Effective Fisheries Management Research Articles

A novel approach for rapidly determining the reproductive status of walleye pollock (Gadus chalcogrammus) using Raman spectroscopy

Knowledge of the reproductive biology of fishes is essential for effective fisheries management. Information derived from an understanding of fish reproduction, such as size and age at maturity, is used in models to assess fish stocks and can affect estimates of important ecological processes such as recruitment, abundance, and trophic interactions. Common practices for determining the reproductive status of teleost fishes include macroscopic evaluation of gonads as well as histological analysis. However, macroscopic evaluation can be biased and histological analysis is time-consuming, resulting in limitations to spatial and temporal data availability. Here, we explore Raman spectroscopy of ovaries as a novel approach to rapidly determine the reproductive status of walleye pollock (Gadus chalcogrammus), a commercially and ecologically important species in the North Pacific. We used a two-stage partial least-squares (PLS) regression analysis followed by a linear discriminant analysis (LDA) to classify walleye pollock ovary samples as physiologically mature or immature and to subsequently predict their histologically-determined reproductive stage based on the Raman spectra. Biologically mature samples with visible yolk differentiated from mature and immature samples (non-yolked; 99% accuracy). Non-yolked ovaries that were physiologically mature (either mature non-developing or previously spawned) were further differentiated from physiologically immature ovaries (93% accuracy). In addition, detailed, histologically-determined reproductive stages of yolked samples also differentiated via Raman spectroscopy, but with reduced accuracy (79% - 86% accuracy). Our results indicate that accurate identification of maturity status and the reproductive staging of oocytes of walleye pollock based on spectral data from ovaries is possible. This can provide a fast and efficient way to increase the availability of a key component of reproductive data to inform fisheries research and management.

Research Mapping of Fisheries Resource Management in Coastal Areas: A Bibliometric Analysis

This study conducts a comprehensive bibliometric analysis of the literature on government budget efficiency. This bibliometric analysis explores the evolution and integration of themes within fisheries management research from 1959 to 2024. Utilizing VOSviewer for keyword co-occurrence and network visualization, the study identifies dominant themes such as "fishery management system," "conservation," and "sustainability," along with their interconnections and shifts over time. The analysis highlights a multidisciplinary approach, integrating ecological, economic, and technological aspects to address the challenges of sustainable fisheries management. The prominence of terms related to management strategies and environmental conservation reflects a global commitment to sustainable practices. Collaborative patterns among leading researchers and the evolution of research themes underscore the dynamic nature of this field, emphasizing adaptive management strategies that are informed by both socio-economic and ecological dynamics. The findings suggest that the ongoing integration of advanced technologies and interdisciplinary approaches is crucial for developing effective fisheries management practices that can adapt to environmental uncertainties and ensure the sustainability of both marine resources and dependent communities.

Assessing extraterritorial fishing operations in Türkiye's Contiguous Zone: A decade of observations and implications for fisheries management in the Eastern

The protracted maritime jurisdictional disputes in Türkiye's EEZ in the Eastern Mediterranean have perpetuated economic disparities and engendered lacunae in fisheries management that could undermine marine biodiversity and regional collaboration efforts. This study interrogates the extent and frequency of extraterritorial fishing operations within the contiguous zone of Türkiye's territorial waters, with a particular emphasis on the years 2013 through 2023. Utilizing data acquired from Global Fishing Watch, the analysis delineates the monthly average fishing hours engaged by different gear types-namely small scale, trawl, undefined, and purse seine-across various neighboring countries, including Cyprus, Egypt, Greece, Italy, Libya, and Morocco. Findings reveal a persistent increase in fishing activities within these contentious waters over the observed period, reflecting a rise in the deployment of ship-tracking systems, which have potentially inflated reported fishing hours. This surge underscores the urgent need for comprehensive fisheries management strategies that harmonize economic pursuits with the preservation of delicate marine ecosystems. The study's methodology involved analyzing vessel movements via Marine Traffic and Global Fishing Watch data, assessing parameters such as fishing areas, periods, methods, and national affiliations. The results, illustrated in Tables and Figures without direct citation due to the aggregative nature of the data, show varied patterns of fishing activities. The significant increase in Türkiye's trawl fishing hours in 2022, peaking at 857.29 hours, underscores the intensification of certain fishing practices in the region. The need for resolving international disputes is pivotal for establishing effective fisheries management in the Eastern Mediterranean. The findings advocate for enhanced diplomatic endeavors and cooperative governance among littoral nations, supported by international entities to ensure sustainable exploitation of marine resources and to bridge management gaps illuminated by this decade-long empirical inquiry.

Examining fishing activities based on in-situ tracking and oceanographic characteristics in Aru Sea and surroundings

Fisheries activites and oceanographic conditions have a strong relationship. Understanding the complex interplay between fisheries and oceanographic conditions is essential for effective fisheries management. The aim of this research is to analyze the in-situ fishing activities with oceanographic conditions in the Fisheries Management Area (FMA) or WPP-NRI 718 located in the Aru Sea and its surroundings. The main data source is from open global data ship tracking and oceanographic conditions from satellite data. In general, fishing is conducted around the waters of Aru Island. The fishing grounds are strongly influenced by a combination of environmental factors, including sea surface temperatures, chlorophyll-a (Chlor-a) concentrations, sea surface height, and current velocities. A decrease in fishing patterns around Aru Island waters occurs in the eastern season, where fishing tends to occur in the western region (near Timor-Leste). Based on the oceanographic conditions, fishing tends to occur in regions with warmer conditions ranging from 27 to 29 °C, moderate Chlor-a (1.02–3.01 mg/m3), a relatively high surface height (0.17–0.32 m), and slow surface currents.

Evaluating the ecological impact of fisheries management strategies in Georgia, USA: A review on current practices and future directions

Effective fisheries management is crucial for maintaining the ecological balance and sustainability of marine ecosystems. This review paper examines the current fisheries management strategies employed in the state of Georgia, USA, and evaluates their ecological impact. The review synthesizes existing research on the implementation and outcomes of various management approaches, including gear restrictions, catch limits, seasonal closures, and marine protected areas. It analyzes the efficacy of these strategies in conserving target species, mitigating bycatch, and preserving the overall health of coastal and estuarine environments. Furthermore, the paper identifies emerging challenges, such as the impacts of climate change and shifting species distributions, and explores potential future directions for fisheries management in Georgia. The findings of this review aim to inform policymakers, resource managers, and stakeholders about the strengths and limitations of current practices, and provide recommendations for developing more comprehensive and adaptive management frameworks to ensure the long-term ecological resilience of Georgia's marine ecosystems.

Using joint species distribution modelling to predict distributions of seafloor taxa and identify vulnerable marine ecosystems in New Zealand waters

Effective ecosystem-based management of bottom-contacting fisheries requires understanding of how disturbances from fishing affect seafloor fauna over a wide range of spatial and temporal scales. Spatial predictions of abundance for 67 taxa were developed, using an extensive dataset of faunal abundances collected using a towed camera system and spatially explicit predictor variables including bottom-trawl fishing effort, using a Joint Species Distribution Model (JSDM). The model fit metrics varied by taxon: the mean tenfold cross-validated AUC score was 0.70 ± 0.1 (standard deviation) for presence–absence and an R2 of 0.11 ± 0.1 (standard deviation) for abundance models. Spatial predictions of probability of occurrence and abundance (individuals per km2) varied by taxon, but there were key areas of overlap, with highest predicted taxon richness in areas of the continental shelf break and slope. The resulting joint predictions represent significant advances on previous predictions because they are of abundance, allow the exploration of co-occurrence patterns and provide credible estimates of taxon richness (including for rare species that are often not included in more commonly used single-species distribution modelling). Habitat-forming taxa considered to be Vulnerable Marine Ecosystem (VME) indicators (those taxa that are physically or functionally fragile to anthropogenic impacts) were identified in the dataset. Spatial estimates of likely VME distribution (as well as associated estimates of uncertainty) were predicted for the study area. Identifying areas most likely to represent a VME (rather than simply VME indicator taxa) provides much needed quantitative estimates of vulnerable habitats, and facilitates an evidence-based approach to managing potential impacts of bottom-trawling.

Tracking movements of meagre (Argyrosomus regius) during the spawning season: Preliminary indications of off estuary spawning.

Understanding the spawning behavior of meagre (Argyrosomus regius) is crucial for fisheries management and conservation. Meagre forms large spawning aggregations in estuaries, yet details of its spawning grounds remain elusive. We tagged 41 individuals and monitored their movements throughout several spawning seasons. Detections inside estuaries were limited. Fish detected inside the Tejo estuary during the spawning season performed regular movements toward coastal areas, suggesting potential spawning outside estuaries. Our findings underscore the significance of understanding meagre's migratory patterns for effective fisheries management and conservation strategies, supporting the establishment of spatial and seasonal closures during the spawning season.

Migratory Ecology of Pseudoplatystoma fasciatum in the Amazon Basin Revealed by Otolith Microchemistry

Fish migrate for varied reasons, including to avoid predators and to access feeding, spawning, and nursery habitats, behaviors that enhance their survival and reproductive rates. However, the migratory ecology of many important fishes, especially those in river–floodplain ecosystems, remains poorly understood. One fish of the Amazon Basin whose migratory behavior is poorly understood is the catfish Pseudoplatystoma fasciatum. Here, we used otolith elemental microchemistry to characterize the migration ecology of P. fasciatum in the Amazon Basin. The main research questions of this study were: (1) does P. fasciatum move between waters with different Sr isotopic signatures (87Sr/86Sr) and chemical compositions? (2) What distance do they migrate? (3) Is the migration of P. fasciatum related to age? And (4) does P. fasciatum migrate mainly upstream, downstream, or in both directions? We assessed whether P. fasciatum migrates between waters with different 87Sr/86Sr values, comparing the Sr isotopic signature of otolith transects of each individual with the range of Sr isotopic signatures within the respective rivers. We found that 34% of the 71 fish analyzed migrated between rivers with different Sr isotopic signatures and 66% did not. The mean migration distance migrated was 126 km, with most specimens migrating between 72 and 237 km. Apparently, no fish of age one or age six or older migrated. All fish that migrated were between two and five years of age, with 20% of the specimens that migrated being two years old, 40% three years old, 30% four years old, and 20% five years old. Sixty-six percent of all individuals that migrated between rivers with different Sr signatures did so bidirectionally, while 33% moved unidirectionally. According to our definition of homing behavior in which fish migrated back to the same river where they were born, 41% of all fish that migrated displayed apparent homing behavior. Our findings provide insights into the migratory ecology of P. fasciatum, corroborating and refining knowledge reported in the literature. Our results on the migratory ecology of P. fasciatum have implications for sustainable fisheries conservation and management: conserving P. fasciatum requires habitat maintenance and suitable fishing practices in spawning and nursery habitats, and managers must consider large geographic areas for effective fishery management and conservation.

Directed conservation of the world's reef sharks and rays.

Many shark populations are in decline around the world, with severe ecological and economic consequences. Fisheries management and marine protected areas (MPAs) have both been heralded as solutions. However, the effectiveness of MPAs alone is questionable, particularly for globally threatened sharks and rays ('elasmobranchs'), with little known about how fisheries management and MPAs interact to conserve these species. Here we use a dedicated global survey of coral reef elasmobranchs to assess 66 fully protected areas embedded within a range of fisheries management regimes across 36 countries. We show that conservation benefits were primarily for reef-associated sharks, which were twice as abundant in fully protected areas compared with areas open to fishing. Conservation benefits were greatest in large protected areas that incorporate distinct reefs. However, the same benefits were not evident for rays or wide-ranging sharks that are both economically and ecologically important while also threatened with extinction. We show that conservation benefits from fully protected areas are close to doubled when embedded within areas of effective fisheries management, highlighting the importance of a mixed management approach of both effective fisheries management and well-designed fully protected areas to conserve tropical elasmobranch assemblages globally.

Linking extinction risk to the economic and nutritional value of sharks in small-scale fisheries.

To achieve sustainable shark fisheries, it is key to understand not only the biological drivers and environmental consequences of overfishing, but also the social and economic drivers of fisher behavior. The extinction risk of sharks is highest in coastal tropical waters, where small-scale fisheries are most prevalent. Small-scale fisheries provide a critical source of economic and nutritional security to coastal communities, and these fishers are among the most vulnerable social and economic groups. We used Kenya's and Zanzibar's small-scale shark fisheries, which are illustrative of the many data-poor, small-scale shark fisheries worldwide, as case studies to explore the relationship between extinction risk and the economic and nutritional value of sharks. To achieve this, we combined existing data on shark landings, extinction risk, and nutritional value with sales data at 16 key landing sites and information from interviews with 476 fishers. Shark fisheries were an important source of economic and nutritional security, valued at >US$4 million annually and providing enough nutrition for tens of thousands of people. Economically and nutritionally, catches were dominated by threatened species (72.7% and 64.6-89.7%, respectively). The most economically valuable species were large and slow to reproduce(e.g. mobulid rays, wedgefish, and bull, silky, and mako sharks) and therefore more likely to be threatened with extinction. Given the financial incentive and intensive fishing pressure, small-scale fisheries are undoubtedly major contributors to the decline of threatened coastal shark species. In the absence of effective fisheries management and enforcement, we argue that within small-scale fisheries the conditions exist for an economically incentivized feedback loop in which vulnerable fishers are driven to persistently overfish vulnerable and declining shark species. To protect these species from extinction, this feedback loop must be broken.

Catch yield and selectivity of a modified scallop dredge to reduce seabed impact.

Global scallop fisheries are economically important but are associated with environmental impacts to seabed communities resulting from the direct physical contact of the fishing gear with the seabed. Gear modifications attempting to reduce this contact must be economically feasible such that the catch numbers for the target species is maintained or increased. This study investigated the outcome of reducing seabed contact on retained catch of scallops and bycatch by the addition of skids to the bottom of the collecting bag of scallop dredges. We used a paired control experimental design to investigate the impact of the gear modification in different habitat types. The modified skid dredge generally caught more marketable scallops per unit area fished compared with the standard dredge (+5%). However, the skid dredge also retained more bycatch (+11%) and more undersize scallops (+16%). The performance of the two dredges was habitat specific which indicates the importance of adjusting management measures in relation to habitat type. To realize the potential environmental benefits associated with the improvement in catchability of this gear modification, further gear modification is required to reduce the catch of undersize scallops and bycatch. Furthermore we advocate that technical gear innovations in scallop dredging need to be part of a comprehensive and effective fisheries management system.

The power of collaboration in multifishery improvement initiatives

Abstract Addressing diverse and complex socio-ecological challenges is crucial for achieving ocean sustainability. This is especially true for effective fishery management, which is vital for the sustainability of marine resources. One way of overcoming barriers to fisheries reform is through interdisciplinary collaboration and innovative management and policy approaches. One such approach is market incentives offered by eco-certification against sustainability standards, such as those set by the Marine Stewardship Council (MSC). Complementary interventions that support sustainability improvements are fishery improvement projects (FIPs) and MSC pathway projects. These interventions have clear intermediary and final objectives, and monitoring impact throughout the implementation process remains important. We interviewed participants of a pathway project from five fisheries in South Africa and Mexico using semistructured interviews designed to capture the nonmonetary impacts of these projects as they progress. Our results show that interventions can play a role in facilitating broader collaboration within a fishery and across stakeholder groups, increasing sustainability awareness. Emphasizing the importance of stakeholder engagement and collaboration, we highlight how the project implementation process can lead to communication changes that lead to improved understanding and collaboration. Importantly, we reflect on the suitability of the survey in monitoring progress in such projects.

Communication Approaches and Specialists that Can Improve Fisheries Management

This paper aims to expand fisheries managers' understanding of how the science of communication can facilitate effective fisheries management. We offer context‐specific definitions of four communication approaches that are commonly performed by fisheries managers but poorly defined and can easily be confused or conflated. These are as follows: Outreach, Education, Social Marketing, and Engagement. Further, we explain key evidence‐based principles that support each communication approach and offer practical examples of their application. Finally, we highlight different communication research fields that produce social science for communication practitioners to use in the context of fisheries management. These explanations support our claim that effective communication is required to meet the professional needs of fisheries managers and encompasses meeting the needs of their audiences.

Age, Growth, and Mortality of Pontic Shad, Alosa immaculata Bennett, 1835, in the Danube River, Romania

This study aimed to evaluate the growth, mortality parameters, and exploitation rate of Pontic shad, Alosa immaculata Benett, 1835, in the Danube River, Romania (km 169–197). The sampling collection started with the first signs of Pontic shad migration, on 4 March 2023, and continued weekly until the beginning of June 2023, when the last specimens were caught in the nets. The estimation of the growth, mortality parameters, and exploitation rate was done in FiSAT (FAO-ICLARM Stock Assessment Tools). The von Bertalanffy growth equation was estimated at L∞ = 36.75 cm, the growth coefficient was k = 0.68 year−1, and the theoretical initial age was t0 = −0.67 year−1. The total mortality rate (Z) estimated was 2.76 year−1, with a natural mortality rate (M) and fishing mortality rate (F) of 0.89 year−1 and 1.87 year−1, respectively. The Z/k ratio was found to be 4.11 and the exploitation rate (E) was estimated at 0.68 year−1, indicating the overexploitation of Alosa immaculata stocks. In conclusion, this study provides valuable insights into the population dynamics of Pontic shad in the Danube River, Romania. The assessments of the growth parameters, mortality rates, and exploitation rates highlight a level of overexploitation of Alosa immaculata stocks. These findings underscore the importance of applying effective fishery management strategies to ensure the sustainability and conservation of this valuable fish species in the Danube River ecosystem.

The biodiversity and conservation assessment of Bamui beel in Bangladesh: Current status and threats

A year-long research was conducted with a novel purpose for categorizing and documenting the existing fish diversity and abundance of Bamui beel in Jamalpur district located in Northeast part of Bangladesh, within a time frame from July 2022 to June 2023. A total of 46 fish species were identified that belonged to 18 taxonomical families and 8 orders. The most abundant family was Cyprinidae (25%). Among 46 species, 37% were commonly available (CA) and 11% were abundantly available (AA) in terms of biodiversity status. According to the global conservational status, around 74% were reported as least concerned (LC) whereas 4% were nearly threatened (NT). On the other hand, in consonance with the conservational status of Bangladesh 52% were least concerned (LC) and 11% were endangered (EN). Pielou’s evenness score in Bamui beel was the highest (0.247) in pre-monsoon and the lowest (0.213) in monsoon. Shannon-Weaver diversity index was ranged from 1.992 to 2.114, whereas Simpson’s dominance index value was a maximum of 0.883 in pre-monsoon and a minimum of 0.852 in monsoon. The yearly fish production of the beel was 7.023 metric tons during experimental year. Besides this, small indigenous species (SIS) of fish dominated with 63.34% of the beel's species makeup. Nevertheless, the abundance and diversity of fish species are diminishing daily in this beel. For preserving the fish diversity of Bamui beel calls for the implementation of effective fishery management practices, vigilant monitoring to prevent overfishing, and a strong emphasis on raising awareness among fishermen.

MLP Neural Networks in Sex Classification of a High Commercial Fish on the Artisanal Fisheries in Brazil

The scarcity of data on artisanal fishing, particularly in tropical South American countries, presents an additional hurdle for fisheries management and marine conservation. While artificial intelligence (AI) has found applications in various domains, including marine sciences, most AI models primarily focus on species identification. Unfortunately, these models often overlook data-limited scenarios. This article examines the potential of an MLPtype ANN model in addressing this gap. The model aims to classify the sex of a dioecious (separate sexes) fish species of high commercial importance, shedding light on its implications for fisheries management. Evaluation of the model's classification performance using precision, recall, f1-score, and accuracy reveals promising results exceeding 80% for both sexes across both training and testing phases. These findings underscore the potential of MLP models in aiding Brazil's fishing sector management in grappling with challenges stemming from data scarcity. By providing efficient information essential for decision-making regarding the management of specific fishing stocks, such models offer valuable insights into effective fisheries management strategies.

Environmental DNA metabarcoding for the detection of the silverlip pearl oyster (Pinctada maxima) offshore of Eighty Mile Beach in northwest Australia

Effective fishery management relies on accurate knowledge of the spatial distribution of stocks of target species to efficiently focus fishing efforts. However, the distribution and abundance of species such as the silverlip pearl oyster (Pinctada maxima) can be difficult to determine with traditional survey methods since populations are patchy, often occur in low densities, and individuals can be quite cryptic, living partially buried in sediment. Environmental DNA is increasingly used to survey marine species and has proven to be particularly useful in detecting rare or elusive organisms. Here, we compared the presence of silverlip pearl oysters detected via eDNA metabarcoding to traditional towed video surveys offshore of Eighty Mile Beach, northwest Australia. Seawater samples were collected at the end of towed video transects and sites were categorised into shallow (<40 m depth) or deep (40 m +) groups. We applied an oyster-specific 16S metabarcoding assay as well as a universal 18S assay to identify potential indicator taxa associated with the presence of pearl oysters. Using the 16S assay, we detected silverlip pearl oysters at three of the 12 sites sampled, and found that eDNA records generally matched towed video transect data, with both survey methods detecting the target species predominantly in inshore waters at depths <40 m. Our results indicate that metabarcoding of seawater eDNA can be applied to detect cryptic species of commercial importance but highlight limitations around detecting organisms at very low abundances.

Determination of Growth Indicators of Tilapia sparrmanii (Smith, 1840) in Molepo Dam, South Africa.

&lt;b&gt;Background and Objective:&lt;/b&gt; The sustainable management and conservation of fish biodiversity depends on studying fish biology. In this study, the length-weight relationships and condition factors of &lt;i&gt;Tilapia sparrmanii&lt;/i&gt; were observed to gain a better understanding of their ecological and nutritional conditions. This information is crucial for the effective management of fisheries. &lt;b&gt;Materials and Methods:&lt;/b&gt; During the study, 100 &lt;i&gt;T. sparrmanii&lt;/i&gt; were collected from the Molepo Dam from October, 2022 to March, 2023. This fish's condition factor (CF) and length-weight relationship (LWR) were studied. To determine the size of each fish, the total length was measured using a caliper with a precision of 0.1 mm and the weight using a balance with an accuracy of 0.1 g. Differences were analyzed using ANOVA with the Tukey's &lt;i&gt;post hoc&lt;/i&gt; test. A non-parametric Chi-square test was employed to evaluate the differences in sexes each month. &lt;b&gt;Results:&lt;/b&gt; Their total length and body weight ranged from 4-15 cm and 0.96-57.96 g, respectively. The study found a strong positive relationship between the length and weight of the fish (r = 0.96). The regression coefficient (b) was more than 3.0, indicating a positive allometric growing rate. The condition factors (K) of males and females were not significantly different (p>0.05). The lowest CF value was observed in March (K = 1.01±0.03) and the highest in December (K = 1.73±0.12). The sex ratio of 1.0 male to 1.15 female was observed, which was significantly different from the theoretical ratio of one male to one female. This suggests that males were not significantly more than females (p>0.05). &lt;b&gt;Conclusion:&lt;/b&gt; The study found that &lt;i&gt;T. sparrmanii&lt;/i&gt; in Molepo Dam exhibited allometric growth, as evidenced by a strong correlation between length and weight represented by a high "r" value. This fish is in good condition because it has no competition for food due to ecological factors.

Effect of temperature on metabolic stress and recovery of two Argyrosomus species from simulated catch‐and‐release angling

AbstractCatch‐and‐release (C&amp;R) angling has grown in popularity due to increasing numbers of conservation‐minded anglers and regulations of recreational fisheries. C&amp;R is often assumed to cause low mortality but can cause physiological and physical impairment. Fish metabolism and temperature interact to play a critical role in the biological functioning of fish. Understanding the relationship between temperature, fish metabolism, and physiological impairment is important for effective fisheries management and conservation, particularly for C&amp;R angling in a changing thermal environment. We used respirometry to quantify post‐release metabolic stress and recovery of two popular Namibian angling species (Argyrosomus inodorus and A. coronus) subjected to simulated C&amp;R angling across a range of temperatures. Metabolic stress and recovery time did not differ significantly between warm (A. coronus) and cold‐water (A. inodorus) species at any test temperature. However, several specimens of both species failed to recover physiologically and physically after 10 hours, thereby indicating C&amp;R‐related impairment and potential for mortality. Given the predator‐rich environment of coastal waters in Namibia, best C&amp;R practices are needed to minimise post‐release mortality.

Size at Sexual Maturity of Deep-Sea Unexploited Caribbean Metanephrops binghami (Boone, 1927) and Overexploited Mediterranean Nephrops norvegicus (Linnaeus, 1758) Using Morphometric and Gonadal Staging Approaches

The deep-sea Caribbean lobster (Metanephrops binghami) and the Norway lobster (Nephrops norvegicus) are Nephropidae species of high commercial interest. Although the first one still remains unexploited, the second is overexploited in the Mediterranean Sea. For effective fisheries management, size at sexual maturity is an essential indicator to protect immature individuals from exploitation. The estimation of this indicator can, however, be biased due to the difficulty of differentiating juveniles from adults by their size structure due to the natural process of molting. This study aims to estimate the size at sexual maturity of M. binghami and N. norvegicus females by comparing the effectiveness of the morphometric method versus the macroscopic evaluation of gonad maturity. Samples of M. binghami were collected from the Colombian Caribbean Sea in August and December 2009, March and May 2010, and August 2020 to May 2021. Samples of N. norvegicus were collected from the northwestern Mediterranean Sea from 2019 to 2022. Similar sizes at sexual maturity were found for M. binghami between the morphometric approach (ranging from 28.6 to 33.9 mm cephalothorax length, CL) and the gonadal staging approach (31.4 mm CL). Conversely, for N. norvegicus, the morphometric approach yielded higher measurements (between 27.2 and 30.4 mm CL) than the gonadal approach (26.0 mm CL). This discrepancy might stem from the intense fishing overexploitation conditions of N. norvergicus, leading to a physiological adaptation that enables earlier gonadal maturation at faster rates than morphometric adaptation. Further research is required to elucidate these discrepancies and the effect of overexploitation on physiological (i.e., mature gonads) and functional maturity (i.e., capacity to brood eggs at a larger size).