Five centuries of cod catches in Eastern Canada

Schijns, Rebecca; Froese, Rainer; Hutchings, Jeffrey A.; Pauly, Daniel

doi:10.1093/icesjms/fsab153

Cited by 22 publications

(11 citation statements)

References 36 publications

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“…The outcome of our study is consistent with empirical observations of overfished cod stocks, cautioning that fishing can be a strong selective agent, especially in populations that undergo uninterrupted heavy exploitation for several decades and can lead to a fitness deficit of heavily overfished stocks [ 28 , 46 , 53 ]. While some commercially overexploited stocks such as North Sea cod stock are showing signs of recovery [ 54 ], stocks such are Northern cod stocks struggle to recover their biomasses [ 13 ]. The results presented here warn that the abundance recovery to pre-fishing condition does not necessarily mean that the across-generational fitness has recovered as well.…”

Section: Discussionmentioning

confidence: 99%

“…Reconstructions from historical records have demonstrated that some of today's commercially fished stocks represent merely a remnant of once highly abundant populations [ 12 , 13 ]. For example, cod fisheries date back to the pre-Mesolithic Stone Age [ 14 ], but intense fishing practices have depleted most stocks only in recent decades, with some stocks collapsing to less than 5% of their pre-industrial fishing values [ 13 ]. As a consequence, some stocks may have passed their tipping point of recovery as reflected by the Allee effects [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence, some stocks may have passed their tipping point of recovery as reflected by the Allee effects [ 15 , 16 ]. Regardless of stricter fisheries regulations, moratoriums and the decades passed, stocks such as Canadian stocks, have yet to recover their biomasses from their critical zones [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

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Multiple-batch spawning: a risk-spreading strategy disarmed by highly intensive size-selective fishing rate

2022

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Can the advantage of risk-managing life-history strategies become a disadvantage under human-induced evolution? Organisms have adapted to the variability and uncertainty of environmental conditions with a vast diversity of life-history strategies. One such evolved strategy is multiple-batch spawning, a spawning strategy common to long-lived fishes that ‘hedge their bets' by distributing the risk to their offspring on a temporal and spatial scale. The fitness benefits of this spawning strategy increase with female body size, the very trait that size-selective fishing targets. By applying an empirically and theoretically motivated eco-evolutionary mechanistic model that was parameterized for Atlantic cod ( Gadus morhua ), we explored how fishing intensity may alter the life-history traits and fitness of fishes that are multiple-batch spawners. Our main findings are twofold; first, the risk-spreading strategy of multiple-batch spawning is not effective against fisheries selection, because the fisheries selection favours smaller fish with a lower risk-spreading effect; and second, the ecological recovery in population size does not secure evolutionary recovery in the population size structure. The beneficial risk-spreading mechanism of the batch spawning strategy highlights the importance of recovery in the size structure of overfished stocks, from which a full recovery in the population size can follow.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiple-batch spawning: a risk-spreading strategy disarmed by highly intensive size-selective fishing rate

2022

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“…1). During this period, although exact abundance and biomass estimates are difficult, the landings of Northern cod (to >800 000 t reported in 1968), and previous population modelling, leave little doubt that cod were very abundant across a wide age structure from northern Labrador to the North Cape of the Grand Bank, with the stock likely comprising several million tonnes (e.g., Baird and Bishop 1989;Rose 2004;DFO 2021a;Schijns et al 2021).…”

Section: Stanza 1: the 1960s (And Earlier)mentioning

confidence: 94%

Congruence of stock production and assessment areas? An historical perspective on Canada’s iconic Northern cod

Rose

Rowe

2022

Can. J. Fish. Aquat. Sci.

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Fisheries management requires spatially congruent production and assessment areas. Canada’s Northern cod, initially considered a stock complex distributed from northern Labrador to northern Grand Bank, had its northern boundary reduced to southern Labrador in the early 1970s. Spatial incongruence has resulted in spawning stock biomass (SSB) and recruitment (R) between historical and recent eras. To investigate temporal changes, four stanzas of SSB and R were derived from statistical Perron breaks. In stanza 1, the 1960s, spawning off northern Labrador coincided with higher SSB and R than in following stanzas from the 1970s onward. SSB-R relationships that include 1960s data do not represent potential production from a more southerly distributed stock. Loglinear models of R (density-dependent models did not improve fit) indicated SSB had greatest effect, and with indices of climate and south-north distribution explained 86% of variance. Lack of density-dependence suggests long-standing recruitment overfishing, making reference points problematic. SSB growth is suggested as an alternative management target. Rebuilding the Northern cod to historic abundance requires a full “portfolio” of spawning from northern Labrador to the Grand Bank (a re-managed 2+3KL stock). With a contracted range, lower production should be anticipated.

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“…Fortunately, after twenty years, with much scientific research work done on this problem, it is much better understood. Therefore, there are multiple examples of mismanagement of fisheries resources, with regrettable consequences leading to the over exploitation of many fish resources and their consequences in their environment [9][10][11][12]. In the present paper, populations are evaluated by reconstructing the age structure of each of the years analyzed.…”

Section: Introductionmentioning

confidence: 99%

Stock Effect of Bio-Economic Indicators in an Over- exploited Fishery of the Gulf of Mexico

2023

Aquac Fish Stud

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do not usually pay attention in the effects of mesh openings as means to control the age of first catch (tc), allowing to catch only adults of the fish stock and giving to juveniles usually caught, the opportunity to survive to the adult age and having the chance to breed at least only once in their lifetime. An examination of the population parameter values of several fisheries shows that tc value is at least one year lower than the age of first maturity (tm). This is a circumstance that unavoidably leads these fisheries towards a condition of overexploitation, which in the case of the Gulf Menhaden and other cases, becomes a chronical condition that often leads to a biological and economic crisis. It is remarkable to find out that management regulations usually ignore the need to increase mesh openings to allow juvenile fish being released from the nets and capturing only adults [14]. MethodsThe assessment of the Menhaden stock was made by using a simulation model [15,16]; is based on the general principles of the assessment of exploited fish stocks and is conducted with usually fifteen years of catch data. Thus, with the purpose of formulating better management options, a meta-analysis of data was conducted to evaluate the performance of the fisheries with reference to the output of this model. In each of these options, catch data and the values of the population parameters are used, from the references or estimated directly [17][18][19][20] and are indicated in Table 1. The associated costs and economic benefits of the fishery are taken as a reference for the bio-economic analysis. The model proposed allows

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Five centuries of cod catches in Eastern Canada

Cited by 22 publications

References 36 publications

Multiple-batch spawning: a risk-spreading strategy disarmed by highly intensive size-selective fishing rate

Multiple-batch spawning: a risk-spreading strategy disarmed by highly intensive size-selective fishing rate

Congruence of stock production and assessment areas? An historical perspective on Canada’s iconic Northern cod

Stock Effect of Bio-Economic Indicators in an Over- exploited Fishery of the Gulf of Mexico

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