Consistency and Safety in Electrofishing Methodology
Within the study of electrofishing and fishery habitat management, there are specific guidelines which the management professional must adhere to in order to protect the safety of the wildlife, the boating participants, and the participating patrons. Such guidelines are industry standards and should be understood by all professionals who are participating in the fishing process. To ensure such failsafe mechanisms are in place on a consistent basis, activities must follow a professional and pre-determined path while preparing gear, loading into the watercourse, and performing electrofishing tasks. Professionals will understand that these steps cannot be ignored due to the need for similar results over an extended period of time. Given the adherence to such measures, the potential for a pure data stream and analysis is greatly improved.
Given the scope of lake fishing operations, there are several key safety checks which must be performed prior to placing the boat into the water. Figure 1 demonstrates a standard safety check of the engine and generator systems on a typical electrofishing boat. Boat standardization across the industry is consistent; however, the components will often vary, requiring safety examinations which are constantly aware of standard features. Generally all boats will include a power supply and a power conditioner which are designed to meet the requirements of the specific body of water. By ensuring that the boating materials are properly calibrated for the specific investigation, researchers will ensure that their performance is not inconsistent with previously tested results.
Participants in the electrofishing process will include the boat handler or driver and two additional participants for actually performing the fishing process. It is important that each individual is aware of the expectations of the task prior to moving into the water so that standards systems remain active. The handlers are responsible for placing the seining instruments into the lake for continuous shocking of the fish population. The stun process will involve retrieving the fish via net and charting their data aboard the boat. To ensure that such procedures are accomplished with limited negative affect on the fish, handlers must use care and be actively aware of their shocking methods. Niemla et al. (2000) challenge that within the electrofishing process that there are oftentimes inconsistencies in the population estimation process which can be minimized through a standardized and non-random selection process over a small number of suitable sites. There are alternative mechanisms which can also be used, including a random process or area sweep; however, what is important is that such procedures generate comparable results over time.
One of the most significant challenges given the breadth of the lake environment and results driven electrofishing is to ensure that transets are predictable and time based. In successive examinations, researchers recognize that removal methods will oftentimes underestimate the actual fish population, due to a reduced catchability based on removal statistics (Gatz and Loar, 1988). To ensure that such deviation does not occur, the seining gear must be placed in approximately the same spatial area as participants navigate the lake. Extending the gear to a specific length, i.e. 10 feet, ensures that with each subsequent transet, fish are compared to the previous guidelines and not to a new set of unpredictable data. For appropriate fish sampling, a multiple pass system as highlighted by Kimmel and Argent (2006) may be used for accuracy’s sake; however, standardized systems will focus on length versus width consistency or a linear sampling distance.
Recognizing that fish demographics offer substantial insight to fishery professionals, comparison data is often drawn using specific tools and tracking methods. A length board is a handy and standard tool which is used to compare fish throughout the study. Weight can be charted frequently or at regular intervals in order to gain a sampling of the representative fish population. Data regarding the water quality, temperature, and chemical composition should also be attained during this process through standard testing which includes the use of a dissolved oxygen probe. Implications of such study will become obvious during subsequent examinations and data comparison.
During the multiple pass system, transets are established by visual shore markers which enable the consistent analysis over a period of time. Study of historic data trends by Humpl and Lusk (2006) demonstrated that singular pass systems were oftentimes inaccurate and could not provide researchers with adequate samples for long term comparison. Upon collection of data samples, the return process and docking procedure should mimic that of the initial boat placement, including the shutoff of all powered components prior to exiting the boat. Cataloguing data using visual methods and consistent charting materials enables long term comparison and researchers will be quickly able to identify any inconsistencies in the lake or habitat area.
Considering the variability of lakes and the changing fishing population, such standardized electrofishing techniques ensure that results may be compared based on regular intervals. As biologists continue to develop more standard technologies for fishing bodies of water, integration of standard procedures the process, regardless of materials must be ensured. In this study, the underlying safety checks for the boating system were addressed, highlighting those key points where failure to investigate could mean a failed experiment and a stranded craft. Fishery management involves a relationship between the natural habitat, the visitors, and the investigating professionals; through well directed, consistent efforts, the information gathered can directly assist in charting the long term sustainability of a fish population as well as the surrounding ecology.
References
Gatz, A.J; Loar, J.M. (1988) “Petersen and Removal Population Size Estimates.” Environmental Biology of Fish, Vol. 21, pp. 293-307.
Humpl, M; Lusk, S. (2006) “Effect of Multiple Electro-Fishing on Determining the Structure of Fish Communities in Small Streams.” Folia Zoology, Vol. 55, No. 3, pp. 315-322.
Kimmel,W.G; Argent, D.G. (2006) “Efficacy of Two-Pass Electrofishing Employing Multiple Units to Assess Stream Fish Species Richness.” Fisheries Research, Vol. 82, pp. 14-18.
Niemla, E; Julkunen, M; Erkinaro, J. (2000) “Quantitative Electrofishing for Juvenile Salmon Densitites: Assessment of Catchability During a Long-Term Monitoring Programme.” Fisheries Research, Vol. 48, pp. 15-22.
