| Enregistrements |
Auteur  |
Chassot, E.; Duplisea, D.; Hammill, M.; Caskenette, A.; Bousquet, N.; Lambert, Y.; Stenson, G. |
| Titre |
Role of predation by harp seals Pagophilus groenlandicus in the collapse and non-recovery of northern Gulf of St. Lawrence cod Gadus morhua |
Type |
Article scientifique |
| Année |
2009 |
Publication |
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Revue Abrégée |
Mar. Ecol.-Prog. Ser. |
| Volume |
379 |
Numéro |
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Pages |
279-297 |
| Mots-Clés |
cod; functional response; harp seal; model; predation; recovery |
| Résumé |
A statistical catch-at-age model was developed to assess the effects of predation by the northwest Atlantic harp seal population on northern Gulf of St. Lawrence cod by estimating the relative importance of different sources of mortality that affected the stock during a period of collapse and non-recovery. Cod recruitment at age 1 is modeled via a non-linear stock-recruitment relationship based on total egg production and accounts for changes in female length-at-maturity and cod condition. Natural mortality other than seal predation also depends on cod condition used as an integrative index of changes in environmental conditions. The linkage between seals and cod is modeled through a multi-age functional response that was derived from the reconstruction of the seal diet using morphometric relationships and stomach contents of more than 200 seals collected between 1998 and 2001. The model was fitted following a maximum likelihood estimation approach to a scientific survey abundance index (1984 to 2006). Model results show that the collapse of the northern Gulf of St. Lawrence cod stock was mainly due to the combination of high fishing mortality rates and poor environmental conditions in the early to mid-1990s contributing to the current state of recruitment overfishing. The increase in harp seal abundance during 1984 to 2006 was reflected by an increase in predation mortality for the young cod age-groups targeted by seals. Although current levels of predation mortality affect cod spawning biomass, the lack of recovery of the NGSL cod stock seems mainly due to the very poor recruitment. |
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Eng |
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0171-8630 |
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pas de |
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LL @ pixluser @ |
collection |
15 |
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| Auteur |
Derolez, V.; Bec, B.; Munaron, D.; Fiandrino, A.; Pete, R.; Simier, M.; Souchu, P.; Laugier, T.; Aliaume, C.; Malet, N. |
| Titre |
Recovery trajectories following the reduction of urban nutrient inputs along the eutrophication gradient in French Mediterranean lagoons |
Type |
Article scientifique |
| Année |
2019 |
Publication |
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Revue Abrégée |
Ocean & Coastal Management |
| Volume |
171 |
Numéro |
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Pages |
1-10 |
| Mots-Clés |
Coastal lagoons; Nutrients; Oligotrophication; Recovery; Urban inputs |
| Résumé |
French Mediterranean coastal lagoons have been subject to huge inputs of urban nutrients for decades leading to the eutrophication of these vulnerable ecosystems. In response to new environmental regulations, some of the lagoons have recently been the subject of large-scale management actions targeting the waste water treatment systems located on their watersheds. While the eutrophication of coastal ecosystems is well described, recovery trajectories have only recently been studied. To assess the rapidity and the extent of the effect of the remediation actions, we analysed data from a 14-year time series resulting from the monitoring of nutrients, biomass and the abundance of phytoplankton in the water column of French Mediterranean coastal lagoons covering the whole anthropogenic eutrophication gradient. Following a 50% to 80% reduction in total phosphorus (TP) and total nitrogen (TN) urban loadings from the watershed of hypertrophic and eutrophic ecosystems, the integrative parameters chlorophyll a, TN and TP, provide evidence for a rapid response (1 to 3 years) and for an almost complete recovery, suggesting no hysteresis for the eutrophic lagoon. However, our findings also show that recovery patterns depend on the eutrophication status before remediation and may include feedback responses. The different responses revealed by our results should help stakeholders prioritise remediation actions and identify appropriate restoration goals, especially in light of the targets of the Water Framework Directive (WFD). |
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0964-5691 |
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MARBEC @ isabelle.vidal-ayouba @ |
collection |
2493 |
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| Auteur |
Derolez, V.; Soudant, D.; Malet, N.; Chiantella, C.; Richard, M.; Abadie, E.; Aliaume, C.; Bec, B. |
| Titre |
Two decades of oligotrophication: Evidence for a phytoplankton community shift in the coastal lagoon of Thau (Mediterranean Sea, France) |
Type |
Article scientifique |
| Année |
2020 |
Publication |
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Revue Abrégée |
Estuarine, Coastal and Shelf Science |
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Numéro |
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Pages |
106810 |
| Mots-Clés |
Eutrophication; Mediterranean coastal lagoon; Nutrients; Oligotrophication; Phytoplankton community shift; Recovery |
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en |
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0272-7714 |
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WOS:000539292700003 |
Approuvé |
pas de |
| Numéro d'Appel |
MARBEC @ isabelle.vidal-ayouba @ |
collection |
2776 |
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| Auteur |
Goetze, J.; Langlois, T.; Claudet, J.; Januchowski-Hartley, F.; Jupiter, S.D. |
| Titre |
Periodically harvested closures require full protection of vulnerable species and longer closure periods |
Type |
Article scientifique |
| Année |
2016 |
Publication |
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Revue Abrégée |
Biol. Conserv. |
| Volume |
203 |
Numéro |
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Pages |
67-74 |
| Mots-Clés |
areas; biomass; Fiji; Fisheries management; life-history; Locally managed marine areas; Marine conservation; marine reserves; predatory fish; Recovery; reef fish communities; responses; small-scale fisheries; stereo-video; vulnerability |
| Résumé |
Periodically harvested closures (PHCs) are small fisheries closures with objectives such as sustaining fisheries and conserving biodiversity and have become one of the most common forms of nearshore marine management in the Western Pacific. Although PHCs can provide both short-term conservation and fisheries benefits, their potential as a long-term management strategy remains unclear. Through empirical assessment of a single harvest event in each of five PHCs, we determined whether targeted fishes that differ in their vulnerability to fishing recovered to pre-harvest conditions (the state prior to last harvest) and demonstrated post-harvest recovery benefits after 1 year of re-closure. For low and moderately vulnerable species, two PHCs provided significant pre-harvest benefits and one provided significant post-harvest recovery benefits, suggesting a contribution to longer-term sustainability. PHCs with a combination of high compliance and longer closing times are more likely to provide fisheries benefits and recover from harvest events, however, no benefits were observed across any PHCs for highly vulnerable species. We recommend PHCs have longer closure periods before being harvested and species that are highly vulnerable to fishing (e.g. large species of; grouper, wrasse and parrotfish) are avoided during harvests to avoid overexploitation and increase the sustainability of small-scale fisheries. (C) 2016 Elsevier Ltd. All rights reserved. |
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English |
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0006-3207 |
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pas de |
| Numéro d'Appel |
MARBEC @ alain.herve @ |
collection |
1695 |
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| Auteur |
Goetze, J.S.; Januchowski-Hartley, F.A.; Claudet, J.; Langlois, T.J.; Wilson, S.K.; Jupiter, S.D. |
| Titre |
Fish wariness is a more sensitive indicator to changes in fishing pressure than abundance, length or biomass |
Type |
Article scientifique |
| Année |
2017 |
Publication |
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Revue Abrégée |
Ecol. Appl. |
| Volume |
27 |
Numéro |
4 |
Pages |
1178-1189 |
| Mots-Clés |
artisanal fisheries; Catch Efficiency; Compliance; Conservation; coral-reef management; Customary Management; fish behavior; Fisheries management; Flight Initiation Distance; flight initiation distance; indo-pacific; marine protected areas; periodically harvested closures; predatory fish; Recovery; risk-assessment; stereo-video system |
| Résumé |
Identifying the most sensitive indicators to changes in fishing pressure is important for accurately detecting impacts. Biomass is thought to be more sensitive than abundance and length, while the wariness of fishes is emerging as a new metric. Periodically harvested closures (PHCs) that involve the opening and closing of an area to fishing are the most common form of fisheries management in the western Pacific. The opening of PHCs to fishing provides a unique opportunity to compare the sensitivity of metrics, such as abundance, length, biomass and wariness, to changes in fishing pressure. Diver-operated stereo video (stereo-DOV) provides data on fish behavior (using a proxy for wariness, minimum approach distance) simultaneous to abundance and length estimates. We assessed the impact of PHC protection and harvesting on the abundance, length, biomass, and wariness of target species using stereo-DOVs. This allowed a comparison of the sensitivity of these metrics to changes in fishing pressure across four PHCs in Fiji, where spearfishing and fish drives are common. Before PHCs were opened to fishing they consistently decreased the wariness of targeted species but were less likely to increase abundance, length, or biomass. Pulse harvesting of PHCs resulted in a rapid increase in the wariness of fishes but inconsistent impacts across the other metrics. Our results suggest that fish wariness is the most sensitive indicator of fishing pressure, followed by biomass, length, and abundance. The collection of behavioral data simultaneously with abundance, length, and biomass estimates using stereo-DOVs offers a cost-effective indicator of protection or rapid increases in fishing pressure. Stereo-DOVs can rapidly provide large amounts of behavioral data from monitoring programs historically focused on estimating abundance and length of fishes, which is not feasible with visual methods. |
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English |
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| ISSN |
1051-0761 |
ISBN |
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Médium |
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Approuvé |
pas de |
| Numéro d'Appel |
MARBEC @ alain.herve @ |
collection |
2151 |
| Lien permanent pour cet enregistrement |
