Hypotheses for the decline of cod in the North Atlantic

Myers, RA; Hutchings, Jeffrey A.; Barrowman, Nicholas J.

doi:10.3354/meps138293

Cited by 193 publications

(119 citation statements)

References 14 publications

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“…However, most Canadian stocks declined once again, and to a greater extent, during the late 1980s and early 1990s. Some investigators (Hutchings and Myers 1994, Hutchings 1996, Myers et al 1996 have stated that these declines during the late 1980s and early 1990s were caused entirely by fishing, and indeed SPA modeling indicates a sharp increase in fishing mortality for many of these stocks, most notably those from the eastern Scotian Shelf northward to S. Labrador-E. Newfoundland (Fig. 4).…”

Section: The Effect Of Fisheries On Stock Biomassmentioning

confidence: 99%

“…A series of publications during the mid-1990s (Hutchings and Myers 1994, Myers and Cadigan 1995, Hutchings 1996, Myers et al 1996 stated that there was no evidence of an increase in natural mortality in the S. Labrador-E. Newfoundland stock and other Canadian cod stocks during the period of collapse. It was only after data had accumulated for several additional years that analyses started to provide evidence that natural mortality had indeed increased, and such an increase was then incorporated into SPA models for the stocks in the northern (Fréchet et al 2005) and southern ) Gulf of St. Lawrence and the stock on the eastern Scotian Shelf (Mohn et al 1998).…”

Section: Natural Mortalitymentioning

confidence: 99%

“…(We use SPA as a generic term for such models, which include virtual population analysis, VPA.) It is common in inter-stock comparisons to focus on trends in spawning stock biomass (SSB) (e.g., Myers et al 1996) because of the implicit, though flawed (Marteinsdottir and Begg 2002), assumption of proportionality between SSB and reproductive potential. However, trends in SSB may not reflect the extent of stock decline if the computation of SSB incorporates the decline in age-at-maturity documented for many stocks ).…”

Section: Changes In Total Biomassmentioning

confidence: 99%

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Decline and Recovery of Atlantic Cod (Gadus morhua) Stocks throughout the North Atlantic

Lilly¹,

Wieland²,

Rothschild³

et al. 2008

Resiliency of Gadid Stocks to Fishing and Climate Change

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Many stocks of Atlantic cod (Gadus morhua) on both sides of the North Atlantic are currently at much reduced levels of biomass, but this situation is not in all instances the result of long, continuous decline. Most Northwest Atlantic stocks declined to low levels during the 1970s, but increased during the 1980s before declining even more severely during the late 1980s and early 1990s. Several of these stocks have shown little recovery despite severe restrictions on directed fishing. Many stocks in the Northeast Atlantic have experienced sustained increases and sustained decreases, but generally not in concert. Among-stock comparisons illustrate that fishing has played a dominant role in the dynamics of all cod stocks, but variability in climate has contributed to variability in recruitment, individual growth, and natural mortality. A cooling event during the last three decades of the twentieth century contributed to the rapid decline of several stocks in the Northwest Atlantic, and changes in life-history traits (growth rate, age and size at maturity) and in the biotic environment (predators and prey) may be contributing to recovery being slow.

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Section: The Effect Of Fisheries On Stock Biomassmentioning

confidence: 99%

Section: Natural Mortalitymentioning

confidence: 99%

Section: Changes In Total Biomassmentioning

confidence: 99%

See 1 more Smart Citation

Decline and Recovery of Atlantic Cod (Gadus morhua) Stocks throughout the North Atlantic

Lilly¹,

Wieland²,

Rothschild³

et al. 2008

Resiliency of Gadid Stocks to Fishing and Climate Change

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show abstract

“…The mechanisms through which fishing affects the dynamics of northern cod have been studied extensively (Hutchings & Myers 1994, Hutchings 1996, Myers et al 1996, Myers et al 1997, Rose 2004, Shelton et al 2006, Lilly et al 2008, Hilborn & Litzinger 2009). Our study reinforces the notion that fisheries harvest was an important factor in the collapse of Atlantic cod off Newfoundland during the early 1990s.…”

Section: Fisheries Harvest As a Drivermentioning

confidence: 99%

The role of harp seals, fisheries and food availability in driving the dynamics of northern cod

Buren¹,

Koen‐Alonso²,

Stenson³

2014

Mar. Ecol. Prog. Ser.

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The Atlantic cod Gadus morhua population off Newfoundland collapsed in the early 1990s due to over-exploitation, and despite marked reduction in fishing effort the stock remains depressed. Harp seal Pagophilus groenlandicus predation has been repeatedly proposed as an explanation for this lack of recovery, but other hypotheses include reduced prey availability and/or food quality (i.e. lack of capelin Mallotus villosus), as well as fisheries catches and environmental effects. Using a bioenergetics−allometric model, we gauged the relative contributions of these drivers on the lack of recovery and dynamics of the northern cod stock. Biomass dynamics were best explained by a combination of fisheries removals and capelin availability, whereas seal consumption was found not to be an important driver of the northern cod stock. Prey availability was linked to reduced somatic condition during the 1990s and 2000s. We discuss evidence that suggests that cod may be experiencing depensatory dynamics, but not related to a 'predator pit effect'. Our study suggests that trophic control is bottom-up, and that a depressed capelin stock could be a serious impediment for cod rebuilding.

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“…In the first two, the length of the policy process hinders a fast management response to ecosystem change [117,118]. For example, Myers et al [119] found that as North Atlantic cod populations collapsed, fishing mortality increased until the populations were reduced to very low levels. The fishing mortality was thus reduced too late, and the resulting collapses have generally been very slow to reverse [120].…”

Section: Boxmentioning

confidence: 99%

Global connectivity and cross-scale interactions create uncertainty for Blue Growth of Arctic fisheries

et al. 2018

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A B S T R A C TThe Arctic faces high expectations of Blue Growth due to future projections of easier access and increased biological productivity. These expectations are, however, often based on global and regional climate change projections and largely ignore the complexity of social-ecological interactions taking place across different temporal and spatial scales. This paper illustrates how such cross-scale interactions at, and across, different dimensions (e.g., ecological, socioeconomic and governance) can affect the development of Arctic fisheries; and potentially create uncertainties for future Blue Growth projections. Two Arctic marine systems, The Barents Sea and the Central Arctic Ocean (CAO), are used as focus areas. The former hosts productive fisheries and is mostly covered by the EEZs of Norway and Russia, while the latter is still mainly covered by sea-ice and is a high seas area with no multilevel governance system in place. The examples show that, both systems are affected by a number of processes, beyond the environmental change, spanning a wide range of dimensions, as well as spatial and temporal scales. To address the complexity of the Arctic marine systems calls for an increase in holistic scientific understanding together with adaptive management practices. This is particularly important in the CAO, where no robust regional management structures are in place. Recognizing how cross-scale dynamics can cause uncertainties to the current fisheries projections and implementing well-functioning adaptive management structures across different Arctic sub-systems can play a key role in whether the Blue Growth potential in Arctic fisheries is realized or lost.

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Hypotheses for the decline of cod in the North Atlantic

Cited by 193 publications

References 14 publications

Decline and Recovery of Atlantic Cod (Gadus morhua) Stocks throughout the North Atlantic

Decline and Recovery of Atlantic Cod (Gadus morhua) Stocks throughout the North Atlantic

The role of harp seals, fisheries and food availability in driving the dynamics of northern cod

Global connectivity and cross-scale interactions create uncertainty for Blue Growth of Arctic fisheries

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