Outmigration pathways of stocked juvenile European sturgeon (Acipenser sturioL., 1758) in the Lower Rhine River, as revealed by telemetry

Abstract

Working towards a future Rhine Sturgeon Action Plan the outmigration pathways of stocked juvenile European sturgeon (Acipenser sturio L., 1758) were studied in the River Rhine in 2012 and 2015 using the NEDAP Trail system. A total of 87 sturgeon of 3 to 5 years old (n = 43 in 2012, n = 44 in 2015) were implanted with transponders and released in May and June in the river Rhine at the Dutch‐German border, approximately 160 km from the sea. In total three sturgeons (3%) were found dead on river banks within seven days after the release. Based upon their wounds these sturgeons were likely hit by ship‐propellers. Tracking results were obtained from 57 (66%) of the sturgeons, of which 39 (45%) indicated movement into the Port of Rotterdam. Here the sturgeons remained for an average of two weeks, which suggests they spent time to acclimatize to higher salinities before entering the North Sea. Of the 45 (52%) sturgeons that were confirmed to have entered the North Sea, ten (22%) were recaptured (mainly by shrimpers and gill‐nets) close to the Dutch coastline; nine were alive and were released. From the results we obtained the preferred outmigration pathways, movement speeds and an indication of impacting factors (i.e. ship propellers and bycatch). Bycatches provided also localisations information in the coastal area. A next step to complete this work would be to assess habitat selection in freshwater and downstream migration of young of the year (YOY sturgeons) in the Lower Rhine.

Historical reconstruction of sturgeon (Acipenser spp.) spatiotemporal distribution and causes for their decline in North-Western Europe

“…In addition, remediation of 18th-twentieth century industrial pollution (Villamayor-Tomas et al 2014) has further improved the Rhine's carrying capacity for diadromous fishes (Borcherding et al 2010;Hundt et al 2015). To strengthen the conservation status in the species' northern range, the possibility of re-introducing the European sturgeon in the Rhine is currently under assessment, which includes experimental releases of tagged individuals (Brevé et al 2014(Brevé et al , 2019. However, before actual restocking of this river can be implemented, a thorough habitat feasibility and risk assessment is paramount to reduce 1972) give the year for the last known sturgeon reported from that specific river-section or sea any risks to this critically endangered species (IUCN/SSC 2013).…”

Heart Rate and Acceleration Dynamics during Swim-Fitness and Stress Challenge Tests in Yellowtail Kingfish (Seriola lalandi)

“…Telemetry to monitor fish movement has a long research history of tracking the iconic fish migrations of eels (e.g., [ 15 ]), salmons (e.g., [ 16 ]), sturgeons (e.g., [ 17 ]), tunas (e.g., [ 18 ]) and sharks (e.g., [ 19 ]). More recent is the use of acoustic sensors for measuring real-time acceleration, used as a proxy for activity [ 20 , 21 , 22 , 23 , 24 ].…”

Monitoringsplan Vismigratie Nieuwe Waterweg regio

“…die de volledige breedte van een watersysteem afdekken (permanent netwerk in beheer van RWS, André Breukelaar, zieBrevé et al 2018); deze zenders zijn relatief groot, hebben een bereik van ca 15m boven de antenne-loop die de gehele breedte van de watergang afdekt. De batterijen van de zenders (transponders) die voor schieraal zijn gebruikt gaan 2 jaar mee.…”