Timing of downstream migration and food uptake of juvenile North Sea houting stocked in the Lower Rhine and the Lippe (Germany)

Abstract

In 1992 a stocking programme was established to re‐introduce North Sea houting Coregonus oxyrinchus, which disappeared from the River Rhine in the 1940s, in the Lower Rhine. Juvenile North Sea houting have been stocked since 2001 in a gravel pit lake permanently connected to the Lower Rhine, and in the Lippe, a potamal tributary of the Rhine. Monitoring studies showed that the majority of the small North Sea houting left the gravel pit lake within 4 days after stocking. In the Lippe, some of the juveniles were found in the drift immediately after stocking, generally preferring the middle surface areas of the river. Other North Sea houting waited until dawn before they started their downstream migration. Juveniles immediately started to feed on the zooplankton resources in both waters. Pond studies revealed high growth rates of juvenile North Sea houting, ranging from 0·44 to 0·94 mm day−1. This study suggests that the stocking strategies at both waters of the Lower Rhine comply with the requirements of the migration behaviour of juvenile North Sea houting.

Migration history of North Sea houting (Coregonus oxyrinchus L.) caught in Lake IJsselmeer (The Netherlands) inferred from scale transects of 88Sr:44Ca ratios

“…In the 1980 s, the last known reproducing population of houting in the Danish River Vidå was used to establish a brood-stock in Denmark, whose descendants served as the basis for the reintroduction of houting in Germany (Jäger, 1999). Since 1996, houting have been stocked in the Lower Rhine regularly and in increasing numbers (Borcherding et al, 2006). Catches of houting in Lake IJsselmeer (The Netherlands, Fig.…”

Prognose visstand in en rond het Haringvliet na invoering van het Kierbesluit in 2018

“…Wanneer houting niet de bovenstroomse delen (al is de houting nooit heel diep in het Maas en Rijnstroomgebied opgetrokken) de rivier kunnen bereiken door bijvoorbeeld migratiebarrières, zijn zij genoodzaakt om beneden in de rivier te paaien. De larven komen in februari tot maart uit het ei en zijn dan 10 mm groot (Borcherding et al 2006). De jonge houtingen kunnen langere of kortere tijd in zoet water verblijven, waarna ze naar zee trekken (Borcherding et al 2008).…”

Ontogenetic differentiation of swimming performance and behaviour in relation to habitat availability in the endangered North Sea houting (Coregonus oxyrinchus)

“…Larvae were fed with a diet of commercial rearing food six times a day, whereas juveniles were fed with a diet of frozen Chironomus sp. larvae (Borcherding et al 2006) three times a day.…”

“…By the 1970s and 1980s, remaining populations of the North Sea houting were extirpated from all Danish rivers except the River Vidaa (54 o 55 N; 8 o 52 E). At this point, the species was on the brink of becoming extinct (Jensen et al 2002;Borcherding et al 2006;Madsen and Murray 2007;Hansen et al 2008).…”

“…The program facilitates the free upstream migration of adult North Sea houting and promotes larval and juvenile survival by establishing spawning and nursery areas (Jensen et al 2003). The early life stages are particularly critical for the survival of the species (Jensen et al 2003;Madsen and Murray 2007;Borcherding et al 2006;Hansen et al 2008). However, the ecology, behaviour and habitat requirements and the potential linkage between habitat availability and downstream dispersal of larval and juvenile fish remain unknown.…”