Temporal and spatial patterns in the abundance of jellyfish in the northern Benguela upwelling ecosystem and their link to thwarted pelagic fishery recovery

Flynn, B. A.; Richardson, Anthony J.; Brierley, Andrew S.; Boyer, D. C.; Axelsen, Bjørn Erik; Scott, Lucy; Moroff, Nadine E.; Kainge, Paulus Inekela; Tjizoo, Beau; Gibbons, Mark J.

doi:10.2989/1814232x.2012.675122

Cited by 35 publications

(27 citation statements)

References 96 publications

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“…In the NB, the main spawning area for sardines on the shelf in the north central part of the ecosystem (Kreiner et al 2011) overlaps considerably with the region of highest jellyfish abundance, between 20°S and 24°S (Flynn et al 2012). This overlap highlights the potential for a negative feedback effect of the establishment of a large biomass of jellyfishes on recruitment and recovery potential of the NB sardine stock (Bakun and Weeks 2006).…”

Section: The Role Of Small Pelagic Fishes and What Canmentioning

confidence: 99%

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Roux¹,

Lingen²,

Gibbons³

et al. 2013

BMS

125

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Changes in two contrasting ecosystems of the Benguela upwelling region, one dominated at mid-trophic level by jellyfishes (Namibia, northern Benguela ecosystem, where small pelagic fish abundance has been severely depleted) and one still dominated by small pelagic fishes (South Africa, southern Benguela) were compared in an effort to determine ecosystem trajectories under different exploitation regimes. The role of small pelagic fishes (clupeoids) was highlighted in the context of their importance in maintaining interactions in marine ecosystems. In particular, we examined trophic cascades and possible irreversible changes that promote the proliferation of jellyfishes in marine systems. We found that the presence of large populations of small pelagic fishes has a fundamental role in preserving beneficial trophic interactions in these marine ecosystems. The implications of trophic cascades, such as those observed in the northern Benguela, for ecosystem-based management were apparent. In addition, this comparison provides contrasting case studies to inform the development of management scenarios that avoid ecosystem shifts that affect predators and reduce the value of fisheries production.

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Section: The Role Of Small Pelagic Fishes and What Canmentioning

confidence: 99%

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Roux¹,

Lingen²,

Gibbons³

et al. 2013

BMS

125

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“…Flynn et al . () analysed fisheries‐dependent and independent data as well as published and unpublished information in order to assess if there has been an increase in the abundance of jellyfish. They have provided circumstantial evidence that jellyfish abundance might have increased, but noted that quantitative evidence for this is lacking.…”

Section: What Are the Relative Roles Of Environment And Fishing In Drmentioning

confidence: 99%

“…While there is no doubt that the biomass of pelagic fish is presently much lower than 50 yr ago, there is an ongoing debate regarding the abundance of jellyfish and their potential influence on the failure of the sardine stock to recover. Flynn et al (2012) analysed fisheries-dependent and independent data as well as published and unpublished information in order to assess if there has been an increase in the abundance of jellyfish. They have provided circumstantial evidence that jellyfish abundance might have increased, but noted that quantitative evidence for this is lacking.…”

Section: Relative Importance Of Environmental and Human Driversmentioning

confidence: 99%

Synthesis: climate effects on biodiversity, abundance and distribution of marine organisms in the Benguela

Jarre

Hutchings

Kirkman

et al. 2015

Fisheries Oceanography

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The NansClim project (2010–2013) represented a regional collaboration to assess the effects of climate on Benguela dynamics. Based on in situ (since the 1960s in Namibia and South Africa and 1985 in Angola) and satellite (since the 1980s) observations, the project focussed on four subsystems, namely the Angola subtropical, northern Benguela upwelling, southern Benguela upwelling and Agulhas Bank. This contribution summarizes the findings for selected key questions, ranging from changes in the physico‐chemical habitats, plankton, pelagic and demersal fish communities, to cross‐cutting evaluation at subsystem and regional scales. The results underline the overriding importance to of considering the combined effects of climate and fishing as drivers of the dynamics of the ecosystem components. Each subsystem currently continues to function largely as a separate entity as described in earlier reviews. However, some changes have been observed across several subsystems, e.g., a coherent shift from one relatively stable period to another occurred in the northern and southern Benguela in the mid‐1990s. Future climate change could weaken the boundaries between the four subystems. The findings underline the need for continued regional research collaboration and regional surveys focussed at ecosystem, rather than resource, assessment. Our conclusions include implications for ecosystem‐based fisheries management, and recommendations for future regional research.

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“…Historically, forage fish have often been heavily harvested, and in some areas, species composition has subsequently become dominated by gelatinous zooplankton ('jellyfish') (Lynam et al 2011, Flynn et al 2012, Purcell 2012. In addition to commercial harvesting, anthropogenic pressures such as climate change, hypoxia, and coastal development may positively benefit jellyfish (Parsons & Lalli 2002, Purcell et al 2007, Richardson et al 2009, Purcell 2012 at the expense of forage fish.…”

Section: Introductionmentioning

confidence: 99%

Forty years of change in forage fish and jellyfish abundance across greater Puget Sound, Washington (USA): anthropogenic and climate associations

Greene¹,

Kuehne²,

Rice³

et al. 2015

Mar. Ecol. Prog. Ser.

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Coastal ecosystems face a variety of natural and anthropogenic influences, raising questions about mechanisms by which species abundance and composition change over time. We examined these questions by synthesizing 6 surface-trawling efforts in greater Puget Sound, Washington (USA), spanning 40 yr, and then determining changes in forage fish abundance and composition and jellyfish prevalence. We also assessed whether patterns were associated with potential anthropogenic pressures (human population density and commercial harvest) as well as large-scale climate signals. We found evidence for trends in abundance of all forage species in 4 sub-basins of Puget Sound. Cumulative distribution functions of catch per unit effort indicate that the historically dominant forage fishes (Pacific herring and surf smelt) have declined in surface waters in 2 sub-basins (Central and South Puget Sound) by up to 2 orders of magnitude. However, 2 other species (Pacific sand lance and three-spine stickleback) increased in all 4 sub-basins. Consequently, species composition diverged among sub-basins over the last 40 yr. In addition, jellyfish-dominated catches increased 3-to 9-fold in Central and South Puget Sound, and abundance positively tracked human population density across all basins. The strongest predictors of forage fish declines were human population density and commercial harvest. Climate signals offered additional explanatory power for forage fish but not jellyfish catch. These patterns suggest possible linkages between coastal anthropogenic activities (e.g. development, pollution) and the abundance of forage fish and jellyfish in pelagic waters. Our findings also provide a basis for improving indicators for assessment, monitoring, and spatial planning to rehabilitate pelagic ecosystems.

show abstract

Temporal and spatial patterns in the abundance of jellyfish in the northern Benguela upwelling ecosystem and their link to thwarted pelagic fishery recovery

Cited by 35 publications

References 96 publications

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

Synthesis: climate effects on biodiversity, abundance and distribution of marine organisms in the Benguela

Forty years of change in forage fish and jellyfish abundance across greater Puget Sound, Washington (USA): anthropogenic and climate associations

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