A global assessment of fishing patterns and fishing pressure from 110 different Ecopath models, representing marine ecosystems throughout the world and covering the period 1970–2007, show that human exploitation across trophic levels (TLs) is highly unbalanced and skewed towards low productive species at high TLs, which are around two TLs higher than the animal protein we get from terrestrial farming. Overall, exploitation levels from low trophic species were <15% of production, and only 18% of the total number of exploited groups and species were harvested >40% of their production. Generally, well-managed fisheries from temperate ecosystems were more selectively harvested at higher exploitation rates than tropical and upwelling (tropical and temperate) fisheries, resulting in potentially larger long-term changes to the ecosystem structure and functioning. The results indicate a very inefficient utilization of the food energy value of marine production. Rebuilding overfished components of the ecosystem and changing focus to balancing exploitation across a wider range of TLs, i.e. balanced harvesting, has the potential to significantly increase overall catches from global marine fisheries.
Balanced harvesting (BH) has been proposed as an alternative to the paradigm of more selective fishing as practiced in most European and North American fisheries management. We examine options for the implementation of BH and evaluate the issues raised in such an implementation. Implementation is considered at the whole ecosystem level, in terms of the patterns of removal for all species, both commercial and bycatch. We suggest that a “laissez-faire” approach analogous to the African lakes where BH was first observed is inappropriate in managed developed world fisheries. We consider two further approaches: focusing on either the species caught or on the sizes of animal alone. We find that aiming to harvest all species with an exploitation rate appropriate to their productivity would require a degree of micro-management that is probably unachievable, with all captured species “choking” the fishery in sequence. The size-based approach works with an exploitation rate appropriate to the productivity at size, with no consideration of the species involved. This might superficially be easier to implement, as management would involve a limited number of size classes only. However, problems may arise due to the likely faster capture of the more easily catchable fish, and also likely targeting of the more valuable species within a size class. We identify a possible third option of “broad brush” métier-based management that may resolve some of these problems. Other issues include the management of protected, endangered, and threatened species (including mammals, reptiles, and birds), the management of already severely depleted stocks, and the capture of benthic invertebrates.
This paper explores economic aspects of a recent proposal to shift fisheries to a “Balanced Harvesting” (BH) strategy, as a means to achieve the goal, set by the Convention on Biological Diversity and related to the Ecosystem Approach to Fisheries, of “conservation of ecosystem structure and functioning” within fishery ecosystems. Studies indicate that a BH strategy—broadening the range of species and sizes caught in the aquatic ecosystem, and lowering exploitation rates for some conventionally targeted species—may provide improved ecological performance relative to conventional harvesting strategies. However, the potential economic implications have received little attention to date. This paper provides a preliminary economic assessment of BH, focusing on six main themes: (i) assessing benefits and costs, (ii) factors affecting the economics of BH, (iii) economic issues in implementing the ingredients of BH, (iv) effects of incremental and/or partial implementation of BH, (v) transition options within the harvesting sector of the fishery, and (vi) distributional impacts arising across fisheries, fleet sectors, and fishing gears, and between the present and the future.
Balanced harvest (BH) proposes to distribute a moderate mortality from fishing across the widest possible range of species, stocks, and sizes in an ecosystem, in proportion to their natural productivity so that the relative size and species composition are maintained, in line with the CBD requirement for sustainable use. This proposal has many and not always intuitive implications for fisheries management, e.g. in relation to selectivity, protection of juveniles and spawning sites, models of harvesting strategies, a focus on size and species, the impacts of discarding, aspects of emblematic species and ecosystem services, operational complexity, partial implementation, ecosystem rebuilding, and relations with broader management frameworks. The paper closes with a discussion of BH implementation, concluding that a logical step would be to integrate several separate initiatives to move fisheries into a more ecosystem-conscious context. Implementation challenges will be encountered, but there are lessons to be drawn from fishery ecosystems already close to BH, as in some tropical multispecies fisheries, and further, the implementation challenges are already being taken on in many well-managed fisheries and areas as management begins to address the realities of what ecosystem-based fishery management actually entails.
Since “balanced harvest” was proposed in 2010 as a possible tool in the operationalization of the ecosystem approach to fisheries (EAF), the concept gained extensive international attention. Because maintaining ecosystem structure and achieving maximum sustainable yields have become two of the key international legal obligations in fisheries management, balanced harvest is as topical as ever. An international workshop on balanced harvest, organized by the IUCN Fisheries Expert Group at FAO headquarters in 2014, reviewed the progress in the field and discussed its prospects and challenges. Several articles in this theme set, mostly based on presentations from the workshop, discuss ecological, economical, legal, social, and operational issues surrounding the key management goals. Progress is being made on understanding of the theoretical underpinnings of balanced harvest and its practical feasibility. Yet, a basic debate on the concept of balanced harvest continues. To move the EAF forward, we anticipate and encourage further research and discussion on balanced harvest and similar ideas.
Underwater video recordings in the mouth of a squid trawl were used to evaluate the effectiveness of a trawl configured with drop-chain groundgear to catch longfin inshore squid (Doryteuthis pealeii) and reduce bycatch of finfish in the Nantucket Sound squid fishery off Cape Cod, Massachusetts, USA. Entrance through the trawl mouth or escape underneath the fishing line and between drop chains was quantified for targeted squid, and two major bycatch species, summer flounder (Paralichthys dentatus) and skates (family Rajidae). Additionally, contact and impingement between animals and groundgear were also quantified. Fish and squid swimming behaviours, positions, orientations, and time in the trawl mouth were quantified and related to capture or escape at the trawl mouth. Squid entered the trawl singly and in schools, and no squid were observed escaping under the fishing line. Most squid entered the trawl in the upper portion of the trawl mouth; mantle orientated away from the trawl and swimming in the same direction, and were gradually overtaken, not actively attempting to escape. Summer flounder and skates were observed to remain on or near the seabed, orientated, and swimming in the same direction as the approaching trawl. The majority (60.5%) of summer flounder entered the trawl above the fishing line. Summer flounder that changed their orientation and turned 180° were significantly more likely to enter the trawl (p < 0.05). Most skates (89.7%) avoided trawl entrance and escaped under the fishing line. Neither squid nor summer flounder were observed to make contact or become impinged to the groundgear; however, 35.4% of skates had substantial contact with groundgear, with 12.3% becoming impinged. Video analysis results showed that the drop-chain trawl is effective at retaining targeted squid while allowing skates to escape. However, it is ineffective at avoiding the capture of summer flounder.
Deep-sea coral and sponge habitats support the richest and most complex biological communities in the deep sea. NOAA’s Deep Sea Coral Research and Technology Program is providing the first systematic effort to discover and understand these ecosystems, combining science and information-sharing to help ocean managers conserve valuable habitats. The Program proudly announces its 2016 Report to Congress, highlighting exciting scientific research conducted over the past two-year period and historic conservation measures that have been proposed and enacted based on our Program’s results. The report spans the globe, from the remote Johnston Atoll in the middle of the Pacific Ocean to previously unknown coral gardens teeming with redfish only 25 miles off the coast of Maine. The Deep Sea Coral Research and Technology Program’s website also provides fieldwork reports and a searchable map in the nation’s most comprehensive online database of deep-sea corals and sponges. Armed with such information, the Mid-Atlantic Fishery Management Council is the most recent council to propose measures to protect deep-sea coral habitat from impacts of fishing. The Gulf of Maine also earns a spotlight because its deep-sea coral gardens are a major discovery – in addition to reading the report, take a virtual dive into this offshore habitat!
Migration is part of fishers’ livelihood strategies, and the topic of ‘migration and fisheries’ has gained considerable attention from researchers. Previous works identified negative and positive impacts of migrant fishers on local communities. However, little attention has been given to how social relationships are actually built between migrant fishers and local residents. This paper is based on observations of daily life and social connections in a coastal village in Okinawa, Japan and aims to fill this gap. It also provides a picture of how relationships between migrant fishers and host communities are built. Fieldwork yielded the following results. 1) Migrants moved to Okinawa in various phases; 2) Through their fishing activities, they have established good relationships with other fishers and non-fishing residents; 3) Sharing and selling fishery products has helped migrant fishers and their families gain socio-cultural knowledge and learn about the social conventions of the community, enabling them to integrate themselves into the social fabric of local community life.
The contributions of autonomous underwater gliders as an observing platform in the in-situ global ocean observing system (GOOS) are investigated. The assessment is done in two ways: First, the existing in-situ observing platforms contributing to GOOS (floats, surface drifters, moorings, research/commercial ships) are characterized in terms of their current capabilities in sampling key physical and bio-geochemical oceanic processes. Next the gliders’ capabilities are evaluated in the context of key applications. This includes an evaluation of 140 references presented in the peer-reviewed literature.
It is found that GOOS has adequate coverage of sampling in the open ocean for several physical processes. There is a lack of data in the present GOOS in the transition regions between the open ocean and shelf seas. However, most of the documented scientific glider applications operate in this region, suggesting that a sustained glider component in the GOOS could fill that gap. Glider data are included for routine product generation (e.g. alerts, maps). Other noteworthy process-oriented applications where gliders are important survey tools include local sampling of the (sub)mesoscale, sampling in shallow coastal areas, measurements in hazardous environments, and operational monitoring. In most cases, the glider studies address investigations and monitoring of processes across multiple disciplines, making use of the ease to implement a wide range of sensors to gliders. The maturity of glider operations, the wide range of applications that map onto growing GOOS regional needs, and the maturity of glider data flow all justify the formal implementation of gliders into the GOOS. Remaining challenges include the execution of coordinated multinational missions in a sustained mode as well as considering capacity-building aspects in glider operations as well as glider data use.
Marine spatial planning (MSP) is an approach that has become essential in order to meet coastal states’ commitments to coordinated management between all stakeholders involved, whether the main objective is for economic, recreational or conservation purposes. The lessons learned from MSP over the last decade revealed the importance of applying multidisciplinary approaches to expand and deepen the involvement of stakeholders from economic and political decision-making spheres, as well as considering social and cultural dimensions.
As part of the MSP process in the western tropical Pacific region, a participatory and prospective method was undertaken (the territory game). The method is based on the collective construction of spatial representations by a pool of relevant stakeholders. Both, the spatial outputs, as well as the discussions leading to them, were analysed to evaluate the stakeholders’ current and future visions of the territory.
During the methodological pathway, visions developed ranging from a local scale to areas that covered all oceanic compartments, as well as some even considering the entire region. Local and intangible knowledge and opinions were taken into consideration, and helped to create a comprehensive understanding of the context. In the course of the project, participants proposed socio-ecological management solutions with innovative spatial scales. Furthering this effort, the proposals were shaped to the action capacity of the states concerned; in addition, certain Pacific countries were identified as potential leaders for steering some of the proposed actions.
This approach can help to promote local actors’ involvement in MSP by a collective analysis as well as to strengthen integration of cultural and social aspects. The whole process is based on biophysical and geopolitical scientific information to improve the credibility of the results. The suggested actions could thus be implemented by each state and the Western Pacific region. Though the integration of the results into high-level decision making was not tested yet, the presented approach would allow an increased acceptance of suggested directions and actions by taking into account the different spatial visions of the relevant actors.