The use of artificial spawning substrates in order to understand the factors influencing the spawning site selection, depth of egg strands deposition and hatching time of perch (Perca fluviatilis L.)

Abstract

The distribution of egg strands of perch Perca fluviatilis and factors affecting this distribution, in terms of spawning sites and spawning depths used, was studied in spring 2010 in Chabařovice Lake, Czech Republic, using areas with an artificial spawning substrate (A.S.S.)

Thirty-Year-Old Paradigm about Unpalatable Perch Egg Strands Disclaimed by the Freshwater Top-Predator, the European Catfish (Silurus glanis)

“…Only in one exception, we found a well-preserved perch (150 mm L T ) along with a perch egg strand, but the strand width of 55 mm corresponds with perch female of 256 mm L T [26] implying no relation. Catfish apparently eat perch egg strands directly from the flooded vegetation, which are frequently found in post-mining lakes and are commonly used by perch as spawning substrate [9, 22,24]. In one case, a small part of the spawning substrate (branch of a tree) was also found in the egg cluster extracted from the catfish stomach.…”

“…Perch abundance was estimated by multi-mesh gillnets (see [24] for detailed description). The gillnets were set overnight (September; installed 2 h before sunset, lifted 2 h after sunrise) at depths of 0–3, 3–6, 6–9 and 9–12 m in benthic and 0–5 and 5–10 m (or 0–6 and 6–12 m in 2014, respectively) in pelagic habitats at three to four localities.…”

“…This size limit was set for two main reasons: 1) The SCUBA diving results from 2007 and 2009 have shown that in Milada Lake 97% and 92% of perch egg strands were spawned by females ≥ 230 mm L T [9, 23]. 2) Based on gillnet catches, almost 90% of perch ≥ 230 mm L T were females [24]. Regression analysis was used for determining the relationship between CPUE (catch per unit effort) of perch ≥230 mm L T caught by 1,000 m 2 of gillnets in September of year X-1 and the CPUE of egg strands found by SCUBA divers (egg strands per 10 hours of diving) during spawning season in following spring, i .…”

“…The CPUE of perch caught by gillnets was calculated as the mean of catches of perch individuals ≥230 mm L T over all depth layers of benthic and pelagic habitats. This comparison is not biased by the growing season because female perch of 230 mm L T caught in September of year X-1 will be of approximately the same size in April/May of year X (for more details see [24]). The statistical test was performed in the R environment for statistical computing (version 3.2.2) [27].…”

Extremely shallow spawning of perch (Perca fluviatilisL.) : the roles of sheltered bays, dense semi-terrestrial vegetation and low visibility in deeper water

“…an appropriate spawning site or spawning depth, is essential for the development and survival of the new generation since immobile eggs are vulnerable both to unfavorable biotic and mainly abiotic conditions (Wootton, 1998). In perch [Perca fluviatilis L. in Eurasia and P. flavescens (Mitchill) in North America], the ability to react to different environmental conditions is well known and has been documented in their selection of appropriate spawning sites (Holčík, 1969;Jones, 1982;Treasurer, 1983;Probst et al, 2009;Snickars et al, 2010;Čech et al, 2011;, spawning depth (Gillet and Dubois, 1995;Newsome and Aalto, 1987;Williamson et al, 1997;Huff et al, 2004;Čech et al, 2009, as well as in selection of an appropriate spawning substrate (Čech et al, 2009, 2012) or temperature for incubation of their egg strands Dubois, 1995, 2007;Cech et al, 2011Cech et al, , 2012. It should be taken into account that many factors responsible for the success of perch reproduction may interact with each other, particularly spawning site and spawning substrate (Jones, 1982;Treasurer, 1983), spawning depth and spawning substrate (Čech et al, 2009, 2010) or spawning depth and temperature of incubation (Gillet and Dubois, 1995;.…”