Changes In Fisheries Management Research Articles

Catch per Unit Effort of Decapod Species, C. pagurus and H. gammarus, from a Voluntary Marine Reserve

C. pagurus and H. gammarus are deemed to be declining in abundance in the Berwickshire Marine Reserve from personal communications with local inshore fishers. Fisheries data in the form of catch per unit effort (CPUE) were collected for these two commercially important decapods. Other explanatory variables from fishing activity such as the creel and bait type used, the soak time of the fishing gear, and deployment depth were recorded to provide as much detail as possible to describe the effort applied to catch these decapod species. In this study, CPUE was higher for H. gammarus and C. pagurus outside the Berwickshire Marine Reserve. General additive models (GAMs) were used to describe the effects of the explanatory variables and showed that soak time (days) and depth (m) significantly affected CPUE for C. pagurus, not H. gammarus. Sea temperature (°C) showed a negative correlation with the CPUE of both H. gammarus and C. pagurus; however, a positive correlation was found with the number of C. pagurus caught. The data collected in this study provide a foundation in understanding the current abundance of C. pagurus and H. gammarus in a voluntary marine reserve on the east coast of Scotland, which can be used to inform future changes in fisheries management in Berwickshire.

Spatio‐temporal dynamics of the common skate species complex: Evidence of increasing abundance

AbstractAimThe critically endangered common skate species complex is a large‐bodied and long‐lived batoid, which has experienced local extirpations and population declines over the past century mainly due to overfishing. Due to its decline, fisheries management measures were introduced to prevent further decline and fragmentation of populations. For example, in 2009, a landings prohibition was introduced in the European Union, which banned the retention of common skate onboard commercial fishing vessels with captured individuals to be discarded. We aimed to explore the spatial and temporal population dynamics of the common skate species complex, against the backdrop of changes in fisheries management measures.LocationNortheast Atlantic Ocean.MethodsWe used publicly available fishery‐independent trawl survey data from several regions of the Northeast Atlantic shelf to examine trends in incidence and abundance for the common skate species complex. We also constructed a species distribution model to identify changes in the spatio‐temporal distribution of the common skate.ResultsA sustained increase in the common skate species complex was evident in several areas of its distribution. An increase was observed in five separate trawl surveys encompassing distinct regions of its distribution. Despite the observed increase, little evidence of recolonizing previously extirpated areas was evident.Main ConclusionsThe findings demonstrate the effectiveness of fisheries management measures in contributing to an increase in the common skate species complex. Such measures may also be effective if applied to numerous other batoid species currently threatened with extinction.

Proposed business rules to incorporate climate-induced changes in fisheries management

Abstract Changing oceanic conditions are having impacts on living marine resources (LMRs) and their management, often in ways beyond what we have ever seen before. This is largely manifested as changes in production or location of these LMRs. The challenge has been not only to disentangle the possible causes of these changes to LMR stocks, but then even if clear changes are detected, it has been unclear what we can actually do about them. Here, we propose a set of recommended actions or “business rules” to better address climate-induced changes to LMR production and location. These emphasize a series of diagnostics which can be used to demarcate significance of whether action is necessary, and then if action is deemed necessary, we propose a set of insertion points or “on-ramps” to address the nuances of locational or production changes at every step in the science to management process. These proposed “business rules” for dealing with climate-induced changes to fisheries can always be debated, can always be updated with new information, and can always be adjusted under a given set of circumstances. But, we also assert that it would be wise to start acting on them, as a proposed set of options, given the urgency and exigency of the situation.

The rise of a marine generalist predator and the fall of beta diversity.

Determining the importance of physical and biological drivers in shaping biodiversity in diverse ecosystems remains a global challenge. Advancements have been made towards this end in large marine ecosystems with several studies suggesting environmental forcing as the primary driver. However, both empirical and theoretical studies point to additional drivers of changes in diversity involving trophic interactions and, in particular, predation. Moreover, a more integrated but less common approach to the assessment of biodiversity changes involves analyses of spatial β diversity, whereas most studies to date assess only changes in species richness (α diversity). Recent research has established that when cod, a dominant generalist predator, was overfished and collapsed in a northwest Atlantic food web, spatial β diversity increased; that is, the spatial structure of the fish assemblage became increasingly heterogeneous. If cod were to recover, would this situation be reversible, given the inherent complexity and non-linear dynamics that typify such systems? A dramatic increase of cod in an ecologically similar large marine ecosystem may provide an answer. Here we show that spatial β diversity of fish assemblages in the Barents Sea decreased with increasing cod abundance, while decadal scale changes in temperature did not play a significant role. These findings indicate a reversibility of the fish assemblage structure in response to changing levels of an apex predator and highlight the frequently overlooked importance of trophic interactions in determining large-scale biodiversity patterns. As increased cod abundance was largely driven by changes in fisheries management, our study also shows that management policies and practices, particularly those involving apex predators, can have a strong effect in shaping spatial diversity patterns, and one should not restrict the focus to effects of climate change alone.

Injuries and Fatalities in Danish Commercial Fishing Fleet in 1998–2016

Background: Fishing is a risky occupation as injuries and fatalities in fishing vessels are quite common. This paper investigates the pattern of injuries aboard fishing vessels in Denmark to get a better understanding of areas where further action is needed to reduce the number of injuries and fatalities in Danish fishing vessels. Materials and methods: Data for this study, extracted from the Danish Fishermen’s Occupational Health Service’s database (in the period 1998–2012) and the Danish Maritime Authority’s accident report from 2013 to 2016, include 1840 injuries in Danish fisheries. Result: The results showed decreased injuries in the study period from 45 injuries and deaths per 1000 fishermen reported to the authorities to 12 injuries and deaths per 1000 fishermen in 2016: 2.1% (n = 39) of all reported injuries in the study period resulted in the death of a fisherman and the remaining injuries resulted in sick leave of more than one day; 52.5% (n = 600) of reported injuries involved fishermen who have less than one year’s experience of employment; 29% (n = 407) of injuries took place between 12:00 and 16:00, and the second largest number of injuries, 23.3% (n = 324), took place between 8:00 and 12:00. The incident rate of slip/fall injuries has decreased from 10.06 per 1000 fishermen in 1998 to 3.84 in 2016. The incidence rate of injuries caused by crushing also decreased, from 9.32 accidents per 1000 fishermen in 1998 to 2.56 in 2016. Most of the injuries, 74.5% (n = 1307), happened on the deck of the vessel. Sprain/strain was among the most common injuries (34.2%; n = 538) followed by fracture (24.8%; n = 391). Conclusion: This study indicated that the number of injuries had been gradually decreasing in Danish commercial fishing vessels in the period from 1998 to 2016. The rate of injuries had been declining due to several initiatives such as the establishment of The Danish Fishermen’s Occupational Health Services, training, safety campaigns, technological improvement and structural changes in fisheries management. However, there are still places for improvement.

Ending fishery overexploitation by expanding from local successes to globalized solutions

The United Nations has launched several initiatives to achieve sustainable development, with the most recent being the Sustainable Development Goals within the 2030 Agenda. In a fisheries context, this initiative sets a target of ending overexploitation by 2020. Despite such efforts, the percentage of overfished fish stocks has oscillated around 30% globally since 2009. Here, we show that while developed countries are improving the way they manage their fisheries, developing countries face a worsening situation in terms of overcapacity, production per unit of effort and stock status. This situation is fuelled by economic interdependencies through international trade and fisheries agreements coupled with limited management and governance capacities in developing countries. We conclude that the present successes accomplished in some countries and regions are not sufficient to address the fisheries crisis and achieve the Sustainable Development Goals target globally. We highlight an urgent need to replicate and readapt successful policies and measures in the light of the realities of specific fisheries, and to implement transformational changes in fishery management and governance that influence entire sectors of the economy. About 30% of global fish stocks are overfished, and reducing this is a target of the Sustainable Development Goals. An analysis of fisheries data shows that progress in developed countries is not mirrored in developing countries.

Characteristics and discard mortality of octopus bycatch in Alaska groundfish fisheries

Octopus are caught incidentally in several US federally-managed trawl, longline, and pot fisheries in Alaska. The majority caught are giant Pacific octopus Enteroctopus dofleini. Recent changes in fisheries management in Alaska have resulted in the creation of an octopus species complex with annual catch limits, leading to increased interest in management and catch accounting for this data-poor assemblage. This study characterized the incidental octopus catch in Alaska groundfish fisheries and the mortality rate of octopus caught and discarded at sea. Onboard fisheries observers collected data on octopus weight, sex, and condition at discard in a variety of Alaska groundfish fisheries from 2006 to 2011. A field study aboard a commercial pot-fishing vessel examined delayed mortality resulting from the capture process in giant Pacific octopus during routine pot fishing. Octopus incidental catch varied widely in size and condition at capture for various fishing gear types. Vessels fishing using pot gear captured larger octopus than vessels using longline or trawl gear. Initial condition at capture was best in pot gear, with over 90% of octopus discarded from pot vessels alive in excellent condition. Octopus taken in trawl gear had the highest immediate mortality rate, with 68–94% dead or injured at discard. Giant Pacific octopus held for 24–60h following pot capture showed no signs of delayed mortality or decline in condition. These results suggest that assuming 100% mortality of discarded octopus may overestimate fishing impacts.

Changes in Job Satisfaction Through Time in Two Major New England Fishing Ports

Fishing communities in the U.S. have been the subject of great transformation due to changes in availability of resources and the implementation of different rules and regulations to manage the fisheries and conserve fish stocks. Job satisfaction has been widely regarded as an important component of well-being especially among fishermen because the occupation of fishing includes attributes of ‘adventure,’ ‘challenge,’ and ‘being outdoors’ infrequently found in other employment. It has been previously demonstrated that management driven changes to fishing communities can directly and indirectly affect aspects of fishermen’s job satisfaction and, consequently, their well-being. This paper presents a unique through time comparison of job satisfaction among fishermen between three time periods (1977, 2009/10, and 2013/14) in two major New England fishing ports: New Bedford, Massachusetts, and Point Judith, Rhode Island. Results show important differences between the three time-periods analyzed that can be associated with important changes in fisheries management in the last few decades. Differences found between ports also emphasize important socio-cultural aspects influencing job satisfaction and well-being in fishing communities. This study demonstrates that job satisfaction variables are valuable indicators of change in the context of fisheries and therefore provide valuable information for the development of future management plans that take into account important aspects of fishing community well-being.

Small-Scale Fisheries of Lagoon Estuarine Complexes in Northwest Mexico

Small-scale fisheries of lagoon-estuarine complexes (LECs) in Northwest Mexico were investigated using official landings data. Species groups found in landings were clustered into three categories according to their life cycle and habitat distribution: Lagoon-estuarine (LE), Transition zone (TZ) and Coastal (CO). Average landings were highest for LE (19,606 t yr−1), followed by TZ (7,234 t yr−1), and CO (3,155 t yr−1). In contrast, the total number of fished species groups had an opposite pattern: LE, TZ, and CO bore 31, 66 and 74 species groups respectively. The number of species groups in LE category significantly increased towards LECs of southern latitudes. The families with highest landings in LECs were Penaeidae, Portunidae, Mugilidae, Scombridae, and Lutjanidae. The area of LECs was significantly correlated with the amount of landings recorded for LE category. A similarity analysis of LECs species groups revealed a latitudinal clustering of northern and southern LECs. Overall, fisheries in LECs produced millions of $US per year, which support socioeconomic activities at the local, regional, and national scale. Although the information and landings data on LECs fisheries in Northwest Mexico have limitations for data analysis, our results suggest that changes in fisheries management of LECs, such as bottom-up management actions where resource users can participate, could help establish more sustainable fishing practices in these ecosystems and allow coastal communities to continue obtaining economic benefits and food supply from LECs in Northwest Mexico.

Regional Landscape Change in Fishing Communities of the Mexican North Pacific

The study of rural communities is a key element in understanding economic activities and conserving successful methods of resource management and social organisation. The conceptual and operational research axes were interdisciplinary environmental geography and integrative concept landscape. A participatory geographic information system (PGIS) was built to incorporate scientific and local knowledge. Regional landscape changes were analysed in fishing communities of the Mexican North Pacific, based on three historical maps. The main land- and seascape changes were: extensive stockbreeding disappeared; intensive agriculture increased; human settlements expanded; and fishing zones were created, divided and expanded seawards. Marine environment was the most changeable territory, reflecting the dominance of fishing activities. The PGIS proved to be a useful tool for identifying and understanding the changes in fishery management and the resulting dynamics of marine landscape zoning in the various communities, and in future projects would be equally applicable to coastal management and territorial organisation.

A new role for effort dynamics in the theory of harvested populations and data-poor stock assessment

Research shows that population status can be predicted using catch data, but there is little justification for why these predictions work or how they account for changes in fisheries management. We demonstrate that biomass can be reconstructed from catch data whenever fishing mortality follows predictable dynamics over time (called “effort dynamics”), and we develop a state-space catch only model (SSCOM) for this purpose. We use theoretical arguments and simulation modeling to demonstrate that SSCOM can, in some cases, estimate population status from catch data. Next, we use meta-analysis to estimate effort dynamics for US West Coast groundfishes before and after fisheries management changes in the mid-1990s. We apply the SSCOM using meta-analytic results to data for eight assessed species and compare results with stock assessment and data-poor methods. Results indicate general agreement among all three methods. We conclude that effort dynamics provides a theoretical basis for using catch data to reconstruct biomass and has potential for conducting data-poor assessments. However, we still recommend that index and compositional data be collected to allow application of data-rich methods.

Massive invasion of exoticBarbus barbusand introgressive hybridization with endemicBarbus plebejusinNorthernItaly: where, how and why?

Biological invasions and introgressive hybridization are major drivers for the decline of native freshwater fish. However, the magnitude of the problem across a native species range, the mechanisms shaping introgression as well as invader's dispersal and the relative role of biological invasions in the light of multiple environmental stressors are rarely described. Here, we report extensive (N = 665) mtDNA sequence and (N = 692) microsatellite genotypic data of 32 Northern Adriatic sites aimed to unravel the invasion of the European Barbus barbus in Italy and the hybridization and decline of the endemic B. plebejus. We highlight an exceptionally fast breakthrough of B. barbus within the Po River basin, leading to widespread introgressive hybridization with the endemic B. plebejus within few generations. In contrast, adjacent drainage systems are still unaffected from B. barbus invasion. We show that barriers to migration are inefficient to halt the invasion process and that propagule pressure, and not environmental quality, is the major driver responsible for B. barbus success. Both introgressive hybridization and invader's dispersal are facilitated by ongoing fisheries management practices. Therefore, immediate changes in fisheries management (i.e. stocking and translocation measures) and a detailed conservation plan, focussed on remnant purebred B. plebejus populations, are urgently needed.

Los derechos de pesca: el caso de la pesquería de anchoveta peruana

The implementation of the Maximum Catch Limits per Vessel (LMCE for is acronym in Spanish) in the industrial anchoveta fishery in the year 2009, has generated a wide range of changes in fisheries management. The fishing right, which should strickly represent the resource rent payment done by the owner for the use of a public good, was fixed for ten years in this regime. This research estimates the resource rent for the industrial anchoveta fishery for 2011, which implies a maximum rent, and compares the situation under open access effort and under LMCE system. It will also discuss the fishing rights and private sector’s payments versus the actual rent found in this study.

Qualitative analysis of recreational fisher response and the ecosystem impacts of management strategies in a data-limited situation

The behavioural responses of recreational fishers to changes in fisheries management are rarely investigated and as a result may be poorly understood. Changes in fisher behaviour following the introduction of new management strategies can generate unexpected outcomes, such as a shift towards targeting alternative species. Such changes can create new problems for management but even basic data are rarely available to predict the impacts of behavioural changes. Qualitative modelling can be a useful technique in data-limited situations to investigate potential shifts in management problems. This technique was used to investigate the effects of changes in fisher behaviour following the implementation of a seasonal fishing closure on a suite of high-value demersal scalefish. A simple ‘core’ model was used to investigate the dynamics involved in the general management of recreational fishing. A second more detailed model examined recreational fishing in the West Coast Bioregion of Western Australia. Similar results were obtained between the core and detailed models with an increased abundance of primary target species as a result of the closure and a decline in the alternative target species due to target switching. A strong ‘spike’ in fishing effort following the re-opening of the fishery may actually increase fishing effort as a result of a seasonal closure. Additional management strategies, including increased recreational fishing restrictions were investigated. The study identified the need for an understanding of target switching, effort spikes and the ‘value’ placed on primary versus alternative target species.

Temporal and spatial variation in the diet of a marine top predator—links with commercial fisheries

The huge quantities of waste produced by commercial fisheries worldwide attract large numbers of scavengers. Reducing this wasteful practice is desirable, but may have implications for marine ecosystems as scavengers will face a major shortfall in food. Predicting the impact of reduced discarding requires information on the strength of the link between scavengers and fisheries. We analysed sagittal otoliths regurgitated by great skuas Stercorarius skua over 5 yr from 8 different colonies in Shetland, UK, and over 18 yr from 1 of these sites, in relation to spatial and temporal vari- ation in fisheries activity. The proportions of 2 demersal fish not normally available to skuas, haddock Melanogrammus aeglefinus and whiting Merlangius merlangus, are positively correlated with annual variation in discard estimates. The proportion of whiting at 8 colonies is positively correlated with spatial differences in fish biomass estimates, and blue whiting Micromesistus potassou are only eaten in colonies close to the continental shelf edge, where this species is fished. Non-breeding great skuas tend to eat smaller and significantly more variable discarded fish compared with breeders. Our results indicate that great skuas rely heavily on fishery discards and are also sensitive to spatial and temporal changes in fisheries activity. Differences between breeding status indicate that the non- breeding component of the population may respond differently to changing discard policy. The strength of the link between fisheries and scavengers appear to be species-specific, and testing the strength of these relationships should be an important avenue of future research to interpret the response of scavengers to changes in fisheries management.

Responses of seabirds to depletion of food fish stocks

Life history theory predicts that seabirds will respond to reduction in food abundance by changes in behaviour or breeding effort, buffering adult survival. Empirical data show some support for this but also sometimes indicate a trade-off in which survival of breeding seabirds may be reduced by food shortage. The sensitivity of seabird adult survival rates may be a feature of the detailed ecology of particular species and may be affected by ecological conditions such as the possibilities for prey switching. Fishery managers may set a lower limit biomass to protect fish stock recruitment, often at about 20% of predicted unfished stock biomass. It is unclear whether this threshold would also protect the needs of seabirds dependent on the fish stock. Time series of seabird breeding success and fish stock biomass may indicate minimum densities of food required. These are orders of magnitude more than the consumption by seabird populations. The critical prey density may also vary tremendously among seabird species and is clearly a function of the detailed ecology of each species. It is possible to predict which species will be most sensitive to reduced food supply. Sensitive species may be sentinels of the “health” of the marine ecosystem. For example, in Shetland and elsewhere in the North Sea, breeding success of kittiwakes Rissa tridactyla is particularly sensitive to abundance and quality of sandeels Ammodytes spp. However, seabird communities may be affected by a variety of interactions prompted by changes in fisheries; maintaining food fish levels may not alone be sufficient where communities have altered in composition over decades of fishing, as in the North Sea, and where predator–prey impacts induced by changes in fishery management may disrupt seabird communities.

An analysis of fishing vessel accidents in fishing areas off the northeastern United States

Commercial fishing is one of the least safe occupations. Fishing vessel accident probability and vessel trip probability for fishing areas off the northeastern United States were modeled using logit regression and daily data from 1981 to 2000. Fishing vessel accident probability declined over the study period. Higher wind speeds are associated with greater accident probability. Medium size vessels had the highest accident probability before 1994. Within the study region, accident probability was lower in southern New England and Mid-Atlantic waters than on Georges Bank and in the Gulf of Maine. Accidents are more likely to occur closer to shore than offshore. Accident probability is lower in spring and fall. Changes in fishery management in 1994 have not lead to a general increase in either accident or vessel trip probability. Although higher economic payoff (i.e., revenue of landings) induces more vessels to go fishing, this is not associated with an increase in accidents. The probability models are important building blocks in development and quantitative assessment of management mechanisms related to safety in the commercial fishing industry.

Predation by great skuas at a large Shetland seabird colony

Summary Skuas are top predators in marine ecosystems and may have detrimental effects on seabird communities they prey upon. However, predation rates are poorly understood and poorly quantified. Using a bio‐energetics model we estimate seabird predation by great skuas, Stercorarius skua, at a large UK colony (Hermaness, Shetland). We investigate the influence of dietary specialization and fishery management on predation and explore the effect of experimental removal of specialist bird predators. Great skuas at Hermaness required 491·5 × 106 kJ and 546·6 × 106 kJ of energy in each of two breeding seasons. Breeding skuas fell into one of two groups: a small proportion (5%) of specialist bird predators or the vast majority (95%) that fed opportunistically on birds or specialized on fishery discards. During 1999, great skuas consumed ≈80 000 kg of fish, which increased to over 90 000 kg in 2001. About 13 000 seabirds were consumed by great skuas each year, with 26–29% being consumed by specialist bird predators. Although it is difficult to assess, great skuas appear to be having a negative impact on seabird populations. Altering model inputs to test differing scenarios revealed that reductions in fishery discards would result in increased seabird predation rates. However, proposed changes in fishery management over the period of the study did not reduce discarding rates, which instead increased. Synthesis and applications. The use of a bioenergetics model reveals that great skua predation may negatively affect seabird populations. Availability of fishery discards is an important factor influencing seabird predation rates, but predicting the effect of changes in fishery management may be difficult in the short term. Specialist bird predators consume large quantities of seabird prey, but this is less significant at the population level. Although experimental removal of specialist bird predators may reduce predation at a minimal loss of skuas, it is unclear whether conspecifics may replace them and retain high rates of predation.

GBR-prawn: modelling ecosystem impacts of changes in fisheries management of the commercial prawn (shrimp) trawl fishery in the far northern Great Barrier Reef

GBR-prawn: modelling ecosystem impacts of changes in fisheries management of the commercial prawn (shrimp) trawl fishery in the far northern Great Barrier Reef

GBR-prawn: modelling ecosystem impacts of changes in fisheries management of the commercial prawn (shrimp) trawl fishery in the far northern Great Barrier Reef

GBR-prawn is a “mass-balance” trophic-based ecosystem model (ECOPATH II) of the Great Barrier Reef, which combines a model template of a generalised coral reef ecosystem with results from extensive cross-shelf surveys of the far northern Great Barrier Reef. The enhanced model includes both the trawl and line fisheries, but focuses on the effect of trawling on the penaeid prawn community in the lagoon and inter-reef habitat. Trawl and line-fishing by-catch is specified and monitored, as is the biomass of seabirds and endangered sea turtles. Network analysis of the mixed trophic impacts predicted by the model showed only a minor negative impact on prawn populations by trawling. The balance of positive effects, such as removal of predators or competitors as by-catch, and the negative effects of direct harvest resulted in the apparent minor impact. The impact was also reduced by positive feedback from the discarded trawl by-catch, currently a 6:1 ratio by weight, which either made up a proportion of the prawn diet or was consumed by animals that made up a proportion of the diet of the prawns being harvested. Dynamic and spatial simulations of the model showed that species of prawn were effected differentially, with P. esculentus (tiger prawn) a dominant at low levels of trawling effort and M. endeavouri (endeavour prawn) a better performer at higher levels of trawling. Penaeus longistylus (reef-associated, red-spot king prawn) did poorly when trawled unless a refugia was available. The management strategy of gradual reduction in trawl 25 effort to 50% of current levels resulted in a 59% reduction in P. esculentus and a 64% reduction in M. endeavouri catch. Catch of P. longistylus was also lower than expected due to a spatial concentration of the reduced effort in the more economically attractive inshore lagoon. The effect on by-catch species of reduced trawl effort included increases in sea turtles and small fish omnivores (the latter comprising most of the discards), but also resulted in a decrease in species that feed on discards such as seabirds, groupers, and sharks/rays. Spatial analysis of trawling effort, which included the de-facto provision of refugia areas, showed a marked buffering of the impacts of trawling on by-catch species, particularly sea turtles.