Firmly cemented in history as a connector of people, a facilitator for trade and transport routes and a driver of culture and heritage, the ocean has directly influenced globalization, and humanity more generally, for generations. While the ocean was perhaps once viewed as infinite and insurmountable, globally our oceans, coasts and seas have experienced unprecedented change in recent decades with climate change, loss of biodiversity and overfishing among the challenges being addressed through contemporary ocean governance. Moreover, and crucially as we continue to strive for sustainable ocean futures, the global ocean is increasingly being recognized as a peopled space. This article explores the role of ocean literacy as we look towards achieving sustainable ocean futures.

Between 20 and 24 marine extinctions, ranging from algal to mammal species, have occurred over the past 500 years. These relatively low numbers question whether the sixth mass extinction that is underway on land is also occurring in the ocean. There is, however, increasing evidence of worldwide losses of marine populations that may foretell a wave of oncoming marine extinctions. A review of current methods being used to determine the loss of biodiversity from the world’s oceans reveals the need to develop and apply new assessment methodologies that incorporate standardized metrics that allow comparisons to be made among different regions and taxonomic groups, and between current extinctions and past mass extinction events. Such efforts will contribute to a better understanding of extinction risk facing marine flora and fauna, as well as the ways in which it can be mitigated.

Demographic modelling can reveal options for improved conservation management, especially for rare or long-lived species not amenable to experimentation. Sturgeon (Acipenseridae) include many such species, endangered by demand for caviar, their unfertilized roe, and by dams blocking their migrations. Restocking of sturgeon populations with farm-raised individuals has probably prevented extinctions and widespread extirpations of some species, but it has rarely led to true recovery in Eurasia, given ongoing harvest. We used modified Leslie matrix models to test whether restocking with year-old juveniles instead of weeks-old fry could recover the critically endangered Amur sturgeon (Acipenser schrenckii), endemic to the Amur River basin along the Russia–China border. Without restocking, or even releasing an expert-recommended annual volume of young fry (10 million), we project that three of four Amur sturgeon populations will be nearly extirpated within 30 years. However, restocking with 5% as many (500 000) year-old juveniles annually could grow three populations (currently 0–425 mature females) and slow declines in another so that each has over 6400 mature females within 30 years. Retooling stocking efforts to use fewer juveniles that survive at higher rates than do small fry could buy time to reduce harvesting pressure on Amur sturgeon and for other related sturgeon species.

The origin and development of the Journal of the Marine Biological Association of the United Kingdom is described on the occasion of the publication of the 100th volume. Papers in the Journal demonstrate how the techniques and approaches to the study of the marine environment have evolved over the 120 years of publication. The early papers provided a baseline description of the marine environment and of marine communities that allowed the effects of later perturbations of the environment to be determined. Both the early papers and the long time series of records have proved to be particularly relevant as marine scientists try to predict the long-term results of climatic and anthropogenic effects on the marine ecosystem. The Journal has now become increasingly international, with most papers coming from outside Europe.

Despite the important ecological roles of commercial bêche-de-mer holothuroids in coral reef ecosystems their reproductive biology is poorly studied, including on the Great Barrier Reef (GBR). We investigated reproduction of Stichopus herrmanni, a commercially important species listed as Vulnerable, at One Tree Island, southern GBR. Gonad index, histology and spawning observations indicated an annual reproductive cycle with gamete release in the Austral spring and summer (November–February), as for populations of this species at a similar latitude in New Caledonia. Stichopus herrmanni releases gametes episodically, spawning multiple times during summer. Assimilation of spawning observations from OTI and elsewhere along the GBR and tropical Pacific revealed that gamete release by S. herrmanni is influenced by the lunar cycle, with spawning taking place around the new moon in summer. This species is an aggregative spawner with a behavioural change to attain elevated positions on the reef at dusk prior to spawning. After the spawning season, gametes remaining in the gonads are reabsorbed. Spent gonads completely lacked gametes. There was a quiescence in gonad development in winter with an absence of gonads in some specimens, indicating an aestivation-like period for reproduction. By late-winter (August) recovery stage gonads were distinguished by the initiation of gametogenesis, which coincided with increasing temperature and day length. Our findings contribute to the understanding of the reproductive biology of S. herrmanni, a consideration for future fisheries management in the protection of this Vulnerable species, especially with respect to the increasing global trade in bêche-de-mer.

Small-island coral reef ecosystems are usually closely coupled to the activities of human inhabitants. Ahus Island (Papua New Guinea) is an isolated Pacific island with a rapidly growing population, heavy reliance on marine resources and limited infrastructure. We hypothesized that untreated sewage was driving distinct benthic assemblages around Ahus and neighbouring uninhabited Onetah. At sites with varying proximities to beach toilets, fore-reef herbivorous fish biomass and benthic composition were measured alongside reef-flat sedimentary oxygen consumption (SOC); a high SOC rate reflects high organic input into coastal waters, thus serving as a potential indicator of sewage input. Fish biomass was low (17.1–20.1 g m–2), but consistent between sites. However, cyanobacteria dominated the fore-reef closest to toilets (62 ± 3%) with highest reef-flat SOC, whereas hard corals dominated furthest away (63 ± 1%), where SOC was lowest. To our knowledge, this is the first study that used SOC to detect local differences in sewage pollution. The results indicate that whilst corals can maintain their dominance on overfished reefs, additional sewage stress may drive pronounced benthic shifts, highlighting the urgency to improve small-island waste management.

Throughout the tropics, developing countries and territories are highly dependent on nearshore marine resources for food and income, however information on the sustainability and proper management of these fisheries is lacking. In Pohnpei, Micronesia, the sustainability of a coral reef finfishery was assessed by comparing coral reef fish demand to coral reef biocapacity using a marine ecological footprint (MEF) analysis. Based on geo-referenced satellite and aerial imagery, Pohnpei and surrounding atolls have 184.2 km2 of coral reef habitat with a sustainable finfish yield of 573–1118 t yr−1, however total harvest was estimated at 4068 t yr−1, exceeding biocapacity by 360–710%. The MEF was supported by observed impacts to coral reef resources, including (1) long-term declines in fish spawning aggregation density, (2) reductions in mean size, age and fecundity of key commercial species, (3) reliance on undersized fish, and (4) decadal declines in mean size and abundance of fishes of iconic value and critical to ecosystem maintenance. The commercial fishery was responsible for 68% of finfish catch volume, while reef fish consumption, at 93 kg person−1 yr−1, was among the highest in the region. To sustainably meet current demand, up to 833 km2 of additional reef area would be required. The study illustrates the MEF, at least rudimentarily, reflects biological reality on local reefs and represents a valuable analytical tool in a marine policymaker's toolbox.

This study assessed the Zanzibar sea cucumber fishery using a multidisciplinary approach. Data was collected by (i) interviewing various groups of actors in the fishery and reviewing management documentation and legislation, (ii) by monitoring catches and (iii) through a visual census of coastal sea cucumber populations in areas open and closed to fishing. The fishery showed clear signs of being unsustainable with high fishing effort, and weak formal and informal management institutions. The fishery operation was characterised by an intricate cross-scale structure with both fishers and sea cucumber products being transported across national borders. The visual census of commercial sea cucumber stocks at three sites open to fishing around Zanzibar showed low densities across the range of sea cucumber value groups including low value species. Furthermore, the diversity of commercial sea cucumber species was lower in fished reefs than on a protected reef. The poor status of the sea cucumber populations was confirmed by the perception of an overfished resource by the interviewed actors active in the fishery. This was also depicted by the paucity of high value species, and high representation of low value and newly commercialised species in fishers catch. We conclude that the current state of Zanzibar’s sea cucumber populations is compromising the fisheries self-replenishment and existence and that the fishery is in urgent need of a complete management reform.

Marine reserves are used as a management tool to ensure sustainability of fish stocks. Using an individual-based model, we compare the evolutionary effect of a reserve located on a nursery ground, spawning ground, feeding ground, or in a year-round habitat for sedentary species. We model the evolution of life-history traits, specifically size at maturation and site fidelity. Within species, individuals will differ in the time spent within a reserve depending on their patterns of movement and migration. We predict that the evolutionary effect of fishing depends not only on the survival probability but also on the life-history stages primarily affected by high harvest mortality. Protection against evolution to small maturation size is most effective where a reserve protects a sedentary population or protects the feeding grounds of a population. We also find that protection of the feeding ground of an anadromous stock such as Atlantic salmon may lead to local adaptation enhanced by evolution of higher site fidelity, similar to protection of a sedentary species.

The coral reefs of Papua New Guinea are among the most species diverse in the world, support an important artisanal fishery, but lack an effective national conservation programme. Increased commercialization, population growth, promotion of fisheries development projects, and the live reef food fish trade are expected to increase demand for the country's reef fish. This paper examines how socioeconomic factors affect the condition of the artisanal multi-species coral reef fishery in six sites in Papua New Guinea. Catch characteristics such as diversity, trophic level and body size by landing site were examined along a fishing pressure gradient. Both exogenous factors such as markets and endogenous factors such as fishing pressure were related to the condition of fish catch. In general, the trophic level and lengths of fish captured in Papua New Guinea were relatively high, but were reduced on reefs with high fishing effort near fish markets. Fisheries showed signs of depletion above c. 25 fishing trips per km2 per day and the proximity of markets was a better indicator of overfishing than human population size. A cross-scale approach to fisheries management is required in Papua New Guinea to coordinate decentralized local management, limit the intrusion of extractive enterprises, and develop policies that seek to minimize exogenous pressures on marine resources.

The Galápagos Islands, a world heritage region for the protection of the unique terrestrial and marine wildlife, are also home to a small human population, dependent on fisheries. There was a lucrative sea-cucumber (Stichopus fuscus) fishery in the islands, which began in 1992. After a rapid expansion in the Galápagos archipelago, the fishery has declined and now persists predominantly around the western islands. Initially, the fishery was largely illegal and uncontrollable. Subsequently, a co-management framework developed, with fisher participation. Gradually enforcement improved, apparent corruption declined, and research capacity increased. Although stock abundance surveys have been carried out annually since 1993, the paucity of background biological and fishery information does not allow rigorous stock assessment. The achievements of co-management through the participation of fishers in research and management have been: an acceptance of management controls on numbers of fishers and quotas, a reduction in conflict and increased co-operation. Persistent problems have been: weak enforcement capacity, limited funds for patrolling and research, corruption and declining stock abundance. Proposed application of precautionary principles to management, including a range of fishery indicators, may save the fishery from collapse. The principles are applicable to many other data-poor fisheries globally.

This paper presents the simulator SHADYS (‘simulator halieutique de dynamiques spatiales’). SHADYS is a tool devoted to the representation of spatial processes involved in fisheries dynamics. It puts together three fundamental entities in an explicit spatio-temporal way: the environment, the fish populations under consideration and the fishing fleet. It is based on simple, realistic and well identified mechanisms (density-dependent habitat selection, advection and diffusion of a fish population, fishermen search strategy, etc.) implemented by interfacing numerical models with a GIS (geographic information system). As a virtual laboratory, SHADYS allows experiments to be performed in a theoretical world, such experiments being generally impossible to perform in reality. As an illustration, different scenarios of a marine refugia-based management have been explored using the SHADYS simulator. Different simulations are conducted to assess the short-term effects on yield of a marine protected area. It is shown that for diffusive or migratory species, the yield per recruit as a function of the protected surface can reach a maximum. Under this condition, the concept of ‘space overfishing’ is meaningful. Protected areas then behave like ‘sources’ and exploited areas like ‘sinks’. For resident populations, the larger the protected area is, the lower the catches per recruit are. Regarding the spatial distribution of the fishing effort, it is shown that if it is spatially distributed in order to maximize catches, then fishing boats will slowly tend to be distributed all along the boundaries of the protected area.