Life‐history correlates of extinction risk and recovery potential

Hutchings, Jeffrey A.; Myers, Ransom A.; García, Verónica B.; Lucifora, Luis O.; Kuparinen, Anna

doi:10.1890/11-1313.1

Cited by 179 publications

(190 citation statements)

References 41 publications

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“…Biomass estimates show a similar discrepancy: only one Mediterranean stock has more than half of the biomass that would be consistent with sustainable levels, while 15 Mediterranean stocks have less than 5% of that biomass. Compared with the northeast Atlantic, the warmer Mediterranean would be expected to have fish assemblages that reach smaller maximum sizes and have faster population growth rates 31 , so populations and species should be able to recover from severe overfishing 32 . Our findings are, therefore, contra to these metabolic expectations, which may explain why Mediterranean fish populations have avoided complete collapse in the face of such severe overfishing.…”

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confidence: 99%

Coherent assessments of Europe’s marine fishes show regional divergence and megafauna loss

et al. 2017

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Europe has a long tradition of exploiting marine fishes and is promoting marine economic activity through its Blue Growth strategy. This increase in anthropogenic pressure, along with climate change, threatens the biodiversity of fishes and food security. Here, we examine the conservation status of 1,020 species of European marine fishes and identify factors that contribute to their extinction risk. Large fish species (greater than 1.5 m total length) are most at risk; half of these are threatened with extinction, predominantly sharks, rays and sturgeons. This analysis was based on the latest International Union for Conservation of Nature (IUCN) European regional Red List of marine fishes, which was coherent with assessments of the status of fish stocks carried out independently by fisheries management agencies: no species classified by IUCN as threatened were considered sustainable by these agencies. A remarkable geographic divergence in stock status was also evident: in northern Europe, most stocks were not overfished, whereas in the Mediterranean Sea, almost all stocks were overfished. As Europe proceeds with its sustainable Blue Growth agenda, two main issues stand out as needing priority actions in relation to its marine fishes: the conservation of marine fish megafauna and the sustainability of Mediterranean fish stocks.arine fishes exhibit high biodiversity 1,2 and have been culturally and nutritionally important throughout human history 3 . Europe, in particular, has a well-documented history of exploiting marine fish populations, written records of which commence in the classical works of ancient Greece. Although this historical exploitation has undoubtedly altered populations 4,5 and changed many seascapes 6 , marine defaunation in the region has not been as great as in terrestrial systems 7 . However, the use of ocean space and resources is increasing due to Europe's Blue Growth strategy 8 , the nutritional requirements of an expanding human population are growing 9,10 and marine ecosystems will experience unusually rapid changes in future due to climate change 11,12 . Consequently there are imminent threats both to European marine biodiversity and fish resources 13 . It is important, therefore, to assess the threats of extinction to fish species and to ensure consistency in the management approach by the various agencies involved.We analysed data on the conservation status of 1,020 species of Europe's marine fishes from the recent International Union for Conservation of Nature (IUCN) Red List assessments 14 to identify characteristics that make Europe's fishes most susceptible to extinction risk. We then compared the Red List with 115 fish stock assessments (of 31 species) made by intergovernmental agencies charged with providing advice on the exploitation of commercial fishes. Previous comparisons of this sort applied criteria under various modelling assumptions [15][16][17] or limited the comparison to biomass reference points 18 . ResultsOf the 1,020 European marine fish species that were asses...

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Coherent assessments of Europe’s marine fishes show regional divergence and megafauna loss

et al. 2017

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“…Fisheries biologists studying teleost fishes often calculate it based on lifetime spawners per spawner (α), which is related to the slope near the origin of a stock-recruitment relationship (Denney et al, 2002;Dulvy et al, 2004;Hutchings et al, 2012). In other words, the spawners per spawner incorporates juvenile survival and approximates l α mat b.…”

Section: Introductionmentioning

confidence: 99%

Maximum intrinsic rate of population increase in sharks, rays, and chimaeras: the importance of survival to maturity

Pardo

Kindsvater

Reynolds

et al. 2016

Can. J. Fish. Aquat. Sci.

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The maximum intrinsic rate of population increase r max is a commonly estimated demographic parameter used in assessments of extinction risk. In teleosts, r max can be calculated using an estimate of spawners per spawner, but for chondrichthyans, most studies have used annual reproductive output b instead. This is problematic as it effectively assumes all juveniles survive to maturity. Here, we propose an updated r max equation that uses a simple mortality estimator which also accounts for survival to maturity: the reciprocal of average lifespan. For 94 chondrichthyans, we now estimate that r max values are on average 10% lower than previously published. Our updated r max estimates are lower than previously published for species that mature later relative to maximum age and those with high annual fecundity. The most extreme discrepancies in r max values occur in species with low age at maturity and low annual reproductive output. Our results indicate that chondrichthyans that mature relatively later in life, and to a lesser extent those that are highly fecund, are less resilient to fishing than previously thought.

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“…However, we must first understand how DIs and their variability are linked to abundance. If a DI displays a trend in response to decline or recovery, then the DI can be linked to population abundance, and once general relationships are established, a DI could be used as a population status indicator in the absence of a population index (Bjorndal et al 2000, Saether & Bakke 2000, Caut et al 2006, Hutchings et al 2012. Conversely, if a DI has high interannual variability but no significant trend, the variability itself could affect population growth, abundance, and recovery rates, and is valuable information in itself (Mazaris & Matsinos 2006, Bjorndal et al 2010.…”

Section: Introductionmentioning

confidence: 99%

Trends and variability in demographic indicators of a recovering population of green sea turtles Chelonia mydas

Piacenza¹,

Balazs²,

Hargrove³

et al. 2016

Endang. Species. Res.

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Multiple populations of green sea turtles Chelonia mydas show signs of population recovery. In Hawaii (USA), green turtles have increased 5.4% yr −1 since 1973, but fluctuations in census counts of nesting females make recovery diagnosis difficult. Evaluating demographic rates for temporal change and in relation to population density, and indicators of recruitment to sea turtle nesting populations, will ultimately improve population assessments. Using linear mixed and multistate open robust design models, we estimated the demographic indicators (DIs) of size at maturity, nester carapace length, breeding probability, and adult female survival using 3677 tagged nesting green turtles from 1973 to 2010 in Hawaii. To evaluate changes with density, we correlated the DIs with nesting female counts. We estimated size at maturity, assuming that newly tagged nesters are new recruits and that first-time nesters have statistically significant smaller carapace length than recaptures, but the difference in size was only ~0.5 cm. Mean nester carapace length (range: 89.21−91.69 cm) and breeding probability (range: 0.0766−0.444 yr −1 ) showed directional changes over time, suggesting shifts in age structure that could be due to recruitment. The top-ranked model predicted constant female survival over time (S = 0.929 yr −1 , 95% CI: 0.924−0.933, model likelihood = 1.00). Counter to our hypothesis based on density-dependence, breeding probability increases with increasing nester abundance. This work contributes to a growing set of studies evaluating sea turtle demography for temporal variability and is the first for Hawaiian green turtles. Our study demonstrates that some easily monitored demographic variables may serve as indicators of population change.

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Life‐history correlates of extinction risk and recovery potential

Cited by 179 publications

References 41 publications

Coherent assessments of Europe’s marine fishes show regional divergence and megafauna loss

Coherent assessments of Europe’s marine fishes show regional divergence and megafauna loss

Maximum intrinsic rate of population increase in sharks, rays, and chimaeras: the importance of survival to maturity

Trends and variability in demographic indicators of a recovering population of green sea turtles Chelonia mydas

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