray), sensory information (marmoratus sp.) and fish/prey capture (electric eel). Humans too have known about the physical effects and properties of an ‘unknown force’ (that we now call electricity) for a long time, but did not know the cause. Aristotle (350 BCE) mentions electric rays, and the Greek poet Claudius Claudianus (370–404 BCE) gives a very complete description of the effects of the electric ray on fishermen:

“all that have touched it lie benumbed. … Should it carelessly swallow a piece of bait that hides a hook of bronze and feel the pull of the jagged barbs … emitting from its poisonous veins an effluence which spreads far and wide through the water. The poison's bane leaves the sea and creeps up the line; it will soon prove too much for the distant fisherman. The dread paralysing force rises above the water's level and climbing up the drooping line, passes down the jointed rod, and congeals, e’er he is even aware of it, the blood of the fisherman’s victorious hand. He casts away his dangerous burden and lets go his rebel prey, returning home disarmed without his rod.”

The Encyclopaedia Americana (Anon. 1918) notes that Arabs in the fifteenth century give the same name to lightning and electric rays, thus linking the two phenomena. Interestingly, Michael Faraday (1791–1867), one of the great electrical scientists (and by whose efforts electricity became practical for use in technology), also investigated the properties of the electric ray in the 1830s.

In addition, but not documented in written text, the South American electric eel has long been feared by native tribes. European explorers record the locals driving animals into streams to be immobilised by the eels, whereby they may be captured more easily. One of its names in South America translates as ‘one who puts you to sleep’, and there is documented evidence that it can use the 600 volts it can produce to knock out a human, as well as kill large caiman that are foolish enough to try to capture it (Nye 2014).

In terms of using electricity for fish research and management, the Italian Alessandro Volta made a significant step in 1791 when he published details of the first truly portable electricity supply, the voltaic pile or battery. There is some debate over whether the Mesopotamians used a chemical battery over 2000 years ago, but Volta’s was the first documented battery and was described some 150 years before the earlier artefacts were discovered. Until Volta’s battery, electricity was produced by storing static electricity in ‘Leyden jars’; these could be made to discharge and create short bursts of high voltage, direct current (DC) electricity. The galvanic pile was the first device able to produce a continuous and stable electrical current over a period of time.

It was an Englishman, Isham Baggs, who in 1863 patented the idea of using electricity from batteries for ‘Paralysing fish, birds &c.’ The patent was very thorough and covered what we would now know as standard electric fishing but also the use of electricity to immobilise fish after they have been hooked on a baited line in order to aid capture and minimise the chances of the fish escaping off the hook (a process that is now used in some tuna long-line fisheries) and the use of polarising glasses, made from tourmaline, in order to better observe the position of the fish in the water (Baggs 1863).

Having discovered the effect that electricity had on fish, scientists then began a long process of trying to understand the reason for the effects on fish (and other animals) and the cause of the effects. Mach (1875) described the orientation and movement of fish in an electric field, discovering that fish turn towards an anode (galvanotropism). Herman (1885) also reports orientation in an electrical current and movement towards anodes (galvanotropism and taxis). This was confirmed by Blasius and Schweitzer (1893) and Nagel (1895). Herman and Matthias (1886) reported that fish experienced ‘discomfort’ in a reversed field (cathodic repulsion). Subsequent to these early studies, a considerable amount of research was carried out on the physiological and practical factors that determined the reaction of the fish. Much of this early research was carried out in Germany, France and America, but Russia and Japan also published information relating to electric fishing. Loeb and Maxwell (1896) considered the response was involuntary, with current flowing through the central nervous system and affecting the motorneurones and flexor–extensor muscle systems. Much of this early work, however, had poorly described experimental and output settings, was not particularly applicable to understanding the process in the natural environment and was also often published in obscure journals. More recently, greater attention to detail has improved the description of electrical parameters; however, it is still common for papers not to document waveforms properly (e.g. Van Zee et al. 1996) or note whether water conductivity is specific or ambient.

All of the early research on using electricity for fisheries research used DC fields, but in 1902 a Frenchman, Professor Stéphane Leduc, described using a pulsing waveform to reduce the power demand of electric fishing. This pulsed waveform was a square wave with a frequency of between 20 and 200 Hz and a 0.05–0.005 s duty cycle (described by May 1911). It was derived from interrupting the voltage from the galvanic cell batteries in use at the time, and for some while the waveform was called ‘Leduc’s current’.

Much of the early research on the practical uses of electricity for fisheries management was directed at using electric fields to guide fish or as fish barriers. In 1917, H.T. Burkey was awarded the first of a series of patents for an electric fish screen, and this is probably the first true use of electricity for fisheries management.

The widespread use of electricity to catch fish and use the method for fisheries research and management probably started around the early 1930s (Holzer 1932) with a range of different equipment designs being described by various authors over the succeeding years.

Since the 1940s, many studies have described the practical uses of the method for fisheries research and management and also increased our understanding of how the process works. Each country seems to have had a core of researchers who specialised in furthering our knowledge.

Researchers in America published some of the first details of practical designs for electric fishing equipment and also studies on how the process affected fish. Researchers also demonstrated that the effect on the fish was independent of the central nervous system (as freshly killed fish that had had their spines or spinal cords removed still reacted to an electric field and ‘swam’ towards the anode) and also documented the differences in effect between DC and pulsed DC (pDC) waveforms (Haskell et al. 1954). More recently, researchers have progressed our understanding of factors affecting the effect on fish and the damage that can also be caused if used at inappropriate settings.

In Europe, several countries researched the practical use and physiology of the reaction. France in particular made big advances in the 1960s in researching both the physiology and practical use of the method. Latterly, the Food and Agriculture Organization (FAO) and the European Inland Fisheries Advisory Commission (EIFAC) have taken a lead role in collating research from Europe and identifying areas where more research is required.

Russia carried out a considerable amount of research, much of it ...