Global marine fisheries discards: A synthesis of reconstructed data

As part of the global marine fisheries catch reconstruction project conducted by the Sea Around Us over the last decade, estimates were derived for discards in all major fisheries in the world. The reconstruction process derives conservative but non‐zero time‐series estimates for every fisheries component known to exist, and relies on a wide variety of data and information sources and on conservative assumptions to ensure comprehensive and complete time‐series coverage. Globally, estimated discards increased from under 5 million t/year (t = 1,000 kg) in the early 1950s to a peak of 18.8 million t in 1989, and gradually declined thereafter to levels of the late 1950s of less than 10 million t/year. Thus, estimated discards represented between 10% and 20% of total reconstructed catches (reported landings + unreported landings + unreported discards) per year up to the year 2000, after which estimated discards accounted for slightly less than 10% of total annual catches. Most discards were generated by industrial (i.e. large‐scale) fisheries. Discarding occurred predominantly in northern Atlantic waters in the earlier decades (1950s–1980s), after which discarding off the West Coast of Africa dominated. More recently, fleets operating in Northwest Pacific and Western Central Pacific waters generated the most discards. In most areas, discards consist essentially of marketable taxa, suggesting a combination of poor fishing practices and poor management procedures is largely responsible for the waste discarding represents. This is important in an era of increasing food security and human nutritional health concerns, especially in developing countries.     

Multispecies fisheries management in the Mediterranean Sea: application of the Fcube methodology

Abstract The ecosystem approach (EA) advocates that advice should be given based on a holistic management of the entire marine ecosystem and all fisheries and fleets involved. Recent developments have advanced to multi‐species, multi‐fisheries advice, rather than on a single‐species/fleet/area stock basis, bridging the gap between existing single‐species approaches and the needs of the EA. The Fleet and Fisheries Forecast method (Fcube) method estimates potential levels of effort by fleet in mixed fisheries situations to achieve specific targets of fishing mortality. Data on effort, landings and socioeconomic parameters were used for coastal and trawl fisheries in the Aegean Sea. Results pointed out the strengths and weaknesses of alternative management strategies from both a biological and socioeconomic perspective. Fcube revealed the importance of effort control in the coastal fisheries that are still managed with no effort restrictions. The present findings, although preliminary, revealed that stringent cuts to effort and catch levels are required if EA management goals are to be met. The Fcube methodology, initially developed for mixed fisheries advice in northern European waters that are managed with TACs, also proved promising in providing advice to non‐TAC fisheries.     

Interactions between the implementation of marine protected areas and right-based fisheries management in Australia

Abstract  The declaration of marine protected areas (MPAs) in Australia generates much confusion and controversy between government conservation and fisheries agencies, the fishing industry and NGOs. There are fundamental differences between the principles and practices underpinning the implementation of MPAs and fisheries management. This paper analyses the interactions between these two approaches to natural resource management and highlights the difficulties in integrating them effectively. The major challenges for governments are: poor cooperation between fisheries and conservation agencies; in principle inconsistencies between allocation of fishing rights by fisheries agencies and loss of these rights through MPA declaration; re-allocation of resources between user groups through spatial zoning; lack of fisheries expertise in conservation planning, and inappropriate single-species/single-issue approach to fisheries management. As fisheries agencies are now considering developing their own MPAs as tools for fisheries management, the need to address inconsistencies between conservation and fisheries approaches to the spatial management of natural resources increases further. Better collaboration between government agencies and better coordination of their activities would help more effective and less conflicting management of marine resources.     

The dynamics of collapse in world fisheries

The fear of a rapid depletion of world fish stocks because of over‐exploitation is increasing. Analysis of 1519 main series of the FAO world fisheries catch database over the last 50 years reveals that 366 fisheries’ collapses occurred, that is nearly one fishery of four. The robustness of this result is tested by performing several complementary analyses using different conservative options. The number of collapses has been stable through time since 1950s indicating no improvement in the overall fisheries management. Three typical patterns emerge from the analysis of catch series during the period preceding the collapses: smooth collapse (33%), i.e. a long regular decline, erratic collapse (45%), i.e. a fall after several ups and downs, and a plateau‐shaped collapse (21%), i.e. a sudden fall after a relatively long and stable persistence of high level of catches. Using a simple mathematical model, we relate the plateau‐shaped collapses (which are, by nature, the most difficult to predict) to surreptitiously increasing exploitation and a depensatory mechanism at low population levels. Thus, a stable level of catch over several years is shown to conceal the risk of a sudden collapse. This jeopardizes the common assumption that considers the stability of catch as a goal for fisheries sustainability.     

Distribution and intensity of bottom trawl fisheries in the Patagonian Shelf Large Marine Ecosystem and its relationship with marine fronts

Trawling is a major concern worldwide and there is considerable debate about its impact on marine ecosystems. The Patagonian Shelf Large Marine Ecosystem (PSLME) is an important fishing area in the Southwest Atlantic where bottom trawling is the dominant fishing method. We investigated the distribution of bottom trawl fishing within this region, defining the areas of highest trawling intensity (hotspots) and evaluating their relationship with marine fronts. We focused on the three main oceanographic fronts, the shelf‐break front, the southern Patagonia front and the mid‐shelf front. To estimate fishing effort and trawled areas, we used VMS data from 2006 to 2012. Despite being almost a fully trawlable shelf, we found that the spatial distribution of trawling activity is patchy and trawling hotspots were small, comprising annually <5% of the shelf extension or <7% of the total trawlable area. Contrary to what is believed worldwide, our findings suggest that over the PSLME the magnitude of habitat effects as a result of bottom trawling is relatively small. Regarding the three frontal systems studied, only the shelf‐break front showed a positive relationship with trawl fishing activity. Although trawling hotspots did not overlap with marine fronts, the shelf‐break front receives more trawling effort than expected. We hypothesize that this pattern is due to aggregation of species near or at the front taking advantage of the opportunities provided by this area.     

Diversity of global fisheries governance: Types and contexts

Fisheries governance systems designed to regulate fishing are often described as being highly diverse across countries. However, there is little systematic work that directly examines and describes the (dis)similarities across such systems, and how socio-political and economic contexts drive such variation at a global scale. In this paper, we use 68 indicators from a novel dataset to examine the fisheries governance systems in place to constrain overfishing in national waters across 142 countries. We found that countries cluster in just two distinct governance groups which display different traits to constrain overfishing. Where one group takes a tougher stance on aspects regarding access to its fisheries resources, the other is more focused on gathering fisheries information and publicizing the data. The 10 greatest differences between groups relate to the gathering of information and monitoring of their fisheries, the effectiveness of compliance systems and the existence of policies around sustainability. On these key differences, one group consistently displays more far-reaching governance traits. The overall governance capacity of a country and the national socio-economic importance of fisheries are identified as potential drivers of this variation. Despite their differences, the two groups show substantial overlap for many indicators, particularly those that are inexpensive, but also for certain costly policies. These patterns prompt hypotheses of policy transfer or convergence across fisheries governance systems, most notably regarding ‘low-hanging fruit’ policies.     

Forecasting of jack mackerel landings (Trachurus murphyi) in central‐southern Chile through neural networks

In the present study, the performance of neuronal networks models in monthly landing forecasting of jack mackerel (Trachurus murphyi) in central‐southern Chile (32°S–42°S) was assessed. Thus, monthly estimations for 10 environmental variables, fishing effort (fe) and jack mackerel landings for the period 1973–2008 were used. A preliminary analysis was done in order to remove strongly correlated variables. Sea surface temperature (SST) and fe are established as input variables, then, a non‐linear cross correlation analysis was performed to estimate the lag between the input variables and jack mackerel landings. Two models were adjusted: model one includes both training and testing cases randomly selected using all data involved in the analysed period; for model 2, the data is divided into two time series: the first from 1973 to 2002 used for training and the second between 2003 and 2008 used for validation. The external validation process for model 1 showed an explained variance of 92%, with a standard forecasting error of 30%. The explained variance for model 2 was 81%, with a standard forecasting error of 38%. Finally, the sensitivity analysis for both models showed the fe as the most influential variable to jack mackerel landings, which presents functionality depending on anthropogenic effects rather than environmental conditions.     

Recent evolution of the fishing exploitation in the Thau lagoon, France

Fisheries activity in the Thau marine lagoon (Mediterranean coast of France) has an old tradition and involves different types of gears (set nets, traps and lines) that are used seasonally with varying frequencies in different areas. A survey of fishing activity, main fishing methods and main commercial species composition in the lagoon was carried out to assess the current fishing effort and seasonal yield. Many important changes in fishing effort and in the most important target species occurred during the last 10 years. A gradual decline in eel, Anguilla anguilla (L.), catches followed by an increase of other commercially-exploited species, particularly the gilthead sea-bream, Sparus aurata L., was observed.     

Tracking interactions: Shifting baseline and fisheries networks in the largest Southwestern Atlantic reef system

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Contribution of marine fisheries to worldwide employment

Marine fisheries contribute to the global economy, from the catching of fish through to the provision of support services for the fishing industry. General lack of data and uncertainty about the level of employment in marine fisheries can lead to underestimation of fishing effort and hence over‐exploited fisheries, or result in inaccurate projections of economic and societal costs and benefits. To address this gap, a database of marine fisheries employment for 144 coastal nations was compiled. Gaps in employment data that emerged were filled using a Monte Carlo approach to estimate the number of direct and indirect fisheries jobs. We focused on estimating jobs in the small‐scale fishing sector. We characterized small‐scale fishing as (i) primarily geared towards household consumption or sale at the local level; (ii) conducted at a low level of economic activity; (iii) minimally mechanized; (iv) conducted within inshore areas; (v) minimally managed; and/or (vi) undertaken for cultural or ceremonial purposes. In total, we estimated that 260 ± 6 million people are involved in global marine fisheries, encompassing full‐time and part‐time jobs in the direct and indirect sectors, with 22 ± 0.45 million of those being small‐scale fishers. This is equivalent to 203 ± 34 million full‐time equivalent jobs. Study results can be used to improve management decision making and highlight the need to improve monitoring and reporting of the number of people employed in marine fisheries globally.     

Incidental catch of marine turtles by Spanish bottom trawlers in the western Mediterranean

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Toward sustainable harvest strategies for marine fisheries that include recreational fishing

Recreational fishing (RF) is a large yet undervalued component of fisheries globally. While progress has been made in monitoring, assessing, and managing the sector in isolation, integration of RF into the management of multi-sector fisheries has been limited, particularly relative to the commercial sector. This marginalises recreational fishers and reduces the likelihood of achieving the sector's objectives and, more broadly, achieving fisheries sustainability. We examined the nature and extent of RF inclusion in harvest strategies (HSs) for marine fisheries across 15 regions in 11 nations to define the gap in inclusion that has developed between sectors. We focused on high-income nations with a high level of RF governance and used a questionnaire to elicit expert knowledge on HSs due to the paucity of published documents. In total, 339 HSs were considered. We found that RF inclusion in HSs was more similar to the small-scale sector (i.e., artisanal, cultural, or subsistence) than the commercial sector, with explicit operational objectives, data collection, performance indicators, reference points, and management controls lacking in many regions. Where specified, RF objectives focused on sustainability, economic value and catch allocation rather than directly relating to the recreational fishing experience. Conflicts with other sectors included competition with the commercial sector for limited resources, highlighting the importance of equitable resource allocation policies alongside HSs. We propose that RF be explicitly incorporated into HSs to ensure fisheries are ecologically, economically, and socially sustainable, and we recommend that fisheries organisations urgently review HSs for marine fisheries with a recreational component to close the harvest strategy gap among sectors.     

Relationships between catch and effort in Fijian multispecies reef fisheries subject to different levels of exploitation

Abstract The catch-per-unit-effort (CPUE) and value-of-catch-per-unit-effort (VPUE) of reef-associated fish species from six Fijian native fishing grounds ( qoliqoli ) subject to different fishing intensities were determined using records of fishing activity from a voluntary logbook scheme. Line and spear fishing techniques were used for more than half the total fishing time (h person^-1 d^-1) in all qoliqoli , and yet the favoured technique in a given qoliqoli was frequently less efficient (lower CPUE) than other techniques. The popularity of relatively ineffective fishing methods implies that fishermen did not always attempt to maximize their catch rates. To compare fishing effort in different qoliqoli , all effort was rescaled on the basis of its recorded efficiency (measured as multispecies CPUE) and expressed as hours equivalent to boat-based spear fishing over coral by day to catch fish for sale. Total fishing intensity in the six qoliqoli ranged from 72 to 4310 h km^-2 reef year^-1. The relationship between catch and effort was linear at all fishing intensities, suggesting that the qoliqoli were all fished on a sustainable basis. Furthermore, whilst there was a significant difference in CPUE and VPUE between the one or two qoliqoli with lowest fishing intensity and all the others, there were no significant differences between these other qoliqoli in terms of the VPUE of the saleable multispecies boat catch or the CPUE of species from piscivorous and carnivorous genera ( Epinephelus, Lethrinus and Plectropomus ) which the fishermen prefer to catch.     

Spatio‐temporal trends of the Krill fisheries in the Western Antarctic Peninsula and Southern Scotia Arc

Krill fisheries in Antarctica have concentrated their effort on the Western Antarctic Peninsula and Scotia Arc (WAP) in the last decades, following a steady increase in annual catch. Short‐term shifts in habitat exploration may have occurred and may be the cause for the increasing catch. Habitat use and effort in krill fisheries in the WAP during summer between 2012/2013 and 2016/2017, inclusive, were tested to determine how habitat use and effort reflected in the catch. Increasing trends in fishing tow duration and depth of fishing in deeper and colder waters were found. No association of the catch with the habitat explored was found, but catch was higher in years when the variability of explored habitat was lower. The relevance of these findings for fisheries management and conservation of Antarctic marine ecosystems is discussed.     

A preliminary appraisal of the contribution of recreational fishing to the fisheries sector in north-west Trinidad

Abstract An assessment of the recreational fishery in north-west Trinidad was made by questioning participants about the principal fishing methods used, location of activities, catches, effort and cost of fishing. Surface handline methods (live baiting [à la vive] and trolling) and rod and line (banking) were the most common methods used and were pursued mainly in the summer months (April to August). Total fish landings from the fishery were estimated at 1000 t year^-1, equivalent to about 10% of commercial catches for Trinidad. The principal species caught were kingfish, Scomberomorus cavalla (Cuv.), carite, Scomberomorus brasiliensis (Cuv.), cavalli, Caranx hippos (L.), snappers, Lutjanus spp., and groupers, Epinephelus spp. Many of the fishermen sold their catch to offset the costs of the fishing trip and thus competed with commercial fishermen. Recommendations for monitoring and possibly regulating the fishery through a licensing scheme are made.     

Dynamics of floodplain fisheries in Bangladesh, results of 8 years fisheries monitoring in the Compartmentalization Pilot Project

Floodplain fisheries were monitored from 1992 until 2000 in the Compartmentalization Pilot Project in Tangail, Bangladesh. In permanent floodplains about 165 ± 28 kg ha^?1 of fish was caught annually. For seasonal floodplains, this figure was 83 ± 23 kg ha^?1 yr^?1. The fish catch exhibited a strong seasonal variation, with the highest catch in October, when the floodwater recedes towards the river, and the lowest catch during the dry season in April/May. The annual catch varied with the extent of flooding, with high catches in wet years and low catches in dry years. The extent of flooding was quantified through a Flood Index. Plotting the annual yields against this Flood Index provided a significant relation (P < 0.05), confirming the existence of a flood pulse. The fishing effort (f) and the catch‐per‐unit‐effort (CPUE) were significantly related (P < 0.05), whereby the fishing effort increased with increasing CPUE. The results are discussed within the frame of fisheries management in Bangladesh and highlight the need for long‐term data for proper evaluation of fisheries projects and the development of management schemes, and the difficulty of applying standard surplus production models in floodplain fisheries.     

Assessing the impact of population decline on mating system in the overexploited Mediterranean red coral

1. Understanding the interactions among demographic parameters, mating system and population dynamics is key to predict the response of populations to global change. The Mediterranean red coral is a precious octocoral suffering from population decline due to overfishing and warming‐driven mass mortality events.
2. While the demographic consequences of these two pressures are well characterized, little is known regarding their impact on population dynamics and evolution of red coral populations. The main objective of this study was to fill this gap focusing more particularly on mating pattern and genetic drift.
3. Combining sibship and progeny arrays analyses, a genetic characterization of the red coral mating system was conducted. In addition, a synchronic approach was developed comparing mating patterns in two populations with contrasting demographic patterns: a pristine‐like population and a declining population.
4. The results show that polyandry is likely to be the norm in red coral. The similar patterns of genetic diversity between adults and larvae combined with the lack of differential reproductive success among putative fathers did not support significant sweepstakes effects during larval production. While instantaneous biparental inbreeding was detected, no long‐term inbreeding was observed even in the declining population. Mating patterns and effective population sizes in the two populations were not statistically different. Nevertheless, a trend towards a slightly higher inbreeding and a lower number of breeders was observed in the declining population.
5. Accordingly, we hypothesized that an increase in male gamete dispersal may buffer the increase of genetic drift expected in the declining population. This feedback between demographic decline and reproductive pattern may potentially take part in the long‐term persistence of red coral populations. However, the negative trend reported in the declining population unambiguously supports the need to maintain high densities of reproductive colonies to the functioning of red coral populations.

     

Global marine yield halved as fishing intensity redoubles

There is widespread concern and debate about the state of global marine resources and the ecosystems supporting them, notably global fisheries, as catches now generally stagnate or decline. Many fisheries are not assessed by standard stock assessment methods including many in the world's most biodiverse areas. Though simpler methods using widely available catch data are available, these are often discounted largely because data on fishing effort that contributed to the changes in catches are mostly not considered. We analyse spatial and temporal patterns of global fishing effort and its relationship with catch to assess the status of the world's fisheries. The study reveals that fleets now fish all of the world's oceans and have increased in power by an average of 10‐fold (25‐fold for Asia) since the 1950s. Significantly, for the equivalent fishing power expended, landings from global fisheries are now half what they were a half‐century ago, indicating profound changes to supporting marine environments. This study provides another dimension to understand the global status of fisheries.     

Interactions and management for the future of marine aquaculture and capture fisheries

Aquaculture surpassed wild fisheries as the largest supplier of fish for human consumption in 2014 and is expected to supply the majority of seafood for future increases in demand. Marine and coastal aquaculture, collectively referred to as mariculture, currently represents just 36% of aquaculture production but is poised to expand in the decades ahead. One of the most commonly cited concerns regarding this likely expansion is ecological and socioeconomic interactions with wild‐capture fisheries. While attention has largely been drawn to high‐profile negative externalities from fed finfish and crustacean mariculture, not all marine‐based practices are equivalent. Empirical evidence for the different interactions between mariculture and wild fisheries is often sparse. While negative consequences can arise, positive synergies can also occur. By considering mariculture development in the context of fisheries interactions, we suggest that it is possible to minimize conflicts and maximize positive connections between the two sectors. We provide the first comprehensive synthesis of the interactions between mariculture and wild fisheries, characterizing the types of interactions, evaluating available empirical evidence and identifying where management (sector‐specific and cooperative) can play an important role. We highlight potential effects of mariculture on the efficiency, sustainability, and equity of seafood production and identify remaining knowledge gaps.