Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish

Wedekind, Claus; Vonlanthen, Pascal; Guttry, Christian de; Stadelmann, R.; Stadelmann, Noah; Pirat, Aurélien; Perroud, Giulia

doi:10.1016/j.gecco.2022.e02219

Cited by 2 publications

(3 citation statements)

References 48 publications

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“…A relatively low proportion of stocked whitefish of one cohort, as we found for Lake Constance with 17.4% for the 2016 cohort and 24.5% for the 2018 cohort, has also been reported for other lakes in the alpine region (Meng et al, 1986; Müller, 1990) and elsewhere (Salojärvi, 1992; Wanke et al, 2016). Most of the time, natural recruitment occurred in those lakes and several authors argue that stocking is superfluous under these conditions (Gerdeaux, 2004) or that stocked fish only survive in high numbers if natural recruitment is deficient (Wanke et al, 2016; Wedekind et al, 2022). Based on these results and the fact that natural born offspring seem to dominate the whitefish cohorts in Lake Constance, higher proportions of stocked fish in the future are unexpected.…”

Section: Discussionmentioning

confidence: 99%

“…Most of these stocking programs are intended to support local whitefish populations to compensate for a shortfall in natural recruitment or to stabilize fluctuating fishery yield by reducing annual variation in cohort size (Eckmann et al, 1988). Many previous evaluations of effects of larval stocking on yield or year‐class strength in fisheries around the world have found variable effects, with some showing little or no effect (Salojärvi, 1992; Wanke et al, 2017), others showing negative effects (Anneville et al, 2015), and others showing increased harvest (Anneville et al, 2009; Wanke et al, 2016; Wedekind et al, 2022). Furthermore, the impact of stocking programs can vary over time, as in Lake Geneva, where whitefish abundance and fishery yield both increased over the first 10 years of stocking, but subsequent increased fishery yield was mostly driven by increased recruitment resulting from improved limnological conditions (Anneville et al, 2009; Gerdeaux, 2004).…”

Section: Introductionmentioning

confidence: 99%

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A matter of time—Efficacy of whitefish stocking in a large pre‐alpine lake

Baer¹,

Kugler²,

Schubert

et al. 2023

Fisheries Management Eco

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The tradition of stocking whitefish (Coregonus spec.) is widespread throughout Europe and dates back more than a century in some lakes. Despite its broad acceptance as a management action, stocking success is less often studied and might change with shifts in ecosystems. Similar to many other large lakes in Central Europe, Lake Constance is stocked with millions of larvae each year at great cost. The last evaluation of this management practice took place in 2003, and since then several potential impacts on whitefish increased in magnitude (e.g. stickleback invasion, increasing water temperature). Forty‐two million dye‐marked larvae were stocked in 2016 and 36 million in 2018. Recaptures made 1.5 and 3.5 years after stocking revealed that around 20% of the 2016 and 2018 whitefish cohorts consisted of stocked whitefish. This amount is significantly lower than was found in previous experiments. To identify potential factors controlling recruitment, a Beverton‐Holt stock‐recruitment model showed that stocking did not significantly affect year‐class recruitment. We conclude that stocking is no longer cost‐effective, and we recommend that stocking should be reduced in the short term. Furthermore, our results suggest that explanatory variables that previously described recruitment variation of the whitefish population, such as April water temperature, may no longer apply.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A matter of time—Efficacy of whitefish stocking in a large pre‐alpine lake

Baer¹,

Kugler²,

Schubert

et al. 2023

Fisheries Management Eco

View full text Add to dashboard Cite

show abstract

“…The precise role of stocking in landings was not assessed in the studied lakes except in Lake Bourget (Champigneulle and Cachera, 2008), where it did not exceed 15% of the landings. Future studies requiring marking of hatchery fish (Eckmann, 2003) will address stocking efficiency, which is believed to be lake-specific as recent studies in other European lakes have sometimes reported high contributions of whitefish stocking even after re-oligotrophication (Eckmann et al, 2007;Wanke et al, 2016;Wedekind et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

Synchrony in whitefish stock dynamics: disentangling the effects of local drivers and climate

Bourinet¹,

Anneville²,

Drouineau³

et al. 2023

J Limnol

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Synchronic variations in abundance in populations of the same species are common phenomena encountered in various environments, including lakes, and different taxa of freshwater fishes. This phenomenon can be caused by similar environmental conditions across physically separated populations. In the context of the ongoing climate change, it is essential to test this hypothesis, identify the factors driving the synchrony and elucidate the mechanisms, in the attempt to improve fisheries management. This study investigates synchronic variations in European whitefish (Coregonus spp.) populations in five peri-alpine lakes. The hypothesis suggests that shared biotic or abiotic factors contribute to similar trends in whitefish landings. Environmental and seasonal variables impacting the early life stages of the species were analyzed, and the Euclidean distances between the multivariate time series were calculated to identify similarities or dissimilarities in lake environmental parameters. We found that regional winter and spring temperatures were consistent across the lakes, but these factors did not fully account for variations in landings statistics. Wind intensity, water level and zooplankton abundance showed lake-specific patterns that could better explain local conditions and dynamics. Linear models did not reveal a coherent correlation with a common environmental variable across all lakes. However, distinct relationships were found in four of the lakes, with local factors significantly contributing to abundance variations. The spring abundance of Daphnia spp., a primary food source for whitefish larvae, was the main factor correlated with fish landing trends in Lake Geneva and Lake Bourget. Higher availability of Daphnia spp. may decrease intraspecific competition and density-dependent mortality. In Lake Neuchâtel, winter water temperature was negatively correlated with fish abundance proxies, suggesting that warmer winters may compromise reproduction success. Lake Annecy saw an increase in whitefish landings following a substantial reduction in fishing efforts during the late 2000s. A significant negative correlation was found between whitefish landings and fishing efforts. No relationship was found for Lake Aiguebelette, maybe due to a lack of zooplankton data. In conclusion, the observed synchrony in the European whitefish population is likely driven by a combination of interacting environmental and anthropogenic factors rather than a single common variable. Further research and a more detailed dataset are needed to better understand these complex relationships. Cover image: Whitefish (courtesy of Rémi Masson)

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Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish

Cited by 2 publications

References 48 publications

A matter of time—Efficacy of whitefish stocking in a large pre‐alpine lake

A matter of time—Efficacy of whitefish stocking in a large pre‐alpine lake

Synchrony in whitefish stock dynamics: disentangling the effects of local drivers and climate

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