Modelling the time series of capture fishery and aquacultural production in Iran

The trend of capture fishery and aquaculture production in Iran shows an ascending trend. An estimate of future production may be useful for management purposes and providing some clues about the effectiveness of the current plans to reach the goals. We used the data provided by the Food and Agricultural Organization of the United Nation (FAO) to model the time series of the production of aquatics in both sectors. The data covered the years 1980-2018. We predicted the production of aquatics until 2025 using autoregressive integrated moving average models. Several techniques were used to estimate the parameters of the model. However, searching the all possible values of the parameters provided the model with the best predictability. According to the selected model, the production of capture fishery will have ascending trends and increase to 1,513,533 tons in 2025. Aquaculture production will also have an increasing trend, however, the rate of change will be lower than that of the capture fishery. Aquaculture production will reach to 552944 tons in 2025. The forecast is based on the assumption that the rate of changes in the development of capture fishery and aquaculture will remain in the present status. Sudden changes in management practice or environmental conditions may have a remarkable influence on future production

Modelling and forecasting of catfish species yield from Mangochi artisan fisheries of Lake malawi in Malawi

Most of the wild fish stocks in Malawi either are fully or over exploited. This challenge underpins importance of forecasting using available data to support sustainable fisheries management. The study aimed at modelling and forecasting Catfish (Mlamba) species yield from artisan fishery on Lake Malawi in Mangochi District as they are becoming important food fish due to decline of more important fish species such as Oreochromis(Chambo). The study was based on secondary data on fish catches between1976 and 2012, collected from Fisheries Research Unit of the Department of Fisheries in Malawi. The study considered Autoregressive Integrated Moving Average (ARIMA) processes to select an appropriate stochastic model for forecasting the species yield. Appropriate models were chosen based on ARIMA (p, d, q). Autocorrelation function (ACF), Partialautocorrelation (PACF), Akaike Information Criteria (AIC), Box-Ljung statistics, correlogram of residual errors, distribution of residual errors, ME, RMSE, MAPE and MAE. Selected model was ARIMA (0, 0, 1) for forecasting artisan landings of Catfish from Lake Malawi in Mangochi District from 2013 to 2022. Based on the chosen model, forecast for artisan Catfish landings showed mean of 352 tonnes and mean of actual catches was 362 tonnes. However, catches in year 2022 are projected to be 360 tonnes, slightly below the actual catches mean but above 236 tonnes in 2010, assuming other factors remain constant. Confidence intervals of the forecasts included a zero and as such over exploitation of the species cannot be ruled out. Landings of the fishery will increase to 360 tonnes and remain stable through year 2022 necessitating fisheries managementconsideration to improve the trend. Policy makers should secure sustainable exploitation of Catfish species, among artisan fishery in the study area by controlling all fishing effort that lands the species such as gillnets, beach seines, open water seines among others

Prediction of global sea cucumber capture production based on the exponential smoothing and ARIMA models

Sea cucumber catch has followed “boom-and-bust” patterns over the period of 60 years from 1950-2010, and sea cucumber fisheries have had important ecological, economic and societal roles. However, sea cucumber fisheries have not been explored systematically, especially in terms of catch change trends. Sea cucumbers are relatively sedentary species. An attempt was made to explore whether the time series analysis approach (exponential smoothing models and autoregressive integrated moving average (ARIMA) models) is also applicable to relatively sedentary species. This study was conducted to develop exponential smoothing and ARIMA models to predict the short-term change trends (2011-2020), according to the time series data for 1950-2010 collected from the FAO Fishstat Plus database. The study results show that the single exponential smoothing and ARIMA (1, 1, 1) models are best for predicting sea cucumber short-term catches, and the predictive powers of both models are good. However, the accuracies of the models would be better if the data quality was resolved and the variables influencing sea cucumber capture production were fully considered

Modelling the relationships of medium and long-term variations of the anchovy and sardine catches in the Catalan Sea (NW Mediterranean) with the environmental drivers

Versió amb una secció retallada, per drets de l'editorThe understanding of the driving forces involved in the abundance fluctuation of fish populations is an important requirement for conservation and management, especially in the context of environmental changes. In the North Western Mediterranean Sea the catches of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) during the period 1990-2014 have severealy decreased. Although neither of the two populations is considered underexploited, it seems unlikely that overexploitation alone has caused the recent decrease. Furthermore, it is even truer considering that changes in the marine environment have occurred in the studied area during the last 40 years. The general objective of this PhD thesis is to detect the main environmental factors involved in the fluctuations of the abundance of the two small pelagic species in the Catalan Sea. Before focusing on the environmental influences, the spatiotemporal distribution of the purse seine fishery operations was analyzed. The results revealed that the distribution of the fleet captured the features of the distributions of small pelagic populations. These findings contributed to a better understanding and visualization of the spatial distribution of catches, which form the basis of the landings data series studied in the rest of the PhD thesis. We then investigated the local environmental factors and climate index (Western Mediterranean oscillation index; WeMOI) that were strictly linked with landings of both species. We concluded that temperature, salinity, and currents were important drivers for both species, and the WeMOI index favored sardine abundance when it was in positive phase. We highlighted that the relationships between the availability of these small pelagic fishes and these factors were better described by non-linearity. Finally, we provided evidence, independent from the studies directly targeted on early life stages, that the temperature and sea surface height (used as a proxy of mesoscale processes) play an important role in the recruitment variability of these species. Even more importantly we showed that the effects of these drivers were not stationary but transient over time. Although this work is one step forward in the understanding of the abundance variability of the small pelagic fish in the Catalan Sea further investigation focused especially on the synergic effects of fishing combined with environmental factors will still be needed.La comprensió dels factors implicats en la fluctuació d'abundància de les poblacions de peixos és un requisit important per a la conservació i la gestió, especialment en el context dels canvis ambientals. En la Mediterrània occidental, les captures de sardina (Sardina pilchardus) i l'anxova (Engraulis encrasicolus) durant el període 1990-2014 han disminuït bruscament. Malgrat que cap de les dues poblacions es consideri subexplotada, és poc probable que només la sobreexplotació hagi causat la recent disminució. Això és encara més cert si es té en compte que dins a la zona estudiada durant els últims 40 anys s'han produït clars canvis en el medi marí. L'objectiu general d'aquesta tesi doctoral és detectar els principals factors ambientals que intervenen en les fluctuacions de l'abundància de les dues espècies de petits pelàgics del mar català. Abans de centrar-se en les influències mediambientals, s'ha analitzat la distribució espaciotemporal de les operacions de la pesca de teranyina. Els resultats han revelat que la distribució de la flota representa fidelment les característiques de les distribucions de petits pelàgics. Aquestes troballes han contribuït a una millor comprensió i visualització de la distribució espacial de les captures que formen també la base de la sèrie de dades de desembarcament estudiada a la resta de la tesi doctoral. A continuació, s'han investigat les relacions entre els desembarcaments d'ambdues espècies i els factors ambientals locals i l'índex climàtic (Índex d'oscil·lació de la Mediterrània occidental, WeMOI). Es conclou que la temperatura, la salinitat i els corrents són factors importants per ambdues espècies, i l'índex WeMOI afavoreix l'abundància de la sardina quan es troba en fase positiva. Hem destacat que la relacions entre la disponibilitat d'aquestes espècies de petits pelàgics i aquests factors poden ser millor descrits amb models no-lineals. Finalment, aportem evidències, de manera independent d'altres estudis centrats directament en ous i larves, que la temperatura i el nivell superficial del mar (utilitzat com proxy de processos de mesoescala ) tenen un important rol en la variabilitat del reclutament per ambdues espècies. Encara més important, hem mostrat que els efectes d'aquests factors no són estacionaris sinó que han canviat amb el pas del temps. Encara que aquest estudi representa un pas endavant en el coneixement i la comprensió de la variabilitat en l'abundància de petits peixos pelàgics al mar Català, encara és necessària la investigació addicional centrada en l`efecte sinèrgic de la pesca amb els factors ambientals.Postprint (published version

Modelling the relationships of medium and long-term variations of the anchovy and sardine catches in the Catalan Sea (NW Mediterranean) with the environmental drivers

The understanding of the driving forces involved in the abundance fluctuation of fish populations is an important requirement for conservation and management, especially in the context of environmental changes. In the North Western Mediterranean Sea the catches of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) during the period 1990-2014 have severealy decreased. Although neither of the two populations is considered underexploited, it seems unlikely that overexploitation alone has caused the recent decrease. Furthermore, it is even truer considering that changes in the marine environment have occurred in the studied area during the last 40 years. The general objective of this PhD thesis is to detect the main environmental factors involved in the fluctuations of the abundance of the two small pelagic species in the Catalan Sea. Before focusing on the environmental influences, the spatiotemporal distribution of the purse seine fishery operations was analyzed. The results revealed that the distribution of the fleet captured the features of the distributions of small pelagic populations. These findings contributed to a better understanding and visualization of the spatial distribution of catches, which form the basis of the landings data series studied in the rest of the PhD thesis. We then investigated the local environmental factors and climate index (Western Mediterranean oscillation index; WeMOI) that were strictly linked with landings of both species. We concluded that temperature, salinity, and currents were important drivers for both species, and the WeMOI index favored sardine abundance when it was in positive phase. We highlighted that the relationships between the availability of these small pelagic fishes and these factors were better described by non-linearity. Finally, we provided evidence, independent from the studies directly targeted on early life stages, that the temperature and sea surface height (used as a proxy of mesoscale processes) play an important role in the recruitment variability of these species. Even more importantly we showed that the effects of these drivers were not stationary but transient over time. Although this work is one step forward in the understanding of the abundance variability of the small pelagic fish in the Catalan Sea further investigation focused especially on the synergic effects of fishing combined with environmental factors will still be needed.La comprensió dels factors implicats en la fluctuació d'abundància de les poblacions de peixos és un requisit important per a la conservació i la gestió, especialment en el context dels canvis ambientals. En la Mediterrània occidental, les captures de sardina (Sardina pilchardus) i l'anxova (Engraulis encrasicolus) durant el període 1990-2014 han disminuït bruscament. Malgrat que cap de les dues poblacions es consideri subexplotada, és poc probable que només la sobreexplotació hagi causat la recent disminució. Això és encara més cert si es té en compte que dins a la zona estudiada durant els últims 40 anys s'han produït clars canvis en el medi marí. L'objectiu general d'aquesta tesi doctoral és detectar els principals factors ambientals que intervenen en les fluctuacions de l'abundància de les dues espècies de petits pelàgics del mar català. Abans de centrar-se en les influències mediambientals, s'ha analitzat la distribució espaciotemporal de les operacions de la pesca de teranyina. Els resultats han revelat que la distribució de la flota representa fidelment les característiques de les distribucions de petits pelàgics. Aquestes troballes han contribuït a una millor comprensió i visualització de la distribució espacial de les captures que formen també la base de la sèrie de dades de desembarcament estudiada a la resta de la tesi doctoral. A continuació, s'han investigat les relacions entre els desembarcaments d'ambdues espècies i els factors ambientals locals i l'índex climàtic (Índex d'oscil·lació de la Mediterrània occidental, WeMOI). Es conclou que la temperatura, la salinitat i els corrents són factors importants per ambdues espècies, i l'índex WeMOI afavoreix l'abundància de la sardina quan es troba en fase positiva. Hem destacat que la relacions entre la disponibilitat d'aquestes espècies de petits pelàgics i aquests factors poden ser millor descrits amb models no-lineals. Finalment, aportem evidències, de manera independent d'altres estudis centrats directament en ous i larves, que la temperatura i el nivell superficial del mar (utilitzat com proxy de processos de mesoescala ) tenen un important rol en la variabilitat del reclutament per ambdues espècies. Encara més important, hem mostrat que els efectes d'aquests factors no són estacionaris sinó que han canviat amb el pas del temps. Encara que aquest estudi representa un pas endavant en el coneixement i la comprensió de la variabilitat en l'abundància de petits peixos pelàgics al mar Català, encara és necessària la investigació addicional centrada en l`efecte sinèrgic de la pesca amb els factors ambientals

Pesca comercial de tubarões e raias em Portugal

Doutoramento em BiologiaO objectivo do trabalho foi analisar os desembarques de tubarões e raias em Portugal no período 1986 – 2006. Esta análise revelou que os desembarques totalizaram 108.671 ton no referido período de 21 anos. Anualmente foram desembarcados, em média, cerca de 5.175 ton, com exemplares representantes de 8 ordens, 14 famílias e 44 espécies. Genericamente, os desembarques anuais destes grupos animais têm diminuído ao longo do tempo, apesar de se verificar um aumento no preço por quilo. O grupo mais desembarcado foi o das Raias (Raja sp.), responsável por 35.614 ton das capturas, ou seja, 33% do total. A este grupo seguiram-se as Patas-roxas (Scyliorhinus sp.), os tubarões Carocho (Centroscymnus coelolepis), Lixa (Centrophorus squamosus) e Barroso (Centrophorus granulosus), correspondendo a 12%, 12%, 10% e 9% dos desembarques, respectivamente. Na ausência de dados consistentes de CPUE, a comparação dos padrões de desembarques e preço foi utilizada como indicador da evolução do recurso, tendo em conta as várias espécies de elasmobrânquios. Centrophorus granulosus, Cações (Mustelus sp.), Tremelgas (Torpedo sp.), Marrachos (Carcharhinus sp.) e Tubarões-anjo (Squatina sp.) indiciaram sinais de possível sobrexploração, situação esta a merecer a atenção de programas futuros de I & DT. A evolução do esforço de pesca ao longo do tempo, ponderada sob a forma de “número de embarcações de pesca”, registou uma diminuição acentuada, embora substancialmente menor que a diminuição registada nos desembarques das espécies referidas. É pouco provável, por isso, que a diminuição dos desembarques seja fruto, unicamente, da diminuição na frota de pesca, mas sim de uma menor rendibilidade da actividade. Paralelamente, os aumentos de preço observados suplantaram largamente a taxa de inflação média, pelo que o aumento dos primeiros não é justificado inteiramente pelo aumento do segundo. Estes resultados tiveram eco nas análises de componentes principais (MAFA e DFA) conduzidas para as espécies, que validaram padrões de diminuição particularmente elevados nas espécies em que métodos anteriores já haviam apontado sinais de sobrepesca. Os resultados obtidos apontam para o facto de que algumas espécies parecem estar fora dos limites biológicos de segurança e, como tal, há necessidade de serem tomadas medidas de gestão eficazes.Portuguese commercial elasmobranch landings were analyzed for the period 1986 - 2006 and totaled 108.671 ton. An average of 5.175 ton were landed yearly, representing 8 orders, 14 families and 44 species. Annual landings for the fishery generally decreased over time, with a corresponding increase in price per kilogram. The most landed group, Skates (Raja sp.), accounted for 33% of the landings, or 35.614 ton. They were followed by Catsharks (Scyliorhinus sp.), Portuguese dogfish (Centroscymnus coelolepis), Leafscale gulper shark (Centrophorus squamosus) and Gulper shark (Centrophorus granulosus) (accounting for 12%, 12%, 10%, and 9% of the landings, respectively).In the absence of CPUE data, the comparative trends of landings and price were employed as an indicator of the “status” of specific elasmobranch species. Centrophorus granulosus, Smoothounds (Mustelus sp.), Torpedo rays (Torpedo sp.), Requiem sharks (Carcharhinus sp.) and Angel sharks (Squatina sp.) displayed indications of possible overexploitation, and merit the focus of future research. The pattern shown by fishing effort over time (i.e. number of fishing vessels over time) displayed a marked decrease, although this was substantially lesser than the decrease shown by landings of the species mentioned earlier. It is therefore unlikely that such decrease in landings is justified solely by a decrease in number of fishing vessels. Similarly, the increase in price shown by all species was largely superior to the increase in inflation, which would suggest that the increase in inflation alone would not account for the increase in price. All the results and data seem to corroborate the notion that some species are, in fact, under over-exploitation and in need of immediate management. These findings were all substantiated by principal component analysis (MAFA and DFA), which indicated strong decreasing landings patterns in those species where previous methods suggested overfishing

Argyrosomus regius (Asso, 1801) fishery and ecology in portuguese waters, with reference to its relationships to other european and african populations

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultura), Universidade de Lisboa, Faculdade de Ciências, 2014Life history parameters of valuable marine fish remain poorly studied worldwide. The meagre (Argyrosomus regius) is a large sciaenid from European and North African waters that, on its European range, supports regional small-scale and recreational fisheries and is considered a promising candidate species for aquaculture. However, its fisheries and ecology have remained poorly documented. The present work describes (1) progress made on raising scientific and societal awareness on this fish resource, (2) research carried out on the Portuguese fisheries targeting meagre and on the main biological parameters of the species in Portuguese waters. The study of fish remains from archaeological sites showed that both adult and juvenile meagre have been fished in Portuguese estuarine and coastal environments since, at least, the Mesolithic period. Today, two main commercial fisheries on meagre exist: one that targets meagre on the Western coast (within the Tagus estuary and off Peniche); and the other that captures the fish as by-catch in the Southeastern coast of Portugal. Using a new sampling methodology (commercial mark-recapture) a comprehensive set of otoliths and gonads was collected. Analyses of these samples showed that meagre is long-lived (up to 43 years old), displays fast juvenile growth and is reproductively active in spring and summer both in estuaries (Tagus and Guadiana) and adjoining coasts. Furthermore, it shows that both meagre males and meagre females display some signs of precocious maturity and that the meagre females are asynchronous batch spawners that likely have indeterminate fecundity. Moreover, microsatellite work showed that meagre populations in Europe and North Africa are highly fragmented. Finally, a statistical time series methodology is presented (SARIMA) that uses landings under a process control perspective to provided baseline monitoring to fisheries resources currently found in data-poor situation.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/12550/2003, POCTI/MAR/15263/1999 - III Quadro Comunitário de Apoio - 2000-2006); Direção Geral das Pescas e Aquicultura, projeto CORV POCTI/MAR/15263/1999