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Forecasting the major influences of predation and environment on cod recovery in the northern Gulf of St. Lawrence.

Bousquet N, Chassot E, Duplisea DE, Hammill MO - PLoS ONE (2014)

Bottom Line: This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock.Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status.In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.

View Article: PubMed Central - PubMed

Affiliation: Institut de Mathématiques de Toulouse, UMR 5219 CNRS, Université Paul Sabatier, Toulouse, France.

ABSTRACT
The northern Gulf of St. Lawrence (NGSL) stock of Atlantic cod (Gadus morhua), historically the second largest cod population in the Western Atlantic, has known a severe collapse during the early 1990 s and is currently considered as endangered by the Committee on the Status of Endangered Wildlife in Canada. As for many fish populations over the world which are currently being heavily exploited or overfished, urgent management actions in the form of recovery plans are needed for restoring this stock to sustainable levels. Stochastic projections based on a statistical population model incorporating predation were conducted over a period of 30 years (2010-2040) to assess the expected outcomes of alternative fishing strategies on the stock recovery under different scenarios of harp seal (Pagophilus groenlandicus) abundance and environmental conditions. This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock. Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status. Under current or warmer conditions in the Gulf of St. Lawrence, partial recovery might only be achieved by significant reductions in both fishing and predation pressure. In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.

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Related in: MedlinePlus

Cod total catches forecast in years 2010–2040 under water standard conditions.[(a): CIL = 0.25°C] and warming conditions [(b): CIL = 0.75°C], for the reduced catch fishing regime. Plain lines and grey areas indicate median values and 90%-confidence domains, respectively.
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pone-0082836-g008: Cod total catches forecast in years 2010–2040 under water standard conditions.[(a): CIL = 0.25°C] and warming conditions [(b): CIL = 0.75°C], for the reduced catch fishing regime. Plain lines and grey areas indicate median values and 90%-confidence domains, respectively.

Mentions: Under warming conditions, and a reduction of seal abundance by 30%, both moratorium and reduced catch approaches led to a similar fast partial recovery by 2017 (Figure 7b–1). However, under reduced fishing or a moratorium, a 50% reduction of seal abundance allowed the SSB to stabilize above the partial recovery point after 2020 (Figure 5). Under these water warming conditions, a reduced catch approach appeared to be compatible with reaching a recovery within another 10 years and an overall increasing fishery (Figure 8).


Forecasting the major influences of predation and environment on cod recovery in the northern Gulf of St. Lawrence.

Bousquet N, Chassot E, Duplisea DE, Hammill MO - PLoS ONE (2014)

Cod total catches forecast in years 2010–2040 under water standard conditions.[(a): CIL = 0.25°C] and warming conditions [(b): CIL = 0.75°C], for the reduced catch fishing regime. Plain lines and grey areas indicate median values and 90%-confidence domains, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921123&req=5

pone-0082836-g008: Cod total catches forecast in years 2010–2040 under water standard conditions.[(a): CIL = 0.25°C] and warming conditions [(b): CIL = 0.75°C], for the reduced catch fishing regime. Plain lines and grey areas indicate median values and 90%-confidence domains, respectively.
Mentions: Under warming conditions, and a reduction of seal abundance by 30%, both moratorium and reduced catch approaches led to a similar fast partial recovery by 2017 (Figure 7b–1). However, under reduced fishing or a moratorium, a 50% reduction of seal abundance allowed the SSB to stabilize above the partial recovery point after 2020 (Figure 5). Under these water warming conditions, a reduced catch approach appeared to be compatible with reaching a recovery within another 10 years and an overall increasing fishery (Figure 8).

Bottom Line: This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock.Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status.In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.

View Article: PubMed Central - PubMed

Affiliation: Institut de Mathématiques de Toulouse, UMR 5219 CNRS, Université Paul Sabatier, Toulouse, France.

ABSTRACT
The northern Gulf of St. Lawrence (NGSL) stock of Atlantic cod (Gadus morhua), historically the second largest cod population in the Western Atlantic, has known a severe collapse during the early 1990 s and is currently considered as endangered by the Committee on the Status of Endangered Wildlife in Canada. As for many fish populations over the world which are currently being heavily exploited or overfished, urgent management actions in the form of recovery plans are needed for restoring this stock to sustainable levels. Stochastic projections based on a statistical population model incorporating predation were conducted over a period of 30 years (2010-2040) to assess the expected outcomes of alternative fishing strategies on the stock recovery under different scenarios of harp seal (Pagophilus groenlandicus) abundance and environmental conditions. This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock. Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status. Under current or warmer conditions in the Gulf of St. Lawrence, partial recovery might only be achieved by significant reductions in both fishing and predation pressure. In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.

Show MeSH
Related in: MedlinePlus