Long-term changes in the age structure, mortality and biomass of the king weakfish Macrodon atricauda (Günther, 1880) in southern Brazil: Is it resilient enough to avoid collapse?

Cardoso, L. P.; Haimovici, Manuel

doi:10.1016/j.fishres.2015.02.012

Cited by 15 publications

(9 citation statements)

References 27 publications

(46 reference statements)

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“…This suggests a fishery with episodic recruitment which may reduce the resilience of A. atelodus to environmental changes (Pauly et al., 2002). The high level of fishing in the mid‐1950s in NSW may have resulted in a decrease in population abundance resulting in changes to life history characteristics such as smaller length at maturity, high growth rates and relatively short life‐span (Cardoso & Haimovici, 2015) due to phenotype plasticity of the population (Brown‐Peterson & Warren, 2001; Cardoso & Haimovici, 2015; Dieckmann & Heino, 2007). While A .…”

Section: Discussionmentioning

confidence: 99%

Reproductive strategies of a temperate Australian sciaenid (teraglin, Atractoscion atelodus )

2021

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Summary Worldwide there have been declines in stocks of exploited sciaenids. Despite a long history of exploitation, there has been no study of the life history characteristics of the fishery‐important sciaenid, teraglin, Atractoscion atelodus. This study describes the reproductive characteristics of A. atelodus within the major area of its distribution and fishery, New South Wales (NSW) Australia. Characteristics studied included the size and age at maturity, fecundity, spawning mode and season, and these are compared to congeneric species. Atractoscion atelodus displays year‐round batch spawning behaviour with asynchronous oocyte development and indeterminate fecundity. This is unusual for sciaenids, which typically display spring‐summer spawning and only over a few months. The length and age at which 50% of the population matures for both males and females is 36 cm fork length (FL) and 1 year, a smaller size compared to other closely related sciaenids. While the species displays resilient reproductive characteristics such as protracted year‐round spawning, constant supply of vitellogenic oocytes and relatively small/young age at maturity, there are also characteristics that make it susceptible to over‐exploitation. These include highly female skewed sex ratios, as well as their schooling and voracious feeding behaviour leading to the potential for high catch rates.

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Section: Discussionmentioning

confidence: 99%

Reproductive strategies of a temperate Australian sciaenid (teraglin, Atractoscion atelodus )

2021

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“…The decrease in size at maturity was interpreted as an effect of the selective fishing pressure (Cardoso & Haimovici, ). In contrast, the changes in growth and in the age at maturity were interpreted as density‐dependent effects, resulting from the decrease in abundance of M. atricauda (Cardoso & Haimovici, ), and also of striped weakfish Cynoscion guatucupa (Cuvier 1830) (Miranda & Haimovici, ), its main competitor for shrimps, squids and small fishes along the inner shelf of southern Brazil (Martins, ). This interpretation was based on the hypothesis of increased food availability.…”

Section: Preponderance Index For the Prey Items Of Macrodon Atricaudamentioning

confidence: 99%

“…These changes may be a result of the intense fishing pressure on the demersal fish stocks along the continental shelf of southern Brazil, which have caused a decrease in abundance in the last five decades (Haimovici, ; Haimovici et al ., ). The decreased abundance of fish stocks may have resulted in a lower availability of fishes and a higher availability of A. longinaris as prey for M. atricauda , probably due to reduced intra‐ and interspecific competition for food caused by the decreasing abundance of teleosts (Cardoso & Haimovici, ), particularly its main competitor, C. guatucupa (Miranda & Haimovici, ).…”

Section: Preponderance Index For the Prey Items Of Macrodon Atricaudamentioning

confidence: 99%

Density‐dependent changes in the feeding behaviour of Macrodon atricauda of southern Brazil

Cardoso

Haimovici

2016

Journal of Fish Biology

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Long-term density-dependent changes in the population dynamics of the king weakfish Macrodon atricauda of southern Brazil between 1976 and 2013 may be related to a change in diet and an increase in feeding intensity. The importance of the small crustacean, Artemesia longinaris, increased in the diet of adults, whereas the importance of teleosts decreased and the frequency of full stomachs increased. Macrodon atricauda currently benefits from a high availability of A. longinaris, which results in a higher energy intake per individual, which, in turn, induces faster body growth and an earlier onset of sexual maturation.

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“…The main species exploited in the reservoirs are carp (Cyprinus carpio), barbel (Barbus callensis), roach (Rutilus rubilio), and rudd (Scardinius erythrophthalmus), as well as species with higher commercial value, such as mullet (Mugil cephalus and Liza ramada) and pikeperch (Sander lucioperca) (Losse et al 1991). Populations of economically important fishes in the reservoirs remain poorly studied, and there is a critical need for reliable information on the distribution and biomass of these stocks to ensure their effective management (Methot and Wetzel 2013;Cardoso and Haimovici 2015). Hydroacoustic methods provide one potentially important tool for meeting these data requirements.…”

Section: Introductionmentioning

confidence: 99%

Acoustic fish biomass assessment in a deep Tunisian reservoir: effects of season and diel rhythm on survey results

Djemali

Laouar

2017

African Journal of Aquatic Science

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To determine the best acoustic sampling period for obtaining fish biomass estimates of a Mediterranean deep reservoir in Tunisia, we carried out day and night surveys in each of four seasons [spring (April), summer (September), autumn (December) and winter (March)]. A Simrad EK60 echosounder, equipped with two 120 kHz split-beam transducers for simultaneous horizontal and vertical beaming, was used to sample the entire water column.Data collected in December were not usable because fish merged with methane gas bubbles.However, fish abundance varied across the other seasons with a peak in acoustic biomass observed during summer nighttime hours that was associated with high water temperatures.Across seasons, the fish occupied the entire water column, and fish schools were rarely observed. The preferential timeframe (i.e. maximum fish detectability and low gas flux) for acoustic sampling was nighttime hours in summer and daytime hours during spring and winter. Our findings highlight the importance of collecting data across seasons and photoperiods when determining an acoustic sampling strategy.

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Long-term changes in the age structure, mortality and biomass of the king weakfish Macrodon atricauda (Günther, 1880) in southern Brazil: Is it resilient enough to avoid collapse?

Cited by 15 publications

References 27 publications

Reproductive strategies of a temperate Australian sciaenid (teraglin, Atractoscion atelodus )

Reproductive strategies of a temperate Australian sciaenid (teraglin, Atractoscion atelodus )

Density‐dependent changes in the feeding behaviour of Macrodon atricauda of southern Brazil

Acoustic fish biomass assessment in a deep Tunisian reservoir: effects of season and diel rhythm on survey results

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