Fluctuations In Catch Research Articles

Nearshore fish community changes along the Toronto waterfront in accordance with management and restoration goals: Insights from two decades of monitoring.

Aquatic habitat in the Greater Toronto Area has been subject to anthropogenic stressors. The subsequent aquatic habitat degradation that followed led to the Toronto and Region waterfront being listed as an Area of Concern in 1987. Thus, extensive shoreline and riparian habitat restoration have been implemented as part of the Toronto and Region Remedial Action Plan in conjunction with local stakeholders, ministries, and NGOs in an overall effort to increase fish, bird, and wildlife habitat. A key aspect of current fish habitat restoration efforts, monitored by Toronto and Region Conservation Authority, is to account for long-term community changes within the target ecosystem to better understand overall changes at a larger spatial scale. Here we use electrofishing data from the past 20 years with over 100,000 records and across 72km of coastline to show how declines and fluctuations in fish biomass and catch along the waterfront are driven by a few individual species across three main ecotypes, such as coastal wetlands, embayments, and open coast sites, with the remaining species showing a high level of stability. Using community traits and composition for resident species we demonstrate native warmwater species have become more dominant along the waterfront in recent years, suggesting that restoration efforts are functioning as intended. Additionally, piscivore and specialist species have increased in their relative biomass contribution, approaching existing restoration targets. Altogether this waterfront-wide evaluation allows us to detect overall changes along the waterfront and can be beneficial to understand community changes at an ecosystem level when implementing and monitoring restoration projects.

An investigation on the distribution dynamics of kiddi prawn, Parapenaeopsis stylifera (H. Milne Edwards, 1837) along southwest coast of India, using multi-dimensional approach

Along India's southwest coast, the kiddi prawn (Parapenaeopsis stylifera) supports a substantial fishery, known as "karikady fishery" due to its high demand in domestic and international markets. Following implementing "mechanised fishing prohibition," catch fluctuations observed in P. stylifera catches sparked widespread social unrest among stakeholders, who feared that unharvested prawns would be lost to the fishery when these prawns moved away from the coast during the monsoon season. The study derived scientific evidence for to distributional idiosyncrasy of the species with spatial distribution tracking, understanding the correlation of species movement and maturity with environmental parameters, and tracking the individual cohorts through population parameter analysis. Data for the study were collected from commercial vessels, experimental surveys, and analyses was supported by GIS software and SPSS foftware. 18 cruises in the RV Silver Pompano and 3 cruises in RV Matsyakumari at five depths (10, 30, 50, 70, 90 m) were conducted during 2016–2019 off Kerala, southwest coast of India and, and a spatial analysis of the experimental trawling data contributed to evaluating the impact of the environment on the distribution of the species. The study revealed that increased salinity has a statistically significant impact on the expansion of the species, as indicated by geographical data. P. stylifera prefers to settle in areas with high salinity and low temperatures, according to geographical studies. This study not only established that the perception that species migrate away from the coast is rational, but it also established that there is no resource loss as a result of the 'Monsoon trawl ban,' because current fishing methods are capable of catching the larger prawns that have migrated to deeper waters. The study reaffirmed the usefulness of "monsoon trawl ban" in ensuring the long-term viability of the "karikadi" fishery along the southwest coast by assisting in species recruitment during the monsoon season.

Структурні показники та динаміка промислових уловів риб дніпровських водосховищ

Purpose: to establish and analyze the dynamics of the species composition and amounts of commercial fish catches over the past 10 years in the context of assessing the overall efficiency of the fishery exploitation of Dnieper reservoirs. Methodology. As primary materials, data from official commercial fishery statistics and the results of field monitoring studies carried out by the Institute of Fisheries of the National Academy of Sciences on Dnieper reservoirs in the period of 2012‒2022 were used. The intensity of commercial fish harvest was assessed by the annual fishing mortality rate, which was defined as the difference between the total and natural mortality. The total mortality rate was determined graphically by the natural logarithms of the number of age groups in catches; natural mortality — based on the parameters of the von Bertalanffy equation. Statistical data processing was carried out in MS Excel. Findings. The dynamics of commercial catches in the cascade of Dnieper reservoirs in the last 10 years has been characterized by instability with a minimum of 8.9 thousand tons in 2013 and a maximum of 14.0 thousand tons in 2019. The majority of commercial catches was Prussian carp (28.2% of the total catch), common bream (21.1%), roach (20.5%) and silver bream (8.3%). The catch dynamics of all limited species had the same features — a growth in the period 2014‒2016, stabilization until 2019 and a further decrease, which was due to the determining influence of organizational factors. The distribution of fishing pressure by the objects of fishing does not fully correspond to the quantitative parameters of their ichthyomass; the average (2019‒2021) coefficients of annual fishing mortality were: pikeperch — 32.0%, common bream — 22.8%, roach — 24.2%, silver bream — 22.7%, Prussian carp — 19.0%. The maximum catches per unit effort of the gill net in the studied period were recorded for the Kamianske reservoir (348.9±73.4 kg), the lowest (152.0±44.5 kg) — for the Kaniv reservoir. The average fish catch per one gill net per cascade was 245.1±36.3 kg; a trend towards its growth during 2012‒2021 was observed. Originality. Original data on the modern dynamics of the amount and structure of commercial fish catches as a component of scientific support for fisheries exploitation of the Dnieper reservoirs were obtained. Practical value. It has been found that the fluctuations of fish catches in Dnieper reservoirs are largely determined by the influence of external (organizational) factors, which makes it possible to effectively manage the use of fish stocks. It is shown that for some species (in particular, pikeperch), the intensity of fishery exploitation exceeds the optimum, for others (Prussian carp, Black Sea sprat), on the contrary, an increase in the fishing pressure is possible.

Effects of marine climate variability on the relative abundance of Lutjanus purpureus (POEY, 1866) on the Amazon Continental Shelf

AbstractThe aim of this study was to analyze the effects of climate and marine variability on the catches of Lutjanus purpureus in three sectors of the Amazon Continental Shelf. Remote sensing data were compared with landings (CPUE) between 1997 and 2007 and analyzed for partial influence obtained through the Generalized Additive Model. Additionally, significant variables were analyzed through Wavelet Cross‐Spectrum, and periods of high correlation between variables in space and time were identified. The results indicated a high coherence between catch per unit effort (CPUE) and environmental variables on an interannual scale, suggesting that Red Snapper fishing is mainly influenced by the seasonal effects of oceanographic variables. These results suggest that fluctuations in Red Snapper catches between 1997 and 2007 may be the result of natural processes that occur in the Amazon Continental Shelf every year in synergy with environmental variables, which are also indirectly affected by the El Niño–Southern Oscillation (ENSO) pattern.

Artisanal fisheries catch highlights hotspot for threatened sharks and rays in the Republic of the Congo

AbstractGlobal catch rates of sharks and rays from artisanal fisheries are underreported, leading to a lack of data on population status. This forms a major barrier to developing effective management plans, such is the case in Central and West Africa. Over 3 years, we undertook the first systematic quantitative assessment of sharks and rays landed by an artisanal fishery in the Republic of the Congo. During 507 sampling days (mean 14 surveys per month), we recorded 73,268 individuals. These comprised 42 species, of which 81% are considered at an elevated risk of extinction. Landings were dominated by immature individuals, especially for species of conservation concern. Presence of species thought to have largely disappeared from the region such as the African wedgefish (Rhynchobatus luebberti) and smoothback angelshark (Squatina oculata) suggest Congolese waters are a potential stronghold for these species—warranting increased protection. We identified seasonality of catch within years, but not across years. Both inter‐ and intra‐annual trends varied by species, signifying annual fluctuations in catch of each species but consistent catch of all species year‐on‐year. Analysis showed increased catch between the short‐wet and the long‐wet, and the long‐dry seasons (January–February and August–September). Lowest catch was shown to occur during the short‐wet and the short‐dry seasons (October–December), which may provide an opportunity for seasonal closures or gear restrictions.

Shelf break exchange processes influence the availability of the northern shortfin squid, Illex illecebrosus, in the Northwest Atlantic

AbstractThe United States Northern Shortfin squid fishery is known for its large fluctuations in catch at annual scales. In the last 5 years, this fishery has experienced increased availability of Illex illecebrosus along the Northeast US continental shelf (NES), resulting in high catch per unit effort (CPUE) and early fishery closures due to quota exceedance. The fishery occurs within the Northwest Atlantic, whose complex dynamics are set up by the interplay between the large‐scale Gulf Stream, mesoscale eddies, Shelfbreak Jet, and shelf‐slope exchange processes. Our ability to understand and quantify this regional variability is requisite for understanding the availability patterns of Illex, which are largely influenced by oceanographic conditions. In an effort to advance our current understanding of the seasonal and interannual variability in this species' relative abundance on the NES, we used generalized additive models to examine the relationships between the physical environment and hotspots of productivity to changes in CPUE of I. illecebrosus in the Southern stock component, which comprises the US fishery. Specifically, we derived oceanographic indicators by pairing high‐resolution remote sensing data and global ocean reanalysis physical data to high‐resolution fishery catch data. We identified a suite of environmental covariates that were strongly related to instances of higher catch rates. In particular, bottom temperature, warm core rings, subsurface features, and frontal dynamics together serve as indicators of habitat condition and primary productivity hotspots, providing great utility for understanding the distribution of Illex with the potential for forecasting seasonal and interannual availability.

The Catch of Pelagic Fish in Purse Seine Fisheries is Related to Oceanographic Parameters in the Water of the Makassar Strait Tolitoli Regency

This research aims to analyze oceanographic parameters and the number of pelagic fish caught in purse seine fisheries in the Makassar Strait, Toli-Toli Regency. The research was carried out using purposive sampling with purse seine catch data collected at 30 FADs (as research sites). Oceanographic data includes sea surface temperature, currents, pH, dissolved oxygen, and waves collected in situ. Meanwhile, nitrate and phosphate samples were analyzed at the Agricultural Science Study Program Laboratory, Tadulako University. Results of analysis of the composition of pelagic fish species caught in purse seine catches in February 2021 (4 types of fish are classified as economically important fish and the other three types are by-catch). In order of highest catches, they were kites (18,632 kg; 24 FADs), skipjack (15,203 kg; 27 FADs), tuna (4,290 kg; 12 FADs), mackerel tuna (3,060 kg; 4 FADs), tuna (4,500 kg; 1 FAD). ), katombo (253 kg; 2 FADs), and rattan (734 kg; 1 FAD). Close relationship and influence Parameters that have the strongest relationship and influence on fluctuations in pelagic fish catches in purse seine fisheries in the Makassar Strait are salinity, dissolved oxygen and nitrate.

Trophic Ecology Drives Annual Variation in Abundance of Aphidophagous (Coccinellidae, Coleoptera and Chrysopidae, Neuroptera) and Phytophagous (Noctuidae, Lepidoptera) Insects: Evidence From Light Traps

Abstract Using seventeen-year records of daily light trap catches of predatory Neuroptera (Chrysopidae, 13 species) and Coleoptera (Coccinellidae, 10 species), and of phytophagous Lepidoptera (Noctuidae, 79 species) we tested a hypothesis predicting that the range of annual fluctuations of catch size is greater in aphidophages, whose diet occurs irregularly and locally, than in phytophages, whose diet is available regularly and abundantly. The ranges of fluctuations of annual catches measured as the coefficient of variance (standard deviation expressed as a percentage of the average) of detrended annual catches were significantly greater in Chrysopidae (84 ± 7.1%) and Coccinellidae (121 ± 14.0%) than in Noctuidae (66 ± 2.6%). The difference between aphidophages and phytophages remained when we tested differences between the former and the samples of Noctuidae consisting only of those species whose characteristics (abundance, length and timing of flight period, number of generations per season, overwintering stage) were the same as in aphidophages. Similarly, no differences were found between sets of Noctuidae species that have characteristics (abundance, voltinism, period of flight activity) similar to aphidophages and sets of Noctuidae species that have contrary characteristics. Flight abilities of aphidophages are smaller than those of Noctuidae. As a result of this difference a light trap collects populations of aphidophages from a smaller area than populations of Noctuidae. Thus the extent of fluctuations of catch size of aphidophagous and phytophagous species is influenced both by annual differences in food availability and by differences in size of the area from which the individuals assembling to the light source are recruited.

Long-term drivers of catch variability in south-eastern Australia’s largest portunid fishery

Portunid crab fisheries are socially and economically valuable yet are characterised by high inter-annual variability. Competing hypotheses about factors contributing to this variability concern the environment, climate, and fisher behaviour. Here, we investigate variability in commercial catch, through a case study of the most heavily exploited estuary in southeastern Australia (Wallis Lake). Four main hypotheses were identified based on the broader portunid published literature: 1) Freshwater flow may cause poor recruitment due to increased offshore spawning and unfavourable dispersal of larvae, 2) Winter and spring harvesting may impact the following summer harvest by removing the spawning stock biomass (recruit overfishing); 3) Environmental factors including sea surface temperature and onshore winds may influence supply-side processes and recruitment success, contributing to catch fluctuations; and 4) Climatic indices such as the Inter Pacific Oscillation and Pacific Decadal Oscillation (PDO) may correlate with longer-term fluctuations in the fishery. We find evidence in support of hypotheses 2 and 4, with winter harvest negatively impacting the following January - April harvest and the PDO being positively correlated with January - April catch rates. Harvesting in June – November disproportionally impacts large females, and it may be possible to incorporate controls on winter fishing effort through co-management arrangements to achieve the best economic, environmental and social outcomes from the fishery. Such controls may lead to improved summer catch rates by protecting unspawned eggs during the winter months. The hypotheses explored here may provide insight in the variability observed in portunid fisheries around the world.

Long term oscillations of Mediterranean sardine and anchovy explained by the combined effect of multiple regional and global climatic indices

It is widely known that the abundance and distribution dynamics of populations of small pelagic clupeid fish, such as sardines and anchovies, are affected by large-scale climate variability, which may lead to changeovers to new regimes of small pelagics. However, long-distance climatic oscillations, such as El Niño/La Niña and the Pacific Decadal Oscillation, have been little explored in the Western Mediterranean Sea. We investigated the possible effects of the South Oscillation Index (i.e. the atmospheric oscillation coupled with the El Niño/La Niña) and Pacific Decadal Oscillation on fluctuations in catches of European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Western Mediterranean Sea, and their association with regional climate oscillations (i.e. the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, the Western Mediterranean Oscillation index, and the Arctic Oscillation). The study covered two periods: (a) landings between 1950 and 2016; and (b) abundance, biomass, and physical condition (i.e., relative condition index) between 2004 and 2016. The main large-scale climatic oscillations in the region were studied using General Additive Models to investigate the relationship between a time series of species measures of European sardine and anchovy from Geographical Subarea 06. Results show that the long-term Pacific Decadal Oscillation favours sardine landings, whereas the combined effect of the Western Mediterranean Oscillation Index and the Atlantic Multidecadal Oscillation favours anchovy. We discuss potential links between the present findings and changes in the plankton community caused by prevailing winds in the region driven by long-distance climate oscillations and their impact on the reduction in small pelagic fish populations in the study area.

Fish Catch Results Related to Temperature and Chlorophil in Western Waters of Sumatera

The western waters of Sumatera are one of the waters that have the potential of coastal and ocean resources. Oceanographic factors that can be related to high productivity in waters are SST (Sea Surface Temperature) and the distribution of chlorophyll concentration. Sibolga waters are geographically quite strategic, because they are located in the Indian Ocean, most of the catch is landed at the Sibolga Nusantara Fisheries Port. This Study aims to understand the trend of fluctuations in fish catches in the The Waters of Western Sumatera, to examine the effect of chlorophyll on fish catches in the waters of West Sumatera. Sea surface temperature and monthly chlorophyll-a concentrations were obtained from the result of the Aqua Modis months in 2021. Monthly data and data on fishing results were obtained from the Sibolga Nusantara Fisheries Port. The composition of catches in the western waters of Sumatera which landed at PPN Sibolga in 2021there three dominant fish species, namely Cakalang (Katsuwonis Pelamis) 11.655.768 Kg, Layang (Decapterus Sp) 4.589.147 (19,95%), Tembang (Sardinella sp) 2.421.523 (10,53%), the variation of fish catch per unit (CPUE) ;anded at PPN 2021. The Highest occurred in may at 3.809 kg/trip and the lowest occurred in November 1.521,58 kg/trip and the average monthly CPUE in 2021 was 5.105,88kg/trip. Monthly variations of sea surface temperature and chlorophyll-a in the waters of for 12 months (2021) the lowest temperature occurred in August, namely 26,88 0C while the highest temperature in February was 30,92 0C, the highest consentration was in May of 1,56 mg/m3 while the lowest occurred in March at 0,15 mg/m3.

Bali Strait‘s Potential Fishing Zone of Sardinella lemuru

Catch fluctuation of Sardinella lemuru in the Bali Strait in the period 2007 - 2019 shows a significant decrease. The fishermen of this area demanded information on the Potential Fishing Zone (PFZ) specifically targeted for Sardinella lemuru beyond their traditional. PFZ will be very helpful, especially during the famine years. Identification of a Potential Fishing Zone (PFZ) is highly important for increased fishing yields and also reduced fishing time for fishermen. Bali strait is dominated by Sardinella lemuru and contributes 16,2% of the total small pelagic fishery production in Fisheries Management Area (FMA) 573. Bali Strait also supports the fishing industry in Muncar (Banyuwangi-East Java) and Pengambengan (Jembrana-Bali). This study will produce a special PFZ for Sardinella lemuru that is not yet available in Indonesia by using remotely sensed and observer data. Here, we apply the Empirical Cumulative Distribution Function (ECDF) algorithm approach for Sardinella lemuru detection. ECDF was developed using Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) data from Aqua MODIS and extracted according to observer data during 2011-2014. PFZ for Sardinella lemuru in Bali strait was affected by 72,8 % Chl-a conditions and 27,2% by SST conditions. The maximum suitable preference for Sardinella lemuru in Bali Strait is Chl-a condition at 0,2 mg/m3 and SST condition at 28,38°C in northwest monsoon, while in southeast monsoon are 0,97 mg/m3 for Chl-a and 25,61°C for SST. ECDF model result has 69,33% accuracy, which shows the result of Sardinella lemuru PFZ has good accuracy.

Automated detection of coastal upwelling in the Western Indian Ocean: Towards an operational “Upwelling Watch” system

Coastal upwelling is an oceanographic process that brings cold, nutrient-rich waters to the ocean surface from depth. These nutrient-rich waters help drive primary productivity which forms the foundation of ecological systems and the fisheries dependent on them. Although coastal upwelling systems of the Western Indian Ocean (WIO) are seasonal (i.e., only present for part of the year) with large variability driving strong fluctuations in fish catch, they sustain food security and livelihoods for millions of people via small-scale (subsistence and artisanal) fisheries. Due to the socio-economic importance of these systems, an "Upwelling Watch" analysis is proposed, for producing updates/alerts on upwelling presence and extremes. We propose a methodology for the detection of coastal upwelling using remotely-sensed daily chlorophyll-a and Sea Surface Temperature (SST) data. An unsupervised machine learning approach, K-means clustering, is used to detect upwelling areas off the Somali coast (WIO), where the Somali upwelling – regarded as the largest in the WIO and the fifth most important upwelling system globally – takes place. This automatic detection approach successfully delineates the upwelling core and surrounds, as well as non-upwelling ocean regions. The technique is shown to be robust with accurate classification of out-of-sample data (i.e., data not used for training the detection model). Once upwelling regions have been identified, the classification of extreme upwelling events was performed using confidence intervals derived from the full remote sensing record. This work has shown promise within the Somali upwelling system with aims to expand it to the rest of the WIO upwellings. This upwelling detection and classification method can aid fisheries management and also provide broader scientific insights into the functioning of these important oceanographic features.

POLA MUSIM PENANGKAPAN Sardinella fimbriata YANG DIDARATKAN DI PPN PRIGI – JAWA TIMUR

Fringe-scale sardine (Sardinella fimbriata) is one of the dominant species landed in Prigi fishing port. However, in recent years the sardine fishery management might deal with some overfishing indicators of this species . The purpose of this study was to determine the trend of catches, fluctuations in catch per unit effort (CPUE), and the pattern of the fringe-scale fishing season using catch-effort data of purse seine and gillnet landed at PPN Prigi in the period 2011-2020. The results showed that the catch fluctuated every year . CPUE has tended to increase over the last ten years but decreased in 2014 and 2020. The highest CPUE value occurred in 2019 which was 0,21kg/trip. The Peak fishing season occurs in December – March.
 
 
 

Shaping sustainable harvest boundaries for marine populations despite estimation bias

AbstractBiased estimates of population status are a pervasive conservation problem. This problem has plagued assessments of commercial exploitation of marine species and can threaten the sustainability of both populations and fisheries. We develop a computer‐intensive approach to minimize adverse effects of persistent estimation bias in assessments by optimizing operational harvest measures (harvest control rules) with closed‐loop simulation of resource‐management feedback systems: management strategy evaluation. Using saithe (Pollachius virens), a bottom water, apex predator in the North Sea, as a real‐world case study, we illustrate the approach by first diagnosing robustness of the existing harvest control rule and then optimizing it through propagation of biases (overestimated stock abundance and underestimated fishing pressure) along with select process and observation uncertainties. Analyses showed that severe biases lead to overly optimistic catch limits and then progressively magnify the amplitude of catch fluctuation, thereby posing unacceptably high overharvest risks. Consistent performance of management strategies to conserve the resource can be achieved by developing more robust control rules. These rules explicitly account for estimation bias through a computational grid search for a set of control parameters (threshold abundance that triggers management action, Btrigger, and target exploitation rate, Ftarget) that maximize yield while keeping stock abundance above a precautionary level. When the biases become too severe, optimized control parameters—for saithe, raising Btrigger and lowering Ftarget—would safeguard against a overharvest risk (<3.5% probability of stock depletion) and provide short‐term stability in catch limit (<20% year‐to‐year variation), thereby minimizing disruption to fishing communities. The precautionary approach to fine‐tuning adaptive risk management through management strategy evaluation offers a powerful tool to better shape sustainable harvest boundaries for exploited resource populations when estimation bias persists. By explicitly accounting for emergent sources of uncertainty, our proposed approach ensures effective conservation and sustainable exploitation of living marine resources even under profound uncertainty.

Unravelling links between squid catch variations and biophysical mechanisms in South African waters

Using satellite observations, this study uncovers the biophysical drivers of the lucrative chokka squid fishery in South Africa over the last two decades (1998–2017) and addresses their potential links with low squid catches. Chokka squid fishing is crucial to the economic wellbeing of local communities. However, the squid biomass is prone to considerable fluctuations, including abrupt declines with negative socio-economic impacts. We show that the squid catch is significantly and positively correlated with satellite-derived chlorophyll-a (Chl-a, an index of phytoplankton biomass) from year to year in South African coastal waters. Two main phytoplankton blooms are observed to occur seasonally in the austral spring and autumn, peaking in October and April, respectively. From October to April, phytoplankton abundance is influenced by the occurrence of wind-driven upwelling over the South African west coast (southern Benguela) and the central Agulhas Bank (so-called Cold Ridge upwelling), while the surface currents appear more important for shelf edge processes and advection along the Cold Ridge on shorter timescales. Low squid catches are observed in 2001 and 2013 and linked to declines in Chl-a induced by weak winds and relaxed negative wind stress curl over the southwest coast in 2001, and over the southwest coast and the central Agulhas Bank in 2013. Phytoplankton phenology (bloom timing) analysis reveals absent, or shorter and delayed blooms, over the Benguela upwelling region in 2001 and both the Benguela and Cold Ridge upwelling areas in 2013. In contrast, the high catch years of 2004 and 2009, associated with elevated Chl-a, coincide with early and/or prolonged seasonal blooms. These are induced by strong winds over the Benguela upwelling and Cold Ridge areas in 2004, and by intensified negative wind stress curl over the Benguela upwelling area in 2009. These results show that the squid catch fluctuations are potentially predictable and could support policymakers seeking to improve their planning of adaptation strategies and risk mitigation.

The Relationship between Environmental Factors and Catch Abundance of Hairtail in the East China Sea Using Empirical Dynamic Modeling

The East China Sea population of hairtail (Trichiurus lepturus, also known as T. japonicus) is a commercially important element of Chinese fisheries. Hairtail has long been widely exploited. Due to overfishing, however, its production declined over the years. One of solutions to this dilemma is to institute reasonable fishery policies. Generally, skillful short-term and long-term prediction of fish catch is a central tool for guiding the development of fishery policy. Accurate predictions require a comprehensive understanding of the relationship between fluctuations in fish catch and variability in both fishing effort and marine environmental conditions. To investigate the combined impact of fishing effort and marine environments on hairtail catch and to develop models to predict hairtail catch, we applied empirical dynamic modeling (EDM) to data on East China Sea fisheries, including hairtail catch, fishing effort, and marine environmental factors. EDM is an equation-free approach that enables the investigation of various complex systems. We constructed all possible multivariate EDM models to investigate the potential mechanisms affecting hairtail catch. Our analysis demonstrates that all key environmental factors (salinity, summer monsoon, sea surface temperature, precipitation, and power dissipation index of tropical cyclones) have an impact on nutrient supply, which we suggest is the central factor influencing hairtail catch. Finally, our comparison of EDM models with parametric models demonstrates that EDM models overwhelmingly outperform parametric models in analysis of these complex interactions.

Techno-Economic Analysis of Solar Photovoltaic System for Fishery Cold Storage Based on Ownership Models and Regulatory Boundaries in Indonesia

With Indonesia’s marine resources abundance, it is appropriate for Indonesia’s economic growth to gear towards the fisheries sector. Fishery management in Indonesia is still not operating optimally due to a lack of fisheries management infrastructure. This study took place at the Fish Auction Place in Dadap Village, West Java, Indonesia. The actual problem is a fluctuation in fish catch due to seasonal factors that cause instability in fish prices and fishermen’s incomes. Furthermore, there is no cold storage for storing fish when the fish are abundant so that the quality of the fish will decrease. However, fishery cold storage is energy-intensive equipment, and there is a lack of electricity infrastructure in that coastal area. Renewable Energy Sources (RES) are the key for rural electricity because RES prices are lower, especially on-grid solar photovoltaic (PV), than fossil fuel-based. Consequently, the application of solar PV in Indonesia is still not optimal due to limited regulations. Regulations that hinder the economic value of On-grid PV system are the excess energy compensation percentage and the inverter capacity limitation. Therefore, in this study, we have modelled six regulatory scenarios related to On-grid PV system. The scenarios are how the current 65% excess energy compensation is changed to 85% and 100% (1:1 ratio) and remove the regulation regarding inverter capacity limitation. Furthermore, the ownership model of cold storage is also considered by dividing it into two models, which are commercial-based and community-based. These ownership models have different financial instruments. The simulation gives a new result by changing regulation assumptions that On-grid PV system has a lower Levelized Cost of Electricity (LCOE) than existing regulation because it can produce threefold more electricity to the utility grid with higher inverter capacity. Furthermore, the community-based cold storage rental price can be 16 % cheaper on average with all energy system topologies than the commercial-based ownership model. Then, by reducing the capital costs of solar modules and batteries in 2030, solar PV system’s LCOE will be lower by an average of 20%. It will result in an average reduction of 10% on cold storage rental prices. Finally, sensitivity analysis of the energy system is also conducted in this study. The result is that On-grid PV system is the most secure energy source against price fluctuations.

Ancient DNA SNP-panel data suggests stability in bluefin tuna genetic diversity despite centuries of fluctuating catches in the eastern Atlantic and Mediterranean

Atlantic bluefin tuna (Thunnus thynnus; BFT) abundance was depleted in the late 20th and early 21st century due to overfishing. Historical catch records further indicate that the abundance of BFT in the Mediterranean has been fluctuating since at least the 16th century. Here we build upon previous work on ancient DNA of BFT in the Mediterranean by comparing contemporary (2009–2012) specimens with archival (1911–1926) and archaeological (2nd century BCE–15th century CE) specimens that represent population states prior to these two major periods of exploitation, respectively. We successfully genotyped and analysed 259 contemporary and 123 historical (91 archival and 32 archaeological) specimens at 92 SNP loci that were selected for their ability to differentiate contemporary populations or their association with core biological functions. We found no evidence of genetic bottlenecks, inbreeding or population restructuring between temporal sample groups that might explain what has driven catch fluctuations since the 16th century. We also detected a putative adaptive response, involving the cytoskeletal protein synemin which may be related to muscle stress. However, these results require further investigation with more extensive genome-wide data to rule out demographic changes due to overfishing, and other natural and anthropogenic factors, in addition to elucidating the adaptive drivers related to these.

Optimization of Solar PV System for Fishery Cold Storage based on Ownership Model and Regulation Barrier in Indonesia

Fluctuation in fish catch due to seasonal factors causes instability in fish prices, decreasing the quality of fish and fishermen’s incomes because there is no cold storage in some area for storing fish. Applying ownership of cold storage is divided into two models, namely commercial-based and community-based with different financial instruments. Fishery cold storage is an energy-intensive industry and Indonesia is a tropical country with abundant potential for solar irradiation. However, due to limited regulations, the application of solar photovoltaic (PV) in Indonesia is still not optimal. The simulation gives a new result by changing regulation assumptions: the solar photovoltaic on-grid system has a lower Levelized Cost of Electricity (LCOE) because it can produce eightfold more electricity to the grid with higher inverter capacity than before. Furthermore, the rental price of community-based cold storage can be 10 % cheaper on average with all energy system topologies than the rental price for cold storage based on commercial ownership model.