Consequences of error in natural mortality and its estimation in stock assessment models

Punt, André E.; Castillo-Jordán, Claudio; Hamel, Owen S.; Cope, Jason M.; Maunder, Mark N.; Ianelli, James N.

doi:10.1016/j.fishres.2020.105759

Cited by 63 publications

(27 citation statements)

References 91 publications

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“…Estimates resulting from stock assessments that do not consider possible changes in stock structure and life history, such as those observed in this study, can provide a false sense of accuracy as an essential source of uncertainty may be hidden (Kuparinen et al, 2012;Evans et al, 2013). In this context, model misspecifications can lead to several problems for stock assessment, and hence the provision of management advice (Punt et al, 2021). For example, misspecification of growth can overestimate the current biomass relative to the unfished biomass (stock depletion), but this bias may be mitigated or eliminated if the assessment model includes growth variation (Stawitz et al, 2019).…”

Section: Discussionmentioning

confidence: 89%

Changes in the population structure and life history associated with long-term intense fishing of the Argentinian croaker Umbrina canosai in southern Brazil

Haimovici

Kikuchi

Cardoso

2022

Aquat. Living Resour.

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Identifying changes in the population structure and dynamics for fish stocks is important to support its management. Data obtained from 1976 to 2019 allowed to follow up long more than four decades the changes in the population structure and life-history of Umbrina canosai, an intensely exploited demersal sciaenid fish in southern Brazil. Intense fishing caused the truncation of the length/age structure with the loss of most of the bigger/older fishes and the sex ratio change, with increasing frequencies of males. A considerable increase in individual growth was observed and attributed to the lower competition for food due to the reduction in the density of the overall coastal benthic-feeding fish community caused by intense fishing. The large increase in the mortality and the exploitation rate resulted in a drastic decrease in the reproductive potential despite some anticipation in the sexual maturation. Despite the adaptative response to intense fishing, the high exploitation rates and the drastic reduction of the spawning potential ratio in recent years, are clear evidences that U. canosai could be reaching its adaptive capacity for resilience. Therefore, an urgent necessity for a drastic reduction of the fishing mortality to avoid the economic collapse of the fishery is required.

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Section: Discussionmentioning

confidence: 89%

Changes in the population structure and life history associated with long-term intense fishing of the Argentinian croaker Umbrina canosai in southern Brazil

Haimovici

Kikuchi

Cardoso

2022

Aquat. Living Resour.

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“…Here, our experimental results showed that mortality increases in fish with low body condition, suggesting that adult natural mortality from starvation may occur in the wild mainly in winter of recent years (as the proportion of the natural population below critical body condition threshold is much higher in January/February and doubled in recent years). Such a result is also of interest for fisheries science, as misspecification of M in stock assessment models is known to lead to biased estimates of fisheries reference points (Gislason et al, 2010;Johnson et al, 2014;Punt et al 2021). A recent study on Atlantic cod Gadus morhua found, for instance, that using a variable body-condition dependent M instead of a constant one can result in drastic changes in stock diagnosis (up to 40% differences in spawning stock biomass (SSB), F and recruitment; (Casini et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Is starvation a cause of overmortality of the Mediterranean sardine?

Queiros

Saraux

Dutto

et al. 2021

Marine Environmental Research

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Animal mortality is difficult to observe in marine systems, preventing a mechanistic understanding of major drivers of fish population dynamics. In particular, starvation is known to be a major cause of mortality at larval stages, but adult mortality is often unknown. In this study, we used a laboratory food-deprivation experiment, on wild caught sardine Sardina pilchardus from the Gulf of Lions. This population is interesting because mean individual phenotype shifted around 2008, becoming dominated by small, young individuals in poor body condition, a phenomenon that may result from declines in energy availability. Continuous monitoring of body mass loss and metabolic rate in 78 captive food-deprived individuals revealed that sardines could survive for up to 57 days on body reserves. Sardines submitted to long-term caloric restriction prior to food-deprivation displayed adaptive phenotypic plasticity, reducing metabolic energy expenditure and enduring starvation for longer than sardines that had not been calorie-restricted. Overall, entry into critical fasting phase 3 occurred at a body condition of 0.72. Such a degree of leanness has rarely been observed over 34 years of wild population monitoring. Still, the proportion of sardines below this threshold has doubled since 2008 and is maximal in January and February (the peak of the reproductive season), now reaching almost 10% of the population at that time. These results indicate that the demographic changes observed in the wild may result in part from starvation-related adult mortality at the end of the winter reproductive period, despite adaptive plastic responses.

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“…Natural mortality (M) is often considered to be one of the most important parameters in a fish stock assessment, but it is also among the most difficult parameters to estimate using commonly available data (Punt et al 2021). This is the case for redfish.…”

Section: Natural Mortality Mmentioning

confidence: 99%

“…Kenchington (2014) recommended using a measured M for a stock if one is available and refers to these literature methods as applicable mostly in "information-limited" situations. However, it is difficult to experimentally measure M using data typically available and best practice (i.e., Punt et al 2021) is to estimate M within an assessment model, ideally with a prior for M for the specific stock. However, M can easily be confounded with other assessment model misspecifications and a thorough analysis of the assessment M information should be conducted (e.g., Perreault and Cadigan 2021).…”

Section: Natural Mortality Mmentioning

confidence: 99%

Northwest Atlantic redfish science priorities for managing an enigmatic species complex

Cadigan

Duplisea²,

Senay

et al. 2022

Can. J. Fish. Aquat. Sci.

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Redfish (Sebastes spp.) in the Northwest Atlantic (NWA) extend from Baffin Island in the north to the Gulf of Maine in the south. The two most abundant species are S. mentella and S. fasciatus, which are morphometrically similar and difficult to visually distinguish. Redfish are long-lived, slow-growing, late-maturing, tend to produce large year classes episodically, and have complex population structure. Intraspecific genetic groups are abundant in the NWA. They are often semi-pelagic and patchily distributed, which makes them difficult to survey. These are all characteristics that cause difficulties for stock assessment and for sustainable fisheries management. This was the focus of The Ocean Frontier Institute Northwest Atlantic Redfish Symposium in 2018. In this paper we synthesize the information known about NWA redfish. To improve the scientific basis for sustainable harvest strategies, key research recommendations involve: 1) improved biological sampling including species and ecotype; 2) develop integrated stock assessment models; 3) develop harvest strategies with management reference points that are appropriate for redfish; 4) improve fishing technology and practices to avoid capture of small non-marketable redfish and other species.

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Consequences of error in natural mortality and its estimation in stock assessment models

Cited by 63 publications

References 91 publications

Changes in the population structure and life history associated with long-term intense fishing of the Argentinian croaker Umbrina canosai in southern Brazil

Changes in the population structure and life history associated with long-term intense fishing of the Argentinian croaker Umbrina canosai in southern Brazil

Is starvation a cause of overmortality of the Mediterranean sardine?

Northwest Atlantic redfish science priorities for managing an enigmatic species complex

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