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The fate of discards from marine fisheries. A disregarded viewpoint in fisheries management.
... Furthermore, current discard monitoring programs focus primarily on commercial species and have been designed to estimate discard rates per fleet and stock rather than to estimate discard flow into the environment. Reliable quantitative information on the ratio of commercial versus non-commercial discards is relatively sparse (Uhlmann et al. 2013;Depestele 2015), but existing data could be used to speculate on the orders of magnitude changes that non-commercial discards may cause in the energy flow in the ecosystem. Here again, sensitivity analyses will be necessary to complete the present work. ...
A scavenger is an animal that feeds on dead animals (carrion) that it has not killed itself. Fisheries discards are often seen as an important food source for marine scavengers so the reduction of discards due to the Landing Obligation may affect their populations. The literature on scavenging in marine ecosystems is considerable, due to its importance in the trophic ecology of many species. Although discards undoubtedly contribute to these species’ food sources, few can be seen to be solely dependent on carrion (including discards). Ecosystem models predicted that discards contributed very little to the diet of scavengers at a regional scale. A reduction in discards through the Landing Obligation may therefore affect populations for a few species in some areas, but generally this is unlikely to be the case. But it is challenging to identify how important discards might be to scavengers, as they are taxonomically diverse and vary in the role they play in scavenging interactions.
... Furthermore, current discard monitoring programs focus primarily on commercial species and have been designed to estimate discard rates per fleet and stock rather than to estimate discard flow into the environment. Reliable quantitative information on the ratio of commercial versus non-commercial discards is relatively sparse (Uhlmann et al. 2013;Depestele 2015), but existing data could be used to speculate on the orders of magnitude changes that non-commercial discards may cause in the energy flow in the ecosystem. Here again, sensitivity analyses will be necessary to complete the present work. ...
A scavenger is an animal that feeds on dead animals (carrion) that it has not killed itself. Fisheries discards are often seen as an important food source for marine scavengers so the reduction of discards due to the Landing Obligation may affect their populations. The literature on scavenging in marine ecosystems is considerable, due to its importance in the trophic ecology of many species. Although discards undoubtedly contribute to these species’ food sources, few can be seen to be solely dependent on carrion (including discards). Ecosystem models predicted that discards contributed very little to the diet of scavengers at a regional scale. A reduction in discards through the Landing Obligation may therefore affect populations for a few species in some areas, but generally this is unlikely to be the case. But it is challenging to identify how important discards might be to scavengers, as they are taxonomically diverse and vary in the role they play in scavenging interactions.
... Trawl fisheries cause physical disruption of the seabed through contact of the gear components with the sediment. As a result sediment resuspension into the water column occurs in the wake of the gear (Depestele et al. 2015). Mainly the smaller particle sizes are resuspended. ...
... Pikitch et al., 2004). Therefore, while under traditional single-species fisheries management science is mostly 'ahead of policy', science is likely to 'lag behind' when adopting an EAF (Rice, 2011;Depestele, 2015). Further, scientific insights often trigger new research questions, requiring more research. ...
The Ecosystem Approach to Fisheries (EAF) is widely regarded as the best way to manage our living marine resources. While traditional fisheries management focuses on the populations of the target species, an EAF recognizes the complexity of ecosystems in which fisheries operate. Crucial aspects of an EAF are therefore (1) trophic relations between target species, their prey and predators, (2) indirect interactions between fleets - through trophic links and bycatch - and (3) the impact of fishing on marine habitats and species communities. Ignoring these elements in fisheries management lies at the core of different environmental and socio-economic problems, particularly in tropical shrimp fisheries. Triggered by a negative public perception and increasing consumer demand for sustainable products, the fishery for seabob shrimp in Suriname launched a sustainability initiative, resulting in certification by the Marine Stewardship Council (MSC). This eco-label, however, was not an endpoint, but formed the basis for further improvements and was the direct motivation for this doctoral study. In cooperation with the local fisheries administration, the fishing industry, NGOs and the local university, research was conducted on the coastal ecosystem in Suriname, until recently virtually a blind spot for marine biologists. First, we investigated the spatio-temporal distribution of fish and invertebrates in the coastal waters. A second important element was the characterization of the role of seabob shrimp in the marine food web. Thirdly, this study focused on assessing the impact of seabob fisheries on the coastal ecosystem, by examining the composition of commercial catches. The scientific results were translated into recommendations to further support an ecosystem approach to the management of the Suriname seabob fishery. This thesis shows that fisheries can be sustainably managed, even those targeting tropical shrimp. Eco-labelling, participatory management and research can play a crucial role in this process.
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