Search

Global food demand is rising, and serious questions remain about whether supply can increase sustainably1. Land-based expansion is possible but may exacerbate climate change and biodiversity loss, and compromise the delivery of other ecosystem services2–6. As food from the sea represents only 17% of the current production of edible meat, we ask how much food we can expect the ocean to sustainably produce by 2050. Here we examine the main food-producing sectors in the ocean—wild fisheries, finfish mariculture and bivalve mariculture—to estimate 'sustainable supply curves' that account for ecological, economic, regulatory and technological constraints. We overlay these supply curves with demand scenarios to estimate future seafood production. We find that under our estimated demand shifts and supply scenarios (which account for policy reform and technology improvements), edible food from the sea could increase by 21–44 million tonnes by 2050, a 36–74% increase compared to current yields. This represents 12–25% of the estimated increase in all meat needed to feed 9.8 billion people by 2050. Increases in all three sectors are likely, but are most pronounced for mariculture. Whether these production potentials are realized sustainably will depend on factors such as policy reforms, technological innovation and the extent of future shifts in demand. Modelled supply curves show that, with policy reform and technological innovation, the production of food from the sea may increase sustainably, perhaps supplying 25% of the increase in demand for meat products by 2050. [ABSTRACT FROM AUTHOR]

Participatory approaches to fisheries management are gaining increasing support from researchers, non-governmental organizations, and governments in Latin America, and different forms of participatory monitoring have been implemented over the last few decades. Among several advantages, these initiatives allow incorporation of fishers' knowledge on ecology, fishing practices, social aspects, markets, regulations, into different stages of management. In this paper, we analyze key features of participatory monitoring programs in small-scale coastal fisheries in South America (Argentina, Brazil, Chile and Uruguay) through a literature review complemented by expert opinion. Our review considered the fisheries and variables monitored; objectives, duration, institutional context of the monitoring programs; and factors that affect the extent of fishers' participation and the incorporation of fishers' knowledge. We found 14 case studies described in the literature, most of which correspond to benthic fisheries. Most cases focused on ecological and/or catch and effort variables; few initiatives included social variables. Initiatives were mainly driven by researchers in partnership with fishers and other stakeholders under formal or informal institutional arrangements. Institutional arrangements were largely responsible for the effectiveness of participation. In most cases, fishers' participation in monitoring was fostered as a component of a broader participatory co-management approach. Despite the challenges, participatory monitoring approaches are gaining traction in South America, receiving significant support from researchers in most cases, and from nongovernmental organizations in some cases. Increased governmental support for implementing and sustaining long-lasting participatory monitoring programs would strengthen monitoring initiatives that emerge locally. [ABSTRACT FROM AUTHOR]

Since the introduction of Undaria into Nuevo Gulf, Argentina, around 1992, this alien seaweed has now colonized different sites over 700 km of coast, forming dense seasonal forests in waters from 0 to 15 meters in depth. In the spring it is common for plants of Undaria to break away from the substrate and be transported by sea currents. As Undaria gets stuck onto reefs it has the potential to reduce habitat quality for reef fish by physically obstructing refuges. This study aims to assess the impact of Undaria on the abundance of four species of rocky-reef fishes by an observational experiment. Fish abundance on reefs with and without Undaria was estimated by underwater visual census methods. Sites were classified according to their topographical relief, as this was expected to influence the effect of Undaria on the abundance of reef fishes. Fish abundance decreased markedly in low-relief reefs that had been covered by Undaria. In contrast, the drifting Undaria had no effect on the abundance of any of the fish species considered in high-relief reefs, where it tends to cover only the lowest-lying areas, leaving much of the refuges for fish unaffected. In conclusion, the presence of Undaria off the coast of Argentina results in transitory habitat loss for reef fishes inhabiting low-relief reefs during late spring and early summer. Although we do not know how much of a threat this habitat loss represents for the conservation of reef fish populations of northern Patagonia, the documented local impact of Undaria within the gulfs is strong and may affect a number of recreational and commercial activities which are centered on the reefs and their fish assemblages. [ABSTRACT FROM AUTHOR]

The growth pattern of Loxechinus albus in southern Chile was studied using size-at-age data obtained by reading growth bands on the genital plates. The scatter plots of sizes-at-age for samples collected in three different locations indicated that growth is linear between ages 2 and 10. Five different growth models, including linear, asymptotic and non-asymptotic functions, were fitted to the data, and model selection was conducted based on the Akaike information criteria (AIC) and the Bayesian information criteria (BIC). The AIC identified the Tanaka model as the most suitable for two of the three sites. However, the BIC led to the selection of the linear model for all zones. Our results show that the growth pattern of L. albus is different from the predominantly asymptotic pattern that has been reported for other sea urchin species. [ABSTRACT FROM AUTHOR]

Technological advances in the field of underwater video have led to an exponential increase in the use of drifting cameras (DC) and remotely operated vehicles (ROVs) to monitor the diversity, abundance, and size structure of marine life. Main advantages of DCs relative to ROVs are their lower costs and the much simpler logistics required to operate them. This study compares the performance of a new low-cost DC system equipped with a novel measuring device with that of a standard DC bearing an array of laser pointers. The new DC, which can be operated from a small boat, carries a pair of parallel steel “whiskers” that are dragged on the seabed within the field of view of the camera, providing a scale for measuring and estimating the density of benthic biota. An experiment conducted using an array of objects of known sizes laid on the bottom showed that its performance in terms of both size and density estimation was similar to that of the standard technique based on laser pointers. Measurement errors had a negligible negative bias (− 2.3%) and a standard deviation that ranged between 13 and 8% for objects from 25 to 110 mm in size. The whiskers offered a simplified method for density estimation that avoids the need to calculate the width of the field of view, thus reducing the video processing time by around 60% with respect to the standard method. Briefly, the new system offers an efficient low-cost alternative for benthic ecology studies conducted on soft or non-irregular bottoms. [ABSTRACT FROM AUTHOR]

Many small-scale fisheries (SSFs) in Latin America and the Caribbean (LAC) operate in ecologically sensitive areas, where balancing conservation and resource use is challenging. 'Multiple-use' marine protected areas (MPAs) have been implemented to accommodate SSFs (among other uses) within areas designated for conservation, creating opportunities and challenges for SSF governance. We analyzed eleven case studies from LAC to explore: (1) how different MPA institutional designs affect key aspects of SSF governance and (2) the links between these effects and the type of initiative that promoted MPA establishment (origin). Results indicate that the existence of an MPA benefited SSF governance in many ways, with more pronounced positive effects in MPAs with mixed to bottom-up origin supported by well-organized fishing groups. In addition, the presence of supportive MPA authorities that leveraged local capacities and initiatives and adopted flexible and collaborative governance systems made a difference in several cases. Lessons for integrating MPA and SSF governance are drawn. [ABSTRACT FROM AUTHOR]