Sardine Fishery Research Articles

Climate variability impact on Bali sardine fishery: Ecology and fisheries perspective

AbstractThe sardine fishery in Bali is influenced by fishing effort and environmental conditions including temperature and chlorophyll a (chl‐a). Bali's sardine, Sardinella lemuru Bleeker, production decreased significantly during the extreme conditions that occurred in 2010 and 2016. This study assesses the impact of extreme conditions on the sardine fishery of the Bali Strait. Fisheries data were collected from two landing places: Muncar fishing port (Banyuwangi District, East Java Province) and Pengambengan fishing port (Jembrana District, Bali Province) between January 2007 and December 2017. Temperature and chl‐a data were downloaded from satellite readings. Fishing locations were observed by an onboard observer to investigate shifts in fishing grounds. A modified Cobb–Douglas regression model and profile analyses were used to estimate the impact of environmental variables on sardine production and to assess how extreme periods affect the catch composition in the Bali Strait. Seawater temperature and chl‐a concentration had significant impacts on sardine production, but temperature is likely to be less correlated with sardine production than chl‐a concentration. To adapt to extreme weather, purse seiners prefer to modify the vessel type rather than change their fishing ground.

Similarities between Indian oil sardine Sardinella longiceps Valenciennes, 1847 and global sardine fisheries and its management

Similarities between Indian oil sardine Sardinella longiceps Valenciennes, 1847 and global sardine fisheries and its management

Profit and equity trade‐offs in the management of small pelagic fisheries: the case of the Japanese sardine fishery*

The management of small pelagic fisheries is difficult due to environmental regime changes that generate multi‐decadal cyclic fluctuations in stock abundance. Lagged management responses to environmental factors can amplify the effects of fishing and may even result in stock collapse. In this paper, we develop an age‐structured bioeconomic model to explore the effectiveness of alternative management approaches for cyclically fluctuating small pelagic fish stocks. The fishery outcomes are evaluated against the overall profit of the fishery and the intertemporal distribution of fishing profits. The model is parameterised for the Japanese sardine fishery, once the largest fishery in Japan, which has experienced a prolonged period of stock collapse over the last 100 years. The results show that the duration of fishery collapse is mostly determined by the extent of cyclic fluctuations in the recruitment of immature sardines, but the effects of the fluctuations on the fishery are heightened by the cumulative impact of fishing. We further show that restricting fishing reduces the fishery’s overall profits, but smooths the intertemporal distribution of profits, resulting in greater intergenerational equity. This income smoothing effect is particularly pronounced when the stock exhibits high levels of cyclic fluctuations.

Satellite chlorophyll concentration as an aid to understanding the dynamics of Indian oil sardine in the southeastern Arabian Sea

Coastal waters of Kerala, which form an integral part of the Malabar upwelling zone off the southwest coast of India, constitute an important fishing region for small pelagics. Satellite remote sensing data from 1998−2014 were used to test the hypothesis that fluctuations in the landings of Sardinella longiceps, the major pelagic fish landed in the area designated as the South Eastern Arabian Sea (SEAS), are influenced by seasonal variability in phytoplankton biomass (measured as chlorophyll a [chl a] concentration), under the changing strength of physical para - meters such as sea surface temperature (SST), alongshore wind stress, Ekman mass transport, sea level anomaly (SLA) and Kerala rainfall. Multiple linear regression analysis (MLRA) was used to assess the influence of physical forcing mechanisms on chl a concentration on monthly and seasonal scales. We found that SLA, alongshore wind stress, SST and rainfall were ranked 1 to 4, respectively, and the first 3 factors significantly influenced the chl a concentration of SEAS. Pearson’s correlation analysis between monthly chl a and sardine landing (with chl a leading) showed a maximum positive correlation (+0.26) at 2 and 3 mo lags, emphasizing that the influence of chl a on the fishery of S. longiceps is seasonal (r = 0.35 for seasonal lead−lag correlation) in the coastal waters of SEAS. Variation in phytoplankton biomass, as evidenced by chl a fluctuations, seems to have a decisive role in regulating the physiological condition of larvae spawned during the southwest monsoon season, their juveniles and finally the adults that are recruited into the fishery in the next season. Using the quantity of phytoplankton as a predictive tool will exploit the presumptive trophic link to aid understanding of sardine fishery dynamics in upwelling zones.

An overview of small-scale fisheries in the Northern Portuguese coast

An overview of small-scale fisheries in the Northern Portuguese coast

Catch and yield trends of the Portuguese purse seine fishery (2006-2018)

Catch and yield trends of the Portuguese purse seine fishery (2006-2018)

Overfishing and Climate Drives Changes in Biology and Recruitment of the Indian Oil Sardine Sardinella longiceps in Southeastern Arabian Sea

The recent fluctuations in abundance of the Indian oil sardine Sardinella longiceps, a tropical small pelagic clupeid fish, was investigated in the light of overfishing and variations in its habitat ecology in southeastern Arabian Sea. In 2012, its landings peaked to an all-time record making it the fifth largest sardine fishery in the world, and within 3 years the catches were reduced to nearly a tenth of that level. This study examined the fishery dependant factors such as effort, catch rates and expansion of fishing area; the biological variations in fish size, maturity and recruitment; and tried to relate this to the environmental variations in the sardine habitat and food availability. The 2012 mega harvest was a result of a 2-time increase in gear size and engine capacity of fishing crafts and a 3.7-time increase in fishing effort. The female maturation process was strongly influenced primarily by rainfall and then by upwelling and the resulting influx of cold nutrient-rich water in the habitat from April much before the start of the monsoon in June. After 2013, the weak monsoons and the 2015 El Nino Southern Oscillation resulted in a warmer (by an average of 1.1°C) period which negatively impacted the maturation process. The abundance of jellyfishes which are larval and young fish predators in the habitat negatively affected recruitment after 2013. The mismatch in timing of phytoplankton productivity and sardine larvae in the habitat also affected the recruitment success. These environmental divergences coupled with the excessive capture (beyond maximum sustainable yields) of spawning stock and juveniles from 2010 has resulted in this biological catastrophe which has affected the livelihood of thousands of small-scale fishers. A more responsive fisheries administration with timely restriction on fishing effort and protection of spawning stocks by way of fishery closure would have helped minimize the impacts.

A GIS-based framework for addressing conflicting objectives in the context of an ecosystem approach to fisheries management—a case study of the Portuguese sardine fishery

Abstract An ecosystem approach to fisheries management (EAFM) is as a new paradigm in fisheries management. In this study, a combination of geographic information systems (GISs) and multi-criteria decision-making method (MCDM) is proposed as a framework supporting an ecosystem approach to European sardine (Sardina pilchardus, Clupeidae) fishery management in Portugal. This case study was chosen due to the recent severe decline shown by the species. To develop an EAFM for the sardine fishery, a set of criteria were defined based on literature review and expert knowledge. To address multiple conflicting objectives, namely conservation and fisheries, five scenarios were considered: (i) baseline; (ii) nurseries protection; (iii) spawning areas protection; (iv) fishery profit driven, and (v) safeguarding dependent fishing communities. Combination of GIS and MCDM methods highlighted important areas to implement spatial conservation measures for sardine. The analyses indicate that some areas are suitable for conservation in several scenarios, such as the area near Aveiro and the area near the Tejo estuary. However, conservation measures implemented in the area near Aveiro would imply higher economic trade-offs when compared with the actions applied in the region near the Tejo estuary. Results also suggested some of the conservation objectives, such as the protection of sardine eggs and juveniles, to not be compatible. The proposed framework is an important tool supporting EAFM by addressing conflicting objectives, trade-offs and identifying areas that could be considered as potential fishery closure sites or subjected to further analyses.

A frame-based modelling approach to understanding changes in the distribution and abundance of sardine and anchovy in the southern Benguela

A number of ecologically and economically important species in the southern Benguela, including the forage fish sardine Sardinops sagax and anchovy Engraulis encrasicolus, have undergone southward/eastward shifts in their distribution in the 1990s/early 2000s. In addition to the effects of changes in prey availability to top predators, the spatially-distinct nature of the system means the location of a stock has implications for its productivity. The spatial dynamics of small pelagic fish are of particular importance because they are thought to exert wasp-waisted trophic control on the system. An objective-driven frame-based model was constructed to investigate the ability of the approach to represent spatial and population dynamics of sardine and anchovy, and to explore the implications of possible management strategies. Climate variability and fishing pressure were assumed as drivers. Sensitivity analyses were performed and a number of scenarios tested. A frame-based approach appears to be useful within this context. Results suggest that the productivity of the sardine resource within the model is highly dependent on the spatial characteristics of fishing pressure. The role of anchovy within the model system has not yet been fully developed. Increasing our understanding of the relative suitability of environmental conditions of different regions is also important if we are to increase our capacity to predict trends in abundance and distribution. This study shows support for continued careful consideration of spatialized management approaches to the South African sardine fishery.

Identifying ecosystem patterns from time series of anchovy (Engraulis ringens) and sardine (Sardinops sagax) landings in northern Chile

ABSTRACTUseful knowledge acquisition from known and systematized information (data) is a big challenge for researchers, users and finally, decision makers. In this sense, knowledge discovery from data (KDD) process represents a valuable tool for information analysis. Moreover, this work presents an approach through KDD in time series pattern identification for anchovy and sardine fisheries and environmental data, in northern Chile. Time series, multivariate analysis and data mining techniques, along with technical literature review for results validation. The KDD approach and the data mining techniques implemented achieved an integration between these variables, identifying relevant patterns associated with fisheries abundance fluctuations and strong association with environmental changes such as El Niño and long-term cold–warm regimes between them, establishing anchovy and sardine pre-dominant time-periods, associated with environmental conditions are identified. The latter establishes groundwork for studying underlying functional relationships that could reduce gaps in the national fisheries management policies for those fisheries.

Code of practice for reducing accidental mortality of dolphins in purse-seine fisheries

Purse-seine vessels commonly interact with dolphins. The total number of dolphins accidentally killed in the world's purse-seine fisheries may be substantial, even if interaction rates are generally low. This paper describes an industry Code of Practice (CoP) that was established in Australian purse-seine fishery after an observer program detected high dolphin interaction rates that had not been reported in fishery logbooks. Key features of the CoP are search and delay procedures designed to prevent encirclements and release procedures that minimise mortalities. Extrapolation from observer data (3.9% of net sets observed), suggested that 449 dolphin encirclements and 423 mortalities occurred in 2004-05, the year before the CoP was established. A decade later, observer data suggest that annual encirclements and mortalities had been reduced by 87% and 97%, respectively. Searches were highly effective in detecting the presence of dolphins. Dolphins were not encircled in > 85% of net-sets made after searches determined that dolphins were absent from the fishing area. Opening the front of the net resulted in the successful release of all dolphins in > 86% of encirclement events. Discrepancies between interaction rates estimated from observer data and those recorded in logbooks have decreased over time. This study demonstrated that codes of practice that specify changes in fisher behaviour can be effective in mitigating the interactions of purse-seine fisheries with dolphins. The avoidance and release procedures documented in the CoP for the South Australian sardine fishery are simple and, if adopted in other purse-seine fisheries, could substantially reduce global mortality of dolphins.

Do the Brazilian sardine commercial landings respond to local ocean circulation?

It has been reported that sea surface temperature (SST) anomalies, flow intensity and mesoscale ocean processes, all affect sardine production, both in eastern and western boundary current systems. Here we tested the hypothesis whether extreme high and low commercial landings of the Brazilian sardine fisheries in the South Brazil Bight (SBB) are sensitive to different oceanic conditions. An ocean model (ROMS) and an individual based model (Ichthyop) were used to assess the relationship between oceanic conditions during the spawning season and commercial landings of the Brazilian sardine one year later. Model output was compared with remote sensing and analysis data showing good consistency. Simulations indicate that mortality of eggs and larvae by low temperature prior to maximum and minimum landings are significantly higher than mortality caused by offshore advection. However, when periods of maximum and minimum sardine landings are compared with respect to these causes of mortality no significant differences were detected. Results indicate that mortality caused by prevailing oceanic conditions at early life stages alone can not be invoked to explain the observed extreme commercial landings of the Brazilian sardine. Likely influencing factors include starvation and predation interacting with the strategy of spawning “at the right place and at the right time”.

Evaluating fishermen\u2019s conservation attitudes and local ecological knowledge of the European sardine (Sardina pilchardus), Peniche, Portugal

BackgroundEuropean sardines are an important fishing resource in the North Atlantic. Recognized for its great commercial and economic value in southern Europe, this resource currently has low stock indices. From this perspective, fishers’ local ecological knowledge (LEK) is appreciated as an auxiliary tool in the management of sardines in this region. Our goal is to evaluate the LEK and attitudes towards the conservation of Sardina pilchardus in the typical fishing village of Peniche, Portugal.MethodsFrom June to September 2016, we carried out 87 semi-structured interviews. The four main points of the interviews were interviewee profile, fishing structure, fishermen’s LEK and attitudes towards sardine conservation. The interviews were qualitatively and quantitatively analyzed using a 3-point Likert scale. An LEK index and an attitude index were generated. Comparison analyses and correlations were made between the indices and variables of the interviewee profile and the fishing structure.ResultsThe mean LEK index was 0.55 and was classified as moderate. The attitudes index in relation to conservation was 0.76 and was classified as positive. This index had a positive and significant correlation with the LEK index and a significant negative correlation with the fishermen’s age. When the LEK index was compared with the educational level, significant differences were observed only between class A and class C. The result showed that the differences in the attitudes index were statistically significant when the three educational classes were compared.ConclusionsThe fishermen of Peniche in Portugal present moderate informal knowledge about the biology and ecology of sardines. Attitudes towards conservation were predominantly positive. Fishermen with greater LEK, with a higher educational level and at a younger age presented more positive attitudes in relation to environmental conservation issues in the present case of the sardine population. The LEK is not necessarily related to the educational level of the fishermen. We suggest environmental education programs for the communities that depend on this resource. The use of LEK and fishermen’s perceptions can help in the management of the European sardine fishery in Portugal.

The Gulf of California Large Marine Ecosystem: Fisheries and other natural resources

The Gulf of California Large Marine Ecosystem (GoC-LME) is highly productive with a high diversity of marine species, including endemics and endangered, threatened or protected species thus, it is considered one of the ten marine biodiversity hotspots in the world. The significance of such areas typically conflicts with the exploitation of fish resources, making management highly complex. Such complexity is compounded by the insufficient knowledge of what naturally occurs in this environment, where the tendency is to use management models based on single species stock dynamics. This contribution highlights the importance of the GoC-LME, with special emphasis on the state of the fishing as reported by government agencies, and suggests how this diagnosis changes with climate and ecosystem dynamics considerations. A novel focus is also shown where harvesting rates for individual fish resources are estimated from holistic properties of ecosystems, providing an alternative perspective for fisheries management based on ecosystem reference points. We illustrate this using as example the sardine fishery. We also include a brief discussion of the cases of the vaquita (Phocoena sinus), totoaba (Totoaba macdonaldii), and the shrimp fishery of the northern Gulf of California.

Naturalness as a basis for incorporating marine biodiversity into life cycle assessment of seafood

Methods to quantify biodiversity impacts through life cycle assessment (LCA) are evolving for both land- and marine-based production systems, although typically independently from each other. An indicator for terrestrial food production systems that may be suitable to assess marine biodiversity, and is applicable across all food production systems, is a measure of hemeroby or distance from the natural state. We explore the possibility of adapting this approach to marine systems to assess the impact of fishing on seawater column and seafloor systems. The terrestrial hemeroby concept is adapted here for marine ecosystems. Two commercial fishery case studies are used to trial the effectiveness of hemeroby in measuring the influence exerted by fishing practices on marine biodiversity. Available inventory data are used to score areas to a hemeroby class, following a semi-quantitative scoring matrix and a seven-point scale, to determine how far the seafloor and seawater column are from their natural state. Assessment can progress to the impact assessment stage involving characterisation of the hemeroby score, to determine the Naturalness Degradation Potential (NDP) for use in calculating the Naturalness Degradation Indicator (NDI). The method builds on well-established processes for assessing fisheries within the ecosystem-based fisheries management framework and is designed to enhance assessment of fishing impacts within LCA. Australian fisheries case studies were used to demonstrate the application of this method. The naturalness of these fisheries was scored to a hemeroby level using the scoring matrix. The seafloor of the Northern Prawn Fishery and the seawater column of the South Australian Sardine Fishery were both classified as partially close to nature. Impact assessment was carried out following the process outlined for the NDI. The naturalness degradation results were highly sensitive to area calculation method and data. There was also variation in results when using annual or averaged data for catch. Results should therefore be interpreted in the context of these sensitivities. Adaptation of the hemeroby concept to marine habitats may present an opportunity for more informed comparison of impacts between terrestrial and marine systems. Incorporating a measure of naturalness into assessments of food production can be useful to better understand the cost, in terms of transforming ecosystems from natural to more artificial, of meeting growing food demand. Biodiversity is a broad concept not easily captured through one indicator, and this method can complement emerging biotic LCA indicators, to provide a suite of indicators capable of capturing the full impact of fishing on marine biodiversity.

FlowCAM optimization: Attaining good quality images for higher taxonomic classification resolution of natural phytoplankton samples

AbstractTaxonomic data on phytoplankton composition is important for ecological studies, however, such information is not easy to gather. Imaging devices and image classification software have been developed in the past decades for rapid phytoplankton assessment. Taxonomic resolution output of classification software are primarily limited by the quality of images produced by these imaging instruments. FlowCAM has been utilized in several studies for this endeavor. However, the phytoplankton categories that the instrument is currently able to discriminate are still few compared to the outputs of microscopy. This study aimed to produce high resolution FlowCAM images of fixed phytoplankton samples from natural environments without compromising sample analysis time. It was also aimed to optimize the capability of FlowCAM's VisualSpreadsheet software to automatically classify phytoplankton images. The use of FOV300 flow cell and 10X objective combination has proven to be effective in producing good quality images at a faster rate. The modified hardware configuration resulted to FlowCAM counts that were comparable to that of the standard microscopy method. FlowCAM was able to automatically classify images of dominant phytoplankton groups in the two key sardine fishery areas in the Philippines with relatively high accuracy values. These phytoplankton groups are represented by genera with complex morphological structures (e.g., setae) such as Chaetoceros and Bacteriastrum as well as those genera with simple shapes such as Pseudo‐nitzschia (thin‐elongate) and Coscinodiscus (spherical).

The Peruvian sardine, Sardinops sagax: Historical analysis of the fishery (1978–2005)

The historical development of Peru’s sardine (Sardinops sagax) fishery between 1978 and 2005 is described from fishery indicators (landings and effort) and environmental indicators (Pacific Decadal Oscillation [PDO] index, Southern Oscillation Index, and Sea Surface Temperature Anomaly) in order to observe the spatial and temporal variations of the fishery. During this period, the fishery indicators showed that excessive fishing pressure caused the drastic decline in abundance, as demonstrated by the low catch levels in recent years. Regarding the environmental indicators, a positive relationship with sardine landing anomalies was observed; however, the PDO index had a significant positive correlation (rPearson = 0.50; P = 0.0005; n = 45) in comparison with the other indices. The results of this study show that the effects of overfishing and adverse environmental conditions strongly impacted the Peruvian sardine population, with the consequent collapse of the fishery.

A stochastic model for the Iberoatlantic sardine fishery. Global warming and economic effects

The literature of natural resources has made wide use of deterministic dynamic models to optimally manage marine fishery resources. However, the ever-changing weather condition and, most importantly, the warming of ocean waters have a significant impact on the evolution of fishery resources. In fact, the latter of the two is a significant random component closely linked to climate change. This paper uses sea surface temperature (from here on SST) to explain the dynamics of the ecosystem biomass in stochastic growth. Observations of SST, biomass, catch and effort in the area of the Atlantic waters bathing the Iberian Peninsula are used to implement the stochastic dynamic optimization theory in a model of production to obtain optimal results for all of these variables in the short and medium term.

Forecasts of swordfish (Xiphias gladius) and common sardine (Strangomera bentincki) off Chile under the A2 IPCC climate change scenario

Recent studies have demonstrated the effects of climate change on both oceanographic conditions and the relative abundance and distribution of fisheries resources. In this study, we investigated the impacts of climate change on swordfish (Xiphias gladius) and common sardine (Strangomera bentincki) fisheries using predictions of changes from global models (according to the NCAR model and IPCC emissions scenario A2), bioclimate envelope models and satellite-based sea surface temperature (SST) estimates from high-resolution regional models for the simulation period 2015–2065. Predictions of SST from global climate models were regionalised using the Delta statistical downscaling technique. The results show an SST trend of 0.0196°C per year in the study area, equivalent to 0.98°C for the simulation horizon and for a high CO2 emission scenario (A2). The bioclimate envelope models were developed using historical (2001–2011) monthly environmental and fisheries data. These data included the local relative abundance index of fish catch per unit effort (CPUE), corresponding to the total catch (kg) by 1000 hooks in a 1° latitude×1° longitude fishing grid for swordfish and to the total catch (ton) by hold capacity (100m3) in a 10′ latitude×10′ longitude grid for common sardine. The environmental data included temporal (month), spatial (latitude) and thermal conditions (SST). In the first step of the bioclimate modelling performed in this study, generalised additive models (GAMs) were used as an exploratory tool to identify the functional relationships between the environmental variables and CPUE. These relationships were then parameterised using general linear models (GLMs) to provide a robust forecasting tool. With this modelling approach, environmental variables explained 58.7% of the variation in the CPUE of swordfish and 60.6% of the variation in the CPUE of common sardine in the final GLMs.Using IDRISI GIS, these GLMs simulated monthly changes in the relative abundance and distribution of the studied species forced by changes in the regionalised SST projected by the NCAR model under the A2 emission scenario. The simulations predicted a slight decline of 6% (17kg/1000 hooks) and 7% (3.8ton/100m3) for swordfish and common sardine, respectively, in the spatial mean of the potential relative abundance (CPUE) by 2065.

Quantifying the projected impact of the South African sardine fishery on the Robben Island penguin colony

Abstract Quantitative methods are needed to evaluate the ecological effects of fishing forage species upon which predators depend. African penguin Spheniscus demersus numbers at the Robben Island colony rose during the 1990s co-incidental with a marked increase in sardine Sardinops sagax and anchovy Engraulis encrasicolus abundances, but decreased appreciably during the 2000s as sardine suffered a series of poor recruitments. A population dynamics model is developed which relates penguin adult annual mortality to local sardine biomass, and is fit to penguin moult counts and re-sightings of tagged penguins. The predator–prey interaction is best explained by a sardine–penguin mortality relationship with average penguin survival decreasing only when the local sardine biomass is less than approximately one-quarter of the maximum observed. Results suggest that the rapid growth of the colony during the 1990s was driven primarily by immigration. Penguin projections are generated by linking to future sardine abundances predicted under the operational management procedure used to set catch limits for these sardine and anchovy fisheries, and compared with equivalent scenarios without fishing. Results indicate that fishing is likely to have a relatively small impact on penguins, especially when compared with uncertainties that arise from the variable spatial distribution of the sardine population.