Proportion Of Catch Research Articles

Weakly supervised classification of acoustic echo-traces in a multispecific pelagic environment

Abstract In trawl-acoustic methods, machine learning can objectively assign species composition to echo-traces, providing a reproducible approach for improving biomass assessments and the study of schooling behaviour. However, the automatic classification of schools in multispecies environments is challenging due to the difficulty of obtaining ground truth information for training. We propose a weakly supervised approach to classify schools into seven classes using catch proportions as probabilities. A balancing strategy was used to address high dominance of some species while preserving species mixtures. As the composition of schools from multispecific catches was unknown, model performance was evaluated at the school and haul level. Accuracy was 63.5% for schools from single-species catches or those identified by experts, and a 20.1% error was observed when comparing predicted and actual species proportions at the haul level. Positional and energetic descriptors were highly relevant, while morphological characteristics showed low discriminative power. The highest accuracies were obtained for juvenile anchovy and Muller’s pearslide, while sardine was the most challenging to classify. Our multioutput approach allowed the introduction of a metric to assess the confidence of the model in classifying each school. As a result, we introduced a method to classify echo-traces considering prediction reliability.

Temporal allele frequency changes in large-effect loci reveal potential fishing impacts on salmon life-history diversity.

Fishing has the potential to influence the life-history traits of exploited populations. However, our understanding of how fisheries can induce evolutionary genetic changes remains incomplete. The discovery of large-effect loci linked with ecologically important life-history traits, such as age at maturity in Atlantic salmon (Salmo salar), provides an opportunity to study the impacts of temporally varying fishing pressures on these traits. A 93-year archive of fish scales from wild Atlantic salmon catches from the northern Baltic Sea region allowed us to monitor variation in adaptive genetic diversity linked with age at maturity of wild Atlantic salmon populations. The dataset consisted of samples from both commercial and recreational fisheries that target salmon on their spawning migration. Using a genotyping-by-sequencing approach (GT-seq), we discovered strong within-season allele frequency changes at the vgll3 locus linked with Atlantic salmon age at maturity: fishing in the early season preferentially targeted the vgll3 variant linked with older maturation. We also found within-season temporal variation in catch proportions of different wild Atlantic salmon subpopulations. Therefore, selective pressures of harvesting may vary depending on the seasonal timing of fishing, which has the potential to cause evolutionary changes in key life-history traits and their diversity. This knowledge can be used to guide fisheries management to reduce the effects of fishing practices on salmon life-history diversity. Thus, this study provides a tangible example of using genomic approaches to infer, monitor and help mitigate human impacts on adaptively important genetic variation in nature.

Habitat Suitability of the Squid Sthenoteuthis oualaniensis in Northern Indian Ocean Based on Different Weights

Data from the fishery of S. oualaniensis in the northern Indian Ocean from January to March and October to December 2017 to 2019 were modeled with sea surface temperature (SST), wind speed (WS), and photosynthetically active radiation (PAR). In this study, the fishing effort was used to evaluate the suitability index (SI) at SST, WS, and PAR. An integrated habitat suitability model (HSI) was developed with different weighting scenarios and weighting schemes. The optimal case was selected by calculation and comparison with the proportion of catch, effort, and catch per unit effort (CPUE) in the HSI interval (0~0.2, 0.2~0.6, 0.6~1); validation was performed using data from 2019. The weight of the optimal HSI model was 0.25 for sea surface temperature and photosynthetically active radiation, and 0.5 for wind speed. This model yielded the best performance and could accurately predict the fishing ground of S. oualaniensis in the northern Indian Ocean. The findings suggest that the integrated HSI model can predict the distribution of S. oualaniensis commendably, with wind speed as the most important factor affecting the spatial distribution of S. oualaniensis’ habitat in the northern Indian Ocean. By analyzing habitat selection by S. oualaniensis, this study verified and predicted the distribution of squid in the northern Indian Ocean, which allows the distribution of squid resources and fishing grounds to be modeled, and for the sustainable use of squid fishery resources.

Engine size and proportion of catch kept affects fish catch in Pujada Bay, Davao Oriental

This study aimed to calculate the catch per unit effort (CPUE) and determine the status of the finfish population in Pujada Bay. This was conducted through semi-structured interviews, focus group discussion, and validation of actual catch sampling/logbook information taken from the interviews. Fishers mostly catch bigeye scad (Selar crumenopthalmus), flat needlefish (Ablennes hians), horseface unicornfish (Naso fageni), purple eyebrowed tuskfish (Choerodon zamboangae), silver pomfret (Pampus argenteus), and African red snapper (Lutjanus agennes) in Barangay Tamisan and skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) in Barangay Macambol. Results relating socioeconomic and fisheries variables to catch did not produce significant results. Further analysis using regression showed that normal catch was influenced by engine size and the proportion of catch kept by fishers (P≤0.05). Analysis of CPUE of fishers in Tamisan also revealed significant differences with the best catch having the highest CPUE (1.57 kg/hr), normal catch (0.62 kg/hr), and worst catch (0.27 kg/hr) with haul time of 5.46 hours. This was also similar in the case of Macambol which showed significant differences in the catches e.g. best catch having the highest CPUE (7.08 kg/hr), normal (4.37 kg/hr), and worst catch (2.54 kg/hr) with haul time 9.23 hours. Most species caught in Pujada Bay between Tamisan and Macambol are piscivores, other species are molluscivores, omnivores, carnivores, planktivores, and herbivores. Engine size in horsepower and proportion of catch kept by fishers affected the number of fish caught.

The Lobo-lobo fry fishery in the western Visayan Sea, Philippines: Abundance, catch composition, and potential fisheries impact

Lobo-lobo are small fishes that are caught using fine mesh nets in the western Visayan Sea whose market extends outside of the Visayan Sea, and perhaps even outside of the country. With high consumer demands, it is targeted year-round. Catches of fine-meshed boat seines operating in the waters off Concepcion, Iloilo which target large amounts of small and early juvenile fishes were monitored daily from June to December 2016 and June 2020 to October 2021. Results showed that catches were comprised of several species and clearly show the selection for early juveniles by the lobo-lobo fishery. At least 53 families comprise the lobo-lobo catches, dominated by Engraulidae (78.5%) and Clupeidae (13.1%), and are mostly comprised of post-larvae and early juveniles with sizes ranging from 0.2 to 3.6 cm standard length. The estimated total annual catch of the local boat seine fleet during the study period ranged from 313.8 mt to 869.0 mt. The fishing operations are concentrated between Tago and Igbon Islands and appear to be consistent throughout the year, but the composition and proportion of catches differed seasonally. This area appears to be a critical habitat, supporting the growth and survival of several species. Protecting this area and restricting the use of fine-meshed nets targeting fry will likely have an overall positive impact on the local fish stocks.

How an illuminated headline affects catches and species separation in a Celtic Sea mixed demersal trawl fishery

Installing artificial lights on fishing gear is increasingly being explored to alter the behaviour of fish during the capture process and modify selectivity. We investigated the effect of introducing artificial light on a commercial trawler operating in the English southwest mixed demersal fishery. Total catch and species vertical separation were compared and analysed in two identical separator trawls towed simultaneously. One trawl was equipped with blue LEDs along its headline, the other trawl served as a control to allow for pairwise catch comparison. Fishing trials were conducted at night and during the day. In the presence of lights, catches-at-length of haddock (Melanogrammus aeglefinus) were lower during the night and marginally higher during the day. Catches of grey gurnard (Eutrigla gurnardus), megrim (Lepidorhombus whiffiagonis) and whiting (Merlangius merlangus) were unaffected by lights. In terms of vertical separation, in the presence of lights, more haddock were retained in the lower codend during the day and night. Lights also increased the proportion of catches in the lower codend for grey gurnard, whiting and Northern squid (Loligo forbesii), but only during the day. This study shows there are species-specific reactions to artificial light during the trawl capture process and these reactions can be different between day and night. When reviewed with other studies, some common observations are identified, indicating that lights can change the behaviour of some species which normally rise inside the trawl during the capture process, such as haddock. The use of artificial lights offers an alternative method to modify trawl selectivity, by utilising species-specific reactions to light, and the ability to change the position and characteristics of the light, offers many avenues to investigate.

Estimating relative abundance of kawakawa (Euthynnus affinis Cantor, 1849) landed in eastern indian ocean using catch and effort data

Kawakawa (Euthynnus affinis) is a neritic tuna commodity with high economic value, especially for coastal states such as Indonesia. However, there is a lack of information about kawakawa abundance in the Eastern Indian Ocean. This research aims to estimate the relative abundance of kawakawa using catch and effort data, which is often used as a method in fisheries stock assessments. The size distribution of kawakawa was also analyzed in this study. The data was collected through daily monitoring from 16 landing sites along the Fisheries Management Area (FMA) 572 to 573 from 2015 to 2021. The data recorded included catch, day of fishing, fishing gear, and biological data (length and weight). The annual catch per unit of effort (CPUE) analysis of kawakawa reached its maximum in 2018, while the minimum value occurred in 2015. Furthermore, the monthly CPUE demonstrated that the highest catch occurred during the observation years in February and March. The highest catch proportion of kawakawa reached 87.21% in 2017. Finally, the gross tonnage (GT) of the gear showed the most significant factor in the catch.

Timing and magnitude of climate-driven range shifts in transboundary fish stocks challenge their management.

Climate change is shifting the distribution of shared fish stocks between neighboring countries’ Exclusive Economic Zones (EEZs) and the high seas. The timescale of these transboundary shifts determines how climate change will affect international fisheries governance. Here, we explore this timescale by coupling a large ensemble simulation of an Earth system model under a high emission climate change scenario to a dynamic population model. We show that by 2030, 23% of transboundary stocks will have shifted and 78% of the world's EEZs will have experienced at least one shifting stock. By the end of this century, projections show a total of 45% of stocks shifting globally and 81% of EEZs waters with at least one shifting stock. The magnitude of such shifts is reflected in changes in catch proportion between EEZs sharing a transboundary stock. By 2030, global EEZs are projected to experience an average change of 59% in catch proportion of transboundary stocks. Many countries that are highly dependent on fisheries for livelihood and food security emerge as hotspots for transboundary shifts. These hotspots are characterized by early shifts in the distribution of an important number of transboundary stocks. Existing international fisheries agreements need to be assessed for their capacity to address the social–ecological implications of climate‐change‐driven transboundary shifts. Some of these agreements will need to be adjusted to limit potential conflict between the parties of interest. Meanwhile, new agreements will need to be anticipatory and consider these concerns and their associated uncertainties to be resilient to global change.

Seasonal Abundance and Length Patterns of Brown and White Shrimp in Texas Estuaries and Nearshore Waters: Implications for Population and Fishery Dynamics

AbstractPenaeid shrimp are a major contributor to commercial landings in the Gulf of Mexico, with white shrimp Litopenaeus setiferus and brown shrimp Farfantepenaeus aztecus making up the bulk of the landings off Texas. In this study, we examined seasonal trends in white and brown shrimp population demographics (relative abundance, monthly proportion of catch, and length) and their relationship with water quality parameters (water temperature and salinity) across a 36‐year fishery‐independent data set for Texas estuarine and nearshore waters. The primary findings of this analysis were consistent negative trends in seasonal mean TL (April–August) for brown shrimp. These negative trends resulted in decreases in mean TL of up to 20 mm across the time series. Additionally, growth coefficients calculated on an annual scale for brown shrimp showed negative trends as well. White shrimp did not show the same consistently negative trends in mean length or growth. Although expected seasonal trends in CPUE and monthly proportions of catch were observed, the analysis showed few convincing or consistent annual trends in these metrics for either species. We suggest that the differing trends in mean length (i.e., between species) may be explained by summer water temperatures exceeding the optimum growth range for brown shrimp in the latter part of the time series examined here. Such trends in mean length for the brown shrimp population may have implications for population fecundity and may affect the value and efficiency of shrimp harvest in commercial fisheries, though this has yet to be seen. Nevertheless, managers should remain vigilant to any continued negative trends in brown shrimp length and their potential impact on the population and fishery dynamics.

Variation in global distribution, population structures, and demographic history for four Trichiurus cutlassfishes.

BackgroundSpecies-specific information on distribution and demographic patterns provides important implications for conservation and fisheries management. However, such information is often lacking for morphologically-similar species, which may lead to biases in the assessments of these species and even decrease effort towards sustainable management. Here, we aimed to uncover the distribution range, population structure and demographic history for four exploited Trichiurus cutlassfishes using genetics. These cutlassfishes contribute substantial global fisheries catch, with a high proportion of catch harvested from the NW Pacific.MethodsWe chose the widely available mitochondrial 16S ribosomal RNA (16S) as the genetic marker for cutlassfishes. We compiled the 16S sequence data from both the GenBank and a survey of trawler catch samples along the NW Pacific coasts 22–39°N. Genealogical relationships within each species was visualized with haplotype networks and potential population differentiations were further evaluated with AMOVA. Demographic histories were estimated using neutrality test, mismatch analysis, and the Bayesian skyline plot. The reconstructed phylogenetic trees were used to delimit and estimate the divergence time of species and included populations.ResultsIn each of two cosmopolitan species, T. lepturus and T. nanhaiensis, we observed distinct populations along the coasts of warm oceans; such population differentiation might result from historical geographic barriers in the Pleistocene. In the NW Pacific, four Trichiurus species vary in their distribution habitats, which reflect differential ecological niches among these species. The small-sized T. brevis are primarily found in nearshore habitats; the warm-affiliated T. nanhaiensis are present along the path of the Kuroshio Current; the cold-affiliated T. japonicus spatially diverged from the widely-distributed T. lepturus, with the latter mainly occupy in warmer regions. Despite these differences, a single well-mixing fish stock, thus one management unit, was identified in each of the four species, presumably due to expansion of their population sizes predated the Last Glacial Maximum and a lack of distribution barrier. The most dominant T. japonicus, which have at least one magnitude higher effective population size than the others, show a unique abrupt size expansion event at 75 to 50-kilo years ago when the low sea level occurred during the ice age.Main conclusionsThe demographic history revealed by our genetic analyses advances understanding of the current distribution and population structure for these congeneric species. Moreover, the uncovered population structure provides insight into the assessment and management of these species. Such information complements contemporary knowledge about these species and enables us to forecast their ability to resist future environmental and anthropogenic disturbances.

Some Biological Parameters of Yellowfin Tuna (Thunnus albacares) from the Handline Fishery in the Eastern Part of the Banda Sea

Export quality yellowfin tuna (Thunnus albacares) from the handline fishery in the Banda Sea (Ambon and Seram) is vital in supporting coastal communities. To ensure its sustainability, information on their biological parameters is essential, especially for harvest strategy purposes. A combination of port sampling and fisheries surveys were conducted from January to October 2016 to monitor the catch, effort, size (length and weight), and maturity level of yellowfin tuna. An equal catch proportion of yellowfin and bigeye tuna was found during surveys in Masohi, Seram Island. In contrast, two-thirds of the catch landed in Ambon was dominated by yellowfin tuna. The catch rate varied between 25.5-71.9 kg/day. Length of samples distributed between 65-152 cm FL (mode=104 cm FL), whereas estimated live weight ranged from 6.12-148.92 kg. Both females (W=0.000001*FL3.7190) and males (W=0.000001*FL3.7438) possessed allometric growth. The proportion of males was twice that of females (1: 0.5), where most (47%) of samples were found to be mature. The estimated total mortality (Z) is 1.04/year, with the natural mortality (M) and fishing mortality (F) is around 0.55/year and 0.49/year, respectively. The stock condition allegedly reaching its optimum level tagged by the length at first caught (Lc) was slightly higher in comparasion to length at first maturity (Lm50 ) and utilization rate (E) below 0.55/year.

Pre-catch and discard mortality in Northeast Atlantic herring and mackerel fisheries: consequences for stock estimates and advice

Abstract Unaccounted mortality caused by discarding or pre-catch losses is a major challenge for fisheries management. In pelagic fisheries, a considerable proportion of catches may be lost due to intentional release of unwanted catch (slipping) or net bursts (fishing net tears due to the weight of the catch). Here we review and estimate ranges of discard and pre-catch mortality for two important pelagic fisheries, the Northeast Atlantic (NEA) mackerel and Norwegian spring spawning (NSS) herring, and explore the effects on stock estimates and catch advice. We show that mortality caused by discarding, slipping, and net bursts is unknown but probably corresponds to a considerable percentage of total registered catches. Including estimated unaccounted mortality into assessment models leads to underestimation of the stock levels by 3.7–19.5% and 2.8–6.8% for NEA mackerel and NSS herring, respectively, corresponding to up to several million tonnes of fish that die annually due to fishing without being landed. If discard and pre-catch mortality were eliminated, allowed catches could increase by 10–20%. We demonstrate that unaccounted mortality in pelagic fisheries may be substantial, affecting stock estimates and catch advice. This may undermine the sustainable management and efficient use of pelagic resources.

EVALUATION OF DYNATRAP® DT160 AS AN INEXPENSIVE ALTERNATIVE TO CDC TRAPS FOR ADULT MOSQUITO MONITORING IN MALI, WEST AFRICA

Mosquito monitoring traps (i.e., CDC light traps) are crucial tools for basic vector ecology research, risk assessment, and vector control programs. Unfortunately, they are expensive which is often an issue in projects conducted in developing countries. Therefore, it would be desirable to have reliable but inexpensive alternatives based on existing consumer products. We compared an off-the-shelf DynaTrap (model DT160, CCFL tube 365 ± 3 nm UV) modified to fit a CDC trap collection bag and to use a 12V power supply, with two commonly used CDC traps: CDC Miniature Light Trap Model 512 (incandescent light, 6 Volt) and CDC Miniature Downdraft Blacklight (UV) Trap Model 912 (4-Watt blue-black-light tube, 12 Volt), in different ecological settings in southwest (Kenieroba) and northwest (Nioro du Sahel) Mali, West Africa. In northwest Mali, the modified DynaTrap caught a mean of 20.67 ± 2.8 females and 5.38 ± 1.0 male Aedes aegypti which was 16.55% and 10.78% more, respectively, than the CDC incandescent trap (control). The DynaTrap caught a mean of 29.75 ± 2.8 female and 17.92 ± 3.5 male Culex quinquefasciatus. which was 47.76% and 20.70% more than the control CDC incandescent trap. The DynaTrap caught a mean of 2.46 ± 0.5 females and 1.63 ± 0.6 males and 10.16% and 2.45% more female and male An. gambiae s.l., respectively, than the CDC incandescent trap. Trap and catch means were lower at the southwest Mali site. However, trap catch proportions by sex were similar to those in the northwest. The modified DynaTrap outperformed both CDC monitoring traps for less than one third of the cost including the cost of the DynaTrap modifications.

Processing Mixed Mesopelagic Biomass from the North-East Atlantic into Aquafeed Resources; Implication for Food Safety.

Aquaculture produces most of the world’s seafood and is a valuable food source for an increasing global population. Low trophic mesopelagic biomasses have the potential to sustainably supplement aquafeed demands for increased seafood production. The present study is a theoretical whole-chain feed and food safety assessment on ingredients from mesopelagic biomass and the resulting farmed fish fed these ingredients, based on analysis of processed mesopelagic biomass. Earlier theoretical estimations have indicated that several undesirable compounds (e.g., dioxins and metals and fluoride) would exceed the legal maximum levels for feed and food safety. Our measurements on processed mesopelagic biomasses show that only fluoride exceeds legal feed safety limits. Due to high levels of fluoride in crustaceans, their catch proportion will dictate the fluoride level in the whole biomass and can be highly variable. Processing factors are established that can be used to estimate the levels of undesirables in mesopelagic aquafeed ingredients from highly variable species biomass catches. Levels of most the studied undesirables (dioxins, PCBs, organochlorine pesticides, brominated flame retardant, metals, metalloids) were generally low compared to aquafeed ingredients based on pelagic fish. Using a feed-to-fillet aquaculture transfer model, the use of mesopelagic processed aquafeed ingredients was estimated to reduce the level of dioxins and PCBs by ~30% in farmed seafood such as Atlantic salmon.

Stock-of-origin catch estimation of Atlantic bluefin tuna (Thunnus thynnus) based on observed spatial distributions

Atlantic bluefin tuna (Thunnus thynnus) are a large, highly migratory fish distributed throughout the North Atlantic Ocean and adjacent seas currently managed as two discrete stocks: western and eastern. Both stocks forage in the North Atlantic, and a high degree of intermixing occurs, which combined with limited single-stock survey data makes it difficult to assess the abundance and status of individual populations. In this study, we used movement patterns from a multidecadal tagging dataset to create monthly distribution maps for these two major stocks. We then used these maps to separate the overall catch records into stock-specific catch (catch per unit effort, CPUE) time series. We identified an increase in the past two decades in the proportion of catch estimated to come from the eastern stock, attributable to a decrease in CPUE in regions dominated by the western stock, relative to other regions. The stock-specific catch series can be used to improve the accuracy of stock assessments and inform spatial management.

Desempenho de redes de arrasto industrial no sistema “double rig” para captura de camarões e peixes na costa norte do Brasil

As pescarias de arrasto na costa Norte caracterizam-se por fornecerem uma grande quantidade de pescado. Devido essas pescarias capturarem grande biomassa de camarões e peixes, verificou-se a necessidade de avaliar e comparar a proporção da captura destes recursos utilizando redes de arrasto-duplo sistema “double rig”, sendo uma delas modificada. Os dados foram coletados durante o projeto inovação tecnológica para redes de arrasto seletivas à captura de peixes pela frota camaroneira. Na verificação dos recursos, optou-se avaliar a captura de pescada gó Macrodon ancylodon e dos camarões: camarão rosa Farfantepenaeus subtilis e sete barbas Xiphopenaeus kroyeri. A avaliação da proporção da captura entre peixe e camarões foram testadas para ambas as redes; testou-se ainda, a significância da captura das redes, em relação a série temporal, estimou-se a CPUE (Captura/horas de arrasto/dia) das redes, correlações lineares; normalidade da distribuição e suas diferenças significativas. A rede modificada para captura de peixes, obteve biomassa de pescado superior a rede para camarão, porém capturou uma biomassa inferior de camarões, com proporção de peixes superior, assim cumprindo sua premissa. Diferenças significativas foram encontradas nas séries temporais das redes (T:0,017; p<0,05). Em relação a CPUE, ambas as redes obtiveram correlação linear baixa, distribuições normais; diferenças significativas ANOVA (p<0,05) encontradas apenas para rede de peixes (p: 0,008). Dentre os pesqueiros, o denominado ‘zero zero’ destacou-se como principal área de esforço. Diante das resoluções obtidas no estudo, conclui-se que o uso das redes de peixe (rede modificada) mostraram-se eficazes para embarcações camanoeiras durante o período de defeso do camarão.

STUDY ON SPECIES COMPOSITION OF JUVENILE TUNA CAUGHT BY PURSE SEINE FLEET LANDING IN TAMPERAN FISHING PORT, JAVA, INDONESIA

Juvenile yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) are very similar in morphological characteristics, hence it is difficult to distinguish between these two species, especially when they are landed in frozen or defect conditions. The presence of juvenile bigeye tuna in yellowfin catch was first noticed in the 1980s from pole and line fisheries in Maldives. We analyzed the monthly composition structure of juvenile tuna caught by purse seine fleet operating in the South Indian Ocean. Tamperan fishing port was chosen for benchmarking to other small-scale fisheries. The result is expected to be used as an index for increasing the accuracy of juvenile tuna proportion for national catch statistics. A total of 4760 juvenile tunas were examined during monitoring activities. The length ranged 19-65 cm FL with median 40 cm FL for juvenile yellowfin tuna and 44 cm for juvenile bigeye. The whole weight of juvenile tuna ranged from 5 to 7 kg. The length-weight conversion for both species are W = 0.0184*FL3.0086 (R2 = 0.95, n = 4144) for juvenile yellowfin tuna and W = 0.018*FL3.0047 (R2 = 0.93, n = 346) for juvenile bigeye tuna. It can be inferred from the study that in terms of catch proportion of juvenile tuna, it consists of ratio 10:1, whereas for every 10 kg of juvenile tuna contains approximately one kg of bigeye tuna. Besides, the length-weight equation for both species is interchangeable, which means either equation can be performed to convert length to weight for both juvenile yellowfin and bigeye tuna.

Komposisi By-catch Perikanan Lele Laut (Famili Plotosidae) di Perairan Teluk Kolono, Sulawesi Tenggara

The by-catch on the gill net fisheries is the current global fisheries problems and issues. This study aimed to analyze by-catch composition of fishery eel catfish (Plotosidae) in Kolono Bay, Southeast Sulawesi. Sampling was done monthly from April to July 2019, with bottom experimental gillnets of ¾, 1¼, 1½, 1 ¾, and 2 inches mesh sizes. The highest proportion of catches was found in by-catch (62.72%) than the main target, the family Plotosidae (37.28%). The by-catch includes 23 families consisting of two groups namely the useable by-catch 55.57% (19 families) and discarded by-catch 7.15% (4 families). Out of these 23 families, 44 species belong to the Least Concern (LC) and 24 species Not Evaluated (NE) categories on the IUCN red list 2019. The results showed that the use of bottom gillnets in eel catfish fisheries has a low selectivity which is characterized by high diversity and low dominance of by-catch.

Capture Process of White Pomfret (Pampus argenteus) on Gillnet: A Case Study of Pangandaran Regency, Indonesia

Gillnet is a wall of netting that hangs in the water column, typically made of monofilament or multifilament nylon, had the same size and usually used by fisherman in Pangandaran. This research aims to see the capture process of white pomfret (Pampus argenteus) on gillnet in Pangandaran Regency. This research was conducted in August 2018 and January 2019 in Pangandaran. The data used in this research are primary data consisting of the proportion of catches and capture process, whereas secondary data obtained from Dinas Perikanan Pangandaran. The results of this research show that the quantity and weight proportion of main catch > bycatch and captured process of white pomfret dominated by wedged by 94% and the lowest is gilled by 6%.

Cod and climate: a systems approach for sustainable fisheries management of Atlantic cod (Gadus morhua) in coastal Danish waters

This study applied the Systems Approach Framework (SAF) to address the issue of declining Atlantic cod fishery in coastal areas. Interviews of 58 fishers from 26 harbours and meetings with national fisheries organisations and managers revealed the perception of an offshore movement of coastal cod. Numerical modelling based on fishing survey data did not substantiate these perceptions in the data-poor coastal waters. However, Data Storage Tag (DST) information combined with bottom sea water temperature data from the spatio-temporal hydrodynamic Baltic Sea Ice-Ocean Model showed changes in potential cod habitat distribution in the Skagerrak-Kattegat and western Baltic from 1979 to 2016. Subsequently, cod habitats were defined in three categories: (i) potentially suitable (T ≤ 12 °C); (ii) episodic (12 16 °C). The environmental changes were linked to the socio-economic component of cod fishery. Cod catches (weight and monetary value) were retrieved using logbook information and data from the Vessel Monitoring System (VMS, 2005–2016) and the Automatic Identification System (AIS, 2006-2016). General additive modelling significantly showed the largest proportion of catches took place in the potentially suitable habitat whereas catches were lower in the episodic habitat and rare in the unsuitable habitat. The results of this first large-scale SAF application are highly valuable for adapting existing fisheries management by: (i) providing information on habitat shrinkage for Maximum Sustainable Yield (MSY) based stock assessments; (ii) adding a spatio-temporal dimension for coastal productivity relative to the vessel-based Individual Transferable Quota (ITQ) system; and (iii) providing a predictive scenario simulation tool for sustainable management under changing environmental conditions.