Fishing

About: Fishing is a research topic. Over the lifetime, 26543 publications have been published within this topic receiving 455552 citations. The topic is also known as: angling.

Development of the EcoQO for the North Sea fish community

Abstract: Development of the Ecological Quality Objective (EcoQO) for the North Sea demersal fish community is described. Size-based metrics were identified as the most effective indicators of the state of the community, but such metrics are also sensitive to environmental influence. Redefining the large fish indicator (LFI) produced a metric more sensitive to fishing-induced change and therefore more useful to managers. Fish stocks were thought to be exploited at a sustainable rate in the early 1980s, so in a process echoing the precautionary approach to fish stock management, this was considered the reference period for the LFI, suggesting a value of 0.3 as the appropriate EcoQO. The LFI declined from around 0.3 in 1983 to 0.05 in 2001, followed by a recovery to 0.22 in 2008. However, analyses of the longer-term groundfish survey data suggest that, even were fishing pressure to be reduced to early 20th century levels, the LFI would be unlikely to rise much above a value of 0.3. The response of the LFI to variation in fishing pressure suggested a more complex relationship than anticipated, underscoring the need for operational theoretical size-resolved multispecies fish community models to support management towards broader ecosystem objectives.

Profile of a fishery collapse: why mariculture failed to save the large yellow croaker

Abstract: The large yellow croaker (Larimichthys crocea), endemic to East Asia was once one of the three top commercial marine fishes of China PR. Heavily exploited since the 1950s, wild stocks were so severely depleted by the 1980s that most individuals subsequently sold originated from hatcheries. After peaking at about 200 000 tonnes in the mid-1970s, catches of the croaker in China PR declined by over 90% within just 2 decades; according to most decline criteria this would categorize the croaker as “threatened” and management measures, including restocking, were developed. The extensive government-sponsored mariculture program introduced to address food supply and overfishing in the 1980s, particularly of the croaker, was one of the earliest for marine finfish, not only in China PR, a nation with a rich and highly successful history in aquaculture, but globally. In this first, in-depth, profile of a key fishery and early mariculture development, we integrate ecological and biological information with the fishing, management, mariculture and economic history to trace the collapse of wild stocks and assess why management and mariculture did not result in wild stock recovery. Evidence strongly suggests that a combination of heavy exploitation of spawning and over-wintering aggregations, poor management and overfishing pressure were major factors in stock declines, with contributions from pollution, habitat degradation and marine ecosystem shift. Although the croaker proved a highly successful mariculture candidate, with approximately 70 000 tonnes produced in 2005, the highest of any marine fish cultured in China PR, mariculture and restocking have failed to restore croaker stocks and may have, inadvertently, led to biodiversity losses. The detailed history of the croaker is a sobering reminder that successful mariculture, albeit important for food production and livelihoods, is not necessarily a solution to overfishing, and moreover, may have compromised fishery recovery by competing for funds, attention, space, and maybe genetic resources.

Evaluating targets and trade-offs among fisheries and conservation objectives using a multispecies size spectrum model

Abstract: Marine environmental management policies seek to ensure that fishing impacts on fished populations and other components of the ecosystem are sustainable, to simultaneously meet objectives for fisheries and conservation. For example, in Europe, targets for (i) biodiversity, (ii) food web structure as indicated by the proportion of large fish and (iii) fishing mortality rates for exploited species that lead to maximum sustainable yield, F-MSY,F- are being proposed to support implementation of the Marine Strategy Framework Directive. Efforts to reconcile any trade-offs among objectives need to be informed by knowledge on the consequences of alternate management actions. We develop, calibrate and apply a multispecies size spectrum model of the North Sea fish community to assess the response of populations and the community to fishing. The model predicts species' size distributions, abundance, productivity and interactions and therefore provides a single framework for evaluating trade-offs between population status, community and food web structure, biodiversity and fisheries yield. We show that the model can replicate realistic fish population and community structure and past responses to fishing. We assess whether meeting management targets for exploited North Sea populations (fishing species at F-MSY) will be sufficient to meet proposed targets for biodiversity and food web indicators under two management scenarios (status quo and F-MSY). The recovery in biodiversity indicators is 60% greater when fishing populations at F-MSY than if status quo (2010) fishing rates are maintained. The probability of achieving a food web target was 60% under both scenarios in spite of major community restructuring revealed by other indicators of community size structure. Synthesis and applications. Our model can be applied to evaluate indicator targets and trade-offs among fisheries and conservation objectives. There is a significant probability that reductions in fishing mortality below F-MSY would be needed in Europe if managers make a binding commitment to a proposed large fish indicator target, with concomitant reductions in fisheries yield.

Historical changes of the Mediterranean Sea ecosystem: modelling the role and impact of primary productivity and fisheries changes over time.

Abstract: The Mediterranean Sea has been defined "under siege" because of intense pressures from multiple human activities; yet there is still insufficient information on the cumulative impact of these stressors on the ecosystem and its resources. We evaluate how the historical (1950-2011) trends of various ecosystems groups/species have been impacted by changes in primary productivity (PP) combined with fishing pressure. We investigate the whole Mediterranean Sea using a food web modelling approach. Results indicate that both changes in PP and fishing pressure played an important role in driving species dynamics. Yet, PP was the strongest driver upon the Mediterranean Sea ecosystem. This highlights the importance of bottom-up processes in controlling the biological characteristics of the region. We observe a reduction in abundance of important fish species (~34%, including commercial and non-commercial) and top predators (~41%), and increases of the organisms at the bottom of the food web (~23%). Ecological indicators, such as community biomass, trophic levels, catch and diversity indicators, reflect such changes and show overall ecosystem degradation over time. Since climate change and fishing pressure are expected to intensify in the Mediterranean Sea, this study constitutes a baseline reference for stepping forward in assessing the future management of the basin.