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

Abstract

Key-words:Rímov Reservoir, Chabařovice Lake, SCUBA diving, Reed canarygrass Phalaris arudinacea, Goat willow Salix caprea, egg strandsThe roles of wind protected bays, presence of littoral vegetation and light attenuation in the water column on spawning site selection and depth of egg strands deposition by perch Perca fluviatilis was studied inŘímov Reservoir, Czech Republic, in the years 2007 and 2011 using boat observation and SCUBA divers. The data were compared with results from Chabařovice Lake, Czech Republic, where similar monitoring took place in 2007−2010 and 2012. In shallow water ofŘímov Reservoir, the density of egg strands was significantly higher in grass bays compared to both rocky bays and the main reservoir body. Most egg strands were deposited in water less than 0.5 m deep on reed canarygrass Phalaris arudinacea. In year when the littoral vegetation was absent perch were forced to spawn significantly deeper on various types of woody structures. InŘímov Reservoir, which is less vulnerable to wind, 91.1% of egg strands were spawned in water 3 m deep. In contrast, in the wind exposed Chabařovice Lake, even in the presence of littoral vegetation, 90.5% of egg strands were found at depths greater than 3 m. In Chabařovice Lake, the light penetrated to three times greater depth compared toŘímov Reservoir and, similarly, the depth limit to which 95% of egg strands were spawned was three times greater in this lake compared toŘímov Reservoir. This study is the first contribution showing the role of water transparency in controlling the depth distribution of perch egg strands in lakes and reservoirs. En revanche, dans le lac Chabařovice exposé au vent, même en présence la végétation littorale, 90,5 % des rubans d'oeufs ont été trouvés à des profondeurs supérieures à 3 m. Dans le lac Chabařovice, la lumière pénètre trois fois plus en profondeur que dans le réservoirŘímov et, de même, la limite de la profondeur à laquelle 95 % des rubans d'oeufs ont été déposés était trois fois plus élevée dans ce lac que dans le réservoirŘímov. Cette étude est la première contribution montrant le rôle de la transparence de l'eau dans le contrôle de la distribution en profondeur des rubans d'oeufs de perche dans les lacs et les réservoirs.

Effects of habitat type on short‐ and long‐term growth parameters of the European perch (Perca fluviatilisL.)

“…). Older individuals in LPF are in accordance with appearance of earlier spawning and hatching of perch in shallow habitat compared to deeper part of the reservoirs [Čech et al, ,].…”

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

“…Perch reproduction in Milada Lake has been intensively monitored for some years [9,25], previous years have shown an apparent decrease in the abundance of adult perch and a related decrease of perch egg strands since predators, catfish and pike, were stocked [24]. An increase in perch abundance was observed only between the years 2006 and 2007.…”

“…To obtain quantitative assessment of perch egg strands, SCUBA divers monitored their occurrence, numbers and sizes at transects from the shore to a depth of ~20 m in April and May in 2015 (for details of the methodology and results from previous years see [9, 22–25]).…”

Differences in spatial communities of European perch (Perca fluviatilisLinnaeus, 1758) fry in a canyon-shaped reservoir are not attributable to genetics

“…Divergence between populations would have to be facilitated by spawning differences in space and time (Bergek et al., ). In the Římov Reservoir, sparse spawning sites, a restricted littoral zone, and a rather homogenous character of the water mass favour simultaneous spawning and fertilization (Čech, Peterka et al., ). Our results do not reflect the distances among localities 1, 2, and 3 (Table ), which were separated by approximately 5 and 3.5 km, respectively.…”