Future Fisheries Management Research Articles

The complete mitochondrial genome of moonfish Mene maculata (Perciformes: Menidae)

The moonfish M. maculata is economic important species in the marine fishery in China. However, the genetic information of this species remains unavailable. In this study, we report the complete mitochondrial genome sequence of M. maculata. The mitogenome has 16,733 base pairs (53.8% A + T content) and made up of total of 37 genes (13 protein-coding, 22 transfer RNAs, and two ribosomal RNAs), and a putative noncoding control region. This study reports the first available complete mitogenome of Menidae and will provide useful genetic information for future fishery management and aquaculture development of Menidae.

The complete mitochondrial genome of Lutraria maxima Jonas (Veneroida: Mactridae)

The snout otter clam Lutraria maxima Jonas (Veneroida: Mactridae) is an economically important species in the marine bivalves fishery and aquaculture in China. However, the genetic information of this species remains unavailable. In this study, we report the complete mitochondrial genome sequence of L. maxima. The mitogenome has 17,082 base pairs (63.9% A + T content) and made up of a total of 37 genes (13 protein-coding, 22 transfer RNAs and two ribosomal RNAs), and a 1045 bp non-coding control region. The presence of a gene coding for ATPase subunit 8 was also noted. However, as expected in Mactridae, the gene arrangements showed variations with that of the related species. This study adds to the repository of available mitogenomes of various Mactridae and will provide useful genetic information for future fishery management and aquaculture development of Mactridae.

Precision of growth band determination from eyestalk sections of Antarctic krill (Euphausia superba) preserved in formalin

Abstract Age information for commercial fish species is crucial to fishery management. Age information for Antarctic krill (Euphausia superba) will be important for stock assessment modeling and future feedback management of krill fisheries. Samples stored in 70% ethanol provide an opportunity to detect the growth bands of eyestalk sections. Moreover, information derived from samples preserved in formalin will have a greater impact on the feedback management process because this preservation method was more common in previous decades. Out of 162 Antarctic krill individuals preserved in 5% formalin, the growth bands from eyestalk sections of 134 samples were readable. The relationship between the total length and the growth bands in the eyestalk was analyzed. Three main parameters, including exact percent agreement (EPA), coefficient of variation (CV), and average percentage error (APE), were used to evaluate the precision of the growth bands.Results show decreased CV and APE values and an increase in the EPA value with the accumulation of reading runs. This method is direct and uses a grinding and polishing technique before reading, contrary to Krafft et al. (2016) and Kilada et al. (2017). Combined with published studies, specimens collected from autumn to winter in this study can provide a better understanding of Antarctic krill growth. This study presents important information for age determination, particularly for specimens preserved in formalin, and will benefit the stock assessment and acoustic estimation of this species in the future. Further studies are required to validate the correlation between growth bands and age. Additionally, more samples from different seasons and regions are also needed to fully understand the growth dynamics of this species.

Interannual variability in reproductive traits of the Patagonian toothfish Dissostichus eleginoides around the sub-Antarctic island of South Georgia.

Commercial fisheries data, collected as part of an observer programme and covering the period 1997-2014, were utilized in order to define key reproductive traits and spawning dynamics of the Patagonian toothfish Dissostichus eleginoides at South Georgia. Multi-year spawning site fidelity of D. eleginoides was revealed through the identification of previously unknown spawning hotspots. Timing of female spawning was shown to have shifted later, leading to a shorter spawning duration. A decrease in length and mass of female and male spawning fish and a reduced number of large spawning fish was found, evidence of a change in size structure of spawning D. eleginoides. During the study period fewer later maturity stage females (including spawning stage) were observed in conjunction with increased proportions of early stage female D. eleginoides. The findings are discussed in the context of reproductive success, with consideration of the possible effects such spawning characteristics and behaviours may have on egg and larval survival. This work presents the first long-term assessment of D. eleginoides spawning dynamics at South Georgia and provides valuable knowledge for both the ecology of the species and for future fisheries management of this commercially important species.

Length–weight relationships of 9 commercial fish species from the North Aegean Sea

Length-weight relationships are presented for 9 commercial fish species from Psara Island (North Aegean Sea).The species studied are Boops boops, Dentex maroccanus, Helicolenus dactylopterus, Merluccius merluccius, Mullus surmuletus, Pagrus pagrus, Raja clavata, Scyliorhinus canicula and Trachurus picturatus. To our knowledge, there are no published data on the fish stocks of the study area. Estimates of LWR parameters are provided for Dentex maroccanus, Trachurus picturatus and Helicolenus dactylopterus, for which reliable LWR datasets are few in the literature, while none has been published for the Greek seas. The samples were collected from the continental shelf and the upper slope, by using non-selective fishing gear (with a research vessel and a commercial bottom trawler), during two seasonal sampling periods: November 2009 and May 2010.The growth pattern of Boops boops and Scyliorhinus canicula was found to be positive allometric, whereas an isometric growth pattern was determined for the other species in the study. We hope that the LWR obtained here will be used in future fisheries management or conservation research in the study area, for example, to convert lengths to weights, determine fish condition and assess spatial or temporal variability in fish growth.

Social, economic and trade characteristics of the elasmobranch fishery on Unguja Island, Zanzibar, East Africa

Understanding the socio-economic drivers underpinning fishers' decisions to target elasmobranchs is considered vital in determining sustainable management objectives for these species, yet limited empirical data is collected. This study presents an overview of elasmobranch catch, trade and socio-economic characteristics of Zanzibar's small-scale, artisanal fishery. The value of applying this information to future elasmobranch fisheries policy is demonstrated. In August 2015, interviews were conducted with fishers (n = 39) and merchants (n = 16) at two landing sites, Kizimkazi-Dimbani and Mkokotoni, along with the main market site in Stone Town. Additionally, elasmobranch catches were recorded across the same locations between June and August 2015. Elasmobranchs were listed as target species by 49% of fishers interviewed. Whilst most fishers (n = 30) stated that 76–100% of their household income came from fishing, there was variation in how elasmobranch catch and trade contributed. One-third of fishers (n = 36) that caught and sold elasmobranchs reported that 41–60% of their income came from elasmobranch catch. However, for some fishers (n = 8) elasmobranch catch represented 0–20% of their income, whilst for others (n = 4) it represented 81–100%. Differences in fisheries income and elasmobranch price could be attributed to several interacting factors including season, weather, fishing effort, fishing gear, target catch and consumer demand. Further, elasmobranch price was influenced by size and species. The study revealed information on catch, trade, markets and socio-economy that is important for future research, conservation and management of elasmobranchs and fisheries in Zanzibar. The methods utilised have potential for broader application to understudied, artisanal elasmobranch fisheries in the western Indian Ocean.

Discard management: A spatial multi-criteria approach

Discard management needs to draw on scientific research and advice, usually supported by specific statistical modeling analysis. A wide range of statistical analysis methods were applied to fishery data in an attempt to distinguish factors that influence the species discard composition. While such approaches are important, they are still incomplete for disaggregating the economic and spatial-temporal factors for analyzing of this process and obtain a whole view of this issue. Our study aims to fill this gap by identifying, describing, and quantifying factors that influence discards of trawl fisheries using a multivariate approach based on five complementary aspects: “economic”, “vessel characteristics”, “spatial”, “temporal” and “environmental”. In addition, a spatial multi-criteria approach were used to investigate discard hot-spot areas using ecological criteria such as vulnerability and resilience of the discarded species. Using these ecological criteria will concentrate conservation efforts on the most relevant sites minimizing discards of a variety of potentially vulnerable species. This approach was applied to a case study of a multi-species demersal bottom trawl fisheries in north Spain, Cantabrian Sea (ICES area VIIIc). Results showed how spatial and economic factors highly affect species discard composition, identifying specific spatial-temporal discard hot-spots to be preferentially avoided by fishers. Mitigation measures for future fisheries management strategies should be implemented at multiple stages of the discarding process, both in the selection of the fishing grounds and the economic valorization of the discarded species.

Long-term spatial and temporal patterns of sea turtle strandings in southern Brazil

Strandings of marine vertebrates along beaches have been widely used to infer threats and causes of mortality in adjacent waters. Understanding the influence of anthropogenic impacts on sea turtle survival is essential for effective conservation, yet limited data are available on the magnitude and patterns of sea turtle mortalities in southern Brazil. Our study reports sea turtle stranding data obtained from monthly beach surveys undertaken from 1995 to 2014 in the state of Rio Grande do Sul, Brazil, and when possible, we identify causes of mortality associated with different fisheries. A total of 6285 turtles of five species were encountered, with the three most common species being loggerhead (Caretta caretta; n = 3192), green (Chelonia mydas; n = 2572), and leatherback turtles (Dermochelys coriacea; n = 376). Generalized linear models demonstrated that loggerhead and green turtle strandings have increased over the last 10 years. Strandings were highest from October to March, which coincides with the greatest bottom pair trawl, gill net, and possibly double-rig trawl fishing effort near the coast. Our results provide a baseline to compare future sea turtle stranding patterns. For reducing sea turtle mortalities, we suggest that time/area closures and/or reduction in gill net, pair trawl, and possibly double-rig trawl fishing effort in coastal waters of southern Brazil during austral spring and summer be considered for future fisheries management plans.

Age and growth of filefish, Thamnaconus modestus (Günther, 1877) off the Jeju Island of Korea

The age and growth of filefish, Thamnaconus modestus (Gunther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year−1 and t0 = −1.56 for females, L∞ = 41.20 cm, k = 0.18 year−1 and t0 = −2.36 for males, and L∞ = 43.16 cm, k = 0.17 year−1 and t0 = −2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.

The influence of physical and biological processes on the ichthyoplankton communities in the Gulf of Sirte (Southern Mediterranean Sea)

AbstractThis paper reports on the first study on the ichthyoplankton community structure in the Gulf of Sirte and its spatial distribution in relation to environmental conditions and zooplankton abundance. The results make an important contribution to the future management of fisheries in this unexplored, but much exploited, area. Biological samples were collected in July 2008 using a Bongo40 net. In total, 1914 larvae were found and 1652 of these were identified. In particular, bathypelagic taxa were the most abundant, followed by demersal, mesopelagic, pelagic and epipelagic taxa. The ichthyoplankton community had a patchwork distribution influenced by oligotrophic conditions, the bottom depth and oceanographical features. The results suggest that environmental forcings were able to transport the ichthyoplankton to productive areas. Indeed, maximum fish egg densities were found in coastal stations in correspondence with the Atlantic Tunisian Current inflow, whereas larvae were mainly concentrated in the east side of the Gulf, probably as a result of advection by the anticyclonic circulation. Additionally, the distribution patterns of the total larvae density and the different assemblages were well matched with the abundance of the zooplankton, probably determining final larval survival, growth and recruitment.

Brown shrimp (Farfantepenaeus aztecus) density distribution in the Northern Gulf of Mexico: an approach using boosted regression trees

AbstractThe estuarine‐dependent brown shrimp, Farfantepenaeus aztecus, is a significant commercial fishery and important species in the Gulf of Mexico (GOM) ecosystem as well as being a key component in energy transfer between benthic and pelagic food web systems. Because of the economical and ecological importance of brown shrimp, we developed a spatial population model to identify places of high shrimp density under a set of spatial, environmental and temporal variables in the Northern Gulf of Mexico (NGOM). We used fisheries‐independent data collected by the Southeast Area Monitoring and Assessment Program (SEAMAP) from 1992 to 2007 (summer and fall seasons). The relationship between the predictor variables and shrimp density was modeled using Boosted Regression Trees (BRT). Within the environmental variables included in the model, bottom type and depth of the water column were the most important predictors of shrimp density in the NGOM. Spatial predictions performed using the trained BRT model for summer and fall seasons showed a spatial segregation of shrimp density. During the summer, higher densities were predicted near the Texas and Louisiana coast and during the fall, higher densities were predicted further offshore. The model performed well and allowed successful prediction of brown shrimp hot spots in the NGOM. Model results allow fisheries managers to evaluate the potential impact from fisheries on the resource and to develop future fisheries management strategies, understand the biology of brown shrimp as well as assess the potential impacts of oil spills or climate change.

Harvest control rules in modern fisheries management

Abstract Harvest control rules have become an important tool in modern fisheries management, and are increasingly adopted to provide continuity in management practices, to deal with uncertainty and ecosystem considerations, and to relieve management decisions from short-term political pressure. We provide the conceptual and institutional background for harvest control rules, a discussion of the structure of fisheries management, and brief introductions to harvest control rules in a selection of present day cases. The cases demonstrate that harvest control rules take different forms in different settings, yet cover only a subset of the full policy space. We conclude with views on harvest control rules in future fisheries management, both in terms of ideal and realistic developments. One major challenge for future fisheries management is closing the gap between ideas and practice.

Modelling spatial distribution of Patagonian toothfish through life-stages and sex and its implications for the fishery on the Kerguelen Plateau

Size and sex specific habitat preferences are common in animal populations and can have important implications for sound spatial management of harvested species. Patagonian toothfish (Dissostichus eleginoides) is a commercially exploited fish species characterised by its longevity (>50yo) and its extremely broad distribution in depths ranging from 10m to 2500m on most of the Plateaux, banks and seamounts of the Southern Ocean. As many bentho-pelagic fish species, Patagonian toothfish exhibits sexual dimorphism and ontogenetic habitat shift towards deeper waters as they grow. In this study, we modelled the spatial structure of Patagonian toothfish population (median total length and sex composition) in a data-rich area, the Kerguelen Plateau (Southern Indian Ocean), to better understand the ecological drivers of their distributional patterns and inform current and future fishery management strategies. We applied spatially-explicit statistical models to quantify and predict the effects of the complex topography of the Kerguelen Plateau in structuring the spatial distribution of Patagonian toothfish total length and sex ratio, while controlling for gear selectivity and season. Model predictions showed that juvenile toothfish live in shallow regions (shelf and banks) and move downward progressively up to 600m while they grow. Between 600m and 1200m, the downward movement stops and fish settle at their preferred depths. While in this depth range, fish are ∼75cm long and most vulnerable to fisheries. As they approach maturity large fish move downward to deep-sea habitats (from 1200m to >2300m) and head towards the spawning grounds on the western side of the plateau and around Skiff Bank. Importantly, the sex ratio was not evenly distributed across the Plateau; prediction maps revealed a higher proportion of females in the South whereas a strong male-bias sex ratio (70%) occurred in the North-West. Large-scale prediction maps derived from our models assisted in developing hypotheses regarding ecological drivers of Patagonian toothfish habitat-use and movement across different life stages and sex. Such hypotheses are crucial to inform management strategies of this multijurisdictional fishery (France and Australia) at the spatial and temporal scales over which natural processes and fishery extend.

Modelling the oceanic habitats of two pelagic species using recreational fisheries data

AbstractDefining the oceanic habitats of migratory marine species is important for both single species and ecosystem‐based fisheries management, particularly when the distribution of these habitats vary temporally. This can be achieved using species distribution models that include physical environmental predictors. In the present study, species distribution models that describe the seasonal habitats of two pelagic fish (dolphinfish, Coryphaena hippurus and yellowtail kingfish, Seriola lalandi), are developed using 19 yr of presence‐only data from a recreational angler‐based catch‐and‐release fishing programme. A Poisson point process model within a generalized additive modelling framework was used to determine the species distributions off the east coast of Australia as a function of several oceanographic covariates. This modelling framework uses presence‐only data to determine the intensity of fish (fish km−2), rather than a probability of fish presence. Sea surface temperature (SST), sea level anomaly, SST frontal index and eddy kinetic energy were significant environmental predictors for both dolphinfish and kingfish distributions. Models for both species indicate a greater fish intensity off the east Australian coast during summer and autumn in response to the regional oceanography, namely shelf incursions by the East Australian Current. This study provides a framework for using presence‐only recreational fisheries data to create species distribution models that can contribute to the future dynamic spatial management of pelagic fisheries.

Detection of Squid and Pacific Saury fishing vessels around Japan using VIIRS Day/Night Band image

The Suomi National Polar-orbiting Partnership (S-NPP) satellite, which carries a new Day/Night Band (DNB) radiometer, has very high sensitivity to observe anthropogenic light emission sources, especially on the activity of maritime vessels. This study applied DNB images to detect fishing vessel by three case species in Northwest Pacific ocean (Neon flying squid (Ommastrephes bartramii), Japanese common squid (Todarodes pacificus), and Pacific saury (Cololabis saira)). The results of fishing positions and distribution were well validated using location reported data by fisherman. The more application of DNB data could be used to estimate the numbers of fishing vessels, vessel speed from Vessel Monitoring System (VMS), and combined traditional fishing grounds, season time, habits and water temperature to distinguish the fishing species. The DNB data could form the basis for future fisheries management and information system.

Hypolimnetic oxygenation in Twin Lakes, WA. Part II: Feeding ecology of a mixed cold- and warmwater fish community

Line-diffuser hypolimnetic oxygenation (HO) was initiated in North Twin Lake, Washington, in 2009 to mitigate loss of coldwater fishery habitat due to temperature–dissolved oxygen “habitat squeeze” and to reduce internal phosphorus cycling. Active tracking, net-captures, and hydroacoustic analyses demonstrated that trout populations rapidly expanded into increased hypolimnetic habitat within the first few years of oxygenation; however, long-term fishery benefits and many basic ecological aspects of HO have yet to be established. Diet and food web analyses indicate significant changes in feeding ecology of principal coldwater fish species in North Twin in 2012 compared to preoxygenation (2005) and to unoxygenated South Twin in 2012. North Twin rainbow trout (Oncorhynchus mykiss) consumed significantly more large-bodied Daphnia during midsummer 2012 than in South Twin, where rainbow trout fed primarily on littoral amphipods. Additionally, relative gut weight for brook trout (Salvelinus fontinalis) in August 2012 was significantly higher in North Twin compared to South Twin, apparently due to increased access to hypolimnetic zooplankton. Golden shiner (Notemigonus crysoleucas) diets also seem to include more zooplankton in oxygenated North Twin. Littoral-focused largemouth bass (Micropterus salmoides) diets were not altered by HO. Observed changes in feeding ecology following HO have significant implications for future fishery management in the Twin Lakes.

Fisheries in a warming ocean: trends in fish catches in the large marine ecosystems of the world

Trends in annual catches of fish species in the large marine ecosystems (LMEs) of the world were analysed, relating them with changes in sea surface temperature. LMEs are large coastal areas with broad ecosystem similarities, and the vast majority of them have warmed in the period of 1982–2006. Changes in sea water temperature, induced by climate change, affect the geographic distribution of fish species in marine ecosystems. Shifts in distribution of fish will most likely affect the abundance, distribution and composition of fisheries catches. In the present paper, a decreasing trend in the catches of fish species in warming LMEs was observed. Catches in years of cold and warm winters were compared for each of the eight fish species most caught in the world. Generally, mean catches of polar and temperate species were higher in years of warm winters in the LMEs located in the northern part of the species range and in years of cold winters in LMEs of the southern regions of their ranges. Mean catches of subtropical species were higher in cold years in LMEs of lower latitudes and in warm years in LMEs of higher latitude regions. The results obtained for fish catches agree with a poleward shift of fish species as a response to ocean warming, posing challenges for future fisheries management.

Getting more for less: Increasing the accessibility of water column sonar data for fisheries management

Active acoustic technology is of increasing importance for studies examining fish populations and biological abundance in the water column. Multibeam echosounders are employed routinely on NOAA fishery vessels to estimate biomass, conduct trophic- and species-level identification, measure school morphology and behavior, and characterize habitat for commercially important species. These surveys deliver valuable information for ecosystem-based fisheries management but they also produce massive amounts of data that are costly and difficult to maintain. With its ability to store and preserve large datasets, NOAA's National Geophysical Data Center is acquiring and archiving acoustic data collected from NOAA and academic fleets. Through these efforts, an accessible archive of acoustic water column data will be made available to researchers and the public around the world. A web-based search engine will allow anyone to identify where data were collected, what instrument was used, and access the raw data and associated products. Years of decreasing funding for the sciences have necessitated our ability to get more information and more users out of data currently collected. This globally accessible archive is a large step in that direction. Of most importance is identifying how best to tap the archive to benefit current and future fisheries research and management.

Krill, climate, and contrasting future scenarios for Arctic and Antarctic fisheries

AbstractArctic and Antarctic marine systems have in common high latitudes, large seasonal changes in light levels, cold air and sea temperatures, and sea ice. In other ways, however, they are strikingly different, including their: age, extent, geological structure, ice stability, and foodweb structure. Both regions contain very rapidly warming areas and climate impacts have been reported, as have dramatic future projections. However, the combined effects of a changing climate on oceanographic processes and foodweb dynamics are likely to influence their future fisheries in very different ways. Differences in the life-history strategies of the key zooplankton species (Antarctic krill in the Southern Ocean and Calanus copepods in the Arctic) will likely affect future productivity of fishery species and fisheries. To explore future scenarios for each region, this paper: (i) considers differing characteristics (including geographic, physical, and biological) that define polar marine ecosystems and reviews known and projected impacts of climate change on key zooplankton species that may impact fished species; (ii) summarizes existing fishery resources; (iii) synthesizes this information to generate future scenarios for fisheries; and (iv) considers the implications for future fisheries management. Published studies suggest that if an increase in open water during summer in Arctic and Subarctic seas results in increased primary and secondary production, biomass may increase for some important commercial fish stocks and new mixes of species may become targeted. In contrast, published studies suggest that in the Southern Ocean the potential for existing species to adapt is mixed and that the potential for the invasion of large and highly productive pelagic finfish species appears low. Thus, future Southern Ocean fisheries may largely be dependent on existing species. It is clear from this review that new management approaches will be needed that account for the changing dynamics in these regions under climate change.

Bayesian spatio-temporal discard model in a demersal trawl fishery

Spatial management of discards has recently been proposed as a useful tool for the protection of juveniles, by reducing discard rates and can be used as a buffer against management errors and recruitment failure. In this study Bayesian hierarchical spatial models have been used to analyze about 440 trawl fishing operations of two different metiers, sampled between 2009 and 2012, in order to improve our understanding of factors that influence the quantity of discards and to identify their spatio-temporal distribution in the study area. Our analysis showed that the relative importance of each variable was different for each metier, with a few similarities. In particular, the random vessel effect and seasonal variability were identified as main driving variables for both metiers. Predictive maps of the abundance of discards and maps of the posterior mean of the spatial component show several hot spots with high discard concentration for each metier. We argue how the seasonal/spatial effects, and the knowledge about the factors influential to discarding, could potentially be exploited as potential mitigation measures for future fisheries management strategies. However, misidentification of hotspots and uncertain predictions can culminate in inappropriate mitigation practices which can sometimes be irreversible. The proposed Bayesian spatial method overcomes these issues, since it offers a unified approach which allows the incorporation of spatial random-effect terms, spatial correlation of the variables and the uncertainty of the parameters in the modeling process, resulting in a better quantification of the uncertainty and accurate predictions.