Relationships among fisheries exploitation, environmental conditions, and ecological indicators across a series of marine ecosystems

Abstract

Understanding how external pressures impact ecosystem structure and functioning is essential for ecosystem-based approaches to fisheries management. We quantified the relative effects of fisheries exploitation and environmental conditions on ecological indicators derived from two different data sources, fisheries catch data (catch-based) and fisheries independent survey data (survey-based) for 12 marine ecosystems using a partial least squares path modeling approach (PLS-PM). We linked these ecological indicators to the total biomass of the ecosystem. Although the effects of exploitation and environmental conditions differed across the ecosystems, some general results can be drawn from the comparative approach. Interestingly, the PLS-PM analyses showed that survey-based indicators were less tightly associated with each other than the catch-based ones. The analyses also showed that the effects of environmental conditions on the ecological indicators were predominantly significant, and tended to be negative, suggesting that in the recent period, indicators accounted for changes in environmental conditions and the changes were more likely to be adverse. Total biomass was associated with fisheries exploitation and environmental conditions; however its association with the ecological indicators was weak across the ecosystems. Knowledge of the relative influence of exploitation and environmental pressures on the dynamics within exploited ecosystems will help us to move towards ecosystem-based approaches to fisheries management. PLS-PM proved to be a useful approach to quantify the relative effects of fisheries exploitation and environmental conditions and suggest it could be used more widely in fisheries oceanography. Highlights ► We quantified the effects of fishing and environment on two groups of indicators. ► There were consistencies across 12 ecosystems in the association among indicators. ► We derived commonalities in the links among indicators, fishing and environment.

Ecological indicators to capture the effects of fishing on biodiversity and conservation status of marine ecosystems

“…Parallel results developed within the IndiSeas framework suggest that ecological indicators are in fact sensitive to environmental drivers (Fu et al, 2015), which highlights that interactions between the indicators and at least one other extrinsic factor is likely. In addition, analyses of indicators assuming a linear relationship between response indicators and pressure indicators may be too simplistic.…”

“…In addition, analyses of indicators assuming a linear relationship between response indicators and pressure indicators may be too simplistic. In fact, recent comprehensive studies of exploited marine ecosystems suggest that detailed information about past and present exploitation strategies, main productivity mechanisms, and dominant ecological and environmental traits are essential elements to correctly interpret ecological indicators to determine the status of exploited marine ecosystems (Fu et al, 2015;Kleisner et al, 2014;Link et al, 2010;Shannon et al, 2014;Shannon et al, 2010). This emphasises the need to investigate the sensitivity and specificity of indicators to different individual pressures, as well as multiple-interacting pressures, and their responsiveness to management thresholds and reference points (Large et al, 2013Shin et al, 2012).…”

Bridging the Gap between Policy and Science in Assessing the Health Status of Marine Ecosystems

“…An indicator for systematic highresolution habitat mapping and characterization scored high in the indicator-evaluation as it may be a proxy for many of the 56 MSFD indicators. We also recently developed and tested numerous promising indicators that capture effects of fishing on marine biodiversity, e.g., on the positive effects of fishing effort reduction on the increase of large fish indicator (Engelhard et al, 2015) and on the need of using biodiversity and conservation-based indicators complementarily to ecological indicators of fishing pressure to evaluate the overall impact of fishing on exploited marine ecosystems (Fu et al, 2015;Coll et al, 2016). Furthermore, a newly developed indicator based on DNA metabarcoding assesses genetic diversity of macroinvertebrates and microorganisms (Aylagas et al, 2014Carugati et al, 2015;Dell'Anno et al, 2015).…”

One device does not fit all: Limited results of using a Sort‐X grid in the multi‐species trawl fishery in the Gulf of Cádiz

“…Previous studies on the trawl fleet of GoC (Jiménez, Sobrino & Ramos, 2004) identified five métiers targeting the same mixed-species pool, but showing different degrees of directionality in the effort exerted on the main target species (Sobrino et al, 1994). Recent studies showed that the impact of bottom trawlers on demersal stocks is particularly important (Fu et al, 2015;Torres et al, 2013), with discard rates estimated to range from 17% to 47%, depending on the fishing depth and time of the year (Coll, Carreras & Cornax, 2014). Recent studies showed that the impact of bottom trawlers on demersal stocks is particularly important (Fu et al, 2015;Torres et al, 2013), with discard rates estimated to range from 17% to 47%, depending on the fishing depth and time of the year (Coll, Carreras & Cornax, 2014).…”