Introduction

1. Introduction 1 Principles & Techniques of Electrofishing

2. Chapter Objectives • Provide an overview of the • course topics and • common equipment • types • Discuss elements of a framework for progress in EF • Highlight important events in the ongoing development of electrofishing

3. A. Purpose of Course • This course emphasizes the application of basic principles of electricity to improve the practice of electrofishing (EF)

4. A. Purpose of Course • Why do we have this course? • Electrofishing is a versatile and important sampling (and collecting) method for assessing freshwater fish populations and increasingly, invertebrates; samples a wide variety of species and sizes; often the most effective gear type. • Electrofishing often is the glasses we use to view and characterize fish populations and assemblages. • Electrofishing can be complicated. We need to merge concepts and techniques into a knowledge base that is more widely understood and applied to improve electrofishing practice. “The more I know about electricity in fisheries, the more I need (and want) to know.” -James B. Reynolds

5. B. Course Summary Equipment Design & Evaluation Sampling Efficiency Effects on Safety and Standardization Fish Electric Circuit and Field Theory **We also will cover estimation of capture probability and use in population abundance assessment and sampling design.

6. Backpack shocker C. Overview of Techniques Shore-based shockers

7. Electric Seine

8. Tow-barge shocker

9. Boat or Raft shockers

10. “Specialized Equipment” Pre-positioned Area Shocker Parallel Wire Shocker

11. Electofishing Techniques Video • You may view a brief video that demonstrates several techniques in the field. Go to: Electrofishing Techniques

12. D. Definition and Current Status • Electrofishing: the use of electricity to capture or control fish • "History of electric fishing is a classic case of almost pure muddle" (W.G. Hartley) • Many conclusions appear contradictory (“That’s not the way it is in my lake”.) • Current school vs. voltage school • Electrofishing developed independently on many fronts) • The practice of electrofishing has been largely technique driven, not theory driven

13. Voltage required for successful electrofishing increases rapidly, particularly below 100 μS/cm. Good response variable in low water conductivities. Current required for successful electrofishing increases gradually from low current at low water conductivities to increased current at higher water conductivities. Because of linearity, current can be a good r variable to standardize by across water conductivities , particularly for high power capacity equipment as boats.

14. D. Definition and Current Status • Merger of theory and technique is underway and needs to continue. • Need to further develop and apply a set of underlying principles to support electrofishingtechnique (as experimental input for increasing efficiency, power standardization, equipment power evaluation, incorporating catchability) • Two major categories comprising underlying principles: biology and physics • The Power Transfer Theory of Electrofishing can help bridge these categories

15. Framework for Progress in Electrofishing Reynolds (1995)

16. E. History Genesis Period:1860’s – 1930’s 1863:patent for electric fishing awarded • late 1800's:lab experiments on fish reactions (galvanotaxis identified) • 1920’s: • first practical applications; large, stationary power sources used for fish screens in England & Germany • electrical fishing in ponds • Electrical fields around fish screens described • 1930’s: development of more portable electrofishing gear; 1931 article on use of 2 electric seine designs, one stationary design (quadrat), and a boat shocker for gar and carp control; some efficiency studies; primary stream sampling gear is the electric seine.

17. 1930’s Portable Electrofishing Equipment Use of an early design of the electric seine in the 1930’s. AC waveform. One electrode buried in stream bottom, the other electrode in the form of a metal screen between two wooden poles. From Haskell (1940)

18. E. History Development Period: late1940’s – 1960’s Major activities: • Development of portable electrofishing equipment and boat improvement • Refinement of fish diversion screens • Waveform development • Understanding neurophysiology and behavoral mechanisms of fish in electric fields

19. E. History Development Period: late1940’s – 1960’s Development of portable equipment and boat improvement • Shore-based shockers (hand-held electrodes or hand-held anode and floating or stationary cathode with a stationary generator) • First tow-barge electrofishers introduced • Backpack shockers (small generators and batteries coupled with inverters and transformers) • Electrofishing boats (Larimore et al. 1950) • Electric seines • Trawls (modified with a leading electrode array to stimulate fish and crustaceans off of the bottom)

20. E. History Development Period: late1940’s – 1960’s Refinement of fish screens • for fish barriers • Sea lamprey in Great Lakes tributaries • Salmon • Northern pikeminnow • for guidance • Salmon (using knowledge of behavior in electric fields)

21. E. History Development Period: late1940’s – 1960’s Waveform development • DC- primarily used in Europe & Asia • advantage: causes taxis to anode • advantage: fish reactions to DC studied by several labs • advantage: low apparent injury rates • disadvantage: higher power requirements for immobilization; this factor limits portability but lighter weight DC generators began to be developed for electrofishing • AC- North America • advantage: good catchabilities maintained across range of water conductivities • advantage: adaptable to portable equipment • disadvantage: no taxis • disadvantage: fish injury known by late 1940’s

22. E. History Development Period: late1940’s – 1960’s Waveform development • Pulsed DC • produced from AC with half or full-wave rectifiers • less power needed than with continuous DC • high peak Voltage from small power sources • very adaptable to portable systems • cause taxis in some species (but not all) • more waveform options; opportunities to evaluate frequency and pulse width ranges for catchability and efficiency • are injury levels similar to DC?

23. E. History Development Period: late1940’s – 1960’s Fish behavior & neurophysiology in electric fields (theoretical developments) • Lab studies in Germany, France, & the Soviet Union • In the U.S., findings were applied to facilitate juvenile salmon guidance at hydroelectric dams in the Northwest

24. E. History Development Period: late1940’s – 1960’s • Some efficiency studies (electric seine, shore-based shocking, quadrat) • Some synthesis of information: • German textbook (later revised Halsband & Halsband 1984) • French & Russian monographs • Russian monograph by Sternin et al. (1972) • This phase ended with an importance conference: • first international symposium on electric fishing (1966) • proceedings: Fishing with Electricity (Vibert 1967) • the book produced was not widely applied by fisheries biologists

25. E. History Refinement Period:1970’s – 1980’s • Refinements in electrofishing as a scientific sampling technique • Sampling efficiency: selective waveforms for catfish, power transfer theory, specialized techniques (e.g., pre-positioned area shockers) • Population assessment: depletion, capture-recapture • Safety: codes of practice, agency safety policies • Equipment technology: increased variety of pulsed DC available, specialized waveforms, improved boat design, new electrode designs (throwable anodes, deepwater electrodes, spherical electrodes), specialized equipment (PPAS, DOA, anesthesia) • Field operations: sampling design, protocols, “standardization”

26. E. History Refinement Period:1970’s – 1980’s Near the end of this period- • Fish injury warning with pulsed DC (1988) • A.L. Kolz and J.B. Reynolds develop Power Transfer Theory of Electrofishing (1988) • lab work supported this concept • Second international electrofishing symposium (Hull, England 1988) • 2 books: Fishing with Electricity, Developments in Electric Fishing • More readable and useful to practicing biologists

27. E. History Unification Period:1990’s – 2000’s Initiate a merging of theory and technique • Application of principles: • manipulating waveform type (e.g., AC, DC, PDC) and attributes, especially pulsed DC, for increased or consistent efficiency • for an experimental approach, see Framework for Increasing Sampling Efficiency and Precision for a Species.pdf) • electrode design evaluation for improved power distribution to the anode • objective comparison of the electrical outputs of control units • applications of field pattern concepts to evaluate fish barriers

28. E. History Unification Period:1990’s – 2000’s Initiate a merging of theory and technique • Most testing and application of the theory has happened in the 2000’s due to the work of L.E. Miranda (Mississippi State) • The Power Transfer model has been successfully applied in the field (e.g., Burkhardt & Gutreuter [1994] had a ~ 15% increase in sampling consistency), otherwise known as standardizing by power • Additional but still limited field data have shown that the Power Transfer model is sufficient to direct where to “set the dials” in some streams • It appears that the Power Transfer model at least can provide a starting point for selecting minimum power settings needed for successful electrofishing

29. E. History Unification Period:1990’s – 2000’s Other important activities • Developing standardization protocols • especially standardizing by power (see Electrofishing Standardization Protocol.pdf) • merging power predictions for standardization with estimates of equipment power output capability • Estimating catchability and adjusting CPUE to population abundance or density • More agencies developing safety policies • Factors behind fish trauma better understood (e.g., fish injury risk model) • Non-traditional sampling applications (e.g., for aquatic macroinvertebrates)

30. E. History Unification Period:1990’s – 2000’s Developing an international community of practice • www.electrofishing.net • “At electrofishing.net, we provide those interested in electrofishing - scientists, managers, community groups and industry - with a forum for the discussion of all things electrofishing. Over the coming months, content such as articles, gear reviews and other resources (including legislation and codes of practice) will be added to the site.” • Electrofishing listserve • https://www.fws.gov/lists/listinfo/electrofishing

31. F. References See Introduction References.pdf

32. G. Next Step Now proceed to “Electric Circuit Concepts” (Module 2)