2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Massimiliano Drago ◽  
Marco Signaroli ◽  
Meica Valdivia ◽  
Enrique M. González ◽  
Asunción Borrell ◽  
...  

AbstractUnderstanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.


2019 ◽  
Vol 209 ◽  
pp. 117-128 ◽  
Author(s):  
John G. Pope ◽  
Troels Jacob Hegland ◽  
Marta Ballesteros ◽  
Kåre Nolde Nielsen ◽  
Mika Rahikainen

2010 ◽  
Vol 107 (21) ◽  
pp. 9485-9489 ◽  
Author(s):  
S. Zhou ◽  
A. D. M. Smith ◽  
A. E. Punt ◽  
A. J. Richardson ◽  
M. Gibbs ◽  
...  

2020 ◽  
Vol 656 ◽  
pp. 75-87
Author(s):  
KM Depot ◽  
LC Scopel ◽  
SW Kress ◽  
P Shannon ◽  
AW Diamond ◽  
...  

Ecosystem-based fisheries management, which considers the interactions between fisheries, target species, and the physical and biological components of ecosystems, is necessary to ensure that directed fisheries avoid adverse impacts to ecosystems over the long term. The successful implementation of ecosystem-based fisheries management requires an understanding of predator-prey relationships and ways to operationalize such relationships to inform fisheries management. Here, we investigated if the diet of a generalist predator, Atlantic puffin Fratercula arctica, can be used as an indicator of the abundance of 2 commercially exploited prey species (haddock Melanogrammus aeglefinus and Acadian redfish Sebastes fasciatus) in the Gulf of Maine. Because haddock and redfish eaten by puffins are juveniles (age 0), there is potential to use their proportions and lengths in puffin diet to better understand the processes influencing haddock and redfish recruitment. By using principal component analysis to develop measures of diet across multiple puffin colonies, we show both spatial variation and large-scale patterns in the proportions and lengths of haddock and redfish in puffin diet. Spawning stock biomass was a strong predictor of haddock proportion in puffin diet and a moderate predictor of redfish proportion; however, proportions in puffin diet did not predict age-1 recruitment, suggesting that variation in recruitment is caused by processes that occur after the puffin breeding season and which affect the survival of older juveniles. Haddock length on one colony was a moderate predictor of age-1 recruitment. We conclude that puffin diet can be used as an indicator of haddock and redfish abundance.


2021 ◽  
Vol 8 ◽  
Author(s):  
Yuru Li ◽  
Shuyang Ma ◽  
Caihong Fu ◽  
Yongjun Tian ◽  
Jianchao Li ◽  
...  

Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantifying the responses of indicators of FCS (IFCSs) to pressures is a key aspect of ecosystem-based fisheries management. Quantitative methodology has hitherto been rarely applied to evaluate the performance of ecological indicators in response to physical and anthropogenic pressures and management actions. In this study, we adopted a quantitative and flexible framework to quantify the performance of IFCSs in the YS as well as to identify a suite of operational IFCSs to evaluate the status of the FCS via two state-space approaches. A total of 22 IFCSs were tested for their responses to three types of pressures including anthropogenic activities (fishing), large-scale climate change, and regional environmental variables. Our results indicate that the majority of IFCSs have good performance in terms of sensitivity in their responses to pressures, but weak performance in terms of robustness. The IFCSs tend to respond stronger to fishing than to large-scale climatic indices and regional environmental indices both in terms of sensitivity and robustness. A final indicator suite of five best-performing IFCSs was identified. The five IFCSs include total catch (ToC), mean trophic level (MTL), the ratio of catch of large predatory groups to total catch (LPC/ToC), mean temperature of catch (MTC) [or alternatively catch of small pelagic groups (SPC)], and functional evenness based on thermal groups (T-J′FD), all of which show regime shift patterns consistent with climate change. Compared to a reference period (1960–1964), the status of the current FCS has been obviously changed, and the long-term trajectories of the final indicator suite is consistent with that of fishing pressure. This study demonstrates the applicability of the indicator-testing framework in appraising the status of FCS, and facilitates moving towards ecosystem-based fisheries management in the YS.


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