Impact of electric fishing on egg survival of whitefish, Coregonus lavaretus

Abstract

Previous studies on the effects of electrofishing on fish eggs have reported widely varying results, ranging from gentle to adverse impacts on egg survival rates, and this may be attributable to inadequately standardised assessment methods. The impact of electrofishing on the survival of European whitefish, Coregonus lavaretus L., eggs was analysed in laboratory experiments and in a comparative field study. Different anode distances and time points post‐treatment were evaluated after artificial fertilisation with milt of untreated males, and survival rates were determined in the morula stage. In the laboratory, no significant difference in survival rates was found between various time points of stripping the gametes post‐electric shock. In the treatment group, significantly lower survival rates were detected in eggs (98.6%; SE = 0.20%) compared to the control group (99.6%; SE = 0.11%). Analysis of the egg survival rates in relation to effective voltage, rather than anode distance, revealed a significant trend of declining survival with increasing effective voltage. In field studies, eggs of electroshocked fish showed significantly lower survival (94.8%; SE = 1.03%) than untreated controls (98.7%; SE = 0.38%). Although electrofishing enhanced egg mortality, overall survival was noticeably high (>90%), indicating a relatively small impact.

Influence of warming temperatures on coregonine embryogenesis within and among species

“…No embryo transport was required for Lake Southern Konnevesi. Fertilization success was determined by haphazardly taking 10 embryos from each family and assessing under microscopy within 72-hours post-fertilization (Oberlercher & Wanzenböck, 2016). If fertilization was low (\ 30%), the family was removed from the experimental setup.…”

Electrofishing of Landlocked Fall Chinook Salmon Broodstock Negatively Impacts Egg Survival

“…Comparing experimental results can be difficult because fish electroshocking test parameters are unspecified (Oberlercher and Wanzenbock ). Because of Lake Oahe water conductivity, the voltages and amperages used in this study with pulsed‐DC ranges of 240–340 V and 18–20 A were relatively high (Redman et al.…”

“…It has also been used to remove undesirable species (Moore et al 1983) as well as to collect and immobilize broodstock (Redman et al 1998; Barnes et al 1999;Zydlewski et al 2008). Because electrofishing can cause both internal and external damage to the fish being collected (Snyder 2003), particularly salmonids (Oberlercher and Wanzenbock 2016), its use as a fisheries management tool may be limited when dealing with sensitive juveniles or imperiled fish (Miranda and Kidwell 2010). Numerous studies have examined the effects of electrofishing on the fish themselves, whereas others have looked at possible effects on the developing gametes and subsequent progeny.…”

Shining a light on Laurentian Great Lakes cisco (Coregonus artedi): how ice coverage may impact embryonic development

“…Total length, mass, and egg diameter were collected from the spawned adults. Fertilization success was determined by assessing 10 haphazardly selected embryos under microscopy (Oberlercher and Wanzenböck, 2016). If fertilization was low (<30%), the family was removed from the experiment.…”