Sustainable Fisheries Research Articles

Temporal changes in a small-scale artisanal reef fishery in Brazil: Coastal development and its impacts

Small-scale artisanal fisheries perform great economic, social, cultural, and ecological roles worldwide. For fishers in adverse scenarios, resorting to alternatives such sustainable tourism is widely proposed. In this study, we investigate the long-term sustainability (1998–2020) of a small-scale artisanal fishery in Northeast Brazil, where transformations including intense coastal development, the establishment of a marine protected area, and the expansion of tourism occurred in addition to the region’s economic growth and the global trend of technological advancements. This study aims to understand how this fishery has changed over the last two decades while investigating a range of possible threats for its survival. Results demonstrated the impacts of technological innovation on fishing practices, such as the use of spearguns and small outboard motors; an increase in opportunistic fishing associated with a growing coastal population; fading of certain traditional fishing practices that often require fishers with greater experience; a shift for a fishery made up of more opportunistic amateur fishers, as artisanal, small-scale fishers switched to other income sources such as tourism. Although there are benefits from those transformations, which include the possibility of an alternative source of income and the use of technology, fisheries traditions have been affected negatively in terms of social and cultural aspects, and traditional fishing communities are left vulnerable in the absence of national fishery monitoring programs, reliable fishing data, and institutional instability. Local initiatives and empowerment of traditional fishing communities to strengthen fisher identity and participation in fisheries policy decision-making should be strongly encouraged.

Bayesian Network Analysis of Industrial Accident Risk for Fishers on Fishing Vessels Less Than 12 m in Length

The Marine Stewardship Council estimates that approximately 38 million people worldwide work in fisheries, and more than one-third of the global population is dependent on aquatic products for protein, highlighting the importance of sustainable fisheries. The FISH Safety Foundation reports that 300 fishers die every day. To achieve sustainable fisheries as a primary industry, the safety of human resources is of the utmost importance. The International Maritime Organization (IMO) and the International Labor Organization (ILO) have made efforts towards this goal, including the issuance of agreements and guidelines to reduce industrial accidents among fishing vessel workers. The criterion for applying these guidelines is usually a total ship length ≥12 m or ≥24 m. However, a vast majority of registered fishing vessels are <12 m long, and the fishers of these vessels suffer substantially more industrial accidents. Thus, we conducted a quantitative analysis of 1093 industrial accidents affecting fishers on fishing vessels <12 m in length, analyzed risk using a Bayesian network analysis (a method proposed by the Formal Safety Assessment of the IMO), and administered a questionnaire survey to a panel of experts in order to ascertain the risk for different types of industrial accidents and propose specific measures to reduce this risk.

Puzzling parrotfishes: Radiocarbon age validation and updated longevity estimates for western Atlantic species in support of sustainable fisheries management

For management efforts to succeed in Caribbean fisheries, local fishers must support and be willing to comply with fishing regulations. This is more likely when fishers are included in a stock assessment process that utilizes robust scientific evidence, collected in collaboration with fishers, to evaluate the health of fish stocks. Caribbean parrotfishes are important contributors to coral reef ecosystem health while also contributing to local fisheries. Scientifically robust stock assessments require regional species-specific information on age-based key life history parameters, derived from fish age estimates. Evaluation of the accuracy of age estimation methods for fish species is a critical initial step in managing species for long-term sustainable harvest. The current study resulted from a collaborative research program between fish biologists and local fishers investigating age, growth, and reproductive biology of the seven parrotfish species landed in U.S. Caribbean fisheries; specifically, we validated age estimation for stoplight parrotfish Sparisoma viride and queen parrotfish Scarus vetula. This is the first study to directly validate age estimation for any parrotfish species through analysis of Δ14C from eye lens cores. Our age estimation validation results show that enumeration of opaque zones from thin sections of sagittal otoliths for a Sparisoma and a Scarus species provides accurate age estimates. The oldest stoplight parrotfish and queen parrotfish in the Δ14C age estimation validation series were 14 y and 16 y; while the oldest stoplight parrotfish and queen parrotfish we aged to-date using the Δ14C validated age estimation method were 20 y and 21 y, respectively. Fish longevity (maximum age attained/life span) is a key life history parameter used for estimation of natural mortality, survivorship, and lifetime reproductive output. Past reviews on parrotfishes from the Pacific and Atlantic concluded that most Caribbean/western Atlantic parrotfish species are relatively short-lived with estimated maximum ages ranging from 3–9 y. However, information from our collaborative research in the U.S. Caribbean combined with recently published age estimates for Brazilian parrotfish species indicate that many western Atlantic parrotfishes are relatively long-lived with several species attaining maximum ages in excess of 20 y.

Reducing Artisanal Fishery Impact on Marine Community: New Data from Comparison of Innovative and Traditional Gear

Fishery resources overexploitation, together with bycatch and discards, have an impact on marine ecosystems. The adoption of technologically innovative gears is a possible solution to reduce the discard and to enhance the sustainability of fishery, mainly in artisanal fisheries that represent about 80% of the EU Mediterranean fleet. In the perspective of fishery sustainability, it is necessary to study and test alternative gears to the traditional ones, also with collaboration of fishers. In the present study, results of experimental fishing activities carried out in two Mediterranean areas with traditional and innovative gears of small-scale fishing are reported. Thirty-four hauls were carried out to compare the catch of two types of trammel nets: a traditional one and experimental guarding net. Additionally, 12 hauls were carried out to compare collapsible pots and traditional pots. No significant differences were recorded between trammel nets in terms of commercial catch and discard. However, interesting differences in discard composition were recorded, with higher Elasmobranchs presence in trammel nets, including species assessed as critically endangered and vulnerable. The use of trapula pots in place of traditional ones showed a lower discard of specific resources and an advantage for fishers in terms of space occupied on board.

Safe and sustainable fish and seafood system and per- and poly-fluorinated substances occurrence: the role of PFAS toxicity in the assessment.

Fish and seafood are valuable sources of both nutrients and organic contaminants. The expansion of the analytical per- and polyfluoroalkyl substances (PFAS) panel with toxicological characterisation necessitates an update of PFAS intake assessment and management within the context of cumulative exposure. Benthic and demersal seafood, such as clams, squid, and cuttlefish, are more prone to contamination with C9-C14 perfluorocarboxylic acids, exhibiting the highest relative potency factors in terms of immunotoxicity, according to the grid recently proposed by the European Commission Scientific Committee on Health, Environment, and Emerging Risk. Based on the Italian food consumption database referring to demersal and benthic biota such as squid, cuttlefish, crustaceans, and clams, a toxicology-based intake scenario was drafted to highlight the relevant contribution of such wild species to PFAS intake, well above the provisional health-based guidance value of 4.4ng/kg body weight per week. Ensuring consistency between PFAS reduction and substitution policies, environmental quality standards for water bodies, and the issuance of advisories and regulations regarding safe and sustainable intake of fish and seafood is crucial. This is done to prevent a loss of accountability for institutional bodies, which aim to protect fragile (sensitive and vulnerable) groups from PFAS exposure and simultaneously promote 'blue growth' as a sustainable food production system.

Synthesizing the Ecological and Societal Ramifications of Environmental Stressors on Philippine Marine Ecosystems: A Comprehensive Literature Review

Coral reefs, which serve as essential ecosystems that support marine biodiversity and coastal populations, are declining at an alarming rate worldwide, including in the Philippines. This study explores the specific effects of overfishing, the causes, and effects of pollution on Philippine waters to understand better rising sea levels, ocean acidification, the overall impact of climate change on coral reefs, and the value of these coral habitats to local communities. Data were acquired using a qualitative approach through literature reviews of secondary sources. The findings show that overfishing, pollution, climate change, and habitat destruction are major causes of coral reef decline in the Philippines. These factors have resulted in severe reductions in coral cover, biodiversity loss, and decreased ecosystem services. Furthermore, coral reef decline has far-reaching consequences for Philippine biodiversity, including decreased resistance to environmental stressors and greater vulnerability of coastal people. This study highlights the urgency for coordinated conservation initiatives, such as enhanced management tactics, sustainable fishing practices, and climate change mitigation measures. Recommendations include creating marine protected areas, stronger coastal development rules, and public awareness programs to support coral reef protection. Addressing coral reef loss is crucial for protecting Philippine biodiversity and ensuring the long-term viability of marine ecosystems.

Waste to fuel: A detailed combustion, performance, and emission characteristics of a CI engine fuelled with sustainable fish waste management augmentation with alcohols and nanoparticles

All over the world, 130 million tonnes of fish waste have been generated per annum. Improper disposal of such waste leads to environmental pollution, habitat degradation, oxygen depletion, spread of pathogens, parasites, and diseases. From this point of view, this research motivated to benefit from such fish waste by converting an alternative fuel along with various additives for diesel engines. Fish wastes gathered from the fish market are used as feedstock for producing fish waste biodiesel (FWBD) through the transesterification process. The derived fish waste biodiesel (FWBD) 60 %, 20 % diesel, and 20 % n-butanol (C4H9OH) by volume were blended (60FWBD+20Bu+20D) to form the test fuels. Then the fuel blends were used to convert two nano fuels by separately adding zinc oxide and graphene nanoparticles of 100 ppm along with sodium dodecyl sulphate surfactant, and the nanoparticles-added test fuels were exposed to sound waves of 50 kHz in an ultrasonicator for 1 h. These fuels were characterized to derive and ensure the fuel properties for diesel engines and tested such fuels in a 5.2 kW CI engine to do a comparative study. The experiments were conducted at the constant engine speed of 1500 rpm, and varying engine loads from 25 % to 100 % with intervals of 25 %. When the fish waste biodiesel was added to diesel fuel, the engine performance worsened in a given engine load, but it started to improve with the existence of nanoparticles. Compared to 60FWBD+20Bu+20D, graphene-based nano fuel blend recorded 1.99 % higher BTE, but 15.03 % higher NOx. Similarly, compared to 60FWBD+20Bu+20D, zinc oxide-based nano fuel blends recorded 6.75 % higher BTE and reduced NOx, CO, HC, and smoke emissions by 29.97 %, 15.98 %, 22.0 %, and 16.03 % respectively. In conclusion, the present research reveals that fish wastes can be used in diesel engines without any modification on the vehicular system, and this may contribute to both slowing down the rate of depletion of fossil reserves and the waste management of the fish wastes from nature in a useful way.

Long-term substitution of fish oil with alternative sources in Atlantic salmon (Salmo salar): Performance, health, and consumer appeal

Salmon farming in Chile faces the dual challenge of maintaining growth while improving sustainability. One approach to advance sustainability involves the feeds without marine-fishery inputs. This study aimed to evaluate the effect of completely replacing fish oil (FO) on the performance of Salmo salar throghout marine grow-out. The investigation involved fish ranging from 400 g to 4000 g and explored three diets without fish meal, each which included 2.2% EPA + DHA from different sources: FO (control), transgenic canola oil (Can n-3) and Schizochytrium sp. oil (AOV) as unique type of oils. Each diet was randomly distributed in triplicate among nine tanks with a recirculation system maintained at 12 °C, with automatic feeding and a 24-h light photoperiod. Fish density was 29 fish m−3 at day 133 of the experiment and seven fish m−3 at day 319. The diets were isoproteic, isolipidic and isoenergetic. Fish were evaluated at 133 and 319 days of experiment in terms of productive performance, liver health, EPA + DHA and lipid retention efficiency, fatty acid metabolism, response to acute stress, and final product quality. The results showed similar productive performance and liver health among the three diets during both sampling periods. No differences were observed in lipid or EPA + DHA retention efficiency in the whole body or fillet. Eicosanoids and receptors for anti-inflammatory mediators derived from EPA and DHA showed similar or higher capacities in fish fed with Can n-3 and AOV than those fed FO. Responses to induced stress, measured through lactate, cortisol, sodium, potassium, chloride, glucose, and the liver profile were similar between the three diets. Similarly in fillet quality between the three diets. However, sensory analysis revealed a lower intensity of “global aroma” in Can n-3-fed fish fillets and lower evaluations in “typical salmon aroma”, “oily aroma” and “fresh flavor” in AOV-fed fish fillets when they are compared with FO. The nutritional indicators of the final product were similar between the three diets, except for PUFA/SFA, the thrombogenicity index, hypercholesterolemia/hypocholesterolemia, and the health promotion index. In these specific indicators, fish fed with Can n-3 and AOV demonstrated more favorable results for consumer health than the FO-fed fish.

Measurement of Fisheries Provisioning Services and its Pressure to Support Sustainability of Fisheries in The Jatigede Reservoir, Indonesia

Measurement of Fisheries Provisioning Services and its Pressure to Support Sustainability of Fisheries in The Jatigede Reservoir, Indonesia

Nanopore environmental DNA sequencing of catch water for estimating species composition in demersal bottom trawl fisheries

AbstractBycatch and discards, representing unwanted catches, undermine sustainable fisheries and hinder the conservation of vulnerable and endangered species. To effectively monitor bycatch and enhance the effectiveness of management measures while promoting sustainable fishing practices, reliable data is essential. Here, we explore the use of Nanopore metabarcoding to analyze the catch composition in demersal bottom fisheries. We collected eDNA samples directly from an onboard catch holding tank (catch water) for 10 fishing hauls from a fishing vessel operating in the Skagerrak (North‐East Atlantic). The approach involved sequencing a combination of long (~2 kb) and short (~170–313 bp) mitochondrial amplicons and was validated by analyzing a fishery‐related mock community sample and fishing haul replicates. Overall, the detection rate accuracy was 95% for landed species, and replicates obtained from the same fishing haul showed consistent results, validating the robustness of this approach. The detection rate accuracy for all caught species observed on board (including the non‐landed fraction) was 81%. Undetected species were always limited to species in low abundance, but may also be attributed to problems with identifying closely related species due to the impact of sequencing errors and limited diagnostic variation in the genetic regions used. In the future, such biases may be reduced by using additional markers to increase species discrimination power and applying newly available technological advantages in flow cell chemistry to improve sequencing accuracy. In conclusion, this study demonstrates the effectiveness of Nanopore eDNA sequencing of catch water for estimating species composition in demersal bottom trawl fisheries, including catches of non‐commercial and threatened and vulnerable species, without disrupting fishing activities. Incorporating eDNA analysis of catch water may therefore help facilitate effective monitoring, leading to better‐informed fisheries management, biodiversity conservation efforts, and the implementation of relevant legislation such as the EU landing obligation.

A threatened heritage: sustainable alternatives for Mediterranean small-scale fisheries

This study underscores the crucial role of small-scale fisheries (SSF) in promoting sustainable fishing practices within the Mediterranean context, emphasizing the necessity to align fisheries commerce with local seafood consumption. SSF in the Mediterranean, particularly in the Balearic Islands, are vital for local communities, contributing significantly to fish catches, while being deeply intertwined with cultural heritage and traditional values. However, these fisheries face several threats, including resource depletion, management strategies favouring fleet reduction, and increase of seafood imports. Our research investigates the relationships between the local fishing sector and resident population, exploring perspectives on sustainability. We examine SSF activities and perceptions through face-to-face questionnaires in nine fishing ports and assess seafood consumption habits through phone questionnaires. The study reveals an aging fishing sector rooted in family traditions that face administrative hurdles in implementing strategies such as fish tourism and direct sales, but seeks to enhance local product consumption. Despite the traditional relevance of fish in the Mediterranean diet, our findings also show low consumption of fresh and local seafood due to consumer’s limited knowledge on local species and related cooking methods and perceived high costs. However, the cultural importance of these products remains undiminished. To reinforce the cultural heritage of SSF and improve the future perspectives of the sector, we advocated for a multi-pronged approach, including raising consumers’ awareness about local species, controlling local prices, and promoting certified products through a reduction in the administrative burden and by promoting the active involvement of SSF.

Walleye (Sander vitreus, Mitchill 1818) age and sex classification using innovative supervised and unsupervised machine learning and soft computing methodologies

Walleye (Sander vitreus) is a freshwater perciform native to Northern America and Canada with high commercial value. Stocking programs for the species are unable to supply the significant demand, creating stock management problems and an ecosystemic decline. For sustainable fisheries, the age and sex estimation are fundamental to marine stock management. Biological methods for age determination and sex estimation were used in the past, conventional observations and techniques are substituted with machine learning methods, currently underused. The aim of this study is to evaluate the performance of an ensemble of Machine Learning (ML) methods for age and sex classification of walleye. Based on the performance of the ensemble models, appropriate evaluation decides on the age criterion with near optimal performance using supervised and unsupervised ML algorithms on the given fish datasets. The innovation of this work lies in the fact that the species age or sex estimation is based on a paramount involvement of models that diminish the proprietary idiosyncrasies of individual methods on specific datasets. For the same models two approaches were used: applied model algorithms developed both in R and Python (Orange Rapid Application Development environment) programming language provided high accuracy percentages. Among all methodologies, the Decision Tree method provided the best classification, for age estimation with 96% and 98% accuracy using the R and Orange models respectively. For the sex classification, Random Forest performed the best using the R-model with 94% accuracy, outperformed by the AdaBoost model in Orange with 97.6% accuracy. When compared, the models which were developed in Python generally performed better than the corresponding R-models both in age and sex classification. Overall, the proposed ML approach is emphasized as a rapid economic solution to standard fish classification with high accuracy, and thus could be integrated in stock assessment for a more sustainable aquaculture management.

High Loggerhead (Caretta caretta) Bycatch Rate along with Several Endangered Target Species: Two Reasons to Look for Alternative to Traditional Large-Mesh Bottom-Set Gillnets (Garrasia) for More Sustainable Fisheries in the Gulf of Gabès (Tunisia)

Fishery bycatch poses a significant threat to sea turtles. This study provides an updated assessment of Loggerhead turtle (Caretta caretta) bycatch in the Gulf of Gabès, focusing on the impact of the Garrasia gillnets. Through 61 onboard observations conducted alongside fishermen in Zarzis deploying a bottom-set gillnet, called “Garrasia”, and targeting elasmobranch species, comprehensive data were collected, including the number of sea turtles captured, soak time, length of gillnets, location, and biometric data of sea turtles. Analysis revealed a catch per unit effort (CPUE) for sea turtles of 0.63 (95% CI [0.355–0.893]) turtles per kilometer per 24 h with a notably high mortality rate of 92.06% (95% CI [87.3–96.8]). In the Gulf of Gabès, 23 vessels are reported to use Garrasia, resulting in an estimated annual total capture of 3756.53 turtles with a 95% CI [1907.81–5902.30]. These findings underscore the significant impact of Garrasia on sea turtle populations in the Gulf of Gabès. The study calls for immediate collaborative efforts among researchers, local stakeholders, authorities and fishermen to elaborate balanced conservation strategies that consider both ecological sustainability and socio-economic factors, aiming to achieve a sustainable marine ecosystem.

Economic of Small-Scale Hand Line Fishery Fleet Production Based On Driving Power in Every Season in The Small Island Park Conservation Area, Southeast Maluku Regency

The economic benefits of hand line production activities carried out by small fishermen utilizing some inputs to produce high economic value output each season in the Kei Kecil small island park (TPK) conservation area differ according to the driving power. Production cost efficiency, effectiveness of production results, and business profits are very important for the sustainability and development of small-scale hand-line fisheries. This study aims to analyze the economics of small-scale hand line production based on the driving power in each season in the TPK Kei conservation area. The type of data needed is primary and secondary data, and the collection method used is triangulation. The analysis used includes analysis of business profits, production cost efficiency, and effectiveness of production results. The results of the analysis show that the production of hand line carried out in the TPK Kei Kecil conservation area in each season is more efficient and effective in the hand line fishing fleet that uses hand line rowing and the highest business profit is the hand line fishing fleet that uses ketinting driving power. The production of small-scale hand lines in the TPK Kei conservation area is small in each season efficiently, effectively, and profitably.

The conundrum of sustainable fishery: fishers’ experiences of the exclusionary processes of the EU Common Fisheries Policy

This study delves into the effects of the European Union's (EU) quota-based regulations on fishers’ access to marine resources, focusing on the experiences of fishers from North Shields, UK. Employing Hall, Hirsch, and Li's framework of powers of exclusion, this study examines how fishers experience evolving access to sea resources within the EU CFP. The findings illuminate the intricate interplay of regulatory, market, and legitimization powers, which drive exclusionary processes and profoundly influence fishers' access to resources and livelihoods. Importantly, this research underscores the necessity of comprehending the complex dynamics of exclusion within quota-based fisheries management, particularity within the unique socio-cultural contexts of fishing communities. Based on this research, further investigation into the socio-cultural dimensions of fishing is advocated to foster more inclusive policies and practices in fisheries management.

Use of black soldier fly larvae and freshwater shrimp to partly substitute commercial diet for Nile tilapia cultured in smallholder fish farms – A case study in Busia County, Kenya

Fish-farming in Kenya is challenged by the availability and high cost of feed ingredients, especially protein sources. Using black soldier fly larvae (Hermetia illucens) (BSFL) directly or indirectly as a feed ingredient to feed fish is interesting as they efficiently convert organic wastes into high-quality proteins. In addition, the freshwater shrimp (Caridina nilotica) (CN), an important by-catch of the silver cyprinid (Rastrineobola argentea) fisheries in Lake Victoria, could be another alternative protein source. Therefore, this study determined whether dried BSFL or dried CN could partly substitute the commercial diet when growing Nile tilapia (Oreochromis niloticus) in a smallholder farm aggregated in an aquapark. The nutritional values and cost-effectiveness of the alternative feeding strategies were compared to commercial diet (CD) only. During an 84-day experimental period, Nile tilapia were fed one of the three feeding strategies, including the use of only the commercial diet, to be compared with diets replacing 20% of the commercial diet with BSFL or CN. The fish were fed to apparent satiation twice a day. At the end of the trial, biomass, the number of fish, growth, survival rate, total fish production, economic feed conversion rate and productivity per pond, were determined. As such, Body Weight (BW) was similar across feeding strategies (P > 0.05), measured 63.2 ± 3.9, 68.0 ± 7.4 and 68.0 ± 7.4 g for fish-fed diets with CD, BSFL and CN, respectively. Hence, nutritionally and from a production point of view, the three feeding strategies used in this study performed equally well. Notably, the use of BSFL led to a significantly higher economic return (P < 0.05) compared to the use of CN and commercial diet alone. The trials in this study demonstrate that BSFL and CN can be used to partly substitute commercial diet. In addition, the trial show that the use of BSFL to partly substitute the commercial diet can boost sustainable fish production in a smallholder farm set-up aggregated in an aquapark.

Immunological and molecular diagnostic techniques in fish health: present and future prospectus.

Fish health management is critical to aquaculture and fisheries as it directly affects sustainability and productivity. Fish disease diagnosis has taken a massive stride because of advances in immunological and molecular diagnostic tools which provide a sensitive, quick, and accurate means of identifying diseases. This review presents an overview of the main molecular and immunological diagnostic methods for determining the health of fish. The immunological techniques help to diagnose different fish diseases by detecting specific antigens and antibodies. The application of immunological techniques to vaccine development is also examined in this review. The genetic identification of pathogens is made possible by molecular diagnostic techniques that enable the precise identification of bacterial, viral, and parasitic organisms in addition to evaluating host reactions and genetic variation associated with resistance to disease. The combination of molecular and immunological methods has resulted in the creation of novel techniques for thorough evaluation of fish health. These developments improve treatment measures, pathogen identification and provide new information about the variables affecting fish health, such as genetic predispositions and environmental stresses. In the framework of sustainable fish farming and fisheries management, this paper focuses on the importance of these diagnostic techniques that play a crucial role in protecting fish populations and the aquatic habitats. This review also examines the present and potential future directions in immunological and molecular diagnostic techniques in fish health.

Reconciling conflicts between cultural beliefs, and human rights standards in coastal communities of Ghana: preserving cultural rights and promoting sustainable fishing practices

Reconciling conflicts between cultural beliefs, and human rights standards in coastal communities of Ghana: preserving cultural rights and promoting sustainable fishing practices

Comparative Study on Current Fishing Status of Paalameenmadu and Kallar Barmouths in Batticaloa District,

Batticaloa lagoon is one of the productive estuaries on the East coast of Sri Lanka and is connected to the sea at two points, Paalameenmadu and Kallar barmouths. The entire dynamics of the lagoon is based on the seasonal opening and closing of the above barmouths which influences the fish catch composition in nearby fishing areas. This study collects information on current fishing practices, species composition of the catch, and seasonal catch species composition, the level of awareness on fishing regulation and sustainable fishery using semi-structured questionnaire. Fisheries data were collected from 10 major barmouth fishery landing sites from January to April 2021. 210 respondents were selected using a stratified random sampling technique. A semi-structured questionnaire was used to collect responses after a pre-test and analysed with descriptive statistics method using SPSS.  The study revealed that Paalameenmadu barmouth was opened annually and Kallar barmouth has been closed for the last five years. The most practiced crafts in Paalameenmadu are outboard Fiber Reinforced Plastic boats (OFRP) by 35.26% of fishers and small lagoon canoes by 87.04% fishers in Kallar. A total of seven types of fishing gears are used, among them hook and line, cast net, and dragnet were identified as major fishing gears operated. 30 aquatic species have been recorded in the catch, representing 17 families. Among them, dominant fish families are Scombridae 17.11% and Penaeidae 14.81% in Paalameenmadu. In the Kallar, family Penaeidae 18.75% and Gerreidae 16.32% have been recorded. Barmouth opening is favourable for fishing and 38.57% Penaeidae species were caught during barmouth opening period. Community response that Irregular and early barmouth opening have caused a reduction in fish production which impacts on economic activities. Fishermen have good awareness on importance of fishery resources sustainability and these resources need to be preserved for future generations through proper management practices.

Sustainability of dual exploitation (fry and adults) of the fish Semaprochilodus laticeps (Characiformes: Prochilodontidae) in Colombia

Introduction: Semaprochilodus laticeps is a freshwater fish species native to the Orinoco Basin that is exploited in Colombia at two different stages of its life cycle: fry (for the ornamental trade) and adults (for the consumer market). This double exploitation of juveniles and adults raises concerns about the population stability of the species. Objective: To evaluate the sustainability of the exploitation of the species in these two life stages. Methods: 1 277 specimens of S. laticeps were sampled between June and December 2017. Population parameters were estimated from length-frequency data using ELEFAN 1 routine of the FISAT II package. Length at first maturity (Lm) and length at maximum yield (Lopt) were determined using the Froese and Binohlan equations. Virtual population analysis was performed based on Jones length cohort analysis. Results: Population parameters were as follows: K = 0.75, L∞ = 53.1 cm LE, Z = 2.92 yr-1, M = 1.24 yr-1 and F = 1.68. Lm was estimated to be 29.6 cm SL and Lopt at 33.4 cm SL. Of note, 96.3 % of the fish caught in the consumer fishery exceeded Lm and 80 % exceeded Lopt. The results of the virtual population analysis suggested that a very low proportion (0.85 %) of the population was caught as fry, possibly due to natural mortality. Conclusions: Based on the results, as no indicators of overexploitation were identified, it is recommended to continue with the dual use of S. laticeps. It is recommended to maintain the existing conservation measures, such as the closed season during the reproductive period, to ensure sustainable fishery exploitation. The results obtained can serve as a reference to analyze the situation of other species currently fished for both the ornamental (fry) and food (adult) markets.